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MOSQUITO ERADICATION

W. E. HARDENBURG

SANITARY ENGINEER
CERTIFIED MEMBER, AMERICAN ASSOCIATION OF ENGINEERS

First Edition

McGRAW-HILL BOOK COMPANY, Inc.
NEW YORK: 370 SEVENTH AVENUE

LONDON: 6 & 8 BOUVERIE ST., E. C. 4

1922

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THE MAPLE PRESS - YORK PA

PREFACE

Along with the marked increase in public appreciation of
preventive medicine, that has developed in recent years in the
United States, has come a recognition of the great importance
of mosquito eradication, particularly in the South. This has
manifested itself in the launching of anti-mosquito campaigns in
cities, towns and villages in every Southern State, and it is a
foregone conclusion that the success of these will spur other
communities on to action.

Abroad, too, the menace of the mosquito-borne diseases is
being recognized. In the tropical and sub-tropical areas of
Latin-America, the International Health Board of the Rockefeller
Foundation has done, and is doing, very valuable work. Many
American corporations employing labor in those regions have
found that it pays to protect their labor, and are doing so.
Furthermore, the governments of many of the Latin-American
countries are awakening to the heavy toll of the mosquito-
borne diseases, and are taking steps to eradicate them.

The same may be said of many regions in Europe, Asia and
Africa. Anti-mosquito work now is being carried on to a greater
or lesser extent in Italy, Spain and several of the Balkan coun-
tries; in Mesopotamia, India, Ceylon, the Malay Peninsula and
many Pacific islands; in East and West Africa, Madagascar and
various other political subdivisions.

This means that, in the aggregate, an enormous volume of
anti-mosquito work is being done today. And, as the fruits of
this work become better known and appreciated, it will increase
many fold in all the above-mentioned countries. Furthermore,
as other territories, that are today undeveloped, awake, more
anti-mosquito work will have to be done, if man is to exploit
their resources efficiently.

This vast volume of work, both present and prospective,
renders it incumbent that only the best methods should be
employed. While many persons may have a general idea as to
the procedure in mosquito eradication, this is not sufficient for the

567449

vi PREFACE

men in charge of the work. They must know what methods are
best adapted to the particular problem they have in hand, or, in
other words, what is the cheapest way of accomplishing the
desired result. In anti-mosquito work, as in other branches of
engineering, the goal should be to get the best results for the
money available. If the cost of eradicating mosquitoes is to
amount to as much as the toll of the mosquito-borne diseases,
but little is gained.

Although the importance of this matter is self-evident, there
seems to be an amazing paucity of books on mosquito control.
When the writer started in at anti-mosquito work, about the
only material he could find on the subject was stray references
to it in medical works, various pamphlets published by Federal
and State health and agricultural organizations and LePrince
and Orenstein's valuable volume. "Mosquito Control in
Panama," which, however, deals with work under somewhat
exceptional conditions.

So far as the writer knows, this situation still obtains. Asked
repeatedly for the name of some text-book on mosquito control,
he has been unable to mention any one book, with the exception
of LePrince and Orenstein's, that deals adequately with the
subject. It is with a view to supply this deficiency that he has
prepared the present volume.

A conscientious effort has been made to outline the best prac-
tice, both in the United States and abroad. It has been the
special aim of the writer to be concise, so as to avoid making the
volume too bulky, but to omit nothing of value.

The writer takes pleasure in acknowledging here the kindness
of Dr. Harrison G. Dyar, Director of the U. S. National
Museum, in revising part of the chapter on mosquitoes; of
S. F. Hildebrand, Ichthyologist, in revising the chapter on fish
control; and of W. A. Hardenbergh, Sanitary Engineer, in
making many valuable suggestions regarding the book. Credit
is given writers, from whose works extracts have been used,
throughout the volume.

W. E. Hardenburg.
San Diego, Calif.,
June, 1922.

CONTENTS

Page

Preface v

CHAPTER 1.— The Toll of the Mosquito 1

Diseases spread by the mosquito — Transmission of malaria —

/ Characteristics of malaria — Distribution of malaria — Mortality
and morbidity of malaria — Economic significance of malaria — ■
Malaria as a labor problem — Transmission of yellow fever —
Mortality and morbidity — Yellow fever versus malaria control —
Dengue — Filariasis — Economic significance of yellow fever, dengue
and filariasis — The mosquito as an annoyance; effects upon health
— The mosquito as an annoyance; economic significance — Increas-
ing property values.

CHAPTER 2. — Some Disease-bearinc American' Mosquitoes . . 17
The mosquito in general — Life-history of the mosquito — Varia-
tions in eggs, larvae and pupae — Why mosquitoes bite — Identifica-
tion of mosquitoes — Anatomy of the mosquito — Anatomy of the
larvae — The Anophelinae — Identification of the Anophelinae —
A. quadrimaculatus Say — A. crucians Wied. — A. punctipennis
Say — A. occidentalis D. & K. — The Culidnae — Aedes calopus Meig
—Culex jatigans Wied.. — -Some common troublesome mosquitoes —
House group — Fresh-water sylvan group — Salt marsh group.

CHAPTER 3. — Development of Control Measures 50

Historical aspects — Beginning of mosquito control — Sanitary
conquest of the Canal Zone — Anti-mosquito work elsewhere —
Malaria control in U. S. — -Interpreting results — Early U. S. malaria

^ control demonstrations — Demonstration at Electric Mills, Miss. —
Co-operative demonstration at Crossett. Ark. — Work of St.
Louis & Southwestern Railroad — U. S. Anti-mosquito work
during world war — 43 war-project areas protected — Post-war
mosquito control — The situation today — Change in public view-
point — Growth of appreciation — Eradication cheaper than
enduring malaria — Some typical campaign costs.

CHAPTER 4. — Initiating the Campaign 66

Need for statistics — Collection of statistics — The survey — What to
observe — The estimate of cost — Questions of policy — Suggested
policy toward property-owners — Raising funds — Handling the
funds — Obtaining co-operation — Other possible sources of aid —
Planning the work — Personnel — Materials and equipment.

CHAPTER 5. — Administrative Aspects of the Campaign 83

Mosquito-breeding about homes — Planning the inspection system
— Handling the negligent citizen — Complaint bureau — Publicity —

vii

vili CONTENTS

Page

Texts for articles — Other methods of obtaining co-operation —
Daily reports — -Records — Maps.

CHAPTER 6.— Inland Drainage 99

Importance of drainage as an anti-mosquito measure — Limitations
of drainage — Preliminary work — Types of inland drainage prob-
lems — Problem of pond, lake and swamp drainage — Treatment of
seepage outcrops — Drying up a swamp — Ditch construction in
general — Hand ditching on firm ground — Cost of ordinary
hand ditching — Hand ditching in swamps — Blasting ditches
in swamps — Making trial shots — Cleaning out the ditch — Ad-
vantages of blasting ditches — Machine ditching — Some typical
open-ditching machines — Maintenance of open ditches — The weed
burner — Maintenance costs — Permanent lining of anti-mosquito
ditches — -Sub-surface tile drains — Tile drains versus open ditches
— Laying out a tile drainage system — Placing the tile — Tile
drainage costs— Vertical drainage — Typical vertical drainage
operation — Vertical drainage for large areas — Stream re-chan-
eling — Blasting new channels — Clearing streams of logs, etc. — ■
Filling.

CHAPTER 7.— Salt Marsh Drainage 139

The salt marsh problem in general — Agricultural "\ ersus anti-mos-
quito drainage of salt marshes — Design of salt marsh ditches — Salt
marsh ditching by hand — Machine ditching — Filling — Diking and
tide-gating in general — Constructing the dike — -The tide-gate and
sluice-box — Construction of sluices — Gate construction — Specifi-
cations for large sluices — Installation — Other types of tide-gates
— The Calco gate — Operation of tide-gates — Salt marsh shrinkage
— Pumping.

CHAPTER 8.— Oiling 158

Place of oiling in anti-mosquito work — Where oiling is applicable —
Applying the oil — Kind of oil required — Larvicides — The Panama
larvicide — Other larvicidal substances — The sprayer — Drip-cans —
Use of drip-cans — Other methods of applying oil — Frequency of
oiling — Distribution of oil — Storage of oil — Costs of oiling.

CHAPTER 9.— Fish Control 172

Advantages and limitations — How fish destroy larvae — The top
minnow (Gambusia affinis) — The barred killifish (Fundulus hetero-
clitus) — The striped killifish {Fundvlus majalis) — -The fresh-water
killy (Fundulus diaphanous) — The variegated minnow (Cyprinodon
variegatus) — The rain-water fish (Lucania parvia) — The spotted
top minnow (Fundulus notatus) — The star-headed minnow (Fun-
dulus notii) — Other fishes — Procedure in fish control — -Number
of fish required — Distributing the fish — Necessity of aiding the
fish — Plants in relation to fish control — Eliminating larva-pro-
tecting plants — The sub-aqueous saw — Using the saw.

CHAPTER 10.— Screening 195

Place of screening in anti-mosquito work — Rarity of good screen-

CONTENTS ix

Page

ing — Essentials of good screening — Screening of doors — Some
general rules — Screening of windows — Screening of porches —
Screening of chimneys and fire-places — -The life of a screen —
Screening near the sea-side — Conducting a screening campaign —
Value of screening — Cost of screening — Does screening pay?

CHAPTER 11. — Other Measures and Expedients and Points

Requiring Investigation 209

Scope of this chapter — Auxiliary methods and expedients in
general — Direct exterminative measures — The bat as a destroyer
of adult mosquitoes — Other animal foes of the mosquito—
^- Destruction of mosquitoes in dwellings — Harassing the mosquito

— Further protective measures — Use of animals as a protection
against mosquitoes — Application of substances repellent to mos-
quitoes — Use of quinine for malaria — Demonstrations of the value
of mass treatment by quinine — Quinine versus anti-mosquito
measures — Points that require further investigation.

CHAPTER 12.— Rural Mosquito and Malaria Control . . . .219
Unfavorable factors in rural control — Favorable factors in rural
control — Need for a survey — Control measures about the average
home — Further measures — Protecting homes in swamps, etc. —
The rice-field problem — The rice-field problem abroad — Com-
munity measures in rural areas — 'Rural community protective
demonstrations.

APPENDIX A. — Table to Determine Species of Certain Common-
American Mosquitoes 228

APPENDIX B. — Approved Anti-mosquito Ordinance 233

APPENDIX C. — Suggested Anti-mosquito Leaflet for Campaic-n

Educational Work 235

APPENDIX D.— Bibliography 238

INDEX 241

MOSQUITO ERADICATION

CHAPTER I

THE TOLL OF THE MOSQUITO

DISEASES SPREAD BY THE MOSQUITO

While much has been accomplished in recent years in diffusing
information as to the preventability of the mosquito-borne
diseases, it is very doubtful if the public yet has an adequate idea
of the mortality, suffering and loss they occasion and of the
general feasibility and direct economic advantage of mosquito
eradication.

The toll of the mosquito may be regarded from three aspects-
first, the annoyance, suffering and death caused by the diseases
it transmits; second, the economic loss resulting from these
diseases in expenditures for medical aid, nursing and medicines
and in loss of time and productive energy; and, third, the eco-
nomic loss it occasions by holding back development of, and
depressing property values in, sections where it abounds.

Apart from the discomfort and vexation it causes, the mosquito
is the transmitting agent of no fewer than four distinct diseases —
malaria, ye llow fever, dengue a n d filariag js- Of these, malaria
and yellow fever are of the very first importance.

TRANSMISSION OF MALARIA

Malaria is caused by three separate blood parasites or heina-
tocytozoa, Plasmodium malariae (Laveran), Plasmodium vivax
(Grassi and Filetti) and Plasmodium falciparum (Welch).
These produce respectively quartan, tertian and estivo-autumnal
or tropical malaria, all having the same etiology and mode of
transference, despite well-defined clinical differences.

It is now well established that malaria is transmitted in nature
only by the bite of the Anopheles mosquito, this mosquito being
the only animal, other than man, which carries the malaria
parasites. The mosquito is the definitive host and man the
intermediary host, both being necessary to complete the life
cycle of the parasite, which is as follows.

2 MOSQUITO ERADICATION

When man is infected, a non-sexual cycle, known as schizogony,
begins, which takes from 48 to 72 hours. The sporozoite bores
into a red cell, becomes round, increases in size and finally divides
into a number of sporozoites, each of which repeats this process.

Fig. 1. — The malaria parasite and its life cycle. (After John B. Smith, New
Jersey Agricultural Experiment Stations.)

Anopheles Mosquito and Malaria: A, larva; B, pupa; O, adult; D, the blast-
introduced into the blood by the mosquito; E to J, stages through which the
Plasmodium passes in the red blood corpuscles; K, the spores, which enter new
blood corpuscles; L, M, the microgamete; N, O, the macrogamete; P, flagellae
forming; V, union of a flagellum with a macrogamete; R, fusion of nuclei; S,
the vermicule; T to Y, formation of the zygote in the stomach of the mosquito,
the fully developed zygote, Y, rupturing to produce blasts.

In about 2 weeks, the sporozoites become so numerous that the
toxin liberated at each division is sufficient to cause chills.
Eventually, sexual forms appear, the females being known as
macrogametes and the males as microgametocytes. When the

THE TOLL OF THE MOSQUITO

Q © O

Fig. 6. — Stomach of mosquito with oocysts.
(After Craig.)

Fig. 2. — Parasites of tertian malaria.
(After Thayer and Hewetson.)

Fig. 3. — Parasites of estivo-
autumnal malaria. (After
Thayer and Hewetson.)

Fig. 4. — Parasites of quartan malaria.
(After Thayer and Hewetson).

mB>,

Fig. 7. — Sporozoites in oocyst.
After Craig.)

Fig. 5. — Fertilized female
malaria parasite (zygote) ■
(After Craig.)

Fig. 8. — Sporozoites
(After Craig.)

4 MOSQUITO ERADICATION

mosquito bites a person, these forms enter its stomach, where
they combine to form zygotes. The zygotes divide into sporo-
zoites, which finally appear in the salivary glands of the Ano-
pheles. From here they enter the blood of the person bitten by
the mosquito and start again on the non-sexual cycle.

CHARACTERISTICS OF MALARIA

It is noteworthy that it requires about 12 days after entering
the body of the mosquito before the sporozoites appear in its
salivary glands. This means that the mosquito cannot transmit
malaria until 12 days after it has bitten a malaria patient. The
parasite does not seem to injure the mosquito, which may live
many weeks and infect several persons successively. A mean
temperature of less than 60°F. inhibits development of the
parasite in the mosquito.

"A person who once has had malaria," says Rosenau, 1 "is more apt to
have subsequent attacks. Ordinarily there is an increased susceptibility
rather than an immunity. However, repeated infections, especially
during early life, leave a very pronounced resistance. In malarious
regions many children carry the parasites in their circulating blood
without any manifestations of the disease. These carriers are important
factors. in spreading the infection in endemic areas, and must be taken
into account in preventive measures.

"There is no true racial immunity in this disease. Occasionally a
congenital immunity seems to be transmitted ; this must be rare. Practi-
cally all persons who receive the infection for the first time are sus-
ceptible. The freedom from malaria which some persons seem to
enjoy may be accounted for partly by the fact that mosquitoes seldom
bite such persons. It is well known that on account of the odors, or
what not, mosquitoes do not bother certain individuals. No doubt the
infection of a small number of parasites is often overcome largely through
a vigorous phagocytosis.

"Individual resistance varies in different individuals and in the same
individual at different times. The parasite may remain latent in the
spleen and other organs for years. Exposure, over-eating, fasting,
overwork, or worry, or anything that lowers the vitality of such indi-
viduals predisposes to an attack of malaria. The disease often breaks
out in persons in good health leaving a malarial region for a health
resort, whether mountain or seashore."

1 "Preventive Medicine and Hygiene," New York and London, 1918.

THE TOLL OF THE MOSQUITO 5

DISTRIBUTION OF MALARIA

Trask 1 sums up the distribution of malaria in the United
States as follows :

"In the territory extending from the Gulf of Mexico to a line north of
the Ohio River and from the Atlantic seaboard to and into the eastern
part of Kansas, Oklahoma and Texas, few, if any, localities are entirely
free from malaria. In most of the lowlands it is very prevalent; in the
mountains and better drained areas less prevalent.

Fig. 9. — Endemic areas of malaria in the United States. Shaded portions of
map show endemic areas. Shaded circles represent localities in which cases of
malaria occur and in which the disease is probably endemic. (After Trask.)

' The disease is also endemic in southeastern Xew York and parts
of Connecticut, Rhode Island and Massachusetts, and in California
in the Sacramento and San Joaquin valleys.

"There is probably no state in the Union in which the disease is not
present and in which it is not spread by mosquitoes grown locally.

"The disease constitutes one of the big national health problems.
It is also an economic problem of importance."

Elsewhere, malaria is found in nearly every country, its
incidence increasing, as a rule, with proximity to the Equator.

i—

'"Malaria, A Public Health and Economic Problem in the United
States," U. S. Public Health Service, 1917.

6 MOSQUITO ERADICATION

MORTALITY AND MORBIDITY OF MALARIA

Sir Ronald Ross, discoverer of the transmission of malaria
by the mosquito, says:

"Malarial fever is perhaps the most important of human diseases,
and, though it is not often directly fatal, its wide prevalence in almost all
warm climates produces in the aggregate an enormous amount of sick-
ness and mortality."

"Malaria," says Leathers, 1 "is the most prevalent disease in all
semi-tropical and tropical countries. It is the most frequent cause of
sickness and death in those parts of the world that are most densely
populated. It is also the most prevalent disease in the United States,
and at least two-thirds of the cases found in this country occur in the
Southern States.

''Malaria is one of the greatest scourges inflicted upon humanity.
It's a menace to any people or country in which it has a decided inci-
dence. In the number of deaths caused either directly or indirectly
the sickness and suffering, the loss of time and efficiency, the expense,
the lowered vitality of those afflicted and in the reduction of the valua-
tion of property, malaria is without a rival among the diseases afflicting
mankind.

"A careful investigation shows that about 15,000 people die directly
from malaria each year in the United States. This does not take into
consideration the indirect effects of the disease and the consequent
mortality assigned to other causes, which, in reality, malaria is respon-
sible for in large measure. In addition to the mortality accruing from
malaria, there are from 1,500,000 to 3,000,000 people in the United
States sick from this disease annually."

Carter 2 estimates the annual morbidity from malaria in the
United States at 6,000,000 to 7,000,000.

Rose 3 estimates that in India malaria causes on the average
each year about 1,130,000 deaths and more than 100,000,000
cases of illness.

Hoffman 4 gives the mortality from malaria in certain other
countries during designated periods as follows:

1 The Importance of Malaria from a Public Health and Economic Stand-
point, Southern Medical Journal, August, 1918.

2 "The Malaria Problem of the South," U. S. Public Health Service, 1919.

3 Field Experiments in Malaria Control, Journal, American Medical
Association, Nov. 8, 1919.

4 "A Plea and A Plan for The Eradication of Malaria," Prudential
Insurance Company of America, 1917.

THE TOLL OF THE MOSQUITO

Country

Period

Aggregate
population

Deaths

Rate per
100,000

Mauritius

Nicaragua

British Honduras. .
Straits Settlements.

British Guiana

Philippine Islands .

Venezuela

Panama Canal Zone

Porto Rico

Costa Rica

Ceylon

Cuba

Spain

Italy

1910-14
1908-11
1914-15
1910-14
1911-15
1909-13
1908-12
1911-15
1911-15
1911-15
1910-14
1910-14
1906-10
1909-13

3,
1

,842,561

180,000

83,268

,596,554

516,710

29,472,283

13,525,191

677,792

4,675,044

1,999,545

20,817,228

11,561,416

96,717,000

173,356,885

21,686

15,859

491

19,818

6,385

117,139

41,331

949

3,793

1,251

11,304

2,535

10,930

17,399

1,176.9

727.5

589.7

551.0

421.0

397.5

305.6

140.0

81.1

62.6

54.3

21.9

11.3

10.0

ECONOMIC SIGNIFICANCE OF MALARIA
"It is not in the death-rate, however, that the gravest injury
of malaria lies," declares Carter. 1

"It is in its sick-rate; in the loss of efficiency it causes, rather than in
the loss of life. One death from pneumonia should correspond to about
125 sick-days — work-days lost; one from typhoid fever to 400 to 500
sick-days; one from tuberculosis to somewhat more than this among
whites, decidedly less among negroes. A death from malaria, however,
corresponds to from 2,000 to 4,000 sick-days. This loss of efficiency
may really be doubled or trebled, for the man infected with malaria is
frequently half sick all the time.

"And it is the amount of malaria, when it is bad, which appalls.
If 1 per cent of the population is stricken with typhoid fever, it is an
epidemic, and a bad one. Contrast this with 40 per cent to 60 per cent
of a population per annum affected with malaria, and I have seen
outbreaks with 90 per cent, and you gain some idea of the importance
of this disease. The loss of efficiency caused by malaria in the malari-
ous section of the South is beyond comparison greater than that caused
by any other disease, or even by any two or three diseases combined,
including typhoid fever and tuberculosis.

"lam not speaking at random. You have never heard of the preva-
lence of typhoid determining the failure to locate industrial plants.
Yet, at one place where power was abundant and very cheap, the
manager told me that a number of options for cotton mills, wagon
factories, etc. — options which had been taken because of the cheapness
of the power — had been abandoned because of the prevalence of malaria.

1 The Malaria Problem of the South," U. S. Public Health Service, 1919.

L-

8 MOSQUITO ERADICATION

Has the presence of tuberculosis ever prevented a real estate transaction?
I know of a deal involving the purchase of large tract of land for coloniza-
tion — a tract valued at about half a million dollars — not consummated
on account of the prevalence of malaria in that section, and there was
not much malaria either. You have not seen homes abandoned because
of either tuberculosis or typhoid fever. I can assure you that I have
seen them abandoned on account of malaria."

MALARIA AS A LABOR PROBLEM

"It is not going too far," says Hoffman, 1 "to say that malaria
eradication is essentially a labor problem of the first importance;
that an enormous amount of labor inefficiency due to malaria
continues to hinder the progress of semi-tropical and tropical
countries, which, if brought under control and completely done
away with, must needs assist profoundly in the reclamation of the
tropical regions for the practical needs of the world at large."

An interesting investigation of the losses occasioned by malaria
in the cotton-growing section of Louisiana was made by Van
Dine of the U. S. Department of Agriculture. The work involved
a detailed study of the malaria morbidity among 74 tenant
families, comprising 299 persons, men, women and children, on a
typical plantation. There developed from May to October
inclusive 166 cases of malaria in 138 persons, causing a total loss
of time of 1,066 adult days or 6.42 adult days per case. This
was equivalent to loss of the entire working time of 5.54 families.
Reduction of efficiency of the workers amounted to a loss of
time of 9.25 families, making a total loss of time of 14.79 families.
In other words, 60 families would have done the same amount of
work, had there been no malaria, as 74 families did with malaria.
Reduced to money, it was found that the actual loss of time
amounted to $2,200 and loss of efficiency to $4,300, making
a total financial loss due to malaria of $6,500.

From these figures, it will be noted that a community of less
than 300 persons could well have afforded to spend up to $5,000
to $6,000 in anti-mosquito work, while an investment of less
than $3,500 would have returned a dividend of 100 per cent.

TRANSMISSION OF YELLOW FEVER

Although the cause of yellow fever is not definitely known,
the infective agent being apparently ultramicroscopic, the manner

1 "A Plea and A Plan for The Eradication of Malaria," Prudential
Insurance Company of America, 1917.

THE TOLL OF THE MOSQUITO 9

of transmission is well understood. It is now definitely estab-
lished that the disease is conveyed in nature only through the
bite of an infected female Aedes calopu s mosquito.

It is believed that the mosquito becomes infected by biting
persons suffering from yellow fever during the first 3 days of
the fever, experiments indicating that the infective principle
disappears from the blood after that period. The mosquito,
however, is unable to transmit the disease until about 12 days
after it has sucked the blood; from then on, it remains infected
all its life and may communicate the disease to several persons
successively.

So far as is known, man is the only animal subject to yellow
fever, attempts to infect other animals having failed.

The fact that the mosquito can be infected only during the first
3 days of the disease is an important factor in prevention of
yellow fever, since if the patient can be isolated from mosquitoes
during this period, no mosquitoes will be infected and, hence,
the disease cannot spread. Difficulty in diagnosing yellow fever
sometimes renders this impossible.

Although yellow fever has been a scourge for centuries, it was
not until 1900 that the role of the mosquito in transmitting this
dread plague was ascertained and the preventive measures,
based thereon, developed. This epoch-making discovery was
made by a board of American army medical officers. Previously,
it had been believed that the infection was carried in clothing, by
the air, etc.

MORTALITY AND MORBIDITY

Although yellow fever in the United States today is virtually
eliminated, the terrible epidemics of former years in which panic
reigned throughout the South are not yet forgotten. In South
and Central America, the disease is still epidemic in many places,
as well as in other parts of the world. But modern medical and
engineering science is routing it all along the line.

The following compilation from the U. S. Public Health Service 1
reports of cases occurring in various North, South and Central
American countries during the fiscal years indicated, is admit-
tedly incomplete and should be considered only as an indication
of the areas in which the disease is more or less endemic :

1 Annual Reports, U. S. Public Health Service, 1918, 1919, 1920 and 1921.

MOSQUITO ERADICATION

Country

1918

1919

1920

1921

Brazil

86
1
3

482
56

250

Colombia

Ecuador

Honduras

Guatemala

Mexico

Panama Canal Zone

11
180

Peru

287

Salvador

Venezuela

YELLOW FEVER VERSUS MALARIA CONTROL

While the same principles that apply to the prevention of
malaria apply to the prevention of yellow fever, prevention of the
latter is by far the easier. In the first place, the range of breeding
places of Aedes calopus is much more restricted than that of the
Anopheles. Again, the Anopheles mosquito flies much further
than does Aedes calopus. Finally, yellow fever patients remain
infective for only 3 days, while malaria patients carry the
parasites sometimes for years.

It is due for the most part, probably, to the last factor men-
tioned that yellow fever has been so largely eradicated through-
out the United States today, despite the fact that Aedes calopus
is still one of the most widely distributed of the Southern mos-
quitoes. In other words, the chief reason why yellow fever is
not still as prevalent in the South today as malaria is because
there are no human carriers. When an infected person does enter
the territory of Aedes calopus it is necessary only to protect him
from the mosquito for 3 days, and nobody else will be infected.
With malaria, the case is far different ; in almost every community
there are human carriers, who — unless preventive work is under-
taken — are bound to be bitten some time during the summer by
Anopheles mosquitoes, and the Anopheles, of course, pass on the
infection to other persons.

DENGUE

This disease frequently resembles yellow fever in its epidemi-
ology and symptomatology, and, although few persons have ever
died of it, the victim often is left in a more or less disabled condi-
tion for months.

THE TOLL OF THE MOSQUITO

1 1

Dengue is believed to be transmitted by Culex fatigans,
although the causative factor is as yet unknown. Graham 1
described a protozoon which he believed caused the disease, but
Ashburn and Craig 2 assert that a filterable virus is responsible
for it. They placed the period of incubation at 3 days and 14
hours.

Dengue somewhat resembles yellow fever in its rapid com-
municability, sometimes spreading with marvelous rapidity and
infecting virtually every person within its vicinity. Unlike
yellow fever, however, there is no definite immunity.

The prevalence of dengue in the United States and territories
during the fiscal years 1918 and 1919 is reported by the U. S.
Public Health Service as follows:

1918

1919

States and territories

Cases

Deaths

Cases

Deaths

Texas

Louisiana .
Colorado . .
California .
Florida . . .
Porto Rico
Hawaii . . .

24
4

127

12
345

While cases of dengue in the United States are comparatively
few, as indicated by the above table, it is certain that in South
and Central America and other tropical and sub-tropical coun-
tries the morbidity from this disease reaches a not inconsiderable
figure.

FILARIASIS

This disease consists of the infestation of the connective tissues,
lymphatics and body cavities of man with larvae or adults of
filaria, a long, slender threadworm with a curved tail. According
to Rosenau, 3 none of the young worms do any appreciable
injury to the blood, while of the adult worms only one, Filaria

1 Journal of Tropical Medicine, vol. 6, 1903; quoted by Rosenau.

2 Philippine Journal of Science, May 1, 1907; quoted by Rosenau.

3 "Preventive Medicine and Hygiene," New York and London, 1918.

MOSQUITO ERADICATION

Fig. 10. — Mature larvae escaping from proboscis of Culex fatigans; one
mature larvae coiled in base of proboscis. From mosquito dissected after being
infected at Charleston, S. C.

THE TOLL OF THE MOSQUITO 13

bancrofti, which causes elephantiasis, can be viewed as serious.
These worms are transmitted to man by mosquitoes, Culex
fatigans apparently being considered as the chief offender.

The most important filariae of man, according to Rosenau, 1
are:

" (1) Filaria bancrofti, the larva of which is known as Filaria nocturna,
appearing in the blood at night and occurring in all tropical lands, includ-

*%4

"•vast ^

/
J

L. H. WILDEIi

Fig. 11. — Filariae (without sheath) in thoracic muscles of Culex fatigans,
9 hours after ingestion of filarial blood; infected at Charleston, S. C. Teased
preparation.

ing America; (2) Filaria loa, the larva of which is known as Filaria
diurna, occurring in the blood by day and prevalent in West Africa
and India ; (3) Filaria perstans, which persists in the blood both day and
night, and occurs in West Africa and a number of other places."

Rosenau 1 describes the movements of filariae in the body of
mosquitoes fed on the blood of filarial-infested individuals as
follows :

1 "Preventive Medicine and Hygiene," New York and London, 1918.

14 MOSQUITO ERADICATION

"The filarial larvae soon escape from their sheaths in the thickened
blood within the stomach of the mosquito. They pierce the stomach
wall, enter the thoracic muscles of the insect, pass through a metamor-
phosis which takes from 16 to 20 days (longer or shorter, according to
atmospheric temperature) ; they now quit the thorax and a few find their
way to the abdomen; the vast majority, however, pass forward through
the prothorax and neck and, en ering the head, coil themselves up close
to the base of the proboscis and beneath the pharynx and under surface
of the cephalic ganglia."

It is not yet definitely known whether Culex fatigans is the only
species of mosquito which transmits filariasis; for this reason,
anti-mosquito work for the prevention of filariasis should be
directed against all the mosquitoes in the vicinity.

Filariasis occurs throughout the tropics and sub-tropics
generally, and the total morbidity from this infection undoubt-
edly is large. In the United States, occasional cases are reported
in the Southeast, the endemic area reaching as far north as
Charleston, S. C.

ECONOMIC SIGNIFICANCE OF YELLOW FEVER, DENGUE AND

FILARIASIS

While none of these diseases are widely prevalent in the
United States, the impairment of working capacity which the
last two entail — -which probably corresponds in a large measure
with that caused by malaria — no doubt amounts to a not incon-
siderable sum annually.

In the tropical regions, however, where these diseases are much
more common, it is clear that their economic significance must be
very large. The inefficiency of tropical labor has been noted by
virtually all persons who have visited those parts, and it is
apparent that this inefficiency is due largely to malaria, yellow
fever, dengue and filariasis — preventible, mosquito-borne diseases.

THE MOSQUITO AS AN ANNOYANCE; EFFECTS UPON HEALTH

Little need be said as to this phase of the mosquito's activities
and its effects upon the comfort and health of the community,
as anyone who has lived in vicinities that the mosquito frequents
knows how much discomfort it causes.

Not only do they make life miserable for their victims, but,
merely as an annoyance alone, they have a very pernicious effect
upon the health. The illness caused by loss of rest and sleep, by

THE TOLL OF THE MOSQUITO 15

over-wrought nerves and temper and bj r poisonous swellings
that sometimes follow the bites probably would reach an enor-
mous figure, were such cases traced down and recorded.

Another aspect of the effect upon health of annoyance by
mosquitoes is the possibility that they may have some connection
with other diseases than the four hitherto discussed. There are
still man} r diseases whose etiology is as yet comparatively
unknown, and the possibility is by no means remote that further
investigation may show that the mosquito is in some way con-
nected with their transmission.

THE MOSQUITO AS AN ANNOYANCE; ECONOMIC SIGNIFICANCE

But the economic significance of the mosquito as an annoyance
is probably even more apparent than its significance as a menace
to health. The mere fact that mosquitoes are abundant in a
region holds back development of that region and keeps property
values down to a very low figure.

Speaking of the economic benefits of eradicating mosquitoes
along the New Jersey coast, Headlee 1 says:

"Everywhere (that) the drainage has been completed and is main-
tained, the thoughtful residents speak of the great relief afforded. As
the result of an investigation made during the season of 1912-13, shore-
line property values between Jersey City and Rumson were found to
have increased by $5,600,000. It is significant of the influence of
mosquito control on this increase to note that while the increase in the
factory section was only 15 per cent, in the residential portions it
ranged from 25 to 300 per cent. This tallies well with the observation
that parts of the shore, formerly almost uninhabitable because of the
mosquito pest, have now become delightful summer resorts.

"A rather unexpected, but very natural, benefit has appeared as a
result incidental to that drainage necessary to eliminate salt marsh
mosquito-breeding. An estimate, prepared during the year 1912-13,
showed that the salt marshes which had been drained and kept drained
3 years or more were producing 2.6 tons of hay per acre, as compared
with 0.7 ton produced by marshes that are undrained or only recently
drained.

INCREASING PROPERTY VALUES

"It is well-nigh impossible to prepare reliable estimates of the value of
ridding the rest of the salt marsh of mosquito-breeding. The carrying

1 "The Mosquitoes of New Jersey and Their Control,'' New Jersey Agri-
cultural Experiment Stations, Bull. 276, 1915.

16 MOSQUITO ERADICATION

out of this work would remove the greatest bar which now exists to the
proper urban and agricultural development of South Jersey. The
complete occupation of the shore as a summer resort awaits the control
of the mosquito. Across the marsh from this line of summer resorts is
bound to appear the second line of summer residences. Eventually,
the marsh itself will be filled and built up. The agricultural land lying
back of this urban development will be called upon to produce truck and
fruit to supply this national play-ground.

"The salt marsh mosquito stands in the way of this tremendous
development. The marshes should be drained and the mosquito
destroyed."

It is obvious that the same considerations that apply to mos-
quito eradication along the New Jersey coast apply in larger or
lesser degree to mosquito eradication in similar coast areas. It is
equally obvious that they also apply to many inland areas.
There are probably millions of acres in the United States where
eradication of mosquitoes as a mere annoyance alone would
greatly increase, if not double or treble, property values.

CHAPTER II

SOME DISEASE-BEARING AMERICAN MOSQUITOES

THE MOSQUITO IN GENERAL

While mosquitoes have a world-wide distribution, they differ
very materially in their habitat, their appearance, their ability
to transmit disease, the character of their breeding-places and
the mode of continuing their existence from one generation to
another.

From the point of view of habitat, mosquitoes may conven-
iently be divided into three general classes: The domestic mos-
quito, which breeds largely about homes, as Aedes calopus, the
yellow fever mosquito; the fresh-water sylvan mosquito, which
breeds in pools, swamps, streams, ponds, etc., as the Anopheles,
the malaria-carrying mosquito; and the salt-marsh mosquito,
which breeds almost entirely in brackish marshes along the sea, as
Culex sollicitans. It is the domestic and fresh-water sylvan
mosquitoes which constitute the menace to health.

Of its own volition, the mosquito seldom travels far. Experi-
ments indicate that, as a rule, the inland mosquito does not fly
more than half a mile or so from its breeding-place and that the
average flight is much less than this distance. The}'' may, how-
ever, be wafted considerable distances by the wind, and this fact
should be borne in mind in planning anti-mosquito work; the
control area should extend, say, a mile or more in the direction of
the prevailing wind, while the other side may be reduced in width
to half a mile.

LIFE HISTORY OF THE MOSQUITO

Although the mosquito is a winged animal, no fewer than
three of the four stages of its life are aquatic, and these are the
first. The egg is laid in a quiet pool or other suitable breeding-
place; if the weather is warm, in a couple of days the eggs hatch
out into larvae (wiggletails or wrigglers) ; in 4 or 5 days more the
larvae turn into pupae; this stage lasts 2 or 3 days, when the
adult mosquito emerges from the pupal shell. Therefore, if

18 MOSQUITO ERADICATION

conditions are favorable — that is, if the weather is warm, the
water rich in food and other factors are right — the egg may
develop into an adult mosquito in 8 to 10 days.

The length of life of the adult mosquito varies with conditions.
The average mosquito probably lives several months under
favorable circumstances. Guiteras kept one alive in Havana for
154 days, and it is frequent to keep them alive in laboratories for
70 to 90 days. Without water, however, the mosquito will
perish in 4 or 5 days.

The character of the breeding-place varies with the species and
with conditions. Thus, the domestic mosquitoes generally
choose water impounded in artificial containers about homes,
such as barrels and cisterns, tin cans and bottles, cesspools,
shallow wells, etc. The fresh-water sylvan mosquitoes may be
found occasionally in this class of breeding-place, as well as in
forest pools, swamps, ponds and streams, their usual breeding-
places. The character of breeding-place of any given group
may be modified by conditions.

VARIATIONS IN EGGS, LARVAE AND PUPAE

The eggs, too, vary materially with the different species. The
eggs of the Culex are deposited vertically in large, brownish
rafts; those of the Aedes and Anopheles, on the other hand, are
found isolated, one by one, on their sides.

The habits and appearance of the larvae also present noticeable
differences. Although all larvae are aquatic animals, they are,
nevertheless, nearly all air breathers, lying just under the sur-
face of the water and connecting with the air supply from time
to time by means of a breathing siphon. The Anopheles larvae
recline under the surface of the water in a horizontal position,
while the Culex, Aedes and others, on the contrary, hang with
their heads down.

The pupae of all species do not eat, having no mouth. Like
the larvae, however, they are air breathers, breathing through a
pair of trumpet-shaped tubes which are connected with the thorax.

Some species pass the winter as adults hidden in natural
shelters; others as larvae; and still others as eggs. The eggs
of some mosquitoes will retain their vitality after having been
perfectly dry for months; exposure to water for a few hours will
result in the hatching of larvae. These varied methods of
survival render extinction of the race impossible.

DISEASE-BEARING AMERICAN MOSQUITOES
WHY MOSQUITOES BITE

Mosquitoes bite because blood is believed to be a biological
necessity for full development of the eggs. As this necessity is.
only a feminine one, male mosquitoes are vegetarians, and never
bite. They may be distinguished from the females by the fact
that their antennae are more plumose — that is, more heavily
haired.

'•"'W/iOft,

Fig. 12. — Proboscis of mosquito with lancets (stilette bundle) raised out of
sheath. (After U. S. Public Health Service.)

While biting, the mosquito pierces the skin of its victim by
means of a number of lancets which lie in the beak. As they
enter the skin, the beak covering bends near the middle, thus

Fig. 13. — Proboscis resolved into stilette bundle. (After Daniels.) A,
labrum; B, two mandibles; C, hypopharynx; D, two maxillae; E, sheath (labium).
F, distal end of the sheath.

allowing the head of the mosquito to get up close. The beak
and lancets are described by Headlee' as follows:

"The beak covering, which is the only member of the mouth append-
ages seen by the ordinary observer, corresponds to the labium or lower
lip of the chewing insect. It is grooved length- wise along its upper

1 "The Mosquitoes of New Jersey and Their Control," New Jersey Agri-
cultural Experiment Stations, Bull. 276, 1915-,— r

MOSQUITO ERADICATION

surface and forms a trough in which the delicate piercing lancets lie
and by which they are protected from harm.

"The lancets consist of six parts. The upper is a compound struc-
ture, representing the labrum or upper lip and the epipharynx of the
chewing insect. The epipharynx is grooved length-wise of its lower
surface in such a fashion as to form a complete tube when the hypo-
pharynx is laid against it from below. The hypopharynx is a slender,
flattened piece that fits closely against the open groove of the epipharynx.
Through the tube thus formed, the victim's blood is drawn into the
mosquito's digestive tract. The next pair of lancets are slender sharp-
pointed rods, which correspond to the mandibles or primary jaws of
chewing insects. The next pair of lancets, which correspond to the
maxillae or secondary jaws of chewing insects, are slender and pointed,
but have slightly enlarged barbed ends.

Fig. 14. — Mosquito in the act of sucking blood, the stilette bundle being
free from the sheath, except at the distal end of the sheath. {After
Bahr.)

"Almost, if not quite, coincidently with the moment that the skin is
pierced, a small amount of saliva is injected through the epipharyngeal
groove into the wound, and suction begins very soon after that. The
pumping portion, the fore-intestine, regularly contracts and expands,
drawing the blood from the victim into the mosquito's body. Unless
disturbed, the creature will continue to feed until its abdomen is
distended almost to bursting."

IDENTIFICATION OF MOSQUITOES

Ability promptly to identify the various kinds of mosquitoes is
almost an absolute necessity for the director of an anti-mosquito
campaign. Not only do the methods to be used for their eradica-
tion depend upon the species, but a knowledge of the particular

DISEASE-BEARING AMERICAN MOSQUITOES 21

species prevalent in a community may prevent the expenditure of
large sums in measures directed against species which are not
troublesome there. Furthermore, if occasional mosquitoes are
noted in a community where anti-mosquito work is being carried
on, knowledge of their species will facilitate determination
whether their presence is due to failure of the work or whether
they have blown in from the salt marshes or elsewhere. Again,
determination of the species causing trouble will make it possible
for the director to locate their breeding-places through knowledge
of the habits of that particular species.

This necessary acquaintance with the more common species
of mosquitoes can be obtained only by familiarizing oneself with
the characteristic outer anatomy of the adult and the larvae, so
as to enable one readily to grasp the keys used in classification.
Mere character of breeding-place is not a sufficient basis for
identification.

Adults can only be positively identified if they are in good
shape — not crushed or damaged and not so old that the char-
acteristic markings have worn off. The most favorable age for
identification is 1 or 2 days. As soon as caught, the specimen
should be placed in a jar of cyanide or other toxic gas until dead,
after which it may be pinned through the thorax. If it is desired
to preserve the specimen, it should be carefully placed in a tight-
closing box containing naphthalene, care being taken to attach
an identifying paper to it.

Larvae and pupae may be placed in bottles of 80 per cent
alcohol, which will preserve them indefinitely, so that they will
be available for microscopical examination at any time. They
may, if desired, for permanent reference, be mounted on slides
with Canada balsam.

ANATOMY OF THE MOSQUITO

"The mosquito's body," says Headlee, 1

"like that of most other insects, is made up of three distinct regions —
the head, thorax and abdomen. The head is a globular object having
(1) a pair of eyes, one on each side of the head; (2) a pair of more (male)
or less (female) feathery feelers or antennae; (3) a pair of mouth feelers
or palpi; (4) a long, prominent beak. The thorax is long, elliptical and

lU The Mosquitoes of New Jersey and Their Control," New Jersey Agri-
cultural Experiment Stations, Bull. 276, 1916.

MOSQUITO ERADICATION

bears three pairs of legs on its lower surface and one pair of more or less
transparent wings on its upper surface. The abdomen is long and
narrow and composed of many plainly defined segments. It bears no

on S 1 * 1 tarsal joint.

Fig. 15. — Adult mosquito, (Aedes sollicitans Wlk.) with parts named. (After
John B. Smith, New Jersey Agricultural Experiment Stations.)

appendages other than certain ones connected with reproduction, and
apparently they are not necessary in elementary classification.

"Each leg consists of a small coxa, a long femur, an equally long tibia

DISEASE-BEAR IXC AMERICAN MOSQUITOES 23

ro/ary mouth brushes

antenna/ tuff

antenna

Tfi/'nJ s6cfomina/

^ fburtf, a6<Jom/r>a/
& Se S nier >f

9 rjffh aSJo/Tf/oa/
7g segment - - ---.

5/xth aSc/om/na/
scqmenf-

Seventh abc/om/naf
seamen /

Eighth ahc/om/rra/

Segnjcrrf

Mnfh aSdr/rj/ha/ _
orana/ - =^
y s f3T^pt_ ~

snal tuff J

thorsc/c

,'' nairtuff.i

,' i ana/ siphort

--patch of sca/es
con?6s orpecfens

- Sp/ncs
trachea/ ^//fs

Fig. 16.— Mosquito larva with pan- Darned. {After John B. Smith Y, „•
Jersey Agricultural Experiment Stations.)

MOSQUITO ERADICATION

and a five-jointed foot or tarsus. The last tarsal joint is tipped with
claws.

"The wings have scales, generally collected along the veins. The
color and arrangement of the scales determine the uniformity or spotted
appearance of the wings."

ANATOMY OF THE LARVAE

Headlee 1 describes the larva as follows:

"Like the adult, the wriggler exhibits the three divisions of the body
— head, thorax and abdomen. The head bears a pair of eyes, a pair of

antennal case
head

—-trumjoets or
breatnino lutes

Inorax

e~ue

mnnc case
ec cases

SUJimming
baddies

Fig. 17. — Mosquito pupa with parts named. (After John B. Smith, New
Jersey Agricultural Experiment Stations.)

antennae and rotary mouth brushes. Each antenna exhibits a small
bunch of hairs, which has been designated as the antennal tuft. The
thorax has various tufts of bristles scattered over it, known as the
thoracic tufts. The abdomen consists of eight well-developed segments,
each of which bears some tufts of bristles, known as the abdominal hair
tufts. The eighth segment has grown a process known as the anal tube
or siphon, which bears a double row of spines on its posterior surface
and has the opening of the breathing system at its tip. In nearly all
species, this tube is used to penetrate the water surface film and to reach
the atmospheric air. The ninth segment is small, bears a large group

1 "The Mosquitoes of New Jersey and Their Control," New Jersey Agri-
cultural Experiment Stations, Bull. 276, 1915.

DISEASE-BEARING AMERICAN MOSQUITOES 25

of bristles, the anal tuft and some smaller tufts. The anal opening is
situated at the outer end of this segment and the tracheal gills extend
outward from this opening. On each side of the eighth segment, there is
a little patch of scales that are much used in classification."

The pupa has a small head attached to a very large thorax, with
the abdomen curled around under the latter. The breathing
tubes or trumpets outcrop from the top of the thorax, while
underneath are the leg and wing cases. At the extreme end of the
curled abdomen are the swimming paddles by which this strange-
looking creature moves about from place to place.

THE ANOPHELINAE

Of the sub-family Anophelinae, no fewer than 6 genera, com-
prising at least 25 different species, are believed to transmit
malaria. Knab gives a list of 34 species of American Anopheles,
of which the following have been definitely shown to serve as
hosts for the malaria parasite:

A. albimanus A. argyritarsis A. crucians

A. intermedium A. quadrimaculatus A. pseudomaculipes

A. tarsimaculata A. pseudopunctipennis A. occidentalis

In addition to these, A. punctipennis has been shown to trans-
mit malaria under laboratory conditions, but whether or not it is
an important vector of malaria in nature is not yet entirely
established.

The Anopheles of sanitary importance in the United States
are: A. quadrimaculatus, A. crucians and A. punctipennis in the
East and South, and A. occidentalis along the Pacific coast.

Known transmitters of malaria elsewhere include: A. sinensis
in India; A. costalis in Africa; A. claviger in Spain; and A.
maculipennis, which is believed to be the same as .4. quadri-
maculatus, in other parts of Europe.

IDENTIFICATION OF THE ANOPHELINAE

Adult Anopheline mosquitoes may readily be distinguished
from all other genera by the fact that the wings are distinctly
spotted. Furthermore, in the female, the palpi (the slender rods
found on either side of the beak or proboscis) are about three-
quarters as long as the beak itself, while the same organs in the
females of other species (except one, which has a curved pro-
boscis) are seldom one-quarter the length of the beak.

MOSQ UITO ERA DICA TION

Adult Anopheles also may be identified by their peculiar pos-
ture while resting or biting. On a vertical wall, the head, thorax

Fig. 18. — Head of Anophe-
les, male. (After U. S. Pub-
lic Health Service.)

Fig. 19. — Head of Anophe-
les, female. {After U. S.
Public Health Service.)

and abdomen form one straight line, pointing downward at an
angle of about 60 degrees from the horizontal; other common

1 z 3

Fig. 20. — Resting posture of mosquitoes. (After Sambon.) 1 and 2, Anopheles;

3, Culex pipiens.

mosquitoes sit humped up, both head and abdomen being lower
than the thorax.

Fig. 21. — Ova of Anopheles. Fig. 22. — Culex egg raft. (After

(After U. S. Public Health U. S. Public Health Service.)

Service.)

Adult Anopheles also may be distinguished from other common
mosquitoes by their actions. They seldom bite in the day-time
and rarely bite a person moving about; the Culex,
on the other hand, bites at all times. The
Anopheles does not hum so loudly as other com-
mon mosquitoes.

Fig. 23. — Greatly enlarg-
ed view of a Culex egg.
(After U. S. Public Health
Service.)

Fig. 24/ — Greatly enlarged
view of an Anopheles maculi-
pennis egg. (After U. S. Pub-
lic Health Service.)

DISEASE BEARING AM ERIC AX MOSQUITOES

The eggs of Anopheles may be distinguished from those of
Culex and some other common mosquitoes by the fact that the
former are laid singly and are supported on the surface of the
water by lateral air-spaces, while the latter stand vertically
in closely-packed rafts.

Fig. 25. — Larva of Anopheles. (Afti r
U. S. Public Health Service.)

Fig. 26. — Larva of Culex. (After
U. S. Public Health Service.)

Anopheline larvae may be distinguished from the larvae of all
other genera by the fact that the head is much smaller than the
thorax, that they have virtually no breathing tube and that they

Fig. 27. — Pupa of Anopheles Fig. 28. — Pupa of Culex pipiens.
punctipennis. (After Howard, (After Howard, Dyar and Knob.
Dyar and Knab.)

lie horizontally under, but close to the surface, of the water,
very much like a basking pike. All other common American
larvae, on the other hand, have the head larger than the thorax,
have a long breathing tube and hang head down at an angle of
about 60 degrees from the plane of the water surface. Upon
being frightened, Anopheles larvae usually dart about parallel
to the surface, while other larvae usually dart downward.

MOSQUITO ERADICATION

Anopheles pupae are larger in the antero-posterior direction and
narrow laterally, while Culex pupae are short and broad from side
to side. The breathing siphons of Anopheles pupae are short
and trumpet-like, while those of Culex larvae are long and
narrow.

As a general rule, the Anophelinae prefer natural breeding
places to artificial ones and manifest an aversion for sewage-
polluted water and for brackish water, although they are occa-
sionally found in such waters. Their food, in the larval state,
consists mainly of algal spores, minute insects or crustaceans,
etc. Some authorities state that . they become cannibalistic
when their usual food becomes scarce.

A. QUADRIMACULATUS SAY

Of the three common American malaria-carrying mosquitoes
it is believed that A. quadrimaculatus Say is probably responsible
for more harm than either of the other two.

A. quadrimaculatus may be distinguished from the other Ameri-
can Anopheles by the fact that it is
brownish in color and has from three
to five — but generally four — black-
ish spots on the second and fourth
wing veins, whence its name is
derived. These spots are patches
of black scales.

A . quadrimaculatus passes the win-
ter as an adult female, in cellars,
forests, barns and other sheltered
places. When warm weather comes
in the spring, these females emerge
from their hiding places and deposit
their eggs. From 50 to 75 are laid
at a time. If the weather is favorable, the larvae emerge in 2
or 3 days and begin feeding. In from 4 to 6 days of warm
weather — or much longer in cool — the wrigglers transform into
pupae; 2 or 3 days more and the adult emerges. Breeding
appears to be as continuous from spring to autumn as tempera-
ture and other conditions will allow.

While the favorite breeding-place of A. quadrimaculatus is
grass-bordered pools, ponds, pot-holes, etc., it has been reported
to breed in slowly moving streams. It will also, on occasions,

Fig. 29. — Anopheles quadritnacu
latus, female.

DISEASE-BEARING AMERICAN MOSQUITOES 29

breed in artificial containers. A. quadrimaculatus has also been
known to breed in salt marshes and other brackish water and,
rarely, in sewage-polluted water.

A. quadrimaculatus enters buildings very readily, and the
slightest opening in the screening will be taken advantage of.
If the size of mesh of the screen is less than No. 16 or No. 14,
painted, small-sized individuals will be certain to get in. A.
quadrimaculatus enters inhabited buildings at night and makes
its exit early in the morning, unless so gorged with blood as to be
unable to pass through the screen. In this case it may be
observed resting on the screen next clay.

It has been found, by means of the recovery of stained speci-
mens previously liberated, that A. quadrimaculatus sometimes will
travel more than a mile, although it is not believed that, under
average conditions, the usual flight is as much as that. It is
believed that A. quadrimaculatus could become of sanitary
importance more than a mile from its breeding-place only if the
breeding-place were very extensive and production therein very
heavy.

A. CRUCIANS WIED

As compared with the other Anopheles, the wing of the crucians
is more dusky and the veins, thereof, more prominently marked.
The characteristic marks are three small, blackish spots-
patches of black scales — on the sixth wing vein, thoracic end,
posterior margin. If the specimen be very old, the end spot may
be indistinct.

The crucians has been called the "clay-light Anopheles"
owing to its habit — in contrast with that of A. quadrimaculatus
and A. punctipennis — of biting during the day and early evening.
A. crucians enters dwelling-places fully as readily as does A.
quadrimaculatus; it may also frequent privies and be abundant
underneath houses. Despite these circumstances, A. crucians is
believed to be somewhat less efficient as a vector of malaria
than A. quadrimaculatus.

A. crucians appears to be able to travel somewhat further than
A. quadrimaculatus, recent tests indicating that this species can,
on occasions, fly as far as 7,000 feet.

In its life-habits, A. crucians is similar to A. quadrimaculatus.
It is not so fastidious as to character of breeding-place, however,
and fairly frequently may be found breeding abundantly in

MOSQUITO ERADICATION

brackish waters and waters contaminated with chemicals.
Metz' reports that he has found crucians breeding freely in water
so impregnated with noxious substances from the drain of a
chemical factory that fish were unable to live in it.

A. crucians apparently is not quite so widely distributed as is
A. quadrimaculatus, its habitat evidently being somewhat more

Fig. 30. — Anopheles crucians, female.

restricted. Often, where it is found at all, it is found in great
abundance.

A. PUNCTIPENNIS SAY

This species may be distinguished from other common Ano-
pheles by- the fact that it carries a large square or oblong white or
yellowish patch at the anterior margin of the wing, near the
outer end. Sometimes, there is a blackish patch also noticeable.
The white patch is readily visible to the naked eye, and is
quite perceptible, even when the insect is in the resting position
with the wings crossed. The anterior margin of the wing is
dark, while the balance is lightly spotted with black, with an
almost invisible white spot at the extreme apex.

The life-habits of A. punctipennis are similar to those of A.

i" Some Aspects of Malaria Control Through Mosquito Eradication,"
U. S. Public Health Service, 1919.

DISEASE-BEARING AMERICAN MOSQUITOES

Fig. 31. — Larva of Anopheles crucians. {After John H. Smith, New Jersey

Agricultural Experiment Stations.)
1, larva; 2 head from above; 3, antenna; 4, palpus; 5, mandible; (>, mentum;
7, anal segments from side; 8, anal segments from above, showing spiracles;
9, one of the scales. All are greatly enlarged.

MOSQUITO ERADICATION

quadrimaculatus, except that punctipennis appears to be some-
what less fastidious about the character of the water in which it
breeds.

A. punctipennis apparently does not enter houses so freely as
A. quadrimaculatus and A. crucians. It is generally a porch-
biter, and ordinarily will be found most abundantly in the early
evening. It does not appear to fly so far as A. quadrimaculatus.

This species probably is the most common of the North
American Anopheles.

A. OCCIDENTALIS, D. AND K.

This mosquito, the common malaria carrier of the Pacific
coast, has been considered by some authors to be identical with

A. quadrimaculatus. While the gen-
eral appearance is quite similar to that
of A. quadrimaculatus, there are, accord-
ing to Dyar, well-defined differences in
the male genitalia.

It appears that this mosquito is of
sanitary importance only west of the
Rockies.

THE CTJLICINAE

Fig

32. — Anopheles puncti-
pennis, female.

The sub-family, Culicinae, is sub-
divided into two genera — the Culex
and the Aedes. Species belonging to
both of these genera transmit disease.

Adults of this sub-family may be distinguished from adult
A?wpheles by the fact that the palpi are long in the male and
short in the female, while the Anopheles of both sexes have long
palpi. Another differentiation is the fact that Culicines have
flat abdominal scales, while A7iopheles do not. As already
intimated, the resting position of the Culicines is also very
different from that of the Anopheles.

The difference between Anopheline and Culicine larvae has
already been indicated.

The chief differences between Culex and Aedes may be summed
up as follows:

Adult Culex and Aedes are best distinguished by the shape of
the abdomen; in the Culex, the abdomen is blunt, with short
cerci; in the Aedes, it is tapered, and pointed, with distinct cerci.

DISEASE-BEARING AMERICAN MOSQUITOES

Fig. 33. — Larva of Anopheles punctipennis. (After John B. Smith, New Jersey

Agricultural Experiment Station*.)
1, larva; 2, head above; 3, palpus; 4, mandible; 5, antenna; 6, mentum; 7,
anal segments from the side; 8, anal segments from above, showing the two
spiracles; 9, one of the scales. All are greatly enlarged.

MOSQUITO ERADICATION

Eggs of the Culex are laid vertically in rafts and are generally
of a brownish color, while eggs of the Aedes are laid in clusters
and gradually turn black.

The larvae of Culex are easily distinguished from those of
Aedes by the air-tube; in the Culex, there are many hairs along
its posterior aspect, while in the Aedes, there is but a single tuft
near the end of the pecten.

The pupae manifest few differences.

Anopheles occidentalis, male and female.

AEDES CALOPUS MEIG (STEGOMYIA FASCIATUS FAB.)

Aedes calopus, the yellow fever mosquito, is very widely
distributed, it being found from 38° South to 38° North latitude.
As a rule, Aedes calopus prefers the lowlands, and is rarely found
in the higher parts of the South.

The yellow fever mosquito is essentially a domestic mosquito,
breeding by preference in standing water about houses, such as
that in cisterns, barrels, tin cans, bottles, etc. Rarely, if ever,
is this mosquito found breeding in swamps, pools and streams,
the favorite haunts of the malaria mosquito.

Although Aedes calopus may, as an adult, survive a brief

DISEASE-BEARING AMERICAN MOSQUITOES

winter, this mosquito generally passes the winter in the egg
stage. The eggs, which are shaped something like a cigar and
measure about half a millimeter in length, are laid on the surface
of the water or just above the water-line. They can withstand
freezing and may be kept dry for 6 months without losing their
vitality. They do not form rafts, as do the Culex, but lie singly
or in isolated groups.

Fig. 35. — Aedes calopus, female.

Fig. 36. — Aedes calopus, male.

In about 36 to 48 hours, if the weather is warm, the egg
develops into the larva, which also is very resistant, it being
apparently able to stand freezing for a brief period. A distin-
guishing feature of this larva is the fact that it has a black,
barrel-shaped breathing siphon. This larva is easily scared and
stays at the bottom of the water a good share of the time.

If the weather is warm, the larva turns into a pupa in 5 to
8 days. The pupa stays near the surface of the water most of the
time. In 36 to 48 hours the adult mosquito emerges.

Aedes calopus is of a grayish color and average to smallish
size. It has glistening whitish lyre-shaped marks on the back
of the thorax, with silver-white dots on the sides. There are
white lines at each tarsal joint and on the palpi, while the
scutellum also is white. Outside of the markings, the female is

36 MOSQUITO ERADICATION

distinguished from Anopheles mosquitoes by the fact that the
palpi are rudimentary.

Being smallish, A. calopus can pass through a screen composed
of 16 strands or 15 meshes to the inch. To be effectual, there-
fore, screens should have more than 15 meshes to the inch.

As a rule, A. calopus does not fly nearly so far as the malaria-
carrying mosquitoes, manifesting an apparent desire to remain
about the environment that gave it birth. It is active chiefly
during the daj'-time, resting at night, unless attracted by bright
lights. During the day-time it seeks shade, since it cannot
survive long in the direct sunlight. It is, therefore, chiefly
dangerous in houses or in brush, etc.

Rosenau 1 says: "It ma} r possibly at times fry across the street,
but it is evident that it neither flies far nor is it ordinarily trans-
ported to any great distance on railroad cars, although it may be
carried over seas in ships."

CULEX FATIGANS WIED. (C. QUINQUEFASCIATUS SAY)

This mosquito is believed to transmit both dengue and filariasis
to man. It is very widely distributed over the tropics and sub-
tropics. C. fatigans and A. calopus are two of the commonest
house mosquitoes in the Southern States.

While these two species are constantly associated in that
section, breeding together in house-yards in the same water and in
the same containers, A. calopus has been exonerated as a dissemi-
nator of dengue and filariasis, while C. fatigans has been found
to be almost wholly responsible for the spread of these diseases.

C. fatigans, like A. calopus, is essentially a domestic mosquito,
breeding in fresh water in back-yards, in cisterns, rain-water
barrels, tin cans and other miscellaneous artificial containers.

C. fatigans is a smallish to medium-sized mosquito, ranging
in color from yellow to dark-brown, with light bands at the base
of each segment. Its legs and proboscis are not banded.

Probably the quickest way of distinguishing C. fatigans from
A. calopus is by the fact that the former is essentially a night-
biter, while the latter is a day-biter. This is very perceptible,
wherever the two occur together.

The larva of this species may be distinguished from that of A.
calopus by the fact that its respiratory siphon is brownish and
nearly three times as long as it is broad.

1 "Preventive Medicine and Hygiene," New York and London, 1918.

DISEASE-BEARING AMERICAN MOSQUITOES

C. fatigans passes the winter as an adult female. She hides
away in protected places and, when warm weather comes, lays
her eggs in dark-brown rafts of from 50 to 400 eggs. In about
8 or 9 days, if the weather is favorable, the adult of the new
brood emerges. Breeding is more or less continuous up to cold
weather in the autumn.

C. fatigans ordinarily does not fly far. However, where pro-
duction is heavy, it may travel 2 or 3 miles.

Fig. 37. — Adult female Culex fatigans.

SOME COMMON TROUBLESOME MOSQUITOES

In the next few pages, several of the more common annoying
mosquitoes prevalent in the United States will be discussed
briefly. So far as is known, none of these transmit disease,
but all are more or less troublesome in mosquito eradication
work.

For the purposes of this discussion, it may be convenient,
perhaps, to divide these mosquitoes into rough groups as follows:

MOSQUITO ERADICATION

FlG . 38 ._ AdulfCulex viviens. {After John B. Smith, New Jersey Agricultural

Experiment Stations.)
1, adult female; 2, palpus of same; 3, anterior; 4, middle, and 5, posterior
claws of male. All are greatly enlarged.

DISEASE-BEARING AMERICAN MOSQUITOES

house mosquitoes, fresh-water sylvan mosquitoes and salt-
marsh mosquitoes.

Fig. 39. — Adult of Culex restuans. (After John B. Smith, New Jersey Agricul-
tural Experiment Stations.)
1, adult female; 2, appendage to tip of clasper; 3, clasper of male genitalia:
4, anterior claws of female; 5, mentum of larva; G and 7, antennae of same. All
are greatly enlarged.

HOUSE GROUP

Probably one of the most annoying mosquitoes of this group
is Culex pipiens, Linn., a close relative of C. fatiga?is. This

MOSQUITO ERADICATION

species is very widely distributed and breeds in almost any kind
of water, apparently preferring water that contains sewage.
It will, on occasions, breed in salt water, but it is preferentially
a domestic insect. It enters inhabited houses freely and bites
all night. The adults resemble C. fatigans so closely that it is
difficult to distinguish them. The males differ most in the

Fig. 40. — Adult of Aedes vexans. (After John B. Smith, New Jersey Agricul-
tural Experiment Stations.)
1, adult female; 2, anterior; 3, middle, and 4, posterior, claws of the male.
All are greatly enlarged.

genitalia; the pipiens females have the abdominal banding
continuous, while the females of fatigans generally have the
pale bands interrupted at the sides. The life history of this
mosquito and its habits are very similar to those of C. fatigans.
Culex restuans, Theob., is quite similar to C. pipiens in appear-
ance, being distinguished from it only by the fact that, under a
magnifying glass, two white spots are often noticeable on top of
the thorax and in front of the other white marks. C. restuans

DISEASE-BEARING AMERICAN MOSQUITOES

Fig. 41. — Adult of Aedes canadensis. (After John B. Smith, New Jersey Agri-
cultural Experiment Stations.)
1, adult female; 2, ovipositor; 3, palpus; 4, margin of the wing, showing the
fringe scales; 5, part of vein, showing scales; 6, anterior claws of female; 7, anterior;
8, middle, and 9, posterior claws of male. All are greatly enlarged.

42 MOSQUITO ERADICATION

differs from C. pipiens in that it seems to prefer clear, clean water,
but otherwise its habits, etc., are similar. The larva differs
from that of C. pipiens in that the antennal tuft is less than half-
way between base and tip, while in the case of pipiens larvae it is
generally more than this.

FRESH -WATER SYLVAN GROUP

Aedes vexans, Meig, one of the most important mosquitoes of
this group, is a smallish insect with unspotted wings and un-
handed beak. Its tarsi have narrow light bands at the base, as
do the abdominal segments. The larva has a spotted head.
Its respiratory siphon is about three times as long as it is broad.
The antennae spring from the sides of the anterior part of the
head. This species breeds only in temporary puddles, eschewing
permanent water. Some eggs hatch after every rain; frequently
all perish by drying of the pool. A. vexans, it is said, will fly as
far as 5 miles. This mosquito does not enter houses, but prefers
shady places such as under trees and porches, and bites day and
night.

Aedes canadensis, Theob., has a black proboscis, a brown,
unmarked thorax and unspotted wings. The last tarsal segment
is white; the others are brown with white bands at the base and
tip. A. canadensis is found probably most frequently in forest
pools, etc., and is not supposed to travel far. The larvae are
gray with dark heads. In the early stages the larva has a light
transverse band about its neck. The scales on each side of the
eighth segment are isolated and elongated. The life history
and habits of this insect, generally speaking, are similar to those
of A. vexans.

Mansonia perturbans Wlk. (Coquilletidia perturbans Wlk.) is a
large brown mosquito with a very irritating bite. Both tarsal
and abdominal segments have narrow white bands at the base
and the first tarsal joints have broad bands near the middle.
The proboscis has a broad white band in the middle also. This
species breeds only in permanent swamps. The larvae and
pupae differ from all others in that they remain at the bottom of
the pool, drawing their oxygen supply from certain plant roots,
etc. They are light in color and have a respiratory siphon shaped
like a bottle. The larvae of this species hibernate, attached to
roots, etc.; they are able to withstand freezing. According to

DISEASE-BEARING AMERICAN MOSQUITOES

i:;

Headlee, 1 there is only one brood a year, egg-laying starting when
many of the previous season's larvae are still small. The fact
that the larvae and pupae of this species get their oxygen from
roots under the water renders them invincible to oil. In the case
of this species, use of a larvicide is indicated.

Fig. 42. — Adult of Mansonia perturbans. (After John B. Smith, New Jersey

Agricultural Experiment Stations.)

1, adult female; 2, part of wing vein, showing scales; 3, anterior; 4, middle,
and 5, posterior claws of male tarsi. All are greatly enlarged.

Psorophora ciliata, Fabr., is one of the largest mosquitoes in the
United States. It lays its eggs in depressions likely to collect
water in time of rains. When the rains come, the eggs hatch out.
The larvae are very large, and feed entirely on the larvae of
smaller species, according to Dyar.

1 "The Mosquitoes of New Jersey and Their Control," New Jersey Agri-
cultural Experiment Stations, Bull. 276, 1915.

MOSQUITO ERADICATION
SALT MARSH GROUP

Aedes solliciUuis, Wlk., probably is one of the most troublesome
of the salt marsh mosquitoes. The thorax of this insect is
yellowish on top and the sides are white; broad white bands

Fig. 43. — Adult of Psorophora ciliata. (After John B. Smith, New Jersey

Agricultural Experiment Stations.)
1, adult female; 2, palpus; 3, anterior, and 4, posterior claws of male. All are
greatly enlarged.

encircle the proboscis and feet; and there is a yellow stripe along
the bottom and a white stripe along the top of the abdominal
segments. A. sollicitans breeds exclusively in the salt marshes,
but occasionally, wind conditions being suitable, it travels great

DISEASE-BEARING AMERICAN MOSQUITOES

Fig. 44. — Adult of Aedes sollicitans. (After John B. Smith, New Jersey Agri-
cultural Experiment Stations.)
1, adult female; 2, palpus; 3, anterior; 4, median, .and 5, posterior claws of the
male. All are greatly enlarged.

46 MOSQUITO ERADICATION

distances — sometimes, according to Headlee, 1 as much as 40
miles. The same writer says of it: "It is the greatest single
factor now operative in South Jersey in depressing real estate
values and preventing the proper development of that section
of the State." The larvae, of a grayish color, are large and have
a respiratory siphon only about twice as long as broad. The head
is unmarked. The antennae, sprouting from the sides of the
anterior part of the head, are not pendant. The scales form a

Fig. 45. — Adult of Aedes taeniorhynchus. (After John B. Smith, New Jersey

Agricultural Experiment Slatiojis.)
1, adult female; 2, anterior claws; 3, anterior; 4, median, and 5, posterior
claws of male. All greatly enlarged.

large patch on each side of the eighth segment. The race sur-
vives the winter in egg form in mud or damp earth. They are
able to withstand several months of dry weather, and develop
rapidly as soon as water covers them. Headlee 1 says that if the
water lasts only long enough for the larvae to turn into pupae,
the pupae will get enough moisture from the mud to enable them
to live long enough to reach the adult stage. He continues:
"Apparently, a considerable percentage of the eggs deposited

1 'The Mosquitoes of New Jersey and Their Control," New Jersey Agri-
cultural Experiment Stations, Bull. No. 276, 1915.

DISEASE-BEARING AMERICAN MOSQUITOES

Fig. 46. — Adult of Acdes cantator. {After John B. Smith, New Jersey Agricul-
tural Experiment Stations.)
1, adult female; 2, palpus, and 3, anterior claws of same; 4, anterior; .3, median
and 6, posterior claws of male. All are greatly enlarged.

MOSQUITO ERADICATION

during any one season fail to hatch during that season and remain
in the mud until the following one. By this provision of nature,
the salt marsh is always stocked with eggs, and the appearance
of the brood is a matter of water covering, high temperature and
the absence of fish."

Aedes taeniorhynchus Wied., is a small, black insect, with
narrow white bands around the proboscis, the bases of the
abdominal segments and the bases of the tarsal joints, except
the last, which is wholly white. The larva may be distinguished

Fig. 47. — Culex salinarius, female. (After
Howard.)

Fig. 48. — Culex salinarius, male.
Howard.)

(After

from that of A. sollicitans by the fact that the head is usually
slightly marked. Like A. sollicitans, and A. cantator, this mos-
quito does not breed in permanent marshes, but in temporary
pools of comparatively fresh water along the coast; usually, A.
taeniorhynchus selects less salty water than A. sollicitans. Other-
wise, the habits of A. taeniorhynchus are similar to those of
sollicitans, except that it is not believed to travel so far.

Aedes cantator, Coq., is a large, brownish mosquito with a hairy
thorax; the bases of both the tarsi and the abdominal segments
have a faint, white band about them. The head of the larva
has black spots; otherwise, the larva is similar to that of A.
sollicitans. A. cantator usually selects somewhat fresher water
than does sollicitans, but not quite so fresh as does taeniorhynchus,
its choice apparently being the "back pools," containing a large
admixture of fresh water.

DISEASE-BEARING AMERICAN MOSQUITOES 49

Culex salinarius, Coq., is very similar to C. pipiens, except
that it is somewhat darker and thinner. The larva is distin-
guishable from that of C. pipiens by the fact that it has a longer
breathing siphon, which tapers uniformly from base to tip.
This species, like C. pipiens, winters as an adult, eggs being laid
by gravid females in the spring; the eggs are laid in rafts, similar
to those of C. pipiens. This species occurs over the whole
Eastern part of the United States, breeding in permanent water
in the same way as pipiens, fatigans (quinquefasciatus) and
restuans. It is, perhaps, most common in fresh-water swamps
along the sea-coast but does not occur there exclusively.

CHAPTER III
DEVELOPMENT OF CONTROL MEASURES

HISTORICAL ASPECTS

For centuries, the origin of the mosquito-borne diseases was
shrouded in mystery. At times they were, in common with
other diseases, regarded as scourges sent by God to punish man.
Finally, during the Middle Ages, malaria was discovered to be a
definite disease, with definite symptoms and attributes. As
it was generally prevalent in low, swampy areas, where humid
mists and vapors arose, it is not surprising that the disease was
believed to be caused by this unhealthful atmosphere. From
this belief, the disease derived its name, mal being the Italian
word for "bad" and aria being the equivalent for "air."

Yellow fever was for many years considered as a form of
malaria, and only in comparatively recent times was it discovered
to be a distinct disease.

This belief as to the origin of malaria and yellow fever continued
until well into the nineteenth century, when here and there a
physician arose who, expressed the opinion that there was some
connection between malaria and mosquitoes. A great step
forward was made in 1880, when Alphonse Laveran, a French
army surgeon, announced the discovery of the malaria parasite
in the blood of persons suffering from malaria. In 1884, Laveran
joined the protagonists of the mosquito theory, but was unable
to offer definite proof as to the soundness of the belief.

Fifteen years later, Sir Ronald Ross, a British army surgeon
working in India, discovered the parasites described by Laveran
in the stomach walls of Anopheles mosquitoes which had been
allowed to bite persons infected with malaria, and demonstrated
that they underwent certain changes while in the body of the
mosquito. The life-cycle of the parasite was soon afterward
worked out and the whole course of the disease laid bare. Final
proof of the correctness of the theory of transmission was afforded
in 1900, when Manson and Warren were bitten in London by
infected mosquitoes forwarded from Italy, and shortly thereafter

developed malaria.

DEVELOPMENT OF CONTROL MEASURES 51

Flint having shown in 1868 that yellow fever was distinct
from malaria since its course was not affected by use of quinine,
Finlay, in 1882, announced his belief that the disease in some way
was transmitted by the mosquito. This theory was fully substan-
tiated in 1900-1902 by a board of U. S. Army medical officers,
who proved conclusively that Aedes calopus was the culprit.
Although the infective agent was not found, the discovery that
yellow fever, like malaria, is transmitted by the mosquito was
sufficient to make preventive work possible.

BEGINNING OF MOSQUITO CONTROL

The value of these two epoch-making discoveries was at once
apparent. Since both malaria and yellow fever were transmitted
in nature solely by mosquitoes, the only thing necessary to elimi-
nate both was to control the mosquito. This might be done
either by destroying the mosquito or by rendering it impossible
for it to get access to malaria or yellow fever patients — in
other words, by screening — or by a combination of both methods.

These discoveries meant, to put it in another way, that two of
the chief obstacles to man's conquest of the tropics could be
brushed aside. They meant that no longer could these scourges
of humanity defy all sanitary and medical measures. They
meant that great engineering works like railroads, canals and
other modern necessities of trade could be carried through to
completion anywhere in the tropics.

No delay took place in applying the newly gained knowledge.
The first great demonstration of its soundness was afforded in
1901, when Gorgas freed Havana, Cuba, from yellow fever in
3 months; the city had not previously been without yellow fever
for 150 years. In this classic campaign, both screening and
anti-mosquito methods were utilized.

SANITARY CONQUEST OF THE CANAL ZONE

But it was in the sanitation of the Panama Canal Zone that
Gorgas achieved his greatest triumph. Malaria and yellow
fever had disastrously defeated two attempts by the French to
complete the canal, so when the American government undertook
the great task, Gorgas was placed in charge of the anti-mosquito
work in the whole zone.

Within a few months, yellow fever was almost eliminated.
The last case in the City of Panama was reported in 1905, while

MOSQ 1'ITO ERA DICA TION

the last case in Colon occurred in 1906. Thereafter, yellow fever
was unknown in the Canal Zone.

Progress r in malaria control was slower but no less sure. The
following table 1 will show in an abbreviated form the very-
material reduction in the malaria morbidity and mortality rate
among Canal employes during the latter period of American
construction. The rates are subject to the qualification that they
are based on the number of names on the payroll and not on the
true average number of persons employed:

Year

Average
number of

Death from malaria

Hospital cases of
malaria

employes

Number

Rate per
10,000

Number

Rate per
100

1906

26,547

233

87.8

21,739

81.9

1907

39,343

154

39.1

16,753

42.6

1908

43,890

16.6

12,372

28.2

1909

47,167

11.0

10.169

21.6

1910

50,802

9.8

9,487

18.7

1911

4S,876

9.6

8,987

18.4

1912

50,893

3.9

5,623

11.0

1913

56 . 654

3.7

4,284

7.6

1914

44,329

1.6

2,886

6.5

1915

34 , 785

2.6

1,570

4.5

1916

33,176

0.9

493

1.5

ANTI-MOSQUITO WORK ELSEWHERE

The work at Havana and Panama gave a great impetus to
anti-mosquito campaigns in other parts of the world, and slowly,
but surely, one after the other of the great endemic centers of
yellow fever were cleaned up. Several of the large cities of
Brazil, for centuries known and recognized as foci of the dreaded
"yellow jack," were successfully attacked. In 1905, Belize,
British Honduras, was cleaned up, while in 1906-07 a successful
campaign was conducted in the British West Indies.

In 1905, an epidemic of yellow fever broke out in New Orleans.
Anti-mosquito measures were at once employed and the disease
was soon stamped out, with a total of 3,389 cases and 443 deaths.
This compares very favorably with the figures of the great epi-

1 "A Plea and A Plan for the Eradication of Malaria Throughout the
Western Hemisphere," Prudential Insurance Company of America, 1917.

DEVELOPMENT OF CONTROL MEASURES 53

demic of 1898 (before the manner of transmission of yellow fever
was known) in which there were 13,817 cases and 3,984 deaths.
One of the most important compaigns for the suppression of
yellow fever in recent years was waged in Guatemala in 1918
by the International Health Board. This campaign, directed
by Gorgas, stamped out the epidemic in a few weeks and elimi-
nated one of the last important endemic foci of yellow fever in
Central America. The report of the International Health
Board says:

"The outcome was especially gratifying and encouraging in that it
demonstrated that yellow fever could be controlled with the personnel and
facilities available in Central American countries and at a cost well within
their financial ability."

MALARIA CONTROL IN UNITED STATES

Following the successful campaign for the elimination of yellow
fever along the Gulf Coast and other parts of the South, the
attention of sanitarians throughout that section began to center on
control of malaria. The splendid results of the anti-malaria
campaign in Panama served as an example .of what might be
done, but the people were slow to grasp the situation. The fact
that elimination of yellow fever in the South had been brought
about more bjr isolating patients from mosquitoes than by eradi-
cation of mosquitoes in general obscured the public apprecia-
tion of the possibilities of malaria control. The bulk of the
people took the attitude that to attempt to eliminate mosquitoes
and malaria would be a waste of time.

As a result of this misconception of the situation, it was not
until several years had elapsed that anything very definite was
accomplished. However, in 1914, the U. S. Public Health
Service made an allotment of $17,000 for anti-malaria work,
and, within the next few years several valuable and far-reaching
demonstrations were carried out. The' results of a few of these
will be mentioned here.

INTERPRETING RESULTS

It should be pointed out that, in the following tables, the per-
centages of infection, as found by blood tests prior to commence-
ment of work, should not be considered as representing the total
of infections during the previous malaria season. These blood
test percentages should be regarded as merely that fraction of the

54 MOSQUITO ERADICATION

total number of persons infected who had not been able, either
by natural resistance or by the use of quinine, to banish the Plas-
modia from their systems. Thus at Roanoke Rapids, as will
be seen later, the blood tests in the fall showed 13.75 per cent of
the total population infected with plasmodia; during the mosquito
season, however, about 75 per cent of the total population was
infected, according to the health officer.

It should also be borne in mind, in interpreting the percentages
of reduction of persons reporting infection or illness (history index)
and of physicians' calls, etc., that what may seem like a heavy
remaining infection, despite a considerable reduction due to
control work, may be only recurrences of former infection. As
intimated in Chapter I, chronic cases may regain their acuteness
when the bodily resistance becomes disturbed or weakened,
without there being a new infection at all. Thus, the work may
be very effective and, indeed, prevent any new infection at all,
despite the fact that the history index and the records of physi-
cians' calls may still show quite a percentage of cases. These
chronic cases however, show a marked reduction year by year
when the work is kept up.

Owing to the difficulty of ascertaining in cases of protracted
illness whether the patient is suffering from one chronic infection
or repeated new ones, it has been found generally that compari-
sons of physicians' calls gives a better idea of the effectiveness of
the campaign than comparisons of cases. Just what the relation
of calls to cases may normally be is not definitely known. It is
believed, however, that in general, especially where the sickness
is wide-spread, physicians do not average more than two calls to
a case, and frequently not that.
EARLY UNITED STATES MALARIA CONTROL DEMONSTRATION

Roanoke Rapids, N. C, is a cotton-mill town in the northern
part of the state, having a population, including two nearby
mill villages, of approximately 4,100 in 1913. During the
summers of 1910, 1911, 1912 and 1913, according to the health
officer, 75 per cent of the people of Roanoke Rapids suffered
from malaria. During the same periods, this physician's visits
on account of malaria alone averaged about 50 a day.

Anti-mosquito work was begun under auspices of the U. S.
Public Health Service in January, 1914 and continued until
the end of the season of 1916. The following table 1 shows the

1 " Demonstrations of Malaria Control," U. S. Public Health Service, 1918.

DEVELOPMENT OF COXTROL ME AS CUES

.->;>

reduction in prevalence of malaria as revealed by blood examina-
tions, by house-to-house inquiry and by census of the sick,
together with costs of the work year by year:

1913

1914

1915

1916

Blood tests, per cent infected.

13.75

4.48

3.51

1.58

Per cent reporting fevers

46.60

33.00

19.10

16.70

Persons sick in bed, Oct. 1 . . .

200 . 00

1.00

none

Health officer's daily calls. . . .

50.00

1.00

0.33

Cost of anti-mosquito work.. .

$3683.41

$1233.20

$1237.31

Per capita cost of work

0.80

0.27

This big reduction in the incidence of malaria at comparatively
small cost aroused great enthusiasm among the mill owners,
who previously had suffered serious losses owing to illness of some
emploj^es and seasonal departure of others to escape malaria.
The following is taken from a letter written by the treasurer
of the Roanoke Mills Co. to Surgeon R. H. von Ezdorf: 1

"I will frankly admit that I could not realize what a great change
could be brought about by systematic work and with comparatively
little expense. The money spent in anti-malarial work here has paid
the quickest and most enormous dividends I have ever seen from any
investment, and, after having had our experience, I would, if necessary,
do the work over again if I knew it would cost ten times the amount."

DEMONSTRATION AT ELECTRIC MILLS, MISS.

Electric Mills, Miss., is a lumber town in northern Mississippi,
situated in a flat, rolling country with numerous surrounding
water-courses. The mill physician said that during September,
1912, 95 per cent of all sickness for the month was due to malaria
and that only two white families in town had not been afflicted
with it.

Anti-mosquito work was commenced in May, 1914, by and
under the direction of Assistant Surgeon General H. R. Carter
of the U. S. Public Health Service. The following table 2 shows
the reduction in incidence of malaria year by year, and the cost
thereof :

1 "Demonstrations of Malaria Control," U. S. Public Health Service, 191S.

MOSQUITO ERADICATION

1913

1914

1915

1916

Blood tests, per cent infected i 11 .76 1 3.79

Mill physician's cases yearly 144 .00 85 . 00

Cost of anti-mosquito work $725 . 50

Per capita cost of work 1.21

70.00

$143.80

0.24

1.46

A This blood test was made in May, 1914, but, as it represents the situation
before control work started, it is placed under 1913.

CO-OPERATIVE DEMONSTRATION AT CROSSETT, ARK.

Crossett, Ark., is a lumber town in the low part of the state.
The population in 1916 was estimated at 2,029. Work was
started there in May, 1916, under a co-operative arrangement
between the U. S. Public Health Service and the International
Health Board. The reduction in the incidence of malaria and
costs for the years 1916-17 are given in the tollowing table 1 :

1915

1916

1917

Blood tests, per cent infected 9.43 2.61

Physicians' visits for malaria 2 , 502 . 00 741 . 00

Cost of anti-mosquito work ! $2 , 506 . 40

Per capita cost of work 1 . 24

277.00

,275.45

0.63

In 1917-18 further demonstrations were made in Hamburg,
Lake Village, Dermott, Monticello and Bauxite, Ark. The
reduction of calls for malaria ranged from 78.4 to 97.4 per cent
and the per capita costs from $0.46 to $1.45.

WORK OF ST. LOUIS & SOUTHWESTERN RAILROAD

During 1916, steps were taken by the St. Louis & Southwestern
Railroad to undertake measures for the control of what had been
observed to be an undue incidence of malaria among its employes.
It had been found that during the preceding 4 years, about 25
per cent of all admissions to the hospital at Texarkana had been
for malaria, an annual average of 640 cases having been treated
for about 5 days each; this was equivalent to about 4 per cent of

1(< Malaria Control: A Report of Demonstration Studies,"and "Malaria
Control; Results Obtained by a Local Community," U. S. Public Health
Service, 1917 and 1918.

DEVELOPMENT OF CONTROL MEASURES

15,000 employes, and did not include such cases as were treated
by local physicians. An appropriation of about $3,000 was
made for the purpose of initiating anti-mosquito measures,
which were begun, in co-operation with the U. S. Public Health
Service, at Tyler, Lufkin and Keltys, Tex., early in 1917.

Calls for

Malaria

before and after Contro

Work Started

tfeor in which

work began

13 printed in

/TAUCS

rvj

■■■.

§ 1 §

$ iS 5:

$ 5 s>

S 5> s

HAMBURG

1916 ^■■■■■■■■■■■1

■■■

— ,^

^__

/S/7 ■■■

1918 f

LAKE VILLA

I9I7B1

1918 W

DERM OT T

1917 tallllllllM

/3/SPI

MONT/CELLO

r^Y^Y^T^Y^T^Y^^^^^^^^^^

1917 ^■IIIIIMMi

/9i8m

UX/TE

HIM _ J

1917 ■■■■■■■!

!9I8 ■■

1
9

-4

■

-•

S 1 §

1 fc s

Q c g

<s <i 5

^ ?> £

<\j Rj <\j

Fig. 49. — Results of mosquito eradication campaigns at Hamburg, Lake Village,
Dermott, Monticello and Bauxite, Ark.

The following table shows the cases of malaria admitted to the
hospital at Texarkana from places where anti-mosquito work
was carried on in 1916 and 1917 respectively:

in lc.

1917

Number of cases admitted .
Per cent of decrease

13
59.4

58 MOSQUITO ERADICATION

At Tyler, the sale of physicians' prescriptions containing
quinine decreased about 49 per cent in 1917, as compared with
1916.

Results obtained at Keltys, where malaria formerly had been
severe, are particularly interesting. The manager of the lumber
mill there stated in 1917 that, had malaria prevailed to the same
degree as in 1916, the mill would have been closed about one-
half the time. The net loss of this to the railroad in freight
charges alone would have been about $30,000. l

The railroad prompted by the success of this demonstration,
considerably expanded its work against mosquitoes in later
years. In 1920, its appropriation for this work amounted to
$41,150, while $15,000 additional was appropriated by different
towns along the line under a co-operative plan for mutual malaria
protection. 2

In 1920, the Central of Georgia Railroad appropriated $14,000
for similar work. Several other interstate railroads are also
known to be contemplating making appropriations for this
work.

UNITED STATES ANTI-MOSQUITO WORK DURING WORLD WAR

In view of the heavy morbidity records of army camps in the
South during the Civil and Spanish-American wars, it was
deemed essential, when the United States entered the World
War in 1917, to institute, among other health measures, anti-
mosquito campaigns in the areas surrounding Southern military
cantonments, naval reservations, aviation camps, munition
plants, ship-yards and important war-industrial projects.

It was realized that the introduction of thousands of recruits
and of large forces of labor from areas in which the mosquito-
borne diseases were prevalent would produce new conditions at
and about towns in which this war work was carried on that
would make extra precautionary measures essential. In order
therefore, to provide complete protection, it was decided that
anti-mosquito campaigns should be carried on, not only within
the cantonments, ship-yards and war-industrial areas, but also
within an area a mile wide surrounding such war establishments
and towns near or in which they were situated.

In order to prevent conflict of jurisdiction, army and navy

1 Annual Report, U. S. Public Health Service, 1918, page 23.

2 Annual Report, U. S. Public Health Service, 1920, page 20.

DEVELOPMENT OF CONTROL MEASURES 59

organizations were placed in charge of the anti-mosquito work
within the war-project reservations, while the U. S. Public
Health Service was placed in charge of the work in the mile wide
territories outside of and surrounding the war project areas and
towns adjacent thereto.

"It was not known in advance," says LePrince, 1 "how many camps
were to be established, when or where they were to be located, nor what
force of trained engineers, foremen and labor would be needed; but it
was very apparent that as soon as each camp-site was approved, mos-
quito control measures and drainage operations should be expedited in
order to head off malaria transmission in that locality."

The result of the work was that the sick-rate from mosquito-borne
diseases was cut down to virtually nothing; what little malaria there was
consisted almost entirely of men already infected before reaching the
war-project areas. As LePrince 1 says, "The malaria sick-rate among
enlisted men in camp has been very much lower than it would have been
had the} r stayed at home."

FORTY-THREE WAR-PROJECT AREAS PROTECTED

This great anti-mosquito project was carried out by the Public
Health Service in 43 war-project areas scattered over 15 states.
The area protected covered 1,200 square miles; the population
protected included a civil population of about 1,750,000 and an
average, constantly-changing military and naval population
of 800,000. The total cost of the anti-mosquito work averaged
about $1.80 per acre of territory protected or about 54 cents for
each person protected. About one-third of this cost was met
by the communities involved.

This work was carried on at the following places in the South ;

Alabama — Sheffield, Tuscumbia, Florence, Anniston, Montgomery.
Arkansas — Little Rock, Lonoke.
Florida — Jacksonville.

Georgia — Macon, Augusta, Atlanta, Columbus, Americus.
Kentucky — Louisville.
Louisiana — Lake Charles, Alexandria.

Mississippi — Biloxi, Gulfport, Pass Christian, West Point, Hattiesburg,
Jackson.

North Carolina — Charlotte, Raleigh, Fayetteville, Wilmington.
South Carolina — Columbia, Greenville, Spartanville, Charleston.
Tennessee — Memphis, Millington, Nashville, Chattanooga.
Texas — Dallas, Fort Worth, Houston, San Antonio, Orange.
Virginia — Newport News, Petersburg, Alexandria, Portsmouth, Quantico.

•"Mosquito Control About Cantonments and Ship-yards," U. S. Public
Health Service. 1919.

60 MOSQUITO ERADICATION

POST-WAR MOSQUITO CONTROL

The brilliant results obtained through the war anti-mosquito
work of the U. S. Public Health Service acted as a great stimulus
to further efforts in this direction throughout the South. Many
of the towns in which these campaigns were conducted during
the war have continued the work ever since.

In addition to these and other towns, which conducted their
own work independently, and to the work conducted in many
towns along its lines by the St. Louis & Southwestern Railroad,
more than 40 towns and cities throughout the South initiated
campaigns in 1920 under a co-operative plan which included the
State Health Departments, the International Health Board
and the Public Health Service. This number was considerably
increased in 1921.

Approximately $280,000 was expended by various communities
in anti-mosquito work between July 1, 1919, and June 30, 1920,
according to reports received by the Public Health Service.
These reports were by no means complete, as they included only
those communities which were known to have been directly
influenced in carrying on anti-mosquito work by the activities
of the Service. They did not include many communities
indirectly persuaded of the importance of the work through
Service demonstrations nor thousands of individuals awakened to
the value of protecting themselves from mosquitoes and informed
as to practical methods of doing so.

THE SITUATION TODAY

The following statement, bearing upon the value of anti-
malaria campaigns, their progress and the recent notable change
in public appreciation thereof, by LePrince, 1 who has had direct
supervision of such activities of the Public Health Service since
they were first undertaken, is believed to be an accurate review
of prevailing sentiment along anti-mosquito lines in the United
States today:

"Malaria fevers cause an annual loss of efficiency each year in our
country that is appalling, and the communities that suffer lack interest
in public welfare. In many villages and towns, from 10 to 40 per cent
of the inhabitants are infected. Where such conditions obtain, the
community cannot and does not progress or develop normally.

1 Annual Report, U. S. Public Health Service, 1920.

DEVELOPMENT OF CONTROL MEASURES 61

"It has been definitely demonstrated that many of the localities so
affected can eliminate malaria at a reasonable cost and that the best
way of inducing the public to do so is to carry on carefully planned
demonstration campaigns in badly infected areas. The result of such
campaigns means a much larger annual income for the community,
the county, the state and the Federal Government. Preventive malaria
work is in reality a sound business investment. Up to 1913, no county
or state made any appropriation for malaria-control operations, although
the value of such work was proved 12 years previously.

CHANGE IN PUBLIC VIEW-POINT

"As a result of the malaria investigation work directed by the U. S.
Public Health Service, the public view-point has changed — villages,
towns, county and state officials, as well as business corporations and
railroads, now realize the extent of the large preventable financial loss
they incur each year, and steps are being taken by them to prevent it.
In 1913, one single demonstration control campaign was started.
In 1914, congressional appropriations permitted an allotment of $17,000
by the Service for malaria-control investigations. The people have been
watching the campaigns undertaken and, throughout the country,
they are becoming more and more interested in having their own com-
munity and state undertake this work.

"During the past fiscal year, 64 separate communities carried out
malaria-control campaigns, and appropriated $280,000 therefor. Nearly
all of these places will continue to maintain this freedom from malaria
by proper safe-guards, because they find it a good investment to do so.
This calendar year, 101 places are doing work under the supervision of
the Public Health Sendee, and have already appropriated about
$350,000 therefor. Several states, for the first time in history, have
made annual appropriations for malaria control and other states con-
template doing so. Two railroads are spending for malaria elimination
this year more than four times the Federal allotment referred to — their
past experience shows that it pays to do so.

GROWTH OF APPRECIATION

"Industries in infested areas report from 10 to 40 per cent increased
output after control measures are in operation. Chambers of commerce
report new industries establishing branches in towns where the elimina-
tion of malaria has rendered local labor more efficient, and factory
managers report that, since malaria-control measures were carried out,
there is a more steady supply of labor, that the quality of labor has
improved and the earning capacity of the laborer increased. Lumber-
mill corporations have willingly contributed from $1,000 to $10,000
toward local anti-malaria campaigns, and state it pays them well to

62 MOSQUITO ERADICATION

make such an investment. Because of the change of ideas concerning
the cause and possibilities of prevention of malaria, there is a marked
improvement in the method of screening of houses in malarial districts,
and the percentage of houses kept efficiently screened has increased
very largely. In sections where the hotels at sea-shore resorts were
formerly filled only in the non-fever season, the proprietors report, as a
result of malaria-control measures, they now have all the business they
can handle throughout the entire year.

"Considering the fact that a few years ago hundreds of communities
were seriously affected and with no apparent relief in sight, that the
public in general had no visible proof of the possibilities of malaria
eradication, and too large a proportion of our public was wrongly
informed regarding the cause of malaria, it is gratifying to note that this
year over a hundred of these same places have decided to finance
campaigns for malaria elimination. They have already appropriated
for this season's work nearly 20 times as much as the original annual
Federal appropriation, 1914-1917.

"It is even more encouraging to note that there is a strong demand for
state and county aid along these lines, and that such support has already
been given and has the approval of the public. What is also important
is that a large part of the public now realize that it costs them much
more to continue to suffer and support the financial loss caused by
malaria than it does to eliminate the disease from their community.''

ERADICATION CHEAPER THAN ENDURING MALARIA

LePrince's last sentence embodies a truth that should be
seriously considered by every community that suffers from
malaria. The demonstrations already described in this chapter
prove that the average town can free itself from malaria and
kindred mosquito-borne diseases and the annoyance of mosquitoes
for much less than it costs to endure them.

Estimates of the cost of an attack of malaria vary, but it is
believed that Van Dine's estimate of 6.42 adult days' loss of
time per average reported case is conservative. No matter what
the wage may be, the loss will be considerable. If to this loss
be added the loss occasioned by decreased efficiency, both before
and after the acute attack, the physician's bill and the cost of
medicine, it is apparent that the average cost of a case of malaria
will not be much below $15 or $20 and may be considerably
beyond the latter figure. In addition to this, there is another big,
though not apparent, loss occasioned by decreased efficiency of
those who have only comparatively slight attacks and do not
consult physicians.

DEVELOPMENT OF CONTROL MEASURES 63

It will easily be seen that, where the infection is at all
considerable, the annual loss to a community from malaria may
reach a very high figure. Take Roanoke Rapids for example.
It is asserted that during the malaria season, 75 per cent of the
population of 4,100, or 3,075 persons suffered from malaria. To
be conservative, let us say that only 25 per cent, or 1,025 suffered
from it. Again, instead of putting the loss resulting from each
case at $20, let us put it at $10. The annual loss, then, was
$10,250, nearly three times what the first year's cost of eliminat-
ing malaria was.

Take Crossett. Before work started, the malaria calls of
physicians totalled 2,502 in a single year; the year that work
started the calls totalled 741; the difference is 1,761 calls.
Assuming the physicians made two calls to a case, the reduction
effected by the anti-mosquito work was 880 cases. At $15 a
case, the monetary value of the work was $13,200. Yet the
actual cost of the work for that year was only $2,506.40.

Similar conclusions may be drawn from the facts given in the
accounts of the other demonstrations. And, as a rule, the costs
of the work are considerably less after the first year.

While local conditions are, of course, the determining factor
in regard to costs of anti-mosquito campaigns, it is believed that,
in the average town, the first year's cost should not, as a rule,
much exceed $1 per capita. If this be true, it is clear that it
will pay the community, on a dollar-and-cent basis alone, to
initiate anti-mosquito work if only one person out of every 15 or
20 be infected during the season. This, of course, does not take
into consideration such aspects of the matter as comfort, up-
building the health of the community, etc.

SOME TYPICAL CAMPAIGN COSTS

The following table gives the cost of anti-mosquito campaigns
conducted in towns that co-operated in the 1920 joint demonstra-
tion by the U. S. Public Health Service, the International Health
Board and the Health Departments of the States in which they
are situated: 1

1 Southern Medical Journal, April, 1921.

MOSQUITO ERADICATION

State and town

Area in

square

miles

Popu-
lation,
1920

Total cost

Cost per

square

mile

Cost per
capita

Alabama

Dothan

4.0
4.0
6.0
4.0
4.0
4.0

4.5
3.5
3.0
4.0

4.0

12.5

8.0

4.4
8.6
4.5

4.0
4.0
1.8
2.5
1.0

3.2
2.3

5.5

7.0
8.0
7.5

3.8

5.1

4.0
4.0
6.0
4.0
1.5
5.0
3.0
2.0
6.0
4.0
1.5
1.5
1.0
6.0

0.6
3.6

10,300
6,257
5,000*
1,000*
1,000*
3,500*

5,500
3,864
2,865
2.996

1,908*

11,555*

8,196*

21,782*
12,675
1,216*

5,055*

10,501*

1 , 050

3,007

411*

5,700*

2,100*

11,300*

2,211

5,000*

3,100*

3,060*
6,544

1,081
3,704
6,299
2,099
1,200*
2,741
4,723
1,258
5,060
2,348
1,250*
1,250*
900*
4,290*

1,635
840

$ 4,796.33
3,327.90
2,696.97
2,092.50
2,499. 15
1,882.45

2,355.85
2,190.00
1,660.00*
2,778.79

999. 85
3,984.36
4,452.02

4,775.36
9,040.00
1,420.00

3,059.69
3,412.49
2,019.09
1,540.26
1,088.60

8,972.98

4,980.00

10,052.19

29,400.00*
7,460.77
3,635.77

1,850.00
2,367.00*

1,539.56
799.05
3,775.00*
1,380.00*

315.00

2,250.00*

1,622.01

300.00

3,000.00*

1,863.15

414.00

302. 56

520. 00

889. 12

3,636.32
2,448.79

$1,199.00
832.00
450. 00
523.00
625.00
470.00

523. 00
626. 00
553.00
695.00

250. 00
318.00
557.00

1,080.00

1,052.00

315.00

765. 00
853.00

1,120.00
615.00

1,089.00

2,800.00
2,165.00
1,827.00

4,200.00
934.00
485. 00

485.00
465. 00

384.00
200. 00
627.00
345.00
210.00
450.00
541.00
150.00
500. 00
466.00
276. 00
202.00
520. 00
140. 00

6,050.00
679.00

$ 0.47

Eufala

0.53

Demopolis

Gantt's Quarry

Shelby

2.09
2.50

Mignon

0.54

Arkansas

Eldorado

0.43

Malvern

0.57

Searcy

0.58

Fordyce

0.93

Georgia

Cairo

0.52

0.34

Thomasville

Louisiana

Baton Rouge

Monroe

0.54

0.22
0.71

Bastrop

1.16

Mississippi

Tupelo

0.61

Columbus

Batesville

0.33
1.92

Charleston

Coffeeville

0.51
2.64

North Carolina

Greenville

Farmville

Goldsboro

South Carolina

Bamberg

Chester

Hartsville

1.57
2.37
0.89

13.30
1.49
1.17

Tennessee

Brownsville

Dyersburg

Texas

Alto

0.60
0.36

1.42

Athens

0.22

Bryan

0.60

Calvert

Groveton

0.66
0.26

Hearne

0.32

Jacksonville

0.34

Livingston

0.24

Navasota

0.59

Rusk

0.80

Trinity

0.33

South Groveton

Rock Creek Lumber Co.
Cameron

0.24
0.58
0.21

Virginia

West Point

2.22

Virginia Beach

2.90

Grand total

192.41

199,319

S155.845.32

$808.00

Grand average

$0.78

* Approximate.

It will be noted that at 32 out of the 45 towns the work cost
less than $1.00 per capita. Reducing the cost per square mile
to cost per acre, it appears that the average cost per acre was only
$1.26. Apropos of this, LePrince 1 says:

Southern Medical Journal, April, 1921.

DEVELOPMENT OF CONTROL MEASURES 65

"Investigations that have taken place during past years show that our
richest farms in the best part of our country are paying anywhere from
$2.50 to $10.00 per acre per year as a malaria tax. Now here are 200
square miles, where the cost per acre was $1.26.

"Public sentiment unquestionably is favorable to the control of
malaria by drainage on a big scale; and drainage, supplemented by fish
control and other measures is not only feasible, but it will be done
because it is what the people desire."

CHAPTER IV
INITIATING THE CAMPAIGN

NEED FOR STATISTICS

Although, in any community where mosquitoes are numerous,
their eradication solely as a source of annoyance is probably
well worth the cost of the campaign, it should be borne in mind
that in most communities the campaign is launched primarily
as a health measure, with the object of reducing the toll of
malaria and other mosquito-borne diseases.

Where such a campaign is under consideration, it is necessary
to have some figures of the incidence of the mosquito-borne
diseases in order to show the necessity for the campaign and thus
obtain the money required to conduct it. It is also advisable
to be able to show the reduction in disease resulting from the
work, so that the community will know that the expenditure was
a profitable one from a financial viewpoint.

In order to do this, the director must have at hand reliable
statistics covering the incidence of the mosquito-borne diseases
for one or more years prior to the initiation of the campaign,
as well as those covering the incidence of the same diseases during
the campaign. There must be some basis of comparison.

Of course, the residents of the community will be able to get
some idea of the efficacy of the work by the absence or presence
of mosquitoes in general. However, it is well recognized that
it may be possible to reduce malaria very considerably, and still
have numerous non-Anopheline mosquitoes present. While
anti-malaria campaigns as a rule include eradication of all
mosquitoes, it is well known that certain other common domestic
mosquitoes are much more difficult to control than the Anopheles.

COLLECTION OF STATISTICS

If the community is in a State where malaria and the other
mosquito-borne diseases are reportable or notifiable, records of
the past incidence of the diseases may be obtained from the
State Health Department, the Registrar of Vital Statistics or
other official source, If, however, the community is in a State

IXITIATIXG THE CAMP Aid X

where these diseases are not reported, it will be necessary to get
the figures from other sources. In this case, a beginning should
be made as far in advance of the date of opening of the campaign
as possible.

In an anti-malaria compaign with which the writer was
connected in 1920, no figures as to the incidence of malaria, were
available from official sources. It was, therefore, necessary to
get some figures from the physicians of the community as to the
incidence of the disease during the preceding 2 years.

Owing to the difficulty, in cases where the illness was pro-
longed, of determining whether the patient was suffering from
one original infection or successive ones, it was considered
preferable to obtain from the physicians figures as to their calls
and consultations for malaria rather than as to cases.

Accordingly, each physician of the community was called on,
the situation explained to him and a blank left with him, to be
filled out promptly with data covering his malaria practice for
1918 and 1919 and returned to the director of the campaign.
The blank form is reproduced below.

FORM NO 1 .

1920.

, Director,

Anti-malaria Campaign.
Dear Sir: —

In compliance with your request, I am giving below a summary of malaria
calls made by me during 1918 and 1919. Asterisks indicate that the
figures are approximate only.

Number of Calls for Malaria

Month

1918

1919

1920

White

Colored

White Colored

January

February

March

April

May

June

Julv

August

September

October

November

December

M.D.

MOSQUITO ERADICATION

Each physician was left a number of postcards upon which to
report monthly the number of calls he had made upon persons
suffering from malaria within the area of operations. These were
entered, as soon as received each month, in the 1920 column of the
No. 1 form sent in by that physician. In this way the efficacy
of the control measures each month was visible at a glance.

To get the total for the town, each physician's figures by
months for the years 1918 and 1919, and also for 1920 as they were
received, were added together on another blank similar to Form
No. 1, thus giving at a glance the situation for the town as a
whole.

Where other mosquito-borne diseases are a factor, statistics
regarding them should be collected also.

In cases where it is impracticable to obtain the desired infor-
mation from the physicians of the community, a house-to-house
malaria census may be taken. This method probably will not
be so accurate as the method of obtaining figures from the
physicians for obvious reasons, but will serve as a basis for
comparison.

The following malaria census card is suggested as suitable for
use in ordinary cases:

FORM NO. 2
Malaria Census

(city)

(date)

Head of House Address No. in Family

How Long in City Previous Address

House Screened Condition of Screens

Potential Breeding Places on Premises

Malaria History

Years

Cases in
family

Deaths

Supposed
origin of
infection

Total
days
time
lost

Total

calls of

physician

Re-
marks

INITIATING THE CAMPAIGN 69

Where practicable, data for the 2 years previous should be
obtained; if this is not possible figures for the preceding year
will do. At the conclusion for the season's work, a second census
should be taken, using the same card for the same house and
recording the second results below the first. This will show the
comparison in incidence for each family, before and after initiating
the work.

THE SURVEY

As soon as it has been determined by means of the collection
of statistics relative to the incidence of the mosquito-borne
diseases in the community, that an anti-mosquito campaign
would be justified, the next step is to make a survey of the pro-
posed area of operations, with a view to ascertaining the probable
cost of such a campaign. If at all possible, this should be done
by a sanitary engineer familiar with costs of this kind of work.
Frequently State Departments of Health will send an engineer
to make such a survey gratis.

The following suggested mode of procedure in making the
survey and estimate is taken from the instructions issued
sanitary engineers engaged in the co-operative anti-malaria
demonstration work of the U. S. Public Health Service and the
International Health Board:

"Assuming that it is concluded, from information gathered, that the
making of a survey is worth while, obtain, if available, a map of the area
involved or make a copy of an existing one. If none has been pre-
viously made, you will make a sketch map as you proceed. (Maps
generally may be obtained from the city authorities; if not, an insurance
map may be borrowed from a fire insurance agent.)

"On this map, mark all water-courses, swamps, ponds, ditches, wet
lands, land subject to overflow and other wet places or possible sources
of mosquito-breeding. On flat lands, make inquiry as to how long water
stands thereon in wet periods; look for vegetation that is indicative of a
high water table. Let the map extend to about half a mile from the
residences on the outskirts of town.

WHAT TO OBSERVE

"It is next necessary to note the ditching and filling and clearing or
regrading (of streams and old ditches) that is essential and that which
will probably be necessary. It is not advisable to make estimates for
ditching from observations immediately after rain-storms. The infor-
mation must be carefully gathered; the character of soil, amount of

MOSQUITO ERADICATION

roots to be encountered, extra ditches to care for seepage outcrops,
widths of ditches or streams, etc., must be considered in estimating
costs. Go along each water-course and its branches, estimate the
lengths by pacing, mark them on the map and note at the same time your
estimated cost of such brush-clearing, regrading, ditching, etc., as^is
necessary, step by step. Where ponds, marshes and other wet places
necessitate the installation of new ditches, indicate them on the map,
and enter in your notes the extent and cost of each.

(Photos by E. B. Johnson, C.E.)
Fig. 50. — Brushing streams. The objects are to improve fish control, facilitate

inspection and eliminate shade.

"On flat territory during dry periods, it is frequently difficult to judge
of the amount of water that may stand intermittently on the land, and it
is advisable to note the character of the vegetation and make frequent
inquiry of the native population. If you can get a man well acquainted
with the locality to accompany you, so much the better.

"When the mapping of all breeding-places and collections of water is
concluded and the data collected, sum up the different classes of excava-
tion, brushing, etc., and make an itemized statement thereof to accom-
pany the report of the survey. Determine the local cost of kerosene and
oil, delivered, find out, if necessary, what transportation could be ob-
tained from the town for oil distribution, ascertain whether ditches and
soil would warrant use of a ditching plough, what size ditching gang is
necessary and what number of men will be needed for oiling and main-
tenance (of ditches and streams). As a rule, the brushing (clearing) of
one bank of a ditch (or stream) is sufficient for oiling and inspection
purposes."

INITIATING THE CAMPAIGN

THE ESTIMATE OF COST

When the data mentioned have all been collected, work on the
estimate may be started. The instructions already quoted
provide for estimation of the costs of brushing streams or existing
ditches (one side only) clearing streams or existing ditches
(clearing channel of obstructions, connecting pools in stream
bod, etc.) and of new ditching, as follows:

FORM XO. 3

Waterway

Length,
feet

Brushing,
feet

Clearing,
feet

Ditching,

feet

A-l

A-2

5,000

1,000

750

475

230

4,600
200

1.000
250

B-l

per lineal foot .

475
230

Totals ....
Average cost
Cost

7,455

4,800
.01

$48 . 00

1,250
.03

$37 . 50

705

.05

$35.25

Note. — A-l, A-2, etc., indicate branches of Ditch or Stream A shown on
map. The lineal foot costs, given above for the sake of illustration, should
by no means be taken as applicable to all conditions.

The above estimate gives the cost of the new work necessary —
in other words, the construction cost.

The next thing required is an estimate of the maintenance
cost for the season — that is, the cost of keeping the ditches,
streams, etc., in shape. This consists of keeping grass, weeds,
floating matter and other obstructions out of them. Owing to
the great variations encountered, due to differences in topography,
soil, precipitation, etc., it is impossible to give any general rate
for this work.

The next thing that requires attention is estimation of the
cost of the oil that will be needed and the cost of applying it,
including transportation. Some general information on oiling
jobs is given in the chapter relating to oiling.

The cost of control by means of fish should next be calculated.
This is variable, according to local conditions and the scope of
the work. It should include costs of collection, aquaria, distri-
bution, protection, pond and stream cleaning, etc.

72 MOSQUITO ERADICATION

If the campaign is to include screening, the probable amount
of the work should be figured out and an estimate of the total
cost made. Figures on screening costs may be found in the
chapter on screening.

Individual jobs of magnitude should be listed next. They
may comprise such measures as filling holes and other odd jobs.

A sufficient allowance should be made for cost of tools and
equipment. This can generally be estimated as soon as the
size of the labor force is decided upon.

Another item to be considered is cost of general direction and
inspection for the season. This should include wages and
salaries of the director, inspectors, clerical help, etc., and cost
of any transportation furnished them for directing or inspection
purposes.

Then, to provide for unforeseeable factors, such as floods,
long-continued bad weather and the like, a contingency fund
should be allowed for. The writer usually estimates this at 10
per cent of the total cost of the work.

These various items should be combined into one general
estimate, which would be approximately as follows for a cam-
paign in a typical small town.

FORM NO. 4

Brushing, 44,800 lineal feet at 0.01 $ 448.00

Clearing, 21,250 lineal feet at 0.03 637 . 50

Ditching, 17,705 lineal feet at 0.05 885.25

Maintenance, 77,455 lineal feet at 0.005 387.28

Oiling, 5,000 gallons oil at 0.10 500.00

Applying oil, 1 man 4 months at $90 360.00

Hauling oil, 1 horse and rig, 4 months at $50 200 . 00

Fish control, 1 man 4 months at $90 360 . 00

1 horse and rig, 4 months at $50 200.00

Aquatic plant removal at Smith's Lake 100.00

Individual jobs, cutting brush and weeds at marsh 180.00

Filling big hole at Jones and Brown streets 75 . 00

Tools and equipment, 2 sprayers at $12.50 25.00

10 picks and 10 shovels 40.00

5 faucets for oil-barrels 2 . 00

Miscellaneous articles 25 . 00

Inspection, 1 inspector 8 months at $100 800 . 00

Total $5,225.03

Contingency fund, 10 per cent 522 . 50

Grand total $5,747.53

INITIATING THE CAMPAIGN 73

Note. — It is presumed here that one man with a horse and rig will be able
to do both the oiling and fish work, giving about half of his time to each.
For this reason, the total engagement of 8 months for the man and the horse
and rig is split up into 4 months at oiling and 4 months at fish work.

Figures here given for the sake of illustration should in no way be relied
upon as unit costs for work.

QUESTIONS OF POLICY

With the survey completed and a careful estimate made as
above outlined, the next step is to get the money for the cam-
paign, but before efforts are made in this direction, a definite
policy as to what part of the cost of eradicating breeding places
on private property should be met 'by the property-owner or
tenant and what part should be defrayed out of the anti-mosquito
fund must be decided on.

This question must be definitely settled at this point, because
it is a certainty that a very large portion of the work required
will be on private property. If the public funds are to be spent
without restrictions on private property, the entire amount of
the estimate should be asked for. If, however, private property-
owners are to be compelled to do their own work, the sum required
for the prosecution of the campaign will be greatly lessened. It
will, of course, be necessary to put the public property, such as
streets, parks, municipal grounds, etc., in shape and keep it in
shape, as well as to maintain an adequate inspection force, but
most of the heavy items, such as drainage, oiling, etc., will be
eliminated.

In most of the demonstration projects with which the writer
has been connected, it has been customary to do at least a part
of the work necessary to prevent breeding on private property.
In some cases, everything was done without cost to the property-
owner; in others, the cost of drainage, etc., was charged up to
them, but oiling, fish control, etc., were free; in still others,
routine oiling, fish control and drainage were free, but property-
owners were expected to look after their own cisterns, fish-ponds
and other special breeding places.

There are many angles to this question, which must be care-
fully thought out. The average property-owner does not want
to bother himself with drainage, inspections, oiling, etc. nor can
he be depended upon to do such work thoroughly. And too
many prosecutions will arouse antagonism toward the campaign

74 MOSQUITO ERADICATION

SUGGESTED POLICY TOWARD PROPERTY-OWNERS

It is the belief of the writer that some sort of compromise is
best. It would appear to him that oiling, fish control and other
routine measures rendered necessary by the presence of natural
streams, etc., by rains or other causes not due to the fault of the
property-owner should be carried out by the city forces without
cost to him. On the other hand, he should be compelled to
remedy any condition originating through his negligence,
the continuance of which would cause extra work to the city
forces, such as letting his drain pipes leak and form a pool under
his house, having unscreened or untreated water-barrels about,
letting his pond grow up with aquatic plants so as to impede
control by fish, failing to do necessary drainage work bearing
a reasonable relation to the value of the property, etc. In case
of failure to do the work after reasonable notice, it should be
done by the anti-mosquito forces and its cost charged up to him.

It is not suggested that there be adopted a set rule in the matter
under consideration, since all sorts of situations are bound to
arise which cannot be forseen. The director should be left a
certain latitude to meet these situations. Thus, it would be
unreasonable to ask the owner of a tract of swamp land on the
outskirts of town, worth, say, $5 an acre, to spend $25 an acre to
drain it. There must be power to co-operate and a willingness
to meet the situation on a fifty-fifty basis. On the other hand,
unless there is some general policy determined upon, there is
danger that too much will be asked of willing citizens, while
the unwilling ones get the benefit of the work without having
done their "bit."

RAISING FUNDS

Assuming that a definite decision is made along the lines
suggested by the writer, and that the estimate has been made
accordingly, the next step is to get the money. This should be
obtained preferably from the city, since the work is for the benefit
of all citizens alike. Furthermore, protecting the health of its
citizens is one of the first duties of a municipality.

The first step is for those interested in the matter to put it
before the city authorities. The incidence of the diseases
locally, the large economic loss they cause and the saving to the
community in dollars and cents in eradicating the diseases should
be fully outlined. If possible, the City Health Officer and the

INITIATING THE CAMPAIGN 75

leading physicians should handle the references to the incidence
of the diseases, while the director or a sanitary engineer of the
State Department of Health should vouch for the estimates and
recount achievements against mosquitoes elsewhere.

At the same time the proposed anti-mosquito ordinance should
be submitted with a request that it be adopted. 1

As soon as the matter has been presented to the council, a
publicity campaign should be started with the object of bringing
home to the tax-payers the advantages of the proposed work,
so that they may intelligently indicate to the council their desires
in the matter. Newspaper articles, illustrated lectures and
other methods of publicity should be among the measures used.

By the time the council meets again, a good delegation of
citizens should be prepared to go before it and urge making of
the appropriation and adoption of the ordinance. If the money
is available, and the council sees that the citizens want the
campaign, there should be no further difficulty.

However, as is frequently the case, the council may be in favor
of the campaign, but may not have enough money available,
especially if the appropriations for the year have already been
made. In this case, it may be possible to have the council
adopt the ordinance and appropriate as much as is available,
provided enough money can be obtained elsewhere to meet
the estimate.

In this case, the protagonists of the campaign will have to
raise the balance from other sources. This is generally practi-
cable, if the publicity work has been effective, so that the people
really know what is proposed. The writer has found that
county authorities, chambers of commerce, women's clubs,
individual citizens and corporations and even church and
fraternal organizations will contribute liberally for anti-mosquito
work, provided they are convinced: (1) that the project is
feasible; (2) that it is economically advantageous; and (3) that
the persons proposing it know what they are talking about.

HANDLING THE FUNDS

Once the balance is raised, it should be turned over to the
proper city official, to form, with the sum appropriated by the
city, the anti-mosquito fund. The director of the campaign
should have absolutely a free hand in expending this money

1 An approved anti-mosquito ordinance is printed as Appendix B.

76 MOSQUITO ERADICATION

and in conducting the campaign generally, although, of course,
all payments should be made by the city disbursing officer.
The agreement made by the U. S. Public Health Service, the
International Health Board and the State Health Departments
of the States which participated in the malaria-control demonstra-
tions, with the towns in which the demonstrations were made,
provided as follows with reference to handling of the anti-mos-
quito fund:

"It is understood that the city's appropriation will be made available
not later than March 1, in a lump sum, to be known as the 'Appropria-
tion for Malaria Control Work.' It will be deposited in a local bank and
be subject to draft by the Mayor as provided for below.

(a) "The city council or commissioners will empower the Mayor or
other local authority to issue drafts against the appropriation account,
upon certification by the Sanitary Engineer or other duly accredited
officer.

(b) "All bills and vouchers will be presented to the Sanitary Engineer
for his certification for payment. This certification will be made only
after the accuracy of the time-books and bills has been verified.

(c) "The salary of the inspector and the wages of other employes will
be determined from time to time, and will be submitted to the Mayor
for his approval.

(d) "Changes in the salaries of any of the employes will be made only
upon recommendation by the Sanitary Engineer.

(e) "A financial statement will be made at the end of each month by
the Mayor or his legal representative to the city council or board of
commissioners and to the Sanitary Engineer.

(/) "All accounts will be kept in a multiple column cash-book furnished
by the city, and each item will be charged to its appropriate item number
as given in the estimates of the Sanitary Engineer.

(g) " Drafts for the payment of laborers will be issued by the Mayor or
his legal representative, after certification by the Sanitary Engineer, and
for all money paid to them the local inspectors and laborers will be
required to sign receipts in duplicate, one copy to be retained in the
office of the Mayor and the other given to the Sanitary Engineer."

OBTAINING CO-OPERATION

The financial details all settled, the next step is to make arrange-
ments with property-owners in so far as possible for co-operation
in conducting the campaign. In almost every town, the rail-
roads, street and road departments, industrial concerns and
many individuals with large mosquito-breeding problems will

INITIATING THE CAMPAIGN

be glad to co-operate in a large measure to make the campaign
a success.

In connection with this feature of the work, Derivaux 1 says:

"Public works, and more especially railroad construction operations,
have long been notorious for their incidental contributions to malaria
hazards by creating conditions favoring the development of Anopheles
mosquitoes. Among these conditions may be mentioned: Badly
located and undrained borrow-pits, at times uninterruptedly traversing
thickly settled communities; improperly cut right-of-way ditches

Fig. 51.

(Photo by E. H. Mayooii, C. E.)
-Leaky railway water tower. Mosquitoes bred here in abundance
before control work started.

that have not been provided with outlets; improperly placed culverts
and crossings, installed possibly with a view to saving a few feet of pipe
or yards of masonry, but preventing the off-flow of normal and storm
waters and at times interfering with an entire system of natural surface
drainage; inadequate pro vision for drainage behind or through embank-
ments and fills across valleys, resulting in the impounding of water or
interference with the normal off-flow of a natural watershed; installation
of leaky water-towers or failure of provision to carry off their over-flow."

It appears well to summarize in some detail the steps which
railroads can take in dealing with the mosquito-borne diseases.
Derivaux 2 suggests the following:

(a) "Old Construction Conditions. — Correction or alleviation of
Anopheles-breeding and malaria-producing conditions created in

1 "The Relation of the Railroads in the South to the Problem of Malaria
and Its Control," U. S. Public Health Service, 1918.

2 "The Relation of the Railroads in the South to the Problem of Malaria
and Its Control," U. S. Public Health Service, 1918.

MOSQ UI TO ERA DICA TION

connection with previous construction by: Drainage or filling of borrow
pits and low areas where practicable; proper provision for drainage
(in a sanitary sense) behind embankments and fills across valleys;
replacing to true gradient of culverts where necessary; drainage or other
provision for care of over-flow waters at tanks and towers; clearing of
weeds and refuse at regular intervals (supplemented by oiling, if needed)
from right-of-way ditches, especially in and adjacent to settlements.
(b) "New Construction Conditions. — Consideration of sanitary features
in connection with new construction works ; that is prevention or correc-
tion of conditions menacing the health, especially of settlements and

****** -iMm

*:m . 1 a*

*Lr.

■

» • ^*, • - .

Fig. 52. — A culvert properly placed; it is neither too low nor to<

can form about it.

high. Xo pool

communities. To this end, consultation should be had with the sani-
tary or medical departments before construction is begun. Preference
should invariably be given to sanitary works which will influence as
large a number of individuals as possible."

OTHER POSSIBLE SOURCES OF AID

The same considerations apply, in large measure, to street
and road departments.

Industrial plants often, through carelessness or ignorance,
cause conditions favorable to mosquito-breeding. Cisterns and
fire-barrels may be unscreened or untreated, water may be
allowed to enter under the buildings, drainage may be neglected,
processes that may with little cost be modified may cause
abundant breeding.

Private individuals may have large problems in swamp areas,
in swimming, recreation or fish ponds, cess-pools, etc.

In all the above-mentioned cases, the director should call on

INITIATING THE CAMPAIGN 79

•
the person in charge, point out the necessity of complying with
the anti-mosquito ordinance, make suggestions as to the best
methods to follow, give, if desirable, some idea of the cost and
offer free supervision. In case the problem is one of considerable
magnitude, in relation to the value of the property, it may not
be amiss to offer to participate in doing the work.

It has been the writer's experience that, in most cases, people
will voluntarily co-operate along the lines indicated, if the matter
is properly placed before them. In cases where they will not,
prominent local persons may exert pressure upon them. If
this fails, the only alternative is prompt prosecution.

PLANNING THE WORK

When the above-mentioned canvass of the situation is com-
pleted, the director of the campaign will have a pretty good idea
of what work he will have to do — that is, how much drainage,
oiling, etc., will have to be done by his own forces. The next
step is to lay plans for doing it seasonably and effectively.

It is a good idea to start the actual work early. In the Public
Health Service demonstrations in the South, it was generally
the rule to begin active work by March 1 or shortly thereafter.

In planning the work, it should be remembered that work
which will benefit the largest number of people should be done
first. Hence, problems in the center of town should ordinarily
be tackled before those on the outskirts.

As a general rule, drainage should be completed as early as
possible, since the earlier it is done, the less will be the amount
of oiling required. Furthermore, with the direction of the drain-
age gang off his hands early, the director will have more time for
inspection and supervision of oiling and fish control just as these
matters are becoming of greater importance.

If active work is to start by March 1, enough laborers should
be put on, if practicable, to complete the drainage work in not
more than 3 months, since, by June 1, the director will have
enough other problems before him to keep him busy.

If there is much drainage to do, two or more gangs of laborers
should be organized, each gang having its own foreman. In
this way, it is possible to compare the work of each gang, so that
poor men may be weeded out. The principle of competition
or rivalry also may be utilized in this way to hasten the work.

At the same time, an inspection, oiling and fish control service

MOSQUITO ERADICATION

should be instituted, the size depending upon the amount of
of work and the area of operations. Generally speaking, this
service should be organized in such manner that immediately
an inspector discovers some situation which needs remedying,

Fig. 53. — Above, large pool of stagnant water, affording an ideal breeding-
place for mosquitoes. Below, same pool drained.

the appropriate action is taken without delay, be it emergency
drainage that is required, weekly oiling or stocking a place
with fish.

PERSONNEL

Generally speaking, the man in charge of the drainage work
should have had some experience as a labor foreman, preferably

INITIATING THE CAMPAIGN 81

in earth-work. This does not mean, however, that he will not
need careful drilling in the objectives, methods and management
of anti-mosquito drainage work. He should also be given some
idea as to the costs of this class of work.

For the first few weeks at least, the director himself should
lay out the ditches. He should also frequently inspect the work
to assure himself that money is not being wasted by divergence
from his instructions.

It is the inspection staff, however, that should be picked with
the utmost care. An inspector must be tactful, honest, energetic ;
he must also have a good working knowledge of mosquito eradi-
cation in general, so that when he uncovers a breeding place, he
will know at once what measures to take in dealing with it,
whether to drain, oil or stock with fish. He should also be able
to identify at once any of the disease-bearing mosquitoes.

If the inspector is not tactful, he will get the campaign "in
wrong;" if he is lazy and dishonest, he will lie as to conditions;
if he does not understand the work, he will increase costs and
reduce the efficiency of the campaign. It is imperative to get
good men for this work. Such men as described are not picked
up everywhere. Generally, the writer has had to train his own
men; but it is essential that they be made of the right material.

LePrince 1 says:

"The success of the work will depend very largely on the ability and
personal interest taken in the work by the inspector or foreman in
charge of the oiling and the oiling squad. There must be one reliable
and active person held responsible for the efficienc}' of the field work.
He must go to all possible production areas at frequent intervals and see
and know that the work is being satisfactorily performed, that no known
places are missed, that no mosquito larvae reach the pupal stage of
development and that places needing attention are promptly attended
to. A knowledge of the local conditions of topograph} 7 and possibilities
of water being retained in any locality during unusually wet seasons
is essential. When the pools, ditches and stream-beds become drj',
they must be re-inspected after showers, as some of them may retain
water in pools and need attention. This frequently happens in out-of-
the-way places. The inspector must never assume that everything is
in a satisfactory condition, but must go and see and be certain of it."

In regard to laborers, LePrince adds :

1 "Control of Malaria: Oiling As an Anti-mosquito Measure," U. S.
Public Health Service, 1915.
6

82 MOSQUITO ERADICATION

"In all mosquito control work, it is economy to select intelligent
laborers, who take an interest in the work, and to pay them a higher
wage as they become skilled. The extra pay is saved many times over
in results and saving of material as compared with the work of untrained
labor. The man who notes at a glance whether oil-drips he sees are
working properly and goes out of his way to remove an obstruction in
a stream, because he knows it may save extensive re-grading, and attends
to other apparently trivial but important details, is worth two ordinary
laborers. Incompetent laborers are apt to increase operating expenses,
and are careless about using oil properly. The work to be done may
be scattered over a relatively large area, and the inspector cannot watch
the men closely. His work is of such a character that he must often
leave his laborers and devote his time to inspection."

MATERIALS AND EQUIPMENT

As soon as it is definitely known that a campaign is to be put
on in any community, the director should immediately take steps
to order his materials and equipment.

Arrangements should at once be made for an adequate supply
of oil. Frequently this may be obtained from local concerns,
such as railroads, ice-plants, oil refineries, pumping plants,
oil-wells, oil dealers etc. If possible, it is generally preferable
to get it from local sources, since this may result in lower charges
for freight and also may obviate the necessity of arranging for
storage. If obtained locally, it usually may be delivered a few
barrels at a time as needed. Should this be impossible, however,
or should very large quantities be needed, it probably would be
preferable to buy from the refinery direct, the oil to be shipped in
tank or carload lots. In any event, a definite contract, with
optional amounts stated, if necessary, should be entered into,
so that there will be no possibility of having the supply give out
at a critical time.

Equipment should include enough sprayers and drip cans to
handle any situation that may develop. The sprayers should
be ordered early, like the oil, as it may take some time for them
to reach the seat of the campaign. Enough tools should also be
bought locally for the drainage gang.

CHAPTER V
ADMINISTRATIVE ASPECTS OF THE CAMPAIGN

MOSQUITO-BREEDING ABOUT HOMES

While in previous chapters something has been said of the
breeding habits of the various species of common American mos-
quitoes and of the necessity for careful inspection, it is desired
here to emphasize the fact that, in the average inland town, the
people themselves raise most of the mosquitoes that afflict them.

It has been the writer's observation that it is a comparatively
simple matter to eradicate Anopheles mosquitoes, which, as has
already been pointed out, breed mostly in ditches, pools and
other natural breeding places. But when it comes to eliminating
breeding of house mosquitoes, the director of the campaign has
a man's job on his hands.

Yet, even though the campaign is primarily a health measure-
that is, directed in the first instance against malaria-bearing
mosquitoes — it must nevertheless include suppression of all
mosquitoes to be considered a success by the people who put up
the money. The average person regards mosquitoes as mos-
quitoes, and he would be very apt to consider as "phony" any
malaria reduction figures if he did not notice a corresponding
abatement in the numbers of house mosquitoes.

Yet these average persons are, as intimated above, frequently
responsible for the presence in the community of more mosquitoes
than all the pools, ditches, swamps and streams in flight distance.

The writer has repeatedly found homes in which mosquitoes
were breeding abundantly in 10 to 20 different breeding-places.
There would be a number of tin cans containing water scattered
about different parts of the yard; a rain-water barrel or two;
a non-mosquito-proof cistern; a couple of pools under the house
caused by leaky pipes or drip from the ice-box; an uncovered
cess-pool; a water-trough for stock; and, perhaps, stopped-up
roof gutters. And these cases were not in the slums or the negro
quarter; on the contrary, they were often at the homes of the
leading people of the community.

The writer once received a complaint from the wealthiest

MOSQUITO ERADICATION

woman in town. She had been one of the principal factors in
raising money for the campaign and had taken great pains, as

(Photo by E. H. Magoon, C. E.)
Fig. 54. — View of a home-yard in which 21 potential breeding places were
found, 17 of them actually containing larvae.

she thought, to keep her home in shape. Yet, upon brief
investigation, he found mosquitoes breeding abundantly in five
different breeding places — the cellar, which had partly filled

(Photos by E. H. Magoon, C. E.)
Fig. 55. Fig. 56. Fig. 57.

Fig. 55. — Inspector finds larvae in the inevitable rain-water barrel at the
home of a southern darky.

Fig. 56. — He prevails upon the lady of the house to pour some kerosene into
the barrel to kill the larvae.

Fig. 57. — And to keep the barrel covered thereafter, so that mosquitoes can-
not lay any more eggs in it.

with water after a heavy rain, a large private swimming-pool,
an old, forgotten, defectively-covered cess-pool, a choked-up
roof gutter and an old well, not then in use.

ADMINISTRATIVE ASPECTS OF THE CAMPAIGN

In many Southern towns, parts of the negro districts are not
supplied with city water. In these cases, the negroes either
have shallow wells or else haul water for drinking purposes,
which is generally kept in barrels. Each of these conditions
give rise to a problem of considerable magnitude.

PLANNING THE INSPECTION SYSTEM

The only way in which the conditions above-mentioned can be
overcome is by means of a rigorous system of inspection of

Fig. 58. — Septic tank with screening rotted away — an ideal breeding place for

Culex pipiens.

premises. This should be coupled up with the inspection of
streams, marshes, etc., in the outlying area in such manner that
every spot in which breeding may, by any possibility, take place
be visited once a week or once every 10 days at most.

In planning the inspection work, the community, if large,
should be divided up into inspection areas, with an inspector in
charge of each. If the town is small, perhaps one inspector
can handle it. It has been the writer's experience that one
inspector, doing nothing else, should be able to handle from 30
to 50 average residential blocks, covering the whole area thor-
oughly once a week or once every 10 days. Inspection of the
outlying area — pools, streams, ponds, etc. does not take nearly
so long comparatively as inspection of premises.

MOSQUITO ERADICATION

The inspector should be equipped with a long-handled dipper,
preferably of white enamel, and a small hand mirror, to facilitate
finding larvae. The dipper is used to dip up water from pools,
barrels, etc., for closer scrutiny. The mirror is used to reflect
sunlight upon the surface of the water, so that larvae may be
easily spotted whether at the surface or in the depths. According
to Parham, 1 it was found that one inspector, equipped with

(Photo by E. H. Magoon, C. E).
Fig. 59. — Inspector looking over tub of old bottles and tin cans for mosquito-
breeding.

dipper and mirror, could cover territory requiring four inspectors
not so equipped.

In dealing with conditions found by the inspectors, the
following procedure has been found effective:

On his first covering of his beat, the inspector should take his
time. He should explain his mission to the occupants of the
houses he visits, point out any actual or potential breeding
places, insist politely that they be done away with immediately
and leave an anti-mosquito leaflet. 2 If he sees any condition

1 Naval Medical Bulletin, vol. 15, No. 2, April, 1921.

2 A suggested anti-mosquito leaflet is printed as Appendix C.

ADMINISTRATIVE ASPECTS OF THE CAMPAIGN 87

that he considers should be handled by the anti-mosquito forces,
such as a big pool in a street ditch that needs draining, emergency
oiling to prevent early hatching of a large number of pupae,
etc., he should make a note of it and, on arriving at the office,
should transcribe these notes on appropriate slips of paper made
out somewhat as follows:

FORM NO. 5

Work Order

Date

To Foreman

Location

Work needed

Inspector

The work described above has.

Date

Foreman

These work orders are then gone over by the director and
turned over to the appropriate foreman, be it oiling, fish control,
drainage or maintenance. The foreman to whom it is turned
over performs the work, if the situation requires it, in any
case making a report on the matter in the space left for that
purpose.

Should such action be desirable, the inspector may take a
malaria census, as described in Chapter IV, while covering his
beat for the first time. While it would require some extra time
to do this, the valuable information gained probably would be
worth it.

HANDLING THE NEGLIGENT CITIZEN

On his second trip of inspection, the inspector, wherever he
finds breeding going on through fault of the occupant; of the
premises, should leave a formal notice. A form more or less
similar to the following has been used successfully by the writer:

88 MOSQUITO ERADICATION

FORM NO. 6

CITY OF

OFFICIAL NOTICE

192

To.

You are herewith notified that a mosquito breeding-place exists on your

premises Street, in violation of the City Ordinances.

This mosquito breeding-place is a

You are respectfully advised that you have three days in which to abate
the mosquito breeding-place above mentioned. Failure to do so within the
three days will render you liable to a fine of from $1 to $25 and costs.

Each day that the breeding-place exists, after the three days mentioned,
constitutes a separate offense, under the City Ordinances.

Director, City
Anti-Mosquito Campaign.

The above form is the formal notice required by the ordinance
before prosecution may be initiated. At the end of the 3 days,
the inspector should return to the offender's home. If the work
has not been done, he should consult immediately with the
director of the campaign with a view to laying a complaint.

If a charge is laid, it is necessary that the inspector be on
hand at the proper time to testify. Until he knows his inspectors
thoroughly, it is expedient that the director himself view the
spot to make sure that the situation falls within the scope of
the ordinance, that the inspector has given the notice and that the
demand made is not unreasonable, as, for example, suggesting
expensive drainage work when the situation can just as well be
handled by inexpensive fish control.

Streams, ponds, ditches, pools, etc., which the anti-mosquito
forces are oiling or otherwise working should, of course, also be
carefully inspected weekly and, should any breeding be found,
the inspector should at once report it to the director for appro-
priate action. This has a tendency to keep the workers on the
alert.

COMPLAINT BUREAU

While engaged in co-operative malaria eradication demon-
stration work in Texas, the writer tried out the idea of opening
a complaint bureau. It was considered that this would afford

ADMINISTRATIVE ASPECTS OF THE CAMPAIGN

a good clue to areas in which breeding might be taking place
unknown to the anti-malaria personnel. It was also believed
that the knowledge that poor work would soon be revealed to

|pr" '

^SH

.'■-.'" 6

. "~« .

■■to* '

■^ ^Tn -Mtf

R^kMs

(Pftoto 6{/ £. tf. Magoon, C. E.)
Fig. 60. — Surface cisterns placarded by inspector. Such cisterns make ideal
breeding-places, when, as is usually the case, they are not mosquito-
tight.

the director by sufferers therefrom might stimulate the inspection
staff. Both of these beliefs materialized.

The system followed was repeatedly to outline the plan through
the newspapers, requesting all residents suffering from mos-

(Photo by E. II. Mogoon, C. E.)
Fig. 01. — Inspector dipping for larvae in a borrow-pit.

quitoes to any considerable extent to file complaints, either by
telephone or personally with the anti-malaria office, but not
until each complainant had first thoroughly inspected his own
premises.

90 MOSQUITO ERADICATION

A number of blanks were printed on which to take down the
complaints. These blanks were somewhat as follows:

FORM NO. 7
Complaint

Date

Complainant

Address

Suspected Source of Breeding

Found

Address

Action Taken.

Date Inspector

As indicated by the form, these complaint cards were turned
over by the director to the appropriate inspector, who then
investigated the complaint and reported back what he had found
and what action he had taken.

On the whole, the writer was very well satisfied with the
operation of the complaint bureau. It unquestionably had a
good effect in revealing breeding-places that the anti-malaria
forces were not aware of and also in stimulating the inspectors.
It also helped convince the people that sincere and conscientious
efforts were being made to keep down domestic mosquitoes and,
at the same time, did much to teach them to keep their premises
in shape, since, in a very high proportion of the cases, the com-
plainant himself was found to be raising the mosquitoes.

One slight disadvantage was that people occasionally would
make complaints for which no basis could be found — that is,
no breeding places could be located in the vicinity and neighbors
would report that thej r had noticed no mosquitoes. In such
cases, the time spent in trying to trace down the supposed
breeding-places was wasted. Another disadvantage of the plan
was that it led people to expect too much; often, they would file
a complaint on the strength of having noticed only a single
mosquito.

ADMINISTRATIVE ASPECTS OF THE CAMPAIGN

PUBLICITY

Properly got-out publicity is probably one of the greatest
helps the director of an anti-mosquito campaign can have. If
must be remembered that, in its larger aspects, the whole work
is more than anything else an educational endeavor. If this
be true, the educational end of it is really more important than
the reduction of mosquitoes and should, accordingly, be given
the attention it merits. Even on selfish grounds, the people
should be taught to protect themselves since, in this way, the
work of the director and the expenses of the campaign are
correspondingly decreased.

(Photo by E. H. Mogoon, C. E.)
Fig. 62. — Top of underground cistern, in which breeding was very abundant
until a few Gambusia were put in it.

In much anti-mosquito work, it is customary to cease publicity
activities, once the funds have been raised, but this is a mistake.
The publicity designed to get the money should be but the
beginning.

It has been the practice of the writer to keep up a steady flow
of publicity from the time the work is first broached to and
beyond the end of the campaign. Thus, as soon as it was defi-
nitely decided that the campaign was to be put on in a town, he
would explain the scientific facts upon which the work is based,
refer to the great success of similar work in Cuba, Panama and
elsewhere and then recount the local problems and the methods
to be used in handling them.

Then, as the work progressed, he would issue statements as to
the progress being ^rnade, the percentage of drainage completed,
the formation of an oiling gang, its mode of functioning, the

92 MOSQUITO ERADICATION

appointment of inspectors, their duties, habits of Gambusia
(the anti-mosquito fish), establishment of aquaria, stocking of
streams and ponds, etc.

Accounts of prosecutions should be brief, but complete, with
no comment.

TEXTS FOR ARTICLES

Texts for articles from time to time may be found in discoveries
of unusual breeding-places, decrease in incidence of mosquito-
borne diseases as reported by the physicians, compared with
previous years, statements by prominent local persons as to the
reduction of mosquitoes, comments by traveling men as to
conditions compared with other towns, visits by health officials,
etc.

The writer used to make a practice of issuing a statement
immediately after every heavy rain, advising citizens to look over
their premises, dump the water out of any collections of tin cans,
inspect their roof gutters, screen their rain-water barrels and
cisterns, etc. The articles would be arranged a little differently
each time, but the substance would be virtually the same.

Editors of the various newspapers are almost invariably
genuinely willing to co-operate in this way, taking the view that
the work is a public benefit for the town and worthy of being
"boosted."

A few points, however, should be borne in mind in dealing
with the editors. They are usually busy men and have little
or no time for long-drawn-out conversations. When the director
has occasion to consult with them, he should be brief and to the
point. For the same reason, the director will stand a much
better chance of getting his publicity matter "over," if he will
write it out himself, than if he asks the editor to write it.

In form, the articles should be short and snappy. Rarely
should an article reach half a column in length. Generally, they
should not run more than a quarter of a column. Nor should
they have long, involved preambles. The very first sentence
should uncover the root of the whole business. Long, technical
words should be avoided. Write the article "as though you
were telling it to the policeman."

Another important point to be remembered is that the articles
must contain no disagreeable references to any person. No
comment should be made in regard to any one. Nothing will

ADMINISTRATIVE ASPECTS OF THE CAMPAIGN 93

get one "in wrong" with an editor quicker than ill-considered
references to local persons or institutions.

OTHER METHODS OF OBTAINING CO-OPERATION

Other methods of obtaining the co-operation of the public in
eradicating mosquito-breeding are summarized by LePrince 1 as
follows :

1. "Short talks, direct to school children, showing them how mos-
quitoes are produced in water-containers and asking them to inspect
the back-yards every Saturday morning and empty or oil stagnant
water.

2. "At West Point, Miss., the Mayor sounded the fire siren every
Saturday morning at 9 o'clock as notice to the town folks to go out into
the house-yards and eliminate containers breeding mosquitoes and also
to put a little kerosene into the closet and flush it to get a good oiling of
the Culex pipiens producing sewer ditch.

3. "At Bastrop, the children in the school were asked to look after
their own back-yards. At the end of the season, the teachers asked
each child what he or she had done, and about 92 per cent had helped
in the campaign.

4. "A composition by each pupil on the way to eliminate mosquitoes,
with the best ones published in the local press and one or two small
prizes offered by Chambers of Commerce for the boys and by women's
clubs for girls will help. Don't forget to advertise the progress in the
local paper.

5. "The motion picture houses are generally willing to show notices to
the public without cost, and a few new ones each month will keep up
interest in the work. Radio mat slides are used in preparing these
notices, and cost about $3.00 per 50."

DAILY REPORTS

A complete record of every activity of the anti-mosquito Ibices
should be kept, together with full cost data as to the different
kinds of work. These records should be kept, not only to account
for the money spent, but also to form a basis for estimates for
work in future years or in other places.

Each foreman should be required to submit a daily report of

1 Circular No. 10, Office of Malaria Investigations, U. S. Public Health
Service, April 6, 1920.

MOSQUITO ERADICATION

his work. The experience of the writer has been that it is
impossible for the majority of foremen properly to fill out a
report form that is at all complex. With the average foreman,
about all that can be expected is a record of the number of men
he has and the amount of their time, together with a short
statement of the work accomplished, and even these simple
data will have to be carefully checked.

The following form, and slight modifications of it, have been
used by the writer for several years for all kinds of mosquito
eradication work:

FORM NO. 8

. Foreman
Time Summary

Date

No.

Classification

Hours
worked

Hourly
rate

Amount

Remarks

Foren
Labor

lan. .

er. .

Team
Drive

or truck . .

r. .

Work Summary

Kind of work

Where

Lineal feet
done

Square feet
done

, , Gallons
stocked ., ,
... _ , oil used
with fish j

Foreman
The inspectors also should make out a general report daily,

ADMINISTRATIVE ASPECTS OF THE CAMPAIGN 95

in addition to the notices, etc., mentioned in an earlier part of
this chapter. A form, more or less similar to the following, is
suggested :

FORM NO. 9

Inspector's Daily Report

Date

Number of houses inspected this date

Number of houses found raising mosquitoes

Kinds of mosquitoes

Other places inspected

Other places breeding mosquitoes

Kinds of mosquitoes

Number of official notices issued

Number of prosecutions attended

Number of work orders issued

Remarks

Inspector

These reports will provide some interesting information as to
the progress of the citizens in keeping their homes in shape.
After the campaign has been in progress for a few months, it
will be found almost invariably that, as a result of the educational
work, the ratio of houses visited to houses found raising mosqui-
toes will show a great improvement.

RECORDS

There should, of course, be a complete record of expenditures
of all kinds, and entries in this should be made immediately the
expenditure is made or authorized. This record should prefer-
ably be of such form that the kind of work to which the expendi-
ture is to be charged is clearly apparent.

The following form was used by the writer for several years.
It may be modified to suit the occasion :

MOSQUITO ERADICATION

FORM NO. 10
Expenditures Record

Ending .

Payee

For

what

Order
No.

Amount

Date ap-
proved

Date
paid

Charge
to

Re-
marks

In case any of the bills, payrolls or other entries should include
sums chargeable to two or more different things, such as a com-
bined drainage and inspection payroll or a bill for equipment for
both oiling and fish-control work, such sum should be appro-
priately divided between the two kinds of work and explanation
made under the heading of "Remarks."

Taking the sums expended from the expenditures record and
the quantities of work done from the daily reports of the foremen
or other sources, the director is then able to assemble his cost
data for the different kinds of work. Thus, at any time, he can
add together his expenditures on drainage work — payrolls and
material — as recorded in the expenditures record, add up his
figures of work accomplished from the drainage foreman's daily
reports (or, better yet, accurately measure the work done) and
learn just what his drainage is costing him per lineal foot or other
unit. The same can be done with maintenance, oiling, fish-
control, individual jobs, etc.

On work with which the writer has been associated, it has
usually been customary to do this work every month, as a basis
for the monthly reports required.

It is suggested that separate records of this kind be kept for
the following activities:

Activity Charges to be Included

Supervision Salaries of director and clerical help, if any;

transportation of director.

Inspection Salaries of inspectors; transportation, if any.

Drainage Payrolls of laborers and foremen; materials.

Maintenance of drainage Labor payrolls.

Oiling Cost of oil; transportation; labor payrolls.

Fish-control Labor payrolls; transportation.

Miscellaneous Equipment and other miscellaneous expenses

ADMINISTRATIVE ASPECTS OF THE CAMPAIGN 97

The records of malaria calls made by physicians, described in
Chapter IV, should also be gone over carefully each month, and
any physicians delinquent in reporting should be seen without
delay, since it is imperative, for effective comparison that
complete and accurate figures be obtained.

MAPS

As stated in an earlier chapter a map of the community in
which the work is to be undertaken should be obtained and, if
practicable, several copies should be made of it. A scale of 1
inch to 200 feet or 1 inch to 400 feet is recommended.

(Photo by E. H. Magoon, C. E.)
Fig. 63. — Mosquitoes were breeding abundantly in a little water in the old
kettle clinging to the bank. There was no breeding in the stream itself, how-
ever, owing to the activities of larva-destroying fish.

On one copy of this map, there should be marked all the topo-
graphical features of the community bearing on mosquito produc-
tion, as found during the survey. As old ditches and channels
are cleared (re-channeled), as new ditches are completed, as
marshes are drained, as holes are filled up, as ponds, culverts,
streams, etc., are stocked with fish, as oil stations are organized,
they should be indicated on the map in an appropriate manner,
either by the use of symbols or otherwise.

98 MOSQUITO ERADICATION

One complete copy of the map should be kept in the office of
the director for reference. One, on which places that require
oiling and oil stations, etc., are indicated, should be given the
oiling foreman to assist in working out an oiling schedule.
Another, showing places that may profitably be stocked with
fish, such as pools, streams, swamps, etc., should be given the
fish-control foreman. Another, showing the ditches, etc., should
be given to the ditch maintenance foreman. Each inspector
also should be provided with a copy of the map, with each
one's precinct indicated thereon.

CHAPTER VI
INLAND DRAINAGE

IMPORTANCE OF DRAINAGE AS AN ANTI-MOSQUITO MEASURE

Drainage is one of the most reliable and permanent methods of
mosquito control. Where there is no water in which the mos-
quito eggs may develop, there can be no mosquitoes, and when
once a place is properly drained, it should remain in good shape
for a considerable period, with a certain amount of maintenance.
Unless the anti-mosquito work is a mere temporary expedient,
therefore, drainage will play a large part in it.

The term "drainage," however, as applied to anti-mosquito
work, signifies a procedure somewhat different, as a rule, from
drainage for agricultural and other purposes. Such drainage
work, as a matter of fact, sometimes produces mosquito breeding-
places. For mosquito eradication, the land must not only be
properly drained, but the ditches themselves must be so designed
as not to become sources of breeding.

Drainage, as an anti-mosquito measure, may include any or all
of the following, and maintenance thereof: Ditching, open and
lined; sub-surface tile drains; vertical drainage; re-channeling
of natural water-courses; filling; diking; construction of tide-gates;
pumping.

The last three will be considered in the chapter on "Salt Marsh
Drainage," since it is in salt marsh work that they are generally
employed.

In addition to being a most effective measure by itself, drainage
frequently may be used to great advantage in connection with
fish-control, oiling and other procedures. Examples of such
cases are : Construction of a ditch connecting an isolated, Ashless
pool with water stocked with mosquito-destroying fishes, or low-
ering of a pond to reduce the area that requires to be oiled.

LIMITATIONS OF DRAINAGE

While drainage, in the long run, probably is considerably
cheaper than most other control methods, especially oiling, it

100 MOSQUITO ERADICATION

should not be employed without discrimination. There is no use
in going to a large expense in draining a pond that can be con-
trolled for much less money by stocking it with fish. Nor will
it pay to try to drain a swamp that can be protected at much less
expense by means of levees or dikes and tide-gates.

On the other hand, drainage has many advantages in addition
to its value as an anti-mosquito measure. Large areas of swamp
and marsh lands have been rendered cultivable by proper drain-
age. Furthermore, in many places in the United States today,

Fit;. 04. — Typical anti-mosquito ditching location.

the land is not producing what it should, because it is not drained.
For this reason, money spent on anti-mosquito drainage fre-
quently returns a double profit — it improves the health of the
occupants of the land and also increases the productivity of the
land.

Again, it often happens that the cost of draining swamp land
is more than paid for by the natural resources thereby rendered
accessible. Frequently, the lumber alone thus made available
is worth more than what the drainage cost.

PRELIMINARY WORK

Whether the project be large or small, it generally will pay to
study pretty closely the topography of the area. If the project
be large and the area involved be low and flat, sufficient levels
should be run to enable a contour map to be prepared; the main
ditch systems should be laid off accurately on the map and then be

INLAND DRAINAGE

101

located by instrument in the field, stakes being set at 50- or
100-foot intervals, with the cut at each stake marked thereon.

Even if the project is not large enough to justify this amount of
preliminary work — as will often be the case — it may frequently
be necessary in low, fiat country to run various lines of levels to
ascertain the fall available and the best location for the main
ditches.

Where the country is hilly or rolling, the eye alone may be

Fig. 65. — A common type of anti-mosquito ditch.

sufficient for open-ditch work, although in all cases of doubt, the
level should be used.

As a general rule, open ditches in anti-mosquito work need not
be graded with the accuracy of a sewer trench, though there
should be no low spots. With lined ditches and sub-surface
drains, however, this is not the case; stakes should be set for
these in all cases.

Owing to the fact that mosquitoes do not develop in standing
water for several days, anti-mosquito ditches do not always have
to be as large as ditches for agricultural drainage and other
purposes. Thus, if a ditch will carry off the standing water in

102

MOSQUITO ERADICATION

4 to 6 days, its capacity is sufficient, from a mosquito control
standpoint, although this may not be the case from the stand-
point of agricultural drainage.

TYPES OF INLAND DRAINAGE PROBLEMS

Once the area in which the campaign is to be undertaken has
been gone over, it will often be found that the problems to be met
are varied and numerous. Some breeding-places may be handled

(Photos by E. B. Johnson, C. E.)

Fig. 66. — Left, large cat-tail swamp fed by a spring; right, ditch dug to lead

water around the swamp.

best by means of fish-control; others best by oiling; and still
others best by drainage. The director of the campaign will have
to study each problem by itself and decide which is the best
method of dealing with it. In case of doubt, the method that
seems cheapest for that particular problem should be adopted.
After eliminating those places in which fish-control and oil may
be used to best advantage, a considerable number of places
generally will be left that obviously require drainage. In any
large project, these will, as a rule, be of several different types,
and hence will require different methods of treatment. Among
the different types of areas requiring drainage may be the follow-
ing: Temporary puddles, stagnant ditches, blocked-up streams,
borrow-pits, ponds, lakes and swamps.

INLAND DRAINAGE

103

Hill

Of these, the first three usually present no serious problems,
requiring simply open ditching or re-channeling.

Borrow-pits should be treated in accordance with conditions.
If fairly shallow and advantageously located, they may be
ditched; many are too deep for other than vertical drainage, and
may, perhaps, be stocked with fish or oiled. If they are to be
drained by ditching, the procedure is generally simple.

"It is when we come to ponds, lakes and swamps," says Metz, 1
"that the real problems arise,
and it is best perhaps to consi-
der these three together. Since
the difference between lakes and
ponds is only one of degree, and
since swamps may include either
or both of the other two, it is ob-
vious that, in actual practice,
little distinction can be made that
would involve different methods
of drainage. It is more impor-
tant to classify such areas accord-
ing to the sources of the water,
for, in this case, the distinc-
tions correlate with modes of
treatment.

PROBLEMS OF POND, LAKE
AND SWAMP DRAINAGE

"For instance, one pond or
swamp may be caused by the ac-
cumulation of rain-water and may
fluctuate greatlv with the sea- V

sons, another may be simply a F ™. 67.-Seepag^ outcrop, Case No. 1.

basin in the channel of a sluggish

stream, while a third may be fed from springs and may be bordered by

a seepage outcrop.

"In the first of these, the rain-water swamp, it is merely necessary to
provide a small channel to carry off the surplus water left after the main
flood waters have passed. As a rule, one or two ditches will suffice.

"In the second case, the situation is more difficult, for the water
supply is continuous and fluctuating. The swamp will vary in size
with high and low water in the stream, and a drainage operation of

1 "Some Aspects of Malaria Control Through Mosquito Eradication,"
U. S. Public Health Service, 1919.

104 MOSQUITO ERADICATION

considerable magnitude may be required to eliminate it . . . In case
drainage is decided upon, it will probably take the form of channeling
the stream below the swamp to lower the water and increase the
flow. . . .

"The third case mentioned — that of a swamp fed by a seepage
outcrop — presents the most difficult problem of all. Here we have,
not only an area of standing water, probably full of vegetation, but also
a series of tiny puddles in the form of hoof-prints, etc., along the outcrop
margin. Each of these is a potential breeding-place of the worst kind.
The treatment of such an area requires a special procedure, and, since
the proposition is one that is apt to be found in most any locality, it may
be considered in some detail.

TREATMENT OF SEEPAGE OUTCROPS

"Seepage water usually appears on the hillsides, etc., at the outcrop of
a stratum of water-bearing sand or gravel underlain by an impervious
stratum of clay, shale or other material. The outcrop may be in the
nature of more or less distinct springs or simply a gradual oozing out
through the soil. In either case, it is fed by a water-table below the
surface, and treatment must be aimed particularly at this water-table.
It does not suffice to dig ditches directly away from the springs and down
the hillside. Such a method would require a separate ditch for each
spot from which water is issuing, and would mean, in many cases, a
series of ditches about 12 inches apart along the whole hillside. The
only effectual way of collecting the water in such places is by means of
ditches dug at right angles to the flow of the seepage water, or, in other
words, across the exposed end of the water-table. Such ditches may
then be connected to one or more main ditches, if necessary, and the
water carried down the hillside parallel to the seepage flow. These
points are illustrated roughly in the accompanying sketches of actual
swamps.

"In No. 1, there was a seepage on both sides of a narrow valley, the
water coming out of two hills opposite one another, as shown in the
sketch. As a result, the bottom of the valley in this region was a
typical cat-tail swamp, with water from 1 inch to 2 feet in depth. Since
the source was somewhat up on the hillside, it was useless to dig a
ditch through the bottom of the swamp and down the valley. This
would simply carry off the deep water and leave the seepy marsh as it was.
Instead, a deep, narrow ditch was dug along the margin of each hill,
just at the upper edge of the seepage outcrop and at right angles to the
flow of the seepage water. In this manner, the water-table was inter-
cepted, and all the water that formerly oozed out down the hillside now
seeps into the ditch and is carried off. As a result, the swamp, no longer
fed from the hillside, has dried up.

INLAND DRAINAGE

105

DRYING UP A SWAMP

"In case No. 2, a more complicated situation is presented. Here the
seepage flow is from a large U-shaped bend in a hillside, resulting in a
swamp many acres in extent, with a small lake at the outer edge. The
water-table in this case extended clear across the swamp, but was con-
cealed along a slight elevation running down the middle. On account
of this elevation, it was necessary to drain the right and left halves of the
swampy area separately. As shown in the sketch, a ditch was put

HiM

^tiZF'XJ* ■"■■ - ■ ^2'/> Hal

^ Jfi?'- V~f/. :■ . n . . . • . • *- '^%.J ^

F 1G eg. — Seepage outcrop, Case No. 2. (A/«er .1/V/z.)

along the toe of the hill on each side at the upper margin of the outcrop
and then run off into the lake. But the water-table this time was too
deep to be intercepted entirely by one ditch, and it was necessary to dig
additional intercepting laterals at intervals lower down. On one side,
five such ditches, more or less parallel to one another and at right angles
to the seepage flow, were required to catch all of the water before it
came to the surface.

"In case No. 3, an outcrop on a relatively steep hillside is represented.
Here it was necessary to dig several intercepting laterals parallel to one
another and only a few feet apart in order to catch all of the flow.
When this was done over the area in which the seepage water was actu-

106

MOSQUITO ERADICATION

ally coming out of the ground, the remainder of the swamp lower down
the hillside became completely dry.

"In each of these cases, collection of the water depended upon the
ditches being constructed primarily as intercepting rather than con-
ducting ditches. In the case of swamp No. 1, the ditches happened to
be intercepting and conducting at the same time; but more often
separate conducting ditches must be constructed to carry off the water
after it has collected in the intercepting ditches."

>0r • jfcfr

m*\ '/W, !>W

Fig. 69. — Seepage outcrop, Case No. 3. (After Metz.)

DITCH CONSTRUCTION IN GENERAL

The open ditch is the type of ditching most frequently
employed in anti-mosquito drainage. While the first cost is
undoubtedly less, it is believed, however, that, over a period
of years, some more permanent type of ditch is cheaper, owing
to the more or less continuous maintenance expense that open
ditches require. Open ditches must be kept free from grass,
weeds, debris, etc., and the scouring action of the water in
flood-times must also be repaired.

Ditching may be required on firm, open land, where the expense
is at a minimum, or in wooded swamp areas, where the work
becomes costly and tedious. The methods, of course, will vary
with conditions; thus, on firm ground, machinery may be em-
ployed to great advantage; in swamps, dynamite may be cheapest.

In all cases, however, the following principles are applicable:

1. The ditches should be just as few as will answer the purpose.

2. Wherever possible, they should have clean-cut, sloping-
edges, narrow bottoms and straight courses.

INLAND DRAINAGE 107

To comply with the first principle mentioned, the main ditch
should, in all cases, be constructed first. Frequently it will be
found that laterals, which appeared to be needed before the main
ditch was dug, will not be required at all. If there is any doubt
as to the need for a lateral, it should not be dug.

In regard to the second principle, it may be suggested that, in
average soils, the slopes of the sides of the ditches should be
about 45 degrees; in sand and soft mud, the slope may be flatter,
while, in hard clay and rock, it may be almost vertical. The
bottoms should be made narrow so that, when the flow is small,
the water will have no opportunity to spread out and form pools.
Straightness of course, where the ditches are not laid out by
instrument, may be attained by use of a line, where necessary.
Branch ditches should join main ditches at acute angles or curves,
in order to lessen depositing of silt, sand, debris, etc., at the
junction point.

HAND DITCHING ON FIRM GROUND

Most anti-mosquito ditching is done by hand, probably
because most projects are too small to justify the purchase of
machinery. However, when machinery is available, it should
be used wherever practicable.

The chief tools needed for hand ditching are picks and shovels.
Where the earth is full of roots, a mattox will come in handy.
A tiling spade may be used for finishing off the bottom. Some-
times a hoe will prove valuable. The phosphate drag, a tool
somewhat resembling a potato-hook, only heavier, is useful
for cleaning out ditches or for general work in marshy land that
is full of roots.

In cutting ordinary ditches by hand, no great technical skill
is necessary. Common sense and ability efficiently to handle
men are the chief requisites. Upon beginning work, the ditch
should be laid out by means of lines, so that it will be dug straight.
The men then should be scattered out along the lines, a section
being allotted to each team of two men. As each team finishes
its section, it should be moved forward and given another section.

Constant vigilance is essential to see that the men keep the
bottom even — that is, avoid alternate humps and depressions.
Probably the best way to do this is to select two or three intelli-
gent men and assign them the job of finishing the bottom of the
whole ditch.

108

MOSQUITO ERADICATION

In cases where no instrument is available for checking the
accuracy of the bottom-finishing, water may be admitted to

Fig. 70.

(Photos by E. B. Johnson, C. E.)
Above, extensive swamp; below, ditch that drained it.

the ditch at its upper end and allowed to descend to the lower
end. Presence of pools will indicate a ridge or a depression, as
the case may be, and enable the finishers to correct their errors.

INLAND DRAINAGE

109

(Photos bu E. B. Johnson, C. E .)
FlG 7i._Above, pond caused by seepage from hill; below, ditch at base of hill,
intercepting seepage. Shortly after the ditch was completed the pond dried up.

110

MOSQUITO ERADICATION

If no water is available, the ditch should be inspected after the
first shower, and any corrections that may be needed made then.

COST OF ORDINARY HAND DITCHING

Anti-mosquito ditching is generally estimated on a lineal
foot, rod or mile basis, instead of a cubic yard basis. Costs,
of course, vary materially with the size of the ditch, the nature
of the soil, the rate of wages paid and the efficiency of labor.
For these reasons, it is impossible to give any exact figures as
to costs of hand ditching.

As a general proposition, it may be said that, with ordinary
soil, unskilled labor and wages from $2 to $3 a day, the cost of
the average hand-dug ditch should range somewhere between 2
cents and 5 cents a lineal foot. Swamp work, of course, will
greatly exceed these figures. The presence of large numbers of
roots and stumps also will increase costs.

The following figures represent approximate hand-ditching
costs on several jobs handled by the writer in the South, the
ditches having an average sectional area of from 2 to 4 square
feet and the ditch mileage on each job ranging from 4 to 10
miles:

Project

Wages

Cost per lineal foot

No. 1

No. 2

$3.00
2.50
2.50
2.00

0.056
0.027

No. 3

0.011

No. 4

0.023

HAND DITCHING IN SWAMPS

Ditching by hand in real swamp areas is tedious and costly
in the extreme. Where practicable, the ditches should be laid
out with lines and the men spread out as already described. In
some cases, however, this is not practicable.

In a large anti-mosquito swamp drainage project in Georgia,
with which the writer was connected, the earth was so soft that

INLAND DRAINAGE 111

pails had to be used to dump it out with, and the sides of the
ditches caved in as soon as any considerable depth was reached.
Laborers sank in the mud up to their hips. In order to make
any progress at all, it was found necessary to build a retaining
wall of poles on either side of the proposed ditch. Even then,
much of the mud would seep back into the ditch, so that it was
found practicable to excavate only a few inches at a time. The

(Photos by E. B. Johnson, C. E.)
Fig. 72. — Occasionally, it is necessary to ditch a slough. Here, a channel
3 feet deep and 4 feet wide was dug through the lowest part of the
slough.

ditch would then be left to dry out for two or three days, when a
few inches more would be dug. This kind of work may cost
from 25 cents to $1.00 per lineal foot.

Not all parts of a swamp will be as bad as this, of course, but,
wherever the earth is soft and sloppy, it is a certainty that the
costs are going to be high. Frequently, it is also difficult to
maintain an adequate gang of laborers under such conditions.

While costs of hand ditching in swamps will vary in accordance
with circumstances, it is believed that they will, on the average,
run several times as high as costs of hand-ditching on firm earth.

112

MOSQ UI TO ERA DICA TION

In the project above-mentioned, nearly 40 miles of ditches
were dug, a large proportion of them being in the swamp alluded

Fig. 73. — Above,
lagoon completely
cost less than $50.

(Photos by E. B. Johnson, C. E.)
lagoon that was a bad Anopheles breeding-place; below,
dried up. This was accomplished by a ditch that

to. The cost averaged $723.05 per mile or 13.7 cents per lineal
foot.

INLAND DRAINAGE 113

BLASTING DITCHES IN SWAMPS

A cheaper and much more satisfactory way of ditching in
swamp areas is by use of dynamite.

There are two distinct methods of blasting ditches — the pro-
pagated or transmitted and the electric. The propagated
method can be used only in wet soils, while the electric method
can be used in fairly dry, as well as wet soils. The explosives
and blasting supplies needed and the methods of loading vary
somewhat in the two methods.

Propagated firing requires only the explosive itself and a cap
and some fuse for each couple of hundred feet of ditch, while
electric firing requires wiring, an electric blasting cap for each
charge and a blasting machine or other source of current. This
advantage of the former method is sometimes offset, however,
by the fact that it requires nearly twice as many holes as electric
firing. Theoretically, both methods require about the same
amount of explosive; in practice, however, more will be used in
transmitted firing, unless the work is done very skilfully. The
economy of this method comes largely from a saving of electric
blasting caps and time and the need for little equipment.

MAKING TRIAL SHOTS

In blasting ditches by the propagated method, the first thing
to do is to try a few trial shots to determine the best depth and
spacing for the holes. For ditches up to 3 to 3^ feet deep,
the depth of the holes will generally be from 24 to 30 inches and
the spacing between holes from 18 to 24 inches, although it may
be necessary to change these figures slightly. If water covers
the cartridges in the holes, no tamping is necessary; otherwise
the cartridges should be well tamped with earth. Eight to ten
holes should thus be loaded for the test shots; one hole should be
charged with an extra primer cartridge, and it is also well to put
one additional in each hole adjoining the primer.

If the test shot makes too large a ditch, the spacing may be
increased a little, but should seldom be greater than 24 inches
and then only in warm soil. If the ditch is too deep, it will be an
indication that the depth of holes should be decreased.

Small ditches, say 2 feet deep and 3 feet wide, may be excavated
by using half cartridge charges, but in such case the spacing be-
tween holes should seldom be more than 18 to 20 inches. Larger

114

MOSQUITO ERADICATION

ditches may be obtained by using two or more cartridges to a hole
or by planting a second row of cartridges parallel to the first. In
this case, one electric cap should be used in each row of holes
or else an extra charge or two should be put in between the rows
to insure simultaneous detonation of all the charges.

After the test shots have been fired and the proper loading
and spacing for the material in question thus determined, the line
of the ditch should be laid out; if the area is forested, all trees of

Loading ^ Mow out a stump

-Fuse

^- Edge, of Proposed Ditrfi

■ /Paivi of dynamite

-/PorVS of dynamite

Edge of Proposed Difch

Lay -our far b/a sting ditch, hofes 6emq
Spaced /S" to 24-" a oar-t each
yray.

r Edqe of proposed ditrfi ^

\ __~~^ Dynamite

Section of Plant

Attac/ting cap to dynamite
Fig. 74. — Sketches showing details of blasting ditches by propagated method.

any size along the proposed ditch should be cut down and
removed. Then one man should make the holes with a crowbar
or shovel handle and a second should insert the charges. An
extra charge or two should be planted about large stumps, logs,
etc. Ordinarily lengths of from 150 to 200 feet may be dis-
charged at a time. The hole midway along this distance should
be fitted with a cap and fuse. When this fuse is ignited, the
concussion resulting from the explosion of this charge explodes
the other charges.

INLAND DRAINAGE

115

CLEANING OUT THE DITCH

The ditch resulting from the explosion will be rough and some-
what uneven in depth; occasionally, a few stumps and other
debris will roll back into it. To open it up and even the grade,
two to four men, equipped with phosphate drags and hoes should
follow the blasters, raking out the debris and removing the
humps. This work can be done in a comparatively short time,
and greatly improves the ditch.

Fig. 75. — Blasting ditch in tangled underbrush.

For electrical firing, the procedure is much the same. A few
trial shots should be made for determining the proper depth
and spacing of the holes. As an electric cap is used in each hole,
it is possible to space them further apart in the row than in the
case of propagated firing. The usual distances are 24 to 32
inches for small ditches and up to 48 and 52 inches for large
ditches and heavier loadings. After the charges are planted,
the blasting cap wire from each is connected with the loading

11G

MOSQUITO ERADICATION

wire from the blasting machine. The charges are then exploded
simultaneously by operating the machine.

For larger ditches, the loading may be in deeper holes and with
an explosive of greater strength, or parallel rows of charges may
be employed as already described in the case of propagated blast-

Duplet, leadinq ir/re h b/ashng machine
,s^ (Zonnecf/nq wipe, fo fead/hg tvtnz
fi/asf/bg cap iv/ms connecfed\^

i ^-' uiasnng cap nrrcs connt

-Grac/e qf proposed f//'/ch-

Primed dynamife.
cartridges

Fig. 76. — Loading for blasting ditch, having only a single row of holes, by

electrical firing.

ing. Where very deep ditches are needed, a wide shallow ditch
should be blasted first and then a row or two of holes should be
blasted in the bottom of this ditch.

75 (>/asHng machine.

Fig. 77. — Flan of loading for blasting a ditch, having 2 rows of holes, by elec-
trical firing.

ADVANTAGES OF BLASTING DITCHES

The personnel required for blasting ditches is small. One
laborer should make the holes, another distribute the dynamite
in them under the direction of the foreman, a third and fourth
transport the dynamite to the scene of the blasting and a fifth
and sixth clean out the ditch after the blasting. An experienced
blaster should be in charge of the work.

Under favorable conditions, the work may be carried on at the
rate of 100 to 200 feet per hour by the propagation method with
the crew indicated above, omitting from consideration, of course,
any preliminary clearing that may be required.

Costs of ditching by dynamite vary, of course, with the
character of the soil, size of the ditch and number of roots and
stumps. At six different extra-cantonment jobs in 1918, costs
per lineal foot were: 13, 14, 28, 18, 12 and 33 cents. Wherever
comparisons with hand ditching in swamps were made, it was the
consensus of opinion that blasting was cheaper. 1

1 Transactions of The First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

INLAND DRAIXAGE 117

MACHINE DITCHING

The various types of ditching and trenching machines may be
divided into four general classes, as follows: (1) plows and scoops;
(2) wheel excavators; (3) endless-chain excavators; and (4)
scraper excavators.

For construction of open, V-shaped ditches — the usual type of
anti-mosquito ditch — only the first two classes are generally
used. The endless-chain excavators, designed chiefly for
digging trenches for installation of pipe, which are filled up after
the pipe is laid, usually cut a narrow and, where necessary, a
deep ditch, with vertical banks. Owing to the possibility of
frequent cavings, a trench of such a shape does not, as a rule,
make a satisfactory open ditch.

The scraper excavator is designed chiefly for digging very large
ditches or channels and does not appear to be suited for the type
of ditching usually required in anti-mosquito work.

The last two types of trenching machines, therefore, are,
generally speaking, of value in anti-mosquito work only when the
use of tile drains on a large scale is contemplated or when a
very large excavation, as a new channel for a stream, is
required.

Plows and scoops are usually drawn by horses or mules or
tractors. Almost all of them are lacking in any device for cutting
accurately to grade, thus requiring some hand-work to make the
bottom smooth. There are many types of these implements,
ranging from devices designed primarily to loosen up the earth
to quite elaborate machines that dig a V-shaped ditch up to 3 or
4 feet in depth. Two types of this class of machine are described
below.

Wheel excavators supply their own power for digging and
traveling; this may be generated either by internal combustion
engines or steam engines and boilers. Many of the heavier
machines are equipped with apron tractors. The digging is done
by buckets upon the rim of a wheel that is revolved in the
trench, and, as each bucket reaches the top of the circle, the dirt
falls upon a conveyor belt, which deposits it on the spoil bank.
A shoe often follows the wheel, removing the crumbs and smooth-
ing and grooving the bottom. One machine of this type is
described below.

118

MOSQUITO ERADICATION
SOME TYPICAL DITCHING MACHINES

Implement A. — This device 1 consists of a cutting knife, which
loosens the earth, and a bucket, which removes it. Two men
and a team are required to operate this machine. The cutting
knife is mounted on a steel frame; trimmers for widening the
ditch are bolted to the end of it. The bucket, which holds
about 5 cubic feet of earth, is hinged to the cutter frame by steel

Fig. 78. — Implement A. (After U. S. Bureau of Public Roads.)

straps. The lower end of a wooden handle is attached to a loop
near the bottom of the bucket; a hook on it engages the top of the
bucket between guides that keep the bucket from tipping while
the handle is straight. The depth of each cutting is controlled
by an adjustable shoe in front of the cutting knife. The bucket,
when full, slides out of the ditch, the handle is lifted to disengage
the hook and the bucket falls on its side.

Implement B. — This implement consists essentially of a rever-
sible cutting blade attached to a steel landside at an acute angle.
The cutting blade not only loosens the earth, but also throws it up
on the side of the ditch. The device may be reversed to cut on

1 Based largely on Farmer's Bulletin No. 698, U. S. Department of Agri-
culture, 1915, by D. L. Yarnell,.'

INLAND DRAINAGE

119

either side and may also be adjusted as to width of ditch. It
comes in various sizes and weighs 290 to 425 pounds. Four to
six horses or a tractor are required to operate the largest model,
while the smallest may be operated with 2 or 3 horses. It does
not, of course, cut accurately to grade.

Fig. 79. — Implement B. {Courtesy of Owensboro Ditcher and Grader Company.)

Implement C. — This machine is one of the various types of
wheel excavators and, of course, is considerably more expensive
than the two machines described heretofore. However, it
follows grade very closely and usually makes a perfect ditch at
one cut. Only two men as a rule are required to operate it, the
average daily operating cost, according to the manufacturers,
running from $16.75 for the smallest model to $43 for the largest
model. This machine will average half a mile of completed
ditch of the usual anti-mosquito type and ordinary size every
day according to the manufacturers.

120 MOSQUITO ERADICATION

There seems to be no doubt that, in localities to which it is
suited, machine ditching is considerably cheaper than ditching by
hand.

FlG . 80.— Implement C. (Courtesy of Buckeye Traction Ditcher Company.)

MAINTENANCE OF OPEN DITCHES

One of the most objectionable features of the open ditch, from
an anti-mosquito viewpoint, is the necessity of maintaining it in

INLAND DRAINAGE

121

proper condition — that is, keeping it in such shape that it will
properly drain the area it is supposed to drain and also keeping
it in such shape that it itself will not become a breeding place.
Due to local topography, character of soil and other conditions,
some open ditches or parts thereof may be relatively expensive to
keep in shape.

Fig. 81. — Cleaning out road-side ditches with a ditching machine.

In order to preserve their ability to drain the areas they are
intended to drain, ditches should be kept to the established
grade and proper cross-section; in order to prevent ditches from
themselves becoming breeding-places, obstructions, such as
sticks, leaves and other floatage, deposits of silt and sand and all
vegetable growth, including algae, should be removed from the
ditch periodically. Shovels and hoes are the tools best suited
to this work. Where the ditch is in soft ground, great care is
required not to spoil the grade.

For the removal of rank grass and weeds from ditches, a weed-

122

MOSQUITO ERADICATION

INLAND DRAINAGE 123

burner may sometimes be used to advantage, although this
method is some more costly than doing it by hand.

THE WEED -BURNER

The weed-burner consists of a steel tank (large enough to hold
15 gallons of kerosene and to leave a good-sized air-space above
it) equipped with a double-acting, long-stroke pump, which has
automatic valves and a pressure gage, and two burners, each
connected by a long rubber hose to metal pipes reaching to the
bottom of the tank. The burner is a short length of straight
pipe with a coil at the end. The oil passes down the straight
pipe, through the coil and back to the base of the coil, where it is
atomized through a nozzle. To begin operations, the supply
valves are closed, the burner coils heated until red and the air
pressure brought to 40 pounds. Upon opening the supply
valves, the oil is forced through the hot coils and readily ignites,
producing a bluish flame about 30 inches long and 4 inches in
diameter. If the coil is not heated sufficiently, the flame will be
of a reddish color and of low heat value.

Three men are considered necessary for the operation of this
device — one at each burner and a third pumping to keep the
pressure up to 40 pounds.

Shaw 1 reports that the cost of burning out with this device a
ditch overgrown with weeds and grass amounted to 1.4 cents a
lineal foot as against a cost of 0.35 cent by hand. Lenert 1
reports that a similar burning cost 1.5 cents a lineal foot.

Several commercial arsenical preparations designed to kill
weeds are also on the market and may be used in anti-mosquito
work, where they will not endanger stock.

In periods of drought, a ditch may become a series of stagnant
pools. A small temporary channel may then be made to concen-
trate and drain off this water, or, if the holes are not too numer-
ous, they may be filled with stone or earth. Otherwise, they
may be oiled or stocked with fish.

In cases where the banks of ditches in pasture lands are flat
and soft, both above and below the flow-line, deep impressions,
which hold water, are sometimes made by the hoofs of cattle and
horses. Where practicable, such soft areas should be protected
by fences, and a barrel without a bottom should be installed at a

1 Transactions of Second Annual Anti-Malaria Conference of Sanitary-
Engineers, U. S. Public Health Service, 1921.

121

MOSQUITO ERA DIC A TION

suitable place where it will remain filled with water for the stock
to drink.

While recleaning of open ditches along the lines described will
be required from time to time during the mosquito season, it is a
good plan to get all such ditches in shape early in the season
before the first new broods of mosquitoes appear.

MAINTENANCE COSTS

Maintenance costs vary considerably with local conditions. In
areas where weeds grow rapidly, they probably will prove the

%4**&H

%■

Fig. 83. — Cleaning out an old, clogged up ditch by hand.

most troublesome factor. In some places, the writer has found
it necessary to remove these growths every month or so; this
runs into a large amount of money in a season on a large project.
Again, heavy rains, resulting in rapid run-offs, sometimes ruin the
grade of miles of ditches; sand and mud will be deposited at many
places, while deep holes will be cut into the banks and bottom at
others.

During 1918, on a job with which the writer was connected,

INLAND DRAINAGE

125

approximately 29 miles of ditches were maintained at a cost of
$0,045 a foot or $241.52 a mile for the season; estimating the
season as lasting 6 months, the cost was less than $0,008 a foot or
$40.25 a mile a month. These ditches were kept in almost per-
fect condition at all times — free from grass and weeds and
obstructions of all kinds.

PERMANENT LINING OF ANTI-MOSQUITO DITCHES

Anti-mosquito drainage ditches may be lined to advantage,
where excessive erosion takes place or where maintenance costs
otherwise become excessive.

Fig. 84. — Section of ditch lined with redwood boards.

Materials usually employed for lining ditches are concrete,
stone set in mortar and planks. While the former are more
expensive, they are more permanent and generally give more
satisfaction in the long run.

LePrince 1 says: "Lined ditches are more permanent, easily cleaned,
require less inspection and are ultimately less costly. At some of the
settlements in the Panama Canal Zone, it was found that a large saving
was made by lining certain ditches and parts of ditches with concrete
as against repeated regrading, cleaning and oiling of open earth ditches."

As a rule, the lining should be U-shaped with sloping sides; it is
not always necessary, however, to line the whole depth of the

1 "Malaria Control; Drainage As An Anti-mosquito Measure," U. S.
Public Health Service, 1915.

126

MOSQUITO ERADICATION

ditch. The lining of the bottom and sides up to 3 or 4 inches
above the normal water line generally will answer for small
ditches. In wide ditches, the bottom should slope toward the
center and the side walls may often be nearly vertical.

Fig. 85. — Openjiitch lined with concrete.

A smooth or fancy finish, which adds to the cost, is not essen-
tial. The ditch may be lined roughly with flat stones, the holes
being chinked up and mortar plastered "about ]them. Where

Hzm"

( Ho jtfied offer iefripce)

Fig. 86. — Cross-section of lined main ditch and unlined lateral.

flat stones are not available, a 2-inch layer of concrete, reinforced
with chicken wire of about 2-inch mesh may be used.
LePrince continues:

INLAND DRAINAGE

127

< ^53S^

"In order to avoid scouring out of banks above the lining by storm
water, particularly at sharp curves or bends of ditches, the outer
wall lining should be raised to meet the condition, or the ditch may be
widened or key-walls installed. Key-walls . . . will prevent the
side-scour and under-scour of linings of straight ditches of heavy grades.
The key-wall should extend 6 inches to a foot or more into the ground
below the bottom ditch lining. Branch ditches should enter lined
ditches at an acute angle or on
a curve, with a sharp grade near
the junction.

"In all cases, weep-holes or
seepage-holes, sloping toward the
center or bottom of the ditch
and located just above the key-
wall, should be provided. This
is required to prevent the effect
of currents which may be under
or behind the concrete ditch lining. Weep-holes should be made in
side walls before the concrete has set. They should be used wherever
water might be behind the lining."

Fig. 87.-

(MoJifieJ after U Prince)

-Cross-section of key-wall.

, S/one and qmve/

SUB-SURFACE TILE DRAINS

Tile drainage within the last 25 years has become of great
importance as an agricultural measure to improve crops by
reducing excessive moisture in the soil. Such drainage is of great
value in anti-mosquito work, inasmuch as it
lowers the water-table, thus allowing pools of
surface water to be absorbed more rapidly.
Tile drains also may be used to intercept seepage
water and for other purposes in connection with
anti-mosquito drainage.

Sometimes in an anti-mosquito campaign
it is possible to persuade owners of low-lying,
swampy lands about a town to tile drain them
for agricultural purposes. Where this can be done, a double
benefit is derived — the lands are made more productive and
the mosquito breeding-places thereon permanently eliminated.

Again, in purely anti-mosquito work, it has been found that in
the long run it frequently pays to substitute tile drains for open
ditches. According to the report of the Panama Canal Zone
Health Department for 1919, substitution of tile drains for open
ditches in pasture lands resulted in a considerable saving by

Fig. 88. — Cross-
section of fill over
intercepting tile
drain.

128 MOSQUITO ERADICATION

rendering unnecessary previous oiling of hoof-prints, etc., along
their margins in the wet season. Another considerable economy
resulted from elimination of the necessity for periodical cleaning
of grass and weeds from open ditches.

TILE DRAINS VERSUS OPEN DITCHES

Ditches in which drainage tiles are to be installed must follow
grade exactly; hence, they should be laid out by instrument or
other accurate method and the bottom finishing checked from
time to time. Where the fall is less than 2 inches to 100 feet, very
careful work is required.

Tile drains generally should be laid from 2 to 4 feet deep,
depending upon character of soil and other local conditions. As

the ditches in which they are laid
are filled up as soon as the laying
is completed, they need be of no
particular shape, such as is re-
quired in the case of open ditches;
they may be dug with vertical sides,
if the nature of the soil will permit.
In digging ditches for tile clrain-
Fig. 89. — Cross-section of outlet age by hand, special tile spades are

for a tile drain. i, ■, A , , £ i

generally used. Another useful
instrument is the drain scoop, which comes in various sizes to suit
the size of tile. However, a very large proportion of the ditches
for agricultural tile drainage are dug by machinery today.

A system of tile drainage may consist of a main, sub-mains,
laterals and sub-laterals, or only a main and a lateral. The main
is the drain through which all the water eventually flows. Some-
times, only a single line may be needed.

A proper outlet for the main should be provided in all cases in
order to prevent caving and possible closing of the pipe. Prob-
ably the best protection is a concrete wall, into which the end of
the pipe is set. Where the outlet is low and liable to be sub-
merged in time of flood, a valve should be installed to keep the
water from backing into the drain.

LAYING OUT A TILE DRAINAGE SYSTEM

In laying out a tile drainage system, as few mains and as many
long laterals should be used as possible, as a rule, since, near the
mains, both the laterals and the mains drain the land. For this

INLAND DRAINAGE

129

reason, the system shown in Fig. 91 is preferable to that shown in
Fig. 90, since the cost is less and the drainage more uniform.
In the East, for general farming purposes, the laterals are
placed from 32 to 70 feet apart. In the Middle West, on the
higher lands and closer soils, 132 feet frequently has proved
satisfactory. On level lands with porous subsoils, drains from,
160 to 192 feet apart have given good service. For truck land

Do u

d r^/incd /

U.5. Dcpar/wcnf- of Acjncu/fvre (Afcr5mith)

Fig. 90. — Too much double-drain-
ing — a waste of money.

Fig. 91. — Double-draining re-
duced to a minimum by proper
design.

the laterals should be closer together than for land on which
general farming is carried on.

No tile less than 3 inches in diameter should be used, and best
practice today in the Middle West seems to be to make 5 inches the
minimum size. However, no hard and fast rule can be given.
According to Smith, 1 in the dark silt-loam soils of Illinois and
Iowa,\where the rain-fall approximates 36 inches a year, an 8-
inch tile with a fall of 2 inches to 100 feet will furnish an outlet for

l " Tile Drainage on the Farm," Farmer's Bulletin No. 524, U. S. Department
of Agriculture, 1917.
9

130 MOSQUITO ERADICATION

the complete drainage of 40 acres, while a 4-inch tile will drain
only 6 acres. On the level soils of the South Atlantic and Gulf
States, where the rain-fall is heavier, only about three-fourths of
these areas can be drained with the same size of tile, according to
the same writer.

PLACING THE TILE

"Laying the tile, like digging the ditch, should begin at the outlet,"
says Smith. 1 " Under ordinary conditions, tile should be laid every day
as far as the ditch is made. Any delay in laying may cause injury to the
ditch by rain or by particles falling into it. If the banks are likely to
cave, the tile should be laid as fast as the ditch is completed.

"The smaller sizes are laid from the bank with a hook. Large sizes
must be laid by hand from the bottom of the ditch. All mis-shaped and
cracked tile should be discarded. If a tile does not join closely with a
preceding one, it should be turned over until it fits at the top. Any
large cracks are covered with pieces of tile. Where a lateral joins to a
main or sub-main, the connection should be made with a Y. Neither
a T nor an elbow is desirable, as these check the flow of the water.

"When the tile are laid and inspected, they are ready for priming.
This is done by caving a little earth from the sides of the ditch and letting
it settle gently, so as to keep from knocking the tile out of line. In
sandy soils, there may be danger of sand entering the tiles and clogging
the drain. This can be prevented by covering the joints with pieces of
old sacks or straw.

"After the tile are primed, they may remain without injury for several
days until all the ditches are ready for filling. If the soil is close and it is
desirable to aid the water in reaching the tile quickly, the ditch can be
partially filled with straw or brush, or, better still, with stones and
pieces of brick. Under ordinary conditions, the ditch is most easily
filled with a turn-plow and an evener, which is 12 or 14 feet long. Two
horses are hitched to this plow, one on each side of the ditch and, with
one man to lead or drive and another to hold the plow, the earth is
turned in. There may be extraordinary conditions, however, when a
plow cannot be used. By placing the team on one side of the ditch and a
wooden scraper on the other side in such cases, the dirt can be pulled in
rapidly. Filling by hand is usually the most difficult and most expen-
sive method."

In laying tile for the purpose of intercepting seepage water,
best practice seems to call for a stone or gravel fill over the tile,
instead of the usual earth fill.

i"Tile'Drainage on the Farm," Farmer's Bulletin No. 524, U. S. Department
of Agriculture, 1917.

INLAND DRAINAGE 131

TILE DRAINAGE COSTS

Tile drainage costs may be divided into two phases — that of
the tile delivered at the trench and that of the digging, laying
and filling.

Prices of tile vary in the different sections of the United States,
being cheapest in the Middle West. In the East and South,
tile is about 50 per cent higher than in the Middle West, and in
the Far West about 70 per cent higher, according to Smith. 1
Haulage costs depend, of course, upon the distance.

"Digging the ditch and laying and priming the tile are usually figured
as one operation," says Smith. 1 "This is done either at so much per rod
or by the day, the former being the more common practice ... On
ordinary soils in the Middle West, the average capacity of a good
workman with a 3-foot ditch and not over 5-inch tile is 10 rods a day.
In the East and South sometimes, on account of the character of the
soil, the capacity of a man is from 4 to 8 rods, with the same depth and
size of tile."

"For tile trenching and laying by hand," says Yarnell, 2 "where
experienced men are employed, the rate of progress for one bottom man
and one top man, for the smaller sizes of tile not more than 3 feet deep,
is ordinarily 15 to 30 rods per day, depending largely upon soil condi-
tions. In some sections of the country where the use of unskilled colored
labor is necessary, the same number of men will put in, even with good
supervision, only 5 to 8 rods per day per man."

VERTICAL DRAINAGE

That vertical drainage is an economical and effective method
of eliminating pools of standing water in districts where the water
is held by an impervious stratum overlaying a pervious one has
been repeatedly demonstrated. The principle of course, is to
sink a hole through the impervious layer so that the water may
escape through the porous material. This may be sand or gravel
or limestone and other formations that contain seams and
fissures.

While there is a degree of uncertainty about vertical drainage,
the costs are so low, where the pervious material lies close to the

1 "Tile Drainage on the Farm," Farmer's Bulletin 524, U. S. Department of
Agriculture, 1917.

? " Trenching Machinery L'sed for the Construction of Trenches for Tile
Drains," Farmer's Bulletin 698, U. S. Department of Agriculture, 1915.

132

MOSQUITO ERADICATION

surface, as compared with an expensive ditching project, that it is
often well worth while to try it out in favorable areas.

As a rule, the holes should be lined to prevent clogging up the
avenue of escape for the water by erosion. For the same reason,

it is often desirable to install a drain-head
or other device to keep out the coarser
material carried along by the water.

Gorman 1 describes a typical operation,
which resulted in the complete drying
up of a pond covering nearly an acre, as
follows :

TYPICAL VERTICAL DRAINAGE
OPERATION

"Beginning at a few feet from the water's
edge, on shore, at a shallow part of the pond,
a hole was dug to the limestone stratum with
a post-hole digger. Then, with a long drill, a
hole 12 inches deep was made in the lime-
stone and a stick of dynamite inserted, well-
packed and exploded. The hole was then
cleared out, the drill again used and another
stick of dynamite exploded. This was con-
tinued for three or four times, until drilling
had been carried to a depth of 4 feet or more
in the limestone. Water from the pond was
then directed into the hole. This same
thing was done at two or three other places
around the pond ... As the water drain-
ed and the pond became smaller, other holes
Fig. 92.— Sketch of a verti- were dynamited as described above, and,

after eight holes had been made, the pond
was dry. By observing the rapidity with which the different holes
drained, it was noticed that four of them were especially effective . . .
showing that, in the case of these four, seams in the limestone had been
reached.

"These four effective drains were dynamited several more times and
then, at each of them, holes 2 feet in diameter were dug through the
clay to the limestone. In these holes, resting on the limestone stratum,
12-inch vitrified clay sewer pipes were placed vertically, being built up
to a few inches above the ground. The rest of the hole around the pipe

1 Transactions of the First Annual Conference of Sanitary Engineers, U. S.
Public Health Service, 1919.

/.imeshne. '

INLAND DRAINAGE

133

was then filled with coarse stone and cinders. A main ditch was then
dug in the center of the pond its entire length, with occasional laterals.
This main ditch and the lateral led to the four effective drains described
above.

"The cost of this work, labor at 30 cents per hour, was S173.42. This
included 1,500 feet of ditching and the work on the four rejected drains,
which were filled in."

Bishop 1 describes a vertical drainage project, in which it was
necessary to pierce 40 to 50 feet of clay before the limestone was
reached. The holes were dug with an ordinary post-hole auger
with sectional pipe extensions at a cost of 2 cents per foot. It
has been found, however, that the post-hole auger will not work
in certain soils.

VERTICAL DRAINAGE FOR LARGE AREAS

Sometimes, when the area to be drained is extensive, it is
necessary to make the hole of considerable size. This, of course,

^ Drain- head

m >>>>;wvv>>»w»»>>)>>,MMWW>M»mww* ^^

^P opt

Shaft

Fig. 93. — Profile of pool, drain-head and shaft.

greatly increases the cost of the operation. Stromquist 2 describes
such a hole, which drained a pond covering more than 40 acres
in extent.

A shaft, 7 feet square, was sunk to a depth of about 41 feet,
at which point a fissure, about 4K feet high by \ l A feet wide
was found in a vertical wall of limestone. The shaft was curbed
with 2 by 6 material, double braced, at intervals of 3 feet, and

1 Transactions of the First Annual Conference of Sanitary Engineers,
IT. S. Public Health Service, 1919.

2 Transactions of the First Annual Conference of Sanitary Engineers, U. S.
Public Health Sendee, 1919.

134 MOSQUITO ERADICATION

2 by 12-inch sheathing. A flume was built from one side of the
shaft to the end of the ditch connecting with the lake. The out-
let thus formed proved sufficient to drain the entire lake and
keep it dry.

Sometimes, if the fissure be small, there is a tendency for the
hole to silt up, especially when the water enters the hole directly.
This may be avoided by the use of a drain-head, designed to
keep out floating matter and the coarser sediment. Such a
drain-head may be an elongated, narrow box, laid as a pipe

cover or e/oc" M ,ovfs/d(.

ovrs/ae screen

inside, screen

Shaft-
Fig. 94. — Sketch of a drain-head for vertical drainage.

from the ditch to the hole; the end toward the ditch should be
heavily screened and the other tightly closed; a hole in the
bottom near the closed end, through which the water is to enter
the shaft, also should be well screened; a door on the top of the
box will allow this latter screen to be cleaned from time to
time; the entrance screen of course may be kept clean from the
outside.

STREAM RE-CHANNELING

Contrary to the popular belief that mosquitoes breed only in
stagnant water, they may often be found breeding in abundance
in numerous flowing streams, since in most streams there are
many places where the current is almost imperceptible.

Thus, in a stream in flat country, where the fall is slight, there
are apt to be many quiet pools, suitable for breeding. Even in
a stream with a considerable fall, obstructions may stop the
current or a soft bottom may wash out, resulting in a large, deep
hole. Furthermore, the numerous bends in most streams cause
a considerable loss of fall and hence of velocity.

LePrince 1 says:

"A stream should be made to have steep banks directly above
and below the flow line, uniform grade and width and a straight course,

1 "Malaria Control: Drainage as an Anti-malaria Measure," U. S.
Public Health Service, 1915.

INLAND DRAINAGE

135

and be free from grass, sticks, stones or other obstructions that would
interfere with the current. These conditions are seldom found in
nature, but the nearer a stream approaches them the less will mosquito
breeding be found."

(Photos by E. H. Magoon, C. E.)
Fig. 95. Fig. 96.

Fig. 95. — This pretty pool in a stream-bed was a breeding-place for Anopheles.
Mosquito control was secured by connecting it with a nearby larger pool that
was stocked with minnows.

Fig. 96. — Water in a ditch confined to a narrow channel in order to facilitate
mosquito control. The ditch is oiled by means of a drip-barrel at its
upper end.

BLASTING NEW CHANNELS

The writer has found that, if the stream is very crooked and
much regrading is necesssary, it frequently will pay to disregard
the old channel completely and make a new and straight one.
If the soil conditions are adapted to it — that is, if the soil is
wet and water-soaked — dynamiting probably will prove to be
the cheapest method. The writer once had occasion to re-
channel with dynamite about a mile of a large creek in Georgia,
which averaged 20 feet wide and from 1 to 6 feet deep. A hard
sand stratum which underlay the soft surface ooze at a depth
of about 6 feet provided an ideal base for reaction of the explosion.

130 MOSQUITO ERADICATION

The cost was 33 cents per lineal foot. The total cost of $1,516.35
was divided as follows:

Labor cost of dynamiting $ 123.75

Cost of dynamite 1,260.10

Cost of cleaning channel 132 . 50

Where the old channel is not so crooked, however, it may be
cheaper to utilize it, straightening and regrading it where most

Fig. 97. — A new channel for a stream. Note the straight course and clean

edges.

needed. Places where the stream widens out, probably will
give the most trouble. The best way of dealing with these is
to dig out a channel and use boards or a rough plastered wall,
where necessary, to keep it open; if boards are used, they should
be well filled in behind. Sharp bends where storm water may
scour out and erode the banks may also be advantageously
treated in this way.

CLEARING STREAMS OF LOGS, ETC.

Where the bottom of the stream is soft, so that large pockets
or pools have formed in the channel, such holes may be filled

INLAND DRAINAGE

137

with stone in such manner as to prevent further extension of
them.

Sometimes streams will be found clogged up with log jams,
started by individual logs catching against stumps and trees on
the bank. Such jams will range in size from 20 to 30 logs up to
more than a thousand. According to Williams 1 the best way to
deal with them is to explode three or four bundles of dynamite
(20 pounds each) among the logs at the lower end of the jam;

PcnVS of

planted dynamite^ '

) j^O/d channel

Bewre After

Fig. 98. — Creek before and after straightening by blasting.

the explosion will loosen the logs and the majority of them will
start downstream; a sufficient force of laborers should be posted
along the banks to prevent any new jam formations.

Where the logs are not so numerous but are scattered out
along the banks, they may be cut loose by laborers and then
hauled up out of the water by means of teams.

Any other obstructions, together with weeds, grass, algae and
similar growths, should be removed from streams periodically.

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1910.

138

MOSQUITO ERADICATION

Streams which, during a period of drought, partly dry up,
leaving depressions or "pot-holes" along their courses, should be
treated similarly to ditches which give rise to similar troubles.

FILLING

Collections of water that cannot economically be drained
should be filled when practicable. Wet areas that are most
expensive to control should be eliminated first. Shallow water
in places that are too low to be drained may be concentrated
by filling, so that the remaining water is easier and cheaper to
control.

{Photo by E. H. Magoon, C. E.)
Fig. 99.— Making a fill.

Frequently, it is possible to procure that city trash be dumped
at the place it is desired to fill. This course may not be practi-
cable, however, where the haul is too far or where the place is in
a thickly-inhabited section. In all cases, the trash must be
levelled off so as to prevent the formation of pools, and should be
covered with 6 inches or more of earth in order to prevent odors,
especially in summer. Under no circumstance should potential
water-containers, such as old cans, bottles, etc., be left exposed.

Porous materials, such as cinders, are very good for filling.
In the vicinity of lumber-mills, waste, saw-dust and shavings
are available in quantity, and, when used for filling, should extend
several inches above the surface of the ground.

Areas kept wet by seepage water can seldom be satisfactorily
treated by making a shallow fill of earth.

CHAPTER VII

SALT MARSH DRAINAGE

THE SALT MARSH PROBLEM IN GENERAL

The salt marshes that abound along the Eastern and Southern
coasts of the United States from New York to Mexico constitute
probably the greatest single breeder of mosquitoes in the country.

These low-lying marshes, swept from time to time by the tides,
which fill every hole and depression, make ideal breeding places
and present probably the most difficult problem that there is
from an anti-mosquito point of view, not only on account of the
huge areas they cover, but also on account of the enormous
expense involved.

Fortunately, not all parts of the salt marsh breed mosquitoes
in equal abundance, owing to the activities of larva-destroying
fish, which, when they are present in considerable numbers, eat
the larvae nearly as fast as they hatch from the eggs. However,
there are many parts of the marsh that the fish cannot reach, such
as high-lying and shut-in meadows over which the tides rise only
occasionally. Even where an extra high tide has stocked the
holes with fish, the water soon dries up and the fish die; then, rain
water fills the holes, larva appear and a brood of mosquitoes
gets on the wing.

The problem of preventing mosquito breeding in salt marshes
is thus seen to be one of determining just what parts of the marsh
constitute mosquito production areas and then so treating them
that the tide-water will run off at frequent intervals, will be
constantly stocked with larva-destroying fish or will be kept out
altogether. The methods of accomplishing these results are
ditching, filling and diking and tide-gating.

AGRICULTURAL VS. ANTI-MOSQUITO MARSH DRAINAGE

In the drainage of salt marshes, as in upland drainage, there is a
distinction between drainage for agricultural purposes and drain-
age for anti-mosquito purposes. As a general rule, it may be said

139

140 MOSQUITO ERADICATION

that drainage for agricultural purposes is usually more intensive,
as well as more expensive, than drainage for mosquito control
purposes.

"It seems clear," says Headlee, 1 "that the drainage necessary to
prepare and maintain the marsh in condition for successful agriculture
keeps the water-table so far below the surface that the original vegeta-
tion is destroyed and the marsh undergoes a large shrinkage. In some
cases, this shrinkage is sufficiently great to bring parts of the marsh
below mean tide and to necessitate the use of pumps to keep the water
far enough below the surface of the marsh to permit the growth of
crops.

"In that type of drainage necessary to eliminate mosquito-breeding,
the water need not be maintained at a level lower than 12 inches below
the surface, even during the height of the mosquito-breeding season.
Indeed, at seasons of the year when breeding is not occurring, the gates
can be opened and the tide allowed to circulate freely. It would seem
that this type of drainage should not destroy the salt marsh vegetation
and that the meadow should not, therefore, materially shrink. There
is some evidence to show that, with a proper system of letting the water
on the marsh, the vegetation will not only not be destroyed, but maxi-
mum crops of salt marsh hay can be produced."

DESIGN OF SALT MARSH DITCHES

As a result of the investigations of Dr. John B. Smith, pioneer
in anti-mosquito work in New Jersey, it has been found that the
best type of ditching for the usual salt marsh is a ditch 10 inches
wide by 30 inches deep, with smooth perpendicular sides. This
depth normally reaches the bottom of the sod, and should be
maintained, except where natural slope calls for a deeper cut to
insure the free flow of the water. As the upland is approached
and the sod and underlying muck becomes thinner, the depth of
the ditch is decreased accordingly, neither sand nor subsoil being
cut into, unless the drainage of a pool or other shut-in area
requires it.

Two general plans of ditching have been used in New Jersey.
One plan, known as the parallel system, calls for division of the
territory to be drained into districts on the basis of possible
' outlets, each district to be drained by parallel ditches, sufficiently
close together to remove the surface water. The other plan,
known as the pool-connecting system, consists of running ditches

1 "The Mosquitoes of New Jersey and Their Control," New Jersey Agri-
cultural Experiment Stations, Bulletin No. 276, 1915.

SALT MARSH DRAINAGE

141

from one pool or hole to another, and finally into one or more
outlets. According to Headlee, 1 the parallel plan is now con-
sidered the best practice in New Jersey.

Hew Jersey Aqriculfurat Cuperimenr 5bHons

Fig. 100. — Above, parallel, and below, pool-connecting, systems of salt marsh

ditching. {After Headlee.)

Referring to the amount of ditching per acre necessary, on the
average, to prevent mosquito-breeding in the New Jersey salt
marshes, Headlee 1 says:

1 " Some Recent Advances in Knowledge of the Natural History and the
Control of Mosquitoes," New Jersey Agricultural Experiment Stations,
Bulletin 306, 1916.

142 MOSQUITO ERADICATION

"The estimated requirements range from 90 to 600 lineal feet of 10 by
30 inch ditching, or its equivalent, per acre. As a matter of fact, only
rarely is the former figure practicable, and then under especially favor-
able conditions, and never on the New Jersey salt marshes has the latter
figure been reached. It seems probable that between 200 and 300
feet is the real average. To this must be added an amount of
hole filling and shallow spurring which will add about 10 per cent to
the acre cost."

SALT MARSH DITCHING BY HAND

The type of ditch just described is dug both by hand and by
machinery, the latter being considerably the cheaper.

In hand ditching, the chief tools commonly used are patented
spades of various types, these having been found superior to
ordinary shovels. There are several different makes of these
spades on the market.

In cutting the ditches by hand, it has been found best to remove
the sods in pieces about 10 inches wide by 6 to 8 inches thick by
30 inches long. These are heavy and not easily moved by the
tide; they can also easily be hauled away if desired.

As a general rule, numerous small, shallow pools are found
scattered throughout the marsh; some of these will not drain
readily into the ditches, but are too small to merit drainage by
means of spurs. Such holes may be filled with sods from the
ditches and then smoothed over, in such manner as to prevent
formation of succeeding pools. In a year or so, the grass will
grow over the fill and the hole will be entirely obliterated as a
breeding-place.

Sometimes, portions of the marsh are so shut in that opening
them to the ocean is impracticable. In these cases, the area may
be trenched with the usual ditches to concentrate the water
which should then be stocked with larva-destroying fish.

Particular care should be taken in connection with the outlet
of the ditches. The greater the tide drop and the shorter the
ditch, the greater is its efficiency and its ability to keep clean.
According to Headlee, 1 every ditch should have a strong tidal
outlet, and no ditch depending on a single outlet should be more
than a quarter of a mile long.

1 "Some Recent Advances in Knowledge of the Natural History and the
Control of Mosquitoes," New Jersey Agricultural Experiment Stations,
Bulletin 306, 1916.

SALT MARSH DRAINAGE
MACHINE DITCHING

143

Several types of ditching machines are used in salt marsh
mosquito control work. Headlee 1 mentions a machine consisting
of a gasoline power plant, equipped with revolving drums in

(Photos by Atlantic County, V. J., Mosquito Extermination Commission.)
Fig. 101. — Above, left, front view of the Eaton ditches, showing plow in
distance; above, right, rear view of the plow, showing the ditch and the way sods
are disposed of; below, a ditch cut by the Eaton ditcher.

front and rear, and a plow or trencher which makes the excava-
tion. The power plant, mounted on planks, pulls the trencher
forward by means of a 500 foot steel cable; when it becomes
necessary to move the power plant, an anchor is carried forward,
power is applied to the other drum, which is connected with the

144 MOSQUITO ERADICATION

anchor by another steel cable, and the plant is drawn up to the
anchor.

With a machine of this type and five men, it is possible to cut
3,000 feet of ditches a day, and, under favorable conditions,
sometimes more. Headlee 1 states that this machine cut the cost
of ditching from 2}4 cents a lineal foot in 1912 to less than 1>£
cents in 1916. At that time, he states, the operating and
up-keep cost of ditching with this machine, as shown by cutting
hundreds of thousands of feet, did not exceed 1 cent a lineal foot.

FILLING

While the method of ditching outlined above is perfectly satis-
factory for the larger part of the salt marsh areas, there are
certain sections of marsh that cannot be successfully treated in
this way. There are areas which are so shut in by ridges, fills,
railroad grades and roadways, or so low-lying, that they may be
flooded by every storm or extra high tide and stagnant water
remain on them for weeks. Again, it may happen that on a
broad, open marsh, especially if the range of tides be small,
there are spots or pockets back near the upland too low to drain
by ditching.

In such cases, the problem may be solved either by filling or
by diking and tide-gating.

Filling is applicable only under certain circumstances. Thus,
it is too expensive for general purposes, and is used chiefly in
cases where the area to be filled is small, where it is very valuable
or where it proves to be the most convenient place for a dumping
ground. In making the fill, the trash should be smoothed down
and levelled in such manner that there will be no opportunity
for rain-water pools to form in it.

DIKING AND TIDE-GATING IN GENERAL

This is the accepted method of dealing with the areas described
in the last section. It should be recognized at the outset that
diking and tide-gating a given area is strictly an engineering
problem and that it should be handled as such. Failure to recog-
nize this fact may result in ineffective work and a waste of
money.

1 "Some Recent Advances in Knowledge of the Natural History and the
Control of Mosquitoes," New Jersey Agricultural Experimnent Stations,
Bulletin 306, 1916.

SALT MARSH DRAINAGE

145

Diking is necessary, as a rule, only when the fall of the tide is
not sufficient to draw all the water out of the ditches, when the
drainage ditches pass through material of such a nature that it is
impracticable or unduly expensive to keep them open or when the
area in question is too low to be drained.

Diking implies the construction and installation of tide-gales,
since it is necessary that the streams and ditches carrying water
be given an opportunity to discharge. The main purpose of the
diking is to keep out all but the very highest tides, so that low
areas will not constantly be covered with water and so that the

Dike

Fig. 102. — Method for control of abandoned coastal rice-field.

water-table in the ground will remain at a sufficient depth.
Otherwise, a comparatively slight rain-fall or a high tide would
result in pools that would remain for days.

The dike should, as a rule, be located from 25 to 50 feet from
the edge of the water, so as to leave a narrow strip of marsh to
protect it from wave action. It should be sufficiently high to
keep out all but the very highest of high tides, and proportion-
ately wide. In constructing the dike, due allowance must be
made for shrinkage.

CONSTRUCTING THE DIKE

In constructing the average dike, mud and sods are the chief
materials. A core ditch, about 1 foot wide and 1 foot or more
deep, should first be excavated along the center line of the pro-

1 Hi MOSQUITO ERADICATION

posed dike; the purpose of this is to get a good bond with the
earth. Sods are then laid on either side of this core ditch, and
the interval between them tamped with mud. Another layer
of sods is then placed on top of the first, only a few inches closer
together, and more mud tamped in. This procedure is continued
until the necessary height is reached. The whole may then be
capped with sod or plastered with mud.

The sods and mud generally are obtained from a ditch parallel-
ing the inside of the dike. Sometimes, this ditch receives the
flow from the laterals and conducts it to a convenient tide-gate.
Sometimes, a supply ditch is dug outside the dike, but, if this is
done, care should be taken that it is properly connected with
adequate outlets. In order to prevent caving, no ditch, either
inside or outside the dike, should be located less than 8 or 10
feet from the dike.

"Some dikes," says Headlee, 1 "have been constructed entirely with
mud, but always in places where sod was not available. In such
instances, the mud has been scooped from a trench back of the dike
(forming a ditch paralleling the work and giving useful drainage), and
piled up until a dike of requisite height, with due allowance for shrinkage,
had been built, which was 2 feet wide at the top and as broad at the base
as was demanded by the normal angle of repose. This type of dike does
not withstand the weather or the water as well as the sod type, but is
efficient if carefully looked after."

Dikes vary in size, of course, with the height of the tides.
Usually, along the Atlantic coast, they average from 2 to 4 feet
high, 2 feet wide at the top and 4 to 6 feet wide at the bottom.
The cost varies with the size. Fuchs 2 reports construction of a
dike averaging 2 feet high, 2 feet wide at the top and 4 feet wide
at the bottom at a cost of 35 cents a lineal foot.

To protect the dikes against muskrats, brown rats and other
rodents which may burrow through and undermine the dikes,
it is customary in New Jersey, to insert a piece of chicken wire
vertically in the middle of the core of the dike letting it extend
down as far as 2 to 4 feet below the surface of the marsh.

1 "Some Recent Advances in Knowledge of the Natural History and the
Control of Mosquitoes," New Jersey Agricultural Experiment Stations,
Bulletin 306, 1916.

2 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

SALT MARSH DRAINAGE

147

THE TIDE-GATE AND SLUICE-BOX

At points where streams or large ditches cross the dike, tide-
gates are required. There are several types of these devices,
each being applicable to certain conditions. The type most
commonly used includes a sluice-box and a swinging gate.

The sluice-box ordinarily corresponds to a culvert and lies
at right angles to the dike and underneath it. The length is
determined by the height of the fill and the slope of the filling
material. The cross-section is determined, as for culverts, by
the drainage area, rain-fall and run-off.

The swinging gate is a gate or shutter attached by hinges to
the outer end of the sluice-box and so arranged that it will readily
open with the falling tide and readily close with the rising tide.

The purpose of the sluice-box and gate is to discharge water
at low tide and close up at high tide in such manner as to prevent
the tide from entering. In good construction, the water in the
ditches and streams should be maintained virtually at the eleva-
tion of low tide. A heavy rain may result in the accumulation
of several inches of water, but this will be discharged at the next
low tide.

CONSTRUCTION OF SLUICES

When the outlet of the ditch or stream is deep enough to pre-
vent the tide forcing back accumulations of mud, etc., into the
sluice-box, it is a good plan to submerge the sluice-box below
mean low tide, in order to prevent floating debris from interfering

Top of £>iAc

Mean Lev Tide

3lolce -
box.

Mean lens Tide _

P,l,nj

5lutce -bo*

Fig. 103. — Installation of a sluice-box.

with operation of the tide-gate and also to avoid periodical
wetting and drying, which greatly shortens its life. If it is not
submerged, it must be screened with heavy material.

Where excavation for the sluice-box is necessary, a rude coffer-
dam may be constructed, using earth for the ends, the water
being bailed or pumped out. The box may be set directly on

1 IS

MOSQ UI TO ERA DIG A TION

the earth bottom, if the bottom is hard and smooth, or on
piling driven under the ends and middle of the box. Care should
be taken in installing a box to prevent any possibility of a leak
developing around or under it.

Sluice-boxes are generally built on the dry ground and lowered
into place; to avoid difficulty in this connection, it is usually
well not to make them too large. Should the stream or ditch
carry off too much water for one box, two or more boxes should
be installed side by side.

nWii. ,. ">., ti%

Sketch of sluice-box and tide-gate.

Sluice-boxes may range in size from a section of 1 or 2 square
feet and a length of 6 or 8 feet up to a section of 15 to 18 square
feet and a length of 20 to 30 feet. They are generally made of
2-inch planks nailed to outside ribs at distances of 1}^ to 2 feet
apart. In order to insure tight closing of the gate or shutter,
the outer end of the box is often given a slight slope, usually
about 1 inch per foot.

According to Gies, 1 it is customary in New Jersey to put a
coarse rack or screen at either end of the box, made of 2 by
4-inch lumber, the pieces being spaced parallel to .each other about

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

SALT MARSH DRAINAGE

149

4 inches apart, to keep out heavy floatage and debris, which
might interfere with operation of the gate.

GATE CONSTRUCTION

The gate, like the sluice-box, is usually built of 2-inch plank,
tongue-and-groove material being best. Sometimes, two thick-
nesses of plank are used. To prevent floating of the gate on the

(a) O/wiNfiRy Strap

HINGE

Tbp of D/*e

Sluicc Box

( lr) TlKBER HlNCE

65\

HlNCE

(d) Screw Hook-3oi.t

£YE HlNCE

(e.)ScK£\n Ere -Bolt-
Strap H /*/&£■■

Fig. 105. — Types of hinges for tide-gates. {After Fuchs, U. S. Public Health

Service.)

rising tide, it is often weighted with a piece of old iron nailed or
bolted on the gate near the bottom.

Many kinds of hinges for the gate have been tried out. Fuchs 1
discusses several different kinds of hinges as follows:

(1) "The common strap hinge does not permit enough freedom of
movement of the shutter so it can automatically adjust itself against
the end of the box. Also, it does not permit the easy removal of the
shutter for repairs. (2) The rice-field timber hinge, in which the
shutter is attached to two vertical planks, which swing from a bracket
supported by posts. This type works well and is easily removed, but,
being above water, permits of tampering and rots quickly. (3) Two

150 MOSQUITO ERADICATION

eye-bolts welded together, one bolted to the box, the other to the
shutter. (4) Screw hooks in the shutter, working on eye-bolts on the
box. This works fairly well. (5) Screw eyes in the shutter, working
on a bolt supported by a strap attached to the box. By knocking out
the cotter pin, the bolt can be pulled out and the shutter removed."

Sluice-boxes, according to Fuchs, 1 are the cheapest and most
satisfactory type of tide-gate, where the stream is not too large.
With labor at 35 cents an hour, he gives costs of various boxes as
follows: A 3 by 4 by 16 foot box, placed several feet, under
water, $202; a 2 by 3 by 16 foot box, placed just below low water,
$33; a 2 by 3 by 20 foot box, placed just below low water, $105.
These costs include both labor and materials.

SPECIFICATIONS FOR LARGE SLUICES

Headlee 2 gives the following specifications for sluices and gates
employed as an outlet for a large creek in New Jersey, measuring
from 75 to 80 feet wide:

1. "All sluices shall have an inside measurement of 6 by 3 feet, and
shall be built of 3-inch tongued and grooved long-leaf pine, free from
knots or serious blemish; they shall not be shorter than 15>^ feet and
shall extend from the outside of the dike, facing back under the dike.
These boxes shall be stiffened with 4 by 5-inch ribs, bolted at each
corner with a 3^-inch bolt, properly washered and drawn up with a
satisfactory nut. These ribs shall be placed around the outside of the
box, fitting it closely, at distances of 18 inches apart. The first and
last shall be made flush with the ends of the box. The planking shall be
firmly spiked to these ribs with 6-inch galvanized spikes. The top of
the box shall be covered with 2-inch long-leaf pine spiked on the top of
the ribs.

2. "The dike shall be faced on the river side with plank piling for
120 feet . . . This facing shall consist of 3-inch long-leaf pine
planking, free from knots and serious blemish, not less than 14 feet long,
driven in until the top shall be 1 foot below the level given for the top of
the dike. If the tops of the piles are splintered, split or broomed by
driving, they shall be cut off below the lowest point of injury. In any
case, the cut of ends shall not be such as to make length of pile less than
provided. The top of the piling shall be even and bound together

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

2 "Some Recent Advances in Knowledge of the Natural History and the
Control of Mosquitoes," New Jersey Agricultural Experiment Stations
Bulletin 306, 1916.

SALT MARSH DRAINAGE 151

by running a 3 by 8-inch stringer along the outside and inside surfaces.
Each pile shall be bound to this stringer by a }i-mch bolt, which shall be
furnished with large washers and a suitable nut. The opening for the
sluice-boxes shall be made closely to fit the boxes. The cut ends of the
piling above the box shall be bound together by 3 by 8-inch stringers,
which shall extend, one on the inside and one on the outside, from a point
2 feet beyond one edge of the opening to a point 2 feet beyond the oppo-
site edge of the opening. These stringers shall be set flush with the
cut ends of the piling, and each pile which they cover shall be bound to
them by a J^-inch bolt, properly washered and fitted with a nut. The
cut ends of the piling below the box shall be bound together in the
fashion above described.

INSTALLATION

3. "All sluice-boxes shall be laid on two extra rows of sheet-piling
composed of 3-inch long-leaf pine closely set together. The planking
shall be 10 feet long and driven in until the top shall be 9 inches below
mean tide. The above provision regarding injury due to driving and its
correction shall be observed here. Each row of this sheet piling shall
extend 4 feet each side of the sluice-boxes. Each row shall be bound
together at the top in a fashion similar to that provided for the dike
facing, and the piling at the sides of the boxes shall extend up through
the stringers 1 foot, and the rectangle thus formed shall be made closely
to fit the boxes.

4. "At the sluice-boxes, the inner side of the dike shall be protected
by sheet-piling wing-walls made of 2-inch long-leaf pine without serious
blemish, 14 feet in length, driven in until the top is 1 foot below the level
of the dike. The above provision regarding injury due to driving and
its correction shall be observed here. They shall be bound together at
the top in the same fashion as the dike facing, and shall extend 6 feet on
each side of the sluice-boxes.

5. "The river side of each sluice-box shall be furnished with a 7 by
4-foot gate made of tongued and grooved white pine. It shall be com-
posed of two layers, the inside one being made of 3-inch, 7-foot planking
and the outside one of 2-inch, 4-foot-long planking, laid at right angles
to one another and firmly spiked together. The gate shall be hung in
front of the opening with a suitable hinge, so that it will readily open
with the falling tide and readily close with the rising tide."

OTHER TYPES OF TIDE-GATES

Headlee 1 describes another type of tide-gate, said to be advan-
tageous on account of the greater ease with which it can be kept
in order, as follows:

1 "Some Recent Advances in Knowledge of the Natural History and the
Control of Mosquitoes," New Jersey Agricultural Experiment Stations,
Bulletin 306, 1916.

152

MOSQUITO ERADICATION

"In this case, no box is constructed, but heavily-timbered bulk-heads
are built into the stream until they stand within approximately 6 feet
of each other. To render their relation to each other constant, they are
bound together by heavy cross-timbers. At a point half-way between
the two ends, a pair of heavy, 6 by 6-inch well-braced timbers are set

(Photos by California Corrugated Culvert Company)
Fig. 106. — Battery of Calco culverts and gates in process of installation.

down in such a fashion as to form the support and resting-place for the
tide-gate. Of course, the joints between each of the upright posts and
ths bulk-head against which it stands and between the lower cross
timbers and the bottom are made tight.

"The tide-gate is suspended from a cross-timber located well above
extreme high tide, and hangs against the upright posts. At each end,

SALT MARSH DRAINAGE 153

the bulk-heads are fitted with slots, in which planking can be dropped to
form a coffer-dam. The water between the two bulk-heads has merely
to be pumped out, when these dams are in place to expose the gate for
repairs and the sluice-way for cleaning. The top of the sluice-way thus
formed is left open."

Frequently in salt marshes, areas are found separated from the
main body of water by sand-bars. The outlets from these areas
are channels through shifting sands. Ordinary tide-gates
quickly fill up. A satisfactory way of dealing with such places,
according to Carroll, 1 is to construct a planked well on the inner
side of the bar; the well is connected with the marsh area in
question by a planked ditch; at the entrance of this ditch into the
well, a tide-gate is hung; the well discharges at low tide through
a terra-cotta pipe that passes under the sandy beach and connects
with an iron pipe running out under the water, so as to deliver the
water from the well a foot or two below mean low tide. The iron
pipe is protected against drifting ice, etc., by means of heavy
piling and cross-timbers.

For small streams having a firm sub-soil, a single line of sheet
piling, well braced with large piles, is suggested by Fuchs. 2
In this case, the gate would fit over a hole cut in the piling. This
type of gate would have the advantage of cheapness and
simplicity, but it would have to be extremely well-braced
to withstand the recurring pressure at high tide, which would
have the effect of loosening it, causing leaks. Fuchs 2 reports
that one gate of this design that he tried out failed as a result
of this tide pressure.

THE CALCO GATE

The Calco automatic drainage gate, made by an iron-culvert
company, has given satisfaction on several large diking and
drainage projects. This gate is attached to one end of a corru-
gated iron culvert, somewhat after the fashion that a wooden
gate is attached to a sluice-box. These gates are said to be
sensitive to a difference of head of less than an inch.

The method of installing these gates is similar to that outlined
for wooden gates, except that it is sometimes advisable to put

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

2 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

154

MOSQUITO ERADICATION

a concrete core-wall in the fill, so as to avoid any possibility of
leakage along the pipe.

The following description of a large drainage job, covering
5,600 acres of Columbia River overflow land is compiled from
information furnished by the company:

(Photos by California Corrugated Culvert Covipany)
Fig. 107. — Installing a 7-ton Calco culvert and drainage gate, Columbia River

project.

Two sloughs were selected for the drainage outlets. At one
of these, a battery of five Calco gates, attached to five corrugated
culverts, 6 feet in diameter and 110 feet long, were placed side
by side. A row of piling, 8 feet on centers, intercepted each

SALT MARSH DRAINAGE 155

length of culvert pipe to assure proper settlement and avoid
misplacement after filling over the culverts. At the other
slough, a battery of six gates and culverts was installed in a
similar manner. Owing to the fact that the culverts at the time
of placement would lie below water level, it was necessary in
both installations to lay the culverts with the gates attached.
Each culvert and gate unit weighed more than seven tons. Two
clam-shell dredges employed in the dike work were used to lower
them in place.

As an auxiliary proposition, to take care of high water periods
and freshets, a pumping plant was provided at each slough.
Both installations of pumps and pipe lines were placed directly
over the culverts and gates.

To enclose the 5,600 acres against high water required lYi
miles of dike, of an average height of 12 feet. At the culvert
and gate installations, the height of the embankment over the
top of the culverts was 20 feet. The total cubic yardage of
embankment amounted to 800,000.

The appraised value of the land before improvement was
approximately $50 an acre, and after improvement, $250 an
acre. The cost of all diking, dredging and spillways, was $60
an acre, leaving a net profit of $140 an acre.

OPERATION OF TIDE-GATES

Tide-gates, like all other contrivances, need a certain amount of
attention. In addition to this, it is imperative that they be
operated intelligently.

Tide-gates should be inspected at least once a week and pre-
ferably twice a week. Despite the use of racks and screens,
there is a certain amount of fine debris that is almost bound to
enter the gate and possibly interfere with its operation. Even
though the gate be below mean low tide level, sunken logs and
other like objects frequently enter and lodge in the gate. These
must be removed, if the gate is to function satisfactorily.

There is also another problem in connection with tide-gates.
When the gates are closed, fish cannot enter the marsh and,
when the fish supply gets low, there is apt to be more or less
mosquito breeding. This is particularly the case when sewage
is discharged into the marsh. In order to overcome such breed-
ing, the practice in New Jersey has been to raise the tide-gates
for a week or two each month during the period of the lowest

156 MOSQUITO ERADICATION

tides, throughout the summer. This allows the fish supply to
be kept up.

"Moreover," says Gies, 1 "by raising the gates on one side of the
marsh and allowing water to enter, while keeping the gates on the other
side of the meadow closed, except for discharge of water, it is possible
to get circulation of the water through the ditches across the marsh, and
sweep out breeding by this mechanical action. The gates are all closed
during periods of monthly high tides or storms, so the unusually high
tide-water will not back up over the meadows . . .

SALT MARSH SHRINKAGE

"There is one other point that has not been touched on — that is, the
matter of meadow shrinkage, if the gates remain permanently closed.
Most salt marshes are composed of a top layer chiefly of decayed vegeta-
tion or peat on a foundation of blue clay, mud, sand, etc. The elevation
of the meadow surface is kept up to a point slightly above mean high tide
by the continuing growth and decay of the salt grasses, sedges, rushes,
etc. This class of vegetation needs plenty of salt water to attain maxi-
mum growth, and, hence, if the tide-gates are kept continually closed
and the salt water excluded from the marsh, the growth of the surface
vegetation stops and the spongy top layer of peat dries out and begins
to pack down hard, and the marsh settles down lower and lower. In
parts of Hudson County, New Jersey, this shrinkage has amounted to
several feet.

"Finally, a point is reached where the elevation of the meadow has
become so low that it can no longer be drained by ditches or tide-gates,
and it is necessary to install pumps, which increases the cost of mos-
quito control . . .

" . . . We are keeping the tide-gates open in our own district, not
only for about 2 weeks out of every month during the summer, but dur-
ing the entire non-mosquito-breeding season, from November until
March. We hope, in this way, to keep up our marsh elevation by con-
tinuing our vegetation growth, so that we will not be forced to the extra
expense of pumping."

PUMPING

While small areas of marsh, so low that they will not drain at
low tide, may be filled, large areas of this kind probably will
require pumping.

Whether a given area shall be pumped, what type and what
capacity of pump shall be employed, what ditching must be used

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

SALT MARSH DRAINAGE 157

to bring the water to the pump and to take it away arc engi-
neering questions that can only be decided by a competent
engineer after detailed study of the particular problem.

In parts of Hudson County, New Jersey, where the meadow
elevation is very near mean sea level or lower and in the low-
lying marshes near Philadelphia, Pa., very excellent systems of
pumping have been worked out. These pumps are electrically
driven and are automatic in operation, being regulated as to
starting and stopping by a simple float, which is raised or lowered
by the water on the marsh, and starts or stops the pumps accord-
ingly.

A 12-inch low-head centrifugal electrically driven pump,
installed in a low area of Hudson County, N. J., in 1915 at a
cost of about SI ,300, satisfactorily drained a territory of about
700 acres at a cost during the mosquito season of about $80 a
month.

CHAPTER VIII
OILING

PLACE OF OILING IN ANTI-MOSQUITO WORK

Oiling of water surfaces should be considered as merely supple-
mentary to drainage and other measures of mosquito control.
While oiling alone might, under certain circumstances, suffice,
the expense, over a term of years, would be excessive. For
these reasons, oiling is usually confined to areas which it is
impracticable to drain, stock with fish or otherwise eliminate as
sources of mosquito-breeding, or else is used temporarily, pending
application of other measures.

The purpose of oiling is to cover the surface of the water with a
film of oil, which kills larvae already present in the water and
prevents further deposition of eggs, so long as the film retains its
strength. The larvae are suffocated, through inability to pene-
trate the film with their breathing tubes.

The necessity of oiling as a mosquito control measure will vary,
of course, with temperature, topography, aquatic plant growth,
presence of larva-destroying fish, the nature of the breeding
areas, etc.

WHERE OILING IS APPLICABLE

The greatest virtue of oiling, perhaps, is its applicability to
treating small rain-water pools, too numerous to drain and too
transient to stock with fish, yet often lasting long enough to
produce a brood of mosquitoes. There seems to be no other
method so effective as oiling for dealing with these. Streams,
ponds, swamps etc., may be treated by drainage methods or by
means of fish; breeding in artificial containers about homes may
be eliminated by removing the containers or, where necessary,
screening them; but neither of these methods is suitable for deal-
ing with rain-water pools.

Another large use of oiling is to handle production areas while
steps are being taken to control them by other means. Thus,
the edges of ponds may be oiled, while the process of removing

158

PLACE OF OILING IN ANTI-MOSQUITO WORK

159

larva-concealing vegetation (to facilitate control by means of
fish) is being carried out, Also swamps may be oiled pending
construction of drainage ditches.

APPLYING THE OIL

Ordinarily, oil need be applied only around the edges of large
bodies of water and of swift-flowing streams, since larvae rarely
are found in deep water and are readily wafted away by a swift
current,

Fig.

108. — Oiling a grassy stream until vegetation can be removed for fish

control.

Should deep water be covered with algae, debris or aquatic
plants, such as water lily, closely matted grass, etc., breeding may
take place — since the larvae will be more or less concealed from
the fish — and oil should be applied heavily over the whole surface,
unless other measures are put into effect,

In slowly moving streams, quiet pools, back-waters, etc., are
often found which may prove to be breeding places. These
should be well oiled, unless other steps are taken to prevent
breeding.

Also in cases, where the flow of streams is obstructed by sticks,
weeds, debris and other matter, the oil cannot be depended upon
to penetrate the mass, unless the whole surface is covered liberally.

Ordinarily, it is not necessary that the film of oil be thick;
indeed, much oil is wasted in this way. Where the water surface
is clean, a very thin film, such as will show a faint display of
colors in the sunshine is sufficient. Where the water is foul or

160 MOSQUITO ERADICATION

covered with a scum, more oil is required. The amount of oil
needed in such a case must be determined largely by experience,
since the factors in the case vary so much that no definite state-
ment on the matter can be made.

KIND OF OIL REQUIRED

The oil used must be thin enough to spread and form a film,
since, unless there is a uniform film over the water surface, many
of the larvae will not be suffocated. Probably the best oil for
the purpose is a light fuel oil; frequently such an oil can be pro-
cured thin enough not to require mixing with kerosene; where
only a heavy grade of oil is available, it must be mixed with
enough kerosene to cut it thoroughly, often from 50 to 75 per
cent. Proper mixing requires vigorous stirring until the mixture
has merged into a thin and quick-spreading fluid. The main
practical considerations are that it be thin enough not to clog up
the sprayer and that it spread enough to form a film.

Kerosene alone is fairly satisfactory, but it has a tendency to
evaporate too quickly. It is also generally somewhat more expen-
sive than the fuel oil. Furthermore, in using kerosene, there
is a tendency to use more oil than is essential, as kerosene has
a secondary "spread," or, in other words, covers a larger area
after an hour or two than when at first applied. A film that is
almost too thin to be measured, but which will give an irridescent
reflection in sunlight, will kill Anopheles larvae.

LARVICIDES

Larvicides or substitutes for oil may be utilized to advantage
under some circumstances. On the other hand, however, it
should be remembered that they are often poisonous, less effec-
tive and more costly than oil. These considerations naturally
limit their profitable use, and LePrince 1 suggests that they be
used only under the directions of boards of health or health
officers.

In cases where rains are so heavy and frequent that the oil is
likely to be washed away before it has time to kill the larvae, use
of a larvicide is indicated, provided conditions are such that there
is no danger of poisoning cattle or other stock. Larvicides

1 "Control of Malaria: Oiling as an Anti-mosquito Measure," U. S.
Public Health Service 1919.

PLACE OF OILING IN ANTI-MOSQUITO WORK

161

usually act differently than oil, as they mix with the water and
poison it, killing the larvae rapidly.

Larvicides also may be used, with the same proviso mentioned
above, to treat large wind-swept pools, where the oil film is
blown off to one side, before it has time to kill the larvae. They
have been used successfully in unpasturecl swamp lands, in
fire-barrels, catch-basins, etc.

THE PANAMA LARVACIDE

LePrince 1 summarizes the constituents, method of manufacture
and application of the Panama larvicide — one of the most
popular — as follows:

"One hundred and fifty gallons of crude carbolic acid, containing not
less than 15 per cent of phenols, are heated in an iron tank having a

Fig. 109. — Treating a fire-barrel with the Panama larvicide.

steam coil with steam at 50 pounds pressure; 200 pounds of finely
crushed and sifted common rosin are dissolved in the boiling acid, and
then 30 pounds of caustic soda, dissolved in 6 gallons of water, are
added. There is a mechanical stirring-rod attached to the mixing
li

162 MOSQUITO ERADICATION

tank. The product is ready in a few minutes, yielding about 3}i
barrels. As a mosquito larvicide, it is used by spraying an aqueous
emulsion (1 part of larvicide to 5 of water) over the surface to be treated
and along the margins of pools and ponds or other mosquito-breeding
places, so that the resultant dilution of the larvicide has a thin, milky
opalescence, representing approximately a dilution of 1 to 5,000. A
1 to 1,000 dilution kills the larvae more rapidly, and was used for destruc-
tion of larvae in overflowing pools, etc., and where the use of oil was
not practicable."

This mixture, LePrince reports, in addition to being a good
larvicide and a good disinfectant, also proved to be very useful in
destroying algae. He also found it very useful for thinning
down heavy oil.

OTHER LARVICIDAL SUBSTANCES

Niter cake is a by-product of the manufacture of fertilizer, the
active principle of it being free sulphuric acid. It has been used
successfully for fire-barrels, 3 or 4 pounds of it being dropped
into each barrel. It has not proven altogether satisfactory for
pools, catch-basins, etc., as, it is believed, the alkalinity of the
soil often neutralizes much of the acid. As niter cake, where it is
available at all, can generally be obtained gratis, it may be
used profitably in artificial containers, provided its poisonous
properties do not make it objectionable.

Creosote has been used successfully on a small scale, parallel
with the Panama, mixture, as a substitute for oil. It is, of
course, open to the same objections regarding its poisonous
properties as the Panama mixture. It is said to be particularly
useful in protecting the edges of ponds and streams and in places
where heavy verdure interferes with oil spraying. Fish in a
flowing stream or in a large body of water are not injured by
spraying the margins with creosote, it is reported.

Water gas tar, a by-product of the manufacture of gas, con-
taining phenol, creosote and other larvicidal substances, has also
been reported as a satisfactory substitute for oil. It is applied
similarly to oil. It is said to make a very effective mixture with
kerosene or with kerosene and fuel oil. The proportions recom-
mended by Bishop 1 are: 1 gallon tar to 5 gallons kerosene, and 1
gallon tar to 2 gallons fuel oil and 5 gallons kerosene. He states

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

PLACE OF OILING IN ANTI-MOSQUITO WORK 163

that this mixture does not blow off to one side of a pool so readily
as does the film of oil alone. Water gas tar can generally be
obtained at a nominal cost from any water gas manufacturing
plant.

Paris green, diluted with a large proportion of inert dust and
sown on the breeding-place, much as grain is sown, is reported
by Barber and Hayne 1 to be a satisfactory larvicide for Anopheles
larvae. It is, however, useless for other kinds of larvae, since
they do not feed on the surface. It is reported that 10 cubic
centimeters of Paris green will suffice for at least 1,000 square feet
of water surface. One part of Paris green to 100 parts of some
inert dust, such as road dust, seems to be a favorable mixture.
Barber and Hayne report that the minute quantities of Paris
green used appear to have no effect upon top minnows or other
fish. They suggest, however, that the sower of the poison always
keep to the windward side of the dust cloud.

THE SPRAYER

The usual — and, for general purposes, the best — method of
applying oil to quiet water surfaces is by means of a spray-can,
which consists essentially of a container, a pump and a spray
nozzle at the end of a short rubber tube. The type which seems
to have proven most satisfactory for all-around anti-mosquito
work is what is known as the Panama knapsack sprayer. This
sprayer holds 5 gallons of oil and fits on the back like a knapsack,
the pump being worked over one shoulder and the spray tube
being directed by the opposite hand.

This sprayer will distribute the oil satisfactorily to a distance
of 20 to 30 feet from the operator — a valuable consideration in
swampy or bushy areas. Another advantage is the fact that the
opening of the nozzle can be adjusted, so that heavier oils than
those ordinarily used may be employed. The weight is so dis-
tributed that the operator should not easily become fatigued.
The fact that in walking over rough ground or through bushes,
the operator may have both hands free is also important.

Occasionally, men who oil continuously for several days
develop a sore back, caused by leakage of oil from the spray-can.
This leakage can generally be prevented by using care in not
filling the can too full and by replacing any damaged washers
with good ones.

1 Public Health Reports, Dec. 9, 1921.

1G4

MOSQUITO ERADICATION

Several other types of sprayers are also in use. There are
various styles of pumps adapted to use on barrels, etc; the .barrel

Fig. 110. — The knapsack sprayer.

Eig- 1520

Fig. 111. — Barrel sprayer mounted on a cart.

may be mounted on a barrel cart or, where conditions will permit,
on a truck or wagon or on a boat. Considerable pressure may

PLACE OF OILING IN ANTI-MOSQUITO WORK

165

be developed with some of these pumps, so that a stream of oil
may be thrown 50 feet or more.

While such spray-pumps are very useful for oiling parts of
ponds, lakes, etc., or edges of rivers and streams or pools in open,
accessible territory, they lack the portability of the knapsack
sprayer and usually are of but little value in swamp work or in
areas where the terrain is rough or timbered.

For limited areas and for use about homes, etc., the oil may be
distributed by means of a garden watering-pot or a small insecti-
cide sprayer. An oil-soaked broom may be stirred into many
small pools with good effect.

DRIP CANS

For flowing ditches or streams, "drip-cans" have proven very
satisfactory. These may be adapted to either continuous or
intermittent application, as the case may require.

Drip-cans consist essentially of
a receptacle for oil, arranged in
such a manner that a small quan-
tity of the fluid drips from it into
the water. This is wafted along
by the current and bathes both
banks, also, if the stream is in
good condition — that is, free from
obstructions and vegetation —
covering pools and backwaters,
where breeding is most likely to
take place.

Drip-cans should be suspend-
ed three or four feet above the
stream. If heavy oil is used, this
elevation may profitably be in-
creased, since the impact of the
drops of oil on the water breaks
them up and accelerates forma-
tion of the film. The precaution
should be taken of securing the drip-can in such manner that it
will not be swept away by high water.

In making the drip-can, the outlet ordinarily should be placed
an inch or so from the bottom of the can, so that any settleable
solids in the oil will not cover up the hole. The outlet should be

Fig.

112.— Sketch of
drip-can.

easily-made

166 MOSQUITO ERADICATION

large enough to allow a sufficient number of drops to fall to form
and maintain the film, and no more, it being borne in mind that
the drip will decrease at night and on cool, cloudy days and
increase on hot, sunny days. Sometimes, it has been found that
a more even flow is obtained by introducing a short, soft wick
into the outlet.

"A crude, but cheap and easily made, drip-can," says LePrince, 1
"consists of a 5-gallon can, such as is used for shipping illuminating oil.

A hole is made in its bottom with a 2 or 3-inch
Co/*" round nail. A wad of loose cotton is wrapped

Bo/hm of can •! •

around the nail just below its head. The nail is
then pushed through the hole on the inside of the
can, and ... oil is put in the can, which is
suspended or placed on a stand over the ditch.
Fig" 11.3 —Detail By pulling the point of the nail downwards and
of drip-regulating gently pushing it upward, the flow of oil may be
device - decreased or increased, as desired."

Frequently, a 5-gallon can, having a metal discharge tap, is
used. The tap can generally be adjusted to give within a few
drops of the number desired to be discharged per minute.

USE OF DRIP-CANS

The quantity of oil that should be allowed to drip out depends
upon the spread of the oil, the size and alignment of the stream,
its grade and the absence or presence of obstructions in it.
LePrince 1 suggests from 10 to 20 drops of oil a minute for water
surfaces 1 foot wide. He continues:

"For economical control, a trial should be made at each ditch or
stream where a drip-can is used to determine the desired rate of flow.
The drip-can should be regulated accordingly. In many cases, the drip
need be operated continuously for only 1 or 2 days of each week. With
larger streams, it may be found necessary to operate the drip con-
tinuously, day and night. On long streams or ditches, it is at times
necessary to use several drip-cans. They are then so located that the
next drip-can is installed approximately at the point where the effect
of the drip at the source disappears.

"Continuous dry weather may make it become necessary to discon-
tinue the use of some drips or to change their location. At such seasons,
pools will be left isolated at the sides of a stream and will have to be
filled or separately treated with oil by other methods. When the stream

1 "Control of Malaria: Oiling as an Anti-mosquito Measure," U. S.
Public Health Service, 1915.

PLACE OF OILING IN ANTI-MOSQUITO WORK

167

stops running, the use of drips is discontinued, and any water left in the
stream-bed is oiled with a knapsack sprayer or watering-pot.

" With the best of care, oil drips will clog, due to suspended solids or
heavy constituents in the oil, and must be adjusted as often as necessary.
The disadvantage of oil drip-cans is that they will not give satisfactory
service without proper attention, may become clogged or be washed
away by floods. Their use is generally more effective and economical
than the direct application of oil by sprinkler or knapsack sprayer for
water in motion."

Fig. 114- — Utilizing a drip-can for a flowing stream. Note the drip-can fastened

to the rail to the left of the officer.

OTHER METHODS OF APPLYING OIL

Occasionally, the moving water in a ditch or stream may be
so little that use of a drip-can is not justified. In such cases,
a small bundle of oil-soaked waste, placed at the source of the
water will often prove very efficacious. This will give off a thin
film for a week or so, after which it may be re-soaked in oil and
used again. This same method may be used to control small
springs, seepage water outcrops, etc.

A somewhat similar device, suited for use in similar situations,
is a small bag or box of oil-soaked saw-dust.

Oil-soaked saw-dust has also been used successfully in treating
ponds, lakes, swamps, etc., where there is considerable floatage
or vegetation. In such cases, it is simply broadcast over the
surface, somewhat after the fashion of sowing grain.

There are many other devices for applying oil to water-surfaces,
several of which distribute the oil from above the water; others

1G8 MOSQUITO ERADICATION

are submerged, the oil rising to the surface. It is the opinion
of the writer, however, that usually equally as good work can be
done with the devices already described.

FREQUENCY OF OILING

The frequency with which oiling should take place depends
upon several different factors. Ordinarily, one oiling a week or
every 10 days is sufficient, and this was the basis upon which
most of the oiling was done in the extra-cantonment work of the
U. S. Public Health Service during the World War.

The resistance of larvae and pupae to oil varies with the
different kinds of oil used and with the different genera of
mosquitoes. The Anopheles succumb more easily than the
Culex. Frequently, a good film of oil will kill virtually all the
larvae in a pool in an hour or so. On the other hand, the writer
has observed Culex still active in a cess-pool 2 days after it had
been well oiled.. The oil, in this case, may have been prevented
from forming a perfect film by the floating matter in the pool
or by the gas bubbling to the surface.

Whatever the period necessary to kill the larvae and pupae
may be, once they are dead, several days must elapse before a
new breed can reach the pupal stage. The exact time will, of
course, depend upon the temperature and other factors. If
the weather is very hot and, through early disintegration of the
film, new eggs are deposited promptly, a second brood of larvae
may appear within 3 or 4 days and, within a week, may reach
the pupal stage. Again, if the weather be cold and cloudy the
development of the new brood will be correspondingly delayed.

With the above considerations in mind, it has been suggested
that oiling should be done by inspection — that is, that there
should be no set times for oiling, which should be done only when
it has been determined by careful inspection that oiling is
necessary. However, in view of the obvious risks of this method
arising from possible changes in weather conditions, possible
incompetence or carelessness of inspectors, etc., the writer's
experience has been that best results are obtained by regular
weekly oiling of each place that requires it — that is, has not
dried up or has not been treated effectually by some other method.
If the project is a small one, all the oiling may be done on 1 day
of each week; if a large one, it may be necessary to have a gang
to oil all the time, visiting each place once a week.

PLACE OF OILING IN ANTI-MOSQUITO WORK 169

DISTRIBUTION OF OIL

Where a large area is to be protected from mosquito breeding
by means of oiling, it is obvious that some convenient means of
transporting or distributing the oil must be worked out. In
other words, there must be some system of getting the oil to the
places where it is to be applied.

Even in a small town of from 5,000 to 10,000 inhabitants,
the area in which operations must be conducted will cover several
square miles. Usually, the places that will require oiling will be
found scattered over all parts of this area. Obviously, the oiler
cannot get his oil to all these places without some means of
transportation.

It has been the experience of the writer that procurement of
one or more light trucks, each carrying a barrel or two of oil and
each barrel being equipped with a faucet, is the best solution of
this problem for the average town. The driver of the truck
should also, where practicable, be foreman of the oiling gang.
Knowing the places which must be oiled, he can disperse his
men in such manner that he can easily keep each supplied with
oil, putting in the intervening time in following up and inspecting
the work. If the gang is a small one, or in case of an emergency,
he may assist in the actual oiling.

In smaller towns, where the available funds will not justify
employment of a truck for this purpose, a one-horse wagon,
carrying a barrel of oil on the rear, will serve the purpose.

Where even this is not available, barrels of oil may be dis-
tributed at the principal breeding-places in such manner as to
minimize the amount of walking required of the oiler. This
method also was employed on a very large swamp project upon
which the writer was engaged. At each distributing point-
carefully selected, so as to obviate as much "toting" of oil as
possible — a rack was built, upon which 4 or 5 barrels of oil
were left. A bung-borer and a faucet were also issued to the
oiler, so that, when one barrel was exhausted, he could open
another. When the supply got down to a barrel or so, the oiler
would requisition more oil.

STORAGE OF OIL

Whenever possible, supplies of oil should be stored in isolated
buildings, and if these buildings are fire-proof, so much the better.
Laborers frequently using oil soon become careless with it, and

, ERSITY OF

170 MOSQUITO ERADICATION

every reasonable precaution should be taken to guard against
fire. LePrince 1 recommends a 140°F. flash-test oil, if the oil
is to be stored near any valuable property.
LePrince 1 continues:

"Oil stored in unsafe containers, as wooden barrels or improperly
covered tanks near railroad tracks, is very apt to catch fire. Small
quantities are usually shipped in wooden barrels and, if left exposed in
the sun, leakage occurs and danger from fire is increased. Provision
must be made for fire protection and precautions taken to avoid spilling
on the ground at or near the place of storage. Sufficient sand or loose
earth should be kept available close to where the oil is stored for use in
extinguishing a flame. Oil-storage houses and faucets of storage tanks
or barrels should be kept locked when not actually being used. No
smoking is to be allowed near them."

As indicated above, barrels of oil should not be stored nor left
in any place where the sun can beat down upon them, since, not
only is the fire risk increased, but a very large quantity of oil is
likely to be lost. The warmth of the sun thins the oil, and some
of the barrels are almost certain to leak. The amount of oil that
may be lost in this manner is surprising.

In case it is found necessary to distribute barrels of oil at
various places throughout the area of operations, care should be
taken to place the racks in the shade or else to cover them over.

COSTS OF OILING

So many factors enter into the situation that it is almost
impossible to give any rules to estimate the cost of oiling or even
the amount of oil to be used in any project.

The weather is, perhaps, the most important factor in the case.
A given area may require twice or thrice the amount of oil and
labor one year as another, depending on the amount of rain-fall
and its distribution. Topography is also an important element,
as is soil-type. Again, the conduct of the campaign itself has an
effect upon oiling; if fish control and drainage are pushed, less
oiling will be required, and vice versa.

The following figures,- taken from five different projects with
which the writer was connected, shows the wide fluctuations in
amount of oiling required, costs of oil and costs of applying oil,
even in places of approximately the same area:

1 "Control of Malaria: Oiling as an Anti-mosquito Measure," U. S.
Public Health Service, 1915.

PLACE OF OILING IN ANTI-MOSQUITO WORK

171

Pro-
ject

Area in

square
miles

Months
oiled

Oil per
gallon

Cost
of oil

Applying
the oil;

hauling

Total
cost for
season

Cost per
square

mile per
season

Cost per
square

mile per
month

$0.03

$ 47.52

$ 443.00

0.03

64.35

702.00

0.05

176.25

578. 35

0.08

324.86

1,365.91

22H

0.16

4,486.88

6,425.30

; 490. 52

766.35

754.60

1,690.77

10,912.18

$ 122.63
127.39
188.65
281.80
481.56

$24.53
31.85
37.73
46.96

87.56

* This project was mostly swamp work.

Wages on all the above-mentioned projects averaged around
$2.50 a day. Colored labor was employed principally on all the
jobs. The heading "Applying the oil; hauling," also includes
wages of foremen.

CHAPTER IX
FISH CONTROL

ADVANTAGES AND LIMITATIONS

There is no doubt that fish control, where it is applicable, is one
of the cheapest and most satisfactory methods of fighting the
mosquito. Once a natural breeding-place, such as a lake or
stream, is stocked with the proper kind of fish, about the only

(Photo by E. B. Johnson, C. E.)
Fig. 115. — Perfect fish control at a log pond in Alabama.

work required to maintain their efficiency is occasional cleaning
of its edges. In certain artificial breeding-places, such as foun-
tains, underground cisterns, etc., even this is not required.
Even where such cleaning is necessary, it has been the writer's
experience, however, that, in the long run, fish control is often
cheaper and easier than oiling or ditching. In some places, such
as large, shallow ponds, water-filled clay-pits, etc., fish control is
about the only solution, since often it is not possible to drain such
places, while weekly oiling of large water-surfaces quickly runs

172

FISH CONTROL

173

up into money, even assuming that such a procedure is prac-
ticable. Again, in the writer's opinion, there is no other method
so effective for controlling breeding in shallow wells, some kinds
of cisterns, low culverts that hold water, etc. It is also believed
that fish control, either by itself or in conjunction with ditching,
is the best and cheapest method of control for flowing streams
and ditches, marshes, swamps and many other types of mosquito
breeding-place.

Fish control has its limitations, however. It is not applicable
usually to rain-water pools, since they soon dry up and the fish

(Photo by E. II. Magoon, C. E.)
Fig. 116. — The bucket indicates the water's edge. The water area concealed
by the vegetation affords an ideal breeding-place, as it is inaccessible to the
larva eating fish, which keep the rest of the pond free from larvae.

would die. Nor, as already intimated, is it feasible to stock a
breeding-place with fish and depend upon their unaided efforts to
eliminate mosquito breeding. On the contrary, they will have to
be helped from time to time.

HOW FISH DESTROY LARVAE

Some interesting observations on the manner in which fish
detect and destroy mosquito larvae and on the marvelous self-
protective instincts manifested by the larvae are recorded by
Hildebrand, 1 who says, in speaking of Gambusia affinis:

"I took several large Anopheles larvae from dense vegetation and
placed them in open water among top minnows. With one larva was a

1 "Fishes in Relation to Mosquito Control in Ponds," U. S. Bureau of
Fisheries, 1919

174

MOSQ UI TO ERA DI CAT ION

small piece of bark. The larva hovered over this piece of bark, and the
fish did not detect it. When it was placed in open water, without the
least protection, the fish swam around it, even 'nosed' it, while the larva
lay perfectly motionless. At last, a rather small minnow seized it and
swallowed it. Placed another larva in open water among fish. This
one too lay perfectly still, drifting like a small stick, while fish swam all

Fig. 117.-

(Photo by E. H. Magoon, C. E.)
Dipping up larvae concealed by dense vegetation.

about it, nosing it a time or two, but apparently not detecting that it was
alive and something to eat. Finally, it drifted near a tuft of grass and,
with a surprisingly quick motion, it swam into the vegetation. It was
removed and placed in open water. There it lay motionless for about
5 minutes, when at last it was snapped up by an under-sized minnow.
"These feeding experiments, which were repeated many times, demon-
strated that the protective instinct in mosquito larvae is highly devel-
oped. It was shown many times that the only protection an Anopheles
larva has from fish in open water is inactivity. When the larva thus

FISH CONTROL

175

drifts along, fish evidently mistake it for an inanimate object. The
slightest movement, however, on the part of the wriggler apparently
never goes unseen, and it is instantly seized and devoured by the fish.
It often happens that a mosquito larva placed in open water drifts
toward places of protection before it is discovered by the minnows, and,
if no fish are very near, it moves toward it with a remarkable rate of
speed and quickly places itself over the object.' 7

THE TOP MINNOW (Gambusia affinis)

The top minnow, Gambusia affinis Baird and Gerard, so far as
is known at present, is probably the best fish for general anti-
mosquito work, within its habitat, of any of the North American
pisces. It is known on the Atlantic from Delaware to Mexico
and in the Mississippi Valley from Illinois to Louisiana. It
inhabits both fresh and brackish water, while an occasional

*>z - •.■'• ?-'*

Fig. 118. — Gambusia affinis, female. (After U. S. Bun an of Fisheries.)

straggler is taken in strictly salt water. This fish is viviparous —
that is, it gives birth to its young. It, therefore, requires no
special environment for depositing and hatching its eggs.

The female, which is larger than the male, rarely measures
more than 40 to 45 millimeters in length, although specimens
have been taken measuring as much as 65 millimeters in length.
The average length of the adult male is 25 millimeters. The
young, at the time of birth, are from 8 to 10 millimeters in length.
They grow rapidly at first, but several months elapse before
they reach full size.

The sexes in the young cannot be distinguished externally,
but the anal fin in the male gradually becomes modified into a
long, sharp process which in the sexually mature fish serves as
an intromit tent organ. This process is the characteristic
identification mark of the adult male Gambusia. Gravid female
Gambusia may be identified by a black spot on each side of the

176 MOSQUITO ERADICATION

abdomen, above and in front of the vent. These spots increase
in size and, when they join on the ventral surface, the period of
parturition is near.

The young are extruded singly or in twos and threes; the labor
may last from an hour to a day. The proportion of males born
to females appears to be about 1 to 8 or 9. As many as six broods
a year may be born, each brood ranging from 2 or 3 to 50 or 60.
A peculiar fact in connection with the fertilization of the eggs is
that, apparently, one copulation is sufficient to produce several
broods.

This little fish is one of the hardiest known. It will live
equally well in salt, fresh or stagnant water. In foul or stagnant

Fig. 119. — Gamhusia affinis, male. (After U. S. Bureau of Fisheries.)

water, it has been observed to stick its mouth above the surface
from time to time, making a sucking noise. The object of this
action, it is believed, is to get more oxygen. Its habit of swim-
ming near the surface is correlated with the fact that it seeks most
of its food near the surface. This habit is what gives the fish
its value for anti-mosquito work.

Gamhusia affinis is a very voracious feeder. One medium-
sized female has been observed to eat as many as 165 mosquito
larvae in a single .day. The young begin feeding a few hours
after they are born, and even at this age, the young fish will
swallow a larva half as big as itself.

THE BARRED KILLIFISH (Fundulus heteroclitus)

The barred killifish, also known as the mud-fish, pike-minnow
and salt-water minnow, is probably one of the most effective

FISH CONTROL

111

of the fish enemies of the salt marsh mosquito in the north, beyond
the range of Gambusia.

This fish attains a length of from 4 to 6 inches, and is charac-
terized by banded markings, rounded fins, a short head and
obtuse snout, a projecting lower jaw, a convex tail and a very
flat area between the eyes. While the killifish has the faculty
of changing its color somewhat to approach its prey or to escape

^mKffld|^r^

glSSS^

^ "' J

^5^-

1 l^i*5 IllliJ

gjggssy

ShME^^^

Fig. 120. — Fundulus heteroclitus, female.

an enemy, the general color of the female is olivaceous on top
with a lighter belly, and the male is darkish green on top with a
yellowish belly. Both male and female generally have numerous
spots and markings.

This fish is oviparous. The eggs are very resistant and, as
soon as they are laid, they sink to the bottom in the mud, which

^^gj!^^^^^Vf

¥fjt^*fv%&

WLfc^

5**

Wmw

KwtMb

ft*38

^^^^■^r- -M^ r fc^ :

Fig. 121. — Eundulus heteroclitus, male.

protects them. They hatch out in about 21 days of warm
weather. The young fish hatches with a yolk sac, which soon
disappears, after which it feeds on minute plankton.

Many of the eggs are eaten by its own kind. Other enemies of
the killifish are weakfish, dogfish, smelt, striped bass, etc. Man
frequently uses the young as bait.

The spring migration begins as soon as the weather becomes
warm, and gravid females are found shortly thereafter. The

178

MOSQ I r IT() ERA DICA TION

spawning season lasts until late summer, the yearlings starting
after the elder ones finish. When cold weather comes, the
killifish return to deep water.

Young killifish only a few months old have been known to
devour large numbers of mosquito larvae. Adults have devoured
as many as 25 larvae in succession. Stomach examinations

dti^b

Fig. 122. — Fundulus majalis; male above, female between and young below.
(From Jordan and Evermann, Bull. 47, U. S. National Mxiseum.)

have also revealed adult mosquitoes. This killifish is also an
important enemy of the green-headed fly.

Like Gambusia, Fundulus heteroclitus is equally at home in
salt, fresh or stagnant water. It is found in the most insignifi-
cant pools and ditches, and has been known to push its way over
places where there is barely enough water to cover its back.

FISH CONTROL

179

The ease with which F. heteroclitus may be artificially ferti-
lized and the hardihood of the young embryos make the stocking
of pools and streams with this fish an easy and satisfactory method
of mosquito control.

THE STRIPED KILLIFISH {Fundulus majalis)
This killifish, which may be distinguished from F. heteroclitus
by its color, the fact that its tail-fin is not so convex and that
its average length is an inch or more greater, is also considered
as having some value in anti-mosquito work.

£9ff

Fig. 123. — Fundulus diaphanous; male above and female below. (From Jordan
and Evermann, Bull. 47. U. S. National Museum.)

Males of this species show vertical markings on the sides,
while the females have more or less horizontal markings on the

sides.

This fish enters the marshes with the tide and goes out with it.
Should it get cut off from the ocean, it will, according to Mast, 1
travel overland toward the sea by flopping itself along. Mast
also shows that this fish seems to keep its sense of direction
while traveling overland, which he attributes to internal factors.

THE FRESH-WATER KILLY (Fundulus diaphanous)

This species differs from both of the preceding in that its
tail-fin is not rounded at all, but is squarely cut off. The females"

1 The Behavior of Fundulus with Especial Reference to Overland Escape
from Tide-pools, Journal of Animal Behavior, 1915.

180

MOSQUITO ERADICATION

are olivaceous with pale fins and with sides marked with 15
to 20 dark, vertical bands. The males are a pale, olive color,
and have about the same number of white vertical bands on
their sides.

While this killifish is more or less similar to those previously
described in its other habits, it sticks more closely to fresh water
than do they, and indeed is rarely found in salt or brackish water.

s J fyf K< *3 P £* 5? / V~ « I feSfi

P^*«

'sags

Fig. 124. — Cyprinodon variegatus, male. {From U. S. Bureau of Fisheries.)

Fig. 125. — Cyprinodon variegatus, young. (From U. S. Bureau of Fisheries.)

THE VARIEGATED MINNOW (Cyprinodon variegatus)

This minnow, which occurs on the Atlantic Coast from Cape
Cod to the Rio Grande, ascending streams and inhabiting
brackish waters, is believed to be of some value in anti-mosquito
work, although it subsists mainly upon vegetable matter.

The variegated minnow, also known as the sheeps-head minnow,

FISH CONTROL

181

is very prolific and very active. It is oviparous, the females
spawning virtually the whole summer. The eggs are somewhat
heavier than salt water. This little fish is occasionally found in
strictly salt water, and foul water does not seem to inconvenience
it.

Adult females average about 45 millimeters in length; males
about 48 millimeters. Newly-hatched young are about 4 milli-
meters long.

Fig. 126. — Lucania parvia. (From Jordan and Evermann, Bull. 47, U. S.

National Museum.)

THE RAIN-WATER FISH (Lucania parvia)

This fish, which ranges from Vy^ to 2 inches in length, is not a
top feeder, but has been considered as of some value in anti-
mosquito work. The males are olive or light-brown, the edges
of the scales being darkish; the females have light, olive fins,
with no dark markings.

THE SPOTTED TOP MINNOW (Fundulus notatus)

The spotted top minnow is found in the Mississippi Valley
from Michigan to Louisiana and regions adjacent thereto. It
occurs only in fresh water. While its value in anti-mosquito
work is not fully understood, it appears to be worthy of further
investigation.

THE STAR-HEADED MINNOW (Fundulus notii)

This little fish closely resembles in habits and appearance the
spotted top minnow. Its habitat, however, does not appear
to be large, since, according to Hildebrand, it seems to be confined
to the Atlantic slope from North Carolina to Florida. The
star-headed minnow occurs in fresh water only.

182

MOSQUITO ERADICATION
OTHER FISHES

Several species of sun-fishes have been mentioned by different
writers in connection with anti-mosquito work, but the observa-
tions of Hildebrand indicate that they are of doubtful value.

Fig. 127. — Fundulus nolii. {From U. S. Bureau of Fisheries.)

Fig. 128. — Fountain protected by gold-fish.

Hildebrand 1 considers gold-fish useful in confinement, although
probably of but little value in large bodies of water. Fountains
stocked with gold-fish and kept fairly clear of debris and vegeta-
tion will rarely show any breeding.

1 "Fishes in Relation to Mosquito Control in Ponds," U. S. Bureau of
Fisheries, 1919.

FISH CONTROL 183

Chidester 1 has compiled the following list of other fishes classed
as enemies of the mosquito: Heterandria formosa, Abramis
chrysolenca, Mollinesia latipennia, Girardinus poeciloides, G.
caudimaculatus, Haptochilus, Lucius americanus, Cijprinodon
calaritanus.

PROCEDURE IN FISH CONTROL

The first procedure in connection with the use of fish as an
anti-mosquito measure is to look over the local fishes and ascer-
tain what kinds of larva-destroying fishes there are and which
will be most suitable for the work in hand. Important consider-
ations in this connection are the species of mosquito-destroying
fishes most numerous in the vicinity and the character of the
places in which they are to be used.

In general, it may be said Gambusia affinis should be used
wherever it may be found, since for all-around work it seems
to be superior to any other. Indeed, Gambusia is frequently
imported to regions outside of its natural range on account of its
superiority to the native fishes.

When these matters have been determined, the next step is to
arrange for an aquarium or "hatchery," so that an abundant
supply of fishes will always be at hand for stocking purposes.
Generally, a small, shallow pond can be found for the purpose.
The pond should not be so big, however, that catching will be
difficult. Nor should it, as a rule, be located in the bed of a
stream that is subject to floods, since, in this case, it is possible
that a storm will disperse all the fish. Care should also be used to
obtain an aquarium that is free from bass and other game fish
which feed on Gambusia and other minnows.

On account of the cannibalistic habits of Gambusia affinis, as
well as some of the other larva-eating fishes above-mentioned,
Hildebrand 2 suggests that one corner of the aquarium be screened
off with a%6 inch wire netting to serve as a refuge for the young.

Steps should also be taken to prevent local fishermen from
helping themselves to the minnows or other small fish for use as
bait. It has been found that a little publicity, explaining the

A Biological Study of the More Important of the Fish Enemies of the
Salt Marsh Mosquito," New Jersey Agricultural Experiment Stations,
Bulletin 300, 1916.

2 "Fishes in' Relation to Mosquito Control in Ponds," U. S. Bureau of
Fisheries, 1919.

184 MOSQUITO ERADICATION

purpose of the work and perhaps a notice or two put up at the
aquarium, will generally prevent any considerable losses in this
way.

Fish for stocking the aquarium, if it is not already stocked with
them, may generally be obtained in abundance from nearby
streams or swamps. In this connection, care should be taken not
to draw too many from one source, so as to leave such source
unprotected against mosquitoes.

The number of fish that should be placed in the aquarium will
vary with the size of the aquarium, the requirements of the fish-
control work and the abundance of fish in the vicinity. It should
be borne in mind that these fish, particularly Gambusia, multiply
with great rapidity, especially if those installed in the aquarium
include a number of pregnant females.

Should the aquarium be small and the number of fish therein
very large, it will be necessary to feed the fish. Minced meats
or fish, bread, corn-meal and similar substances are considered
suitable for this purpose.

NUMBER OF FISH REQUIRED

When the aquarium has once been established, the work of
distributing the fish among the places where they are needed may

begin.

The first question that arises in this connection is : How many
fish are necessary in a pond, stream or other breeding-place in
order to prevent mosquito production? Hildebrand 1 answers
this question as follows :

"Data upon which a definite answer could be based are extremely
difficult to obtain, for there are scarcely two ponds which offer identical
conditions. The size of the pond of course must be considered; whether
or not it is subject to wave action is of importance; the presence or
absence of vegetation is very important; and the presence or absence of
enemies of Gambusia (or other larva-eating fish) must not be overlooked.
Even then, we can only make a guess, for Anopheline mosquito larvae,
at least, breed much more prolifically in some ponds than they do in
others for reasons not understood. . . .

"It has been shown . . . that a small number of minnows freed
badly infested pools of mosquito larvae in a short time; also that they
destroyed the mosquito larvae in ponds and kept the ponds free of the

> "Fishes in Relation to Mosquito Control in Ponds," U. S. Bureau of
Fisheries, 1919.

FISH CONTROL

185

aquatic stages of the mosquito, unless protection was provided by plants
and debris. From the knowledge which has thus been gained, we may
conclude that, if a pond furnishes little or no protection for mosquito -
larvae, a small number of top minnows is sufficient, but, if it does
furnish protection, a much larger number is desirable. Anti-mosquito
work, however, may be started with a very small number of Gambusia,
for this fish multiplies rapidly. There appears to be no danger of over-
stocking, as observations indicate that the more fish a pond supports the
more certain are the practical results."

Precisely similar considerations apply to control of streams and
ditches, swamps and marshes.

Fig. 129. — A pool in which fish control cannot be entirely effective on account of

vegetation.

Underground concrete or brick cisterns should be stocked
with anywhere from 5 to 50 fish, depending upon the degree of
infestation, size of the cistern and other conditions. Fish,
particularly Gambusia, cannot be employed in metallic, surface
cisterns, since the water gets too hot and kills the fish.

Low-lying culverts that hold water for any considerable time
should also be stocked liberally with the fish. The writer has
found this to be the cheapest way of handling such culverts.

Shallow wells, where they are abundant, are frequently trouble-
some breeding-places. The writer has found that satisfactory
results follow, if from three to five male Gambusia are lowered
into each of them. Such wells should be inspected frequently,
however, as it often happens that users of the wells haul out the
fish with the water and, not knowing their purpose, do not put

ISC, MOSQUITO ERADICATION

them back. When the fish are let alone, however, they do
satisfactory work.

DISTRIBUTING THE FISH

In anti-mosquito work in which fish are used, best results are
obtained by making some one certain individual responsible
for this phase of the work. This individual should be in charge
of the collection, care and distribution of the fish and of the pond,
marsh and stream cleaning essential for their advantageous use.

Requests for fish made by inspectors or other persons should
be at once turned over to the fish control foreman for action.
In order to speed up distribution of the fish, it is essential that he
have necessary facilities for his work. Among these may be
mentioned nets for catching the fish, suitable receptacles in which
to transport them and means of transportation.

A very useful net for collecting top minnows is a small bobbinet
seine. A net about 12 feet long by 3 feet deep is a good size.
Such a net, if made of good material, is light and durable, and it
can be easily and quickly handled. A dip-net, also made of
bobbinet, may be used to advantage in places where there are so
many roots or so much vegetation that a seine cannot be operated.

Almost any kind of a receptacle for the fish will do, but for
ordinary use in an anti-mosquito campaign, the writer suggests
a milk can, with a cover of gauze or burlap substituted for the
metal cover. When about half-full of water, such a can will
hold several hundred fish very comfortably and but little water
will splash out in ordinary travel.

Transportation may be either by automobile, truck or wagon.
For ordinary use in a small town, the writer suggests a light
roadster with the turtle-box removed or a buggy or buckboard.
Such a vehicle will comfortably carry two cans of fish on the back.
On small jobs, it is likely that the same vehicle used for carrying
oil may be utilized on certain days for hauling fish.

NECESSITY OF AIDING THE FISH

Throughout the South, even in inland areas, it probably will be
found that most streams, ponds, lakes, swamps and similar
natural breeding-places already are stocked with Gambusia or
other larva-destroying fish. In such cases, very little new stock-
ing will be necessary, but the fish will have to be aided, if best
results are to be obtained.

FISH CONTROL

187

This aid must take the form of removing or otherwise eliminat-
ing vegetation and other floating matter, which serve to conceal
the larvae from the fishes and to prevent the fishes from reaching

Fig. 130. — This formidable looking mosquito breeding-place offered quite a
problem. To have cleaned all the circumference, so as to make fish control
practicable, would have cost a lot of money. Instead, it was drained into a
large abandoned gravel pit nearby, the edges of which were already clean. In
this way, complete and permanent fish control was obtained at slight cost.

Fig. 131. — Too much vegetation in this pool for effective fish control.

the larvae, even though the larvae be visible. Just how impor-
tant this matter is is shown by the following observation of
Hildebrand: 1

1 "Fishes in Relation to Mosquito Control in" Ponds," U. S. Bureau of
Fisheries,_1919.

188 MOSQUITO ERADICATION

"It is very interesting to observe how quickly the top minnows learn
to follow the workmen engaged in cutting and raking vegetation from
ponds. They soon become quite tame, and schools of them work
almost under the tools of the laborers, catching mosquito larvae and
other insects as quickly as their hiding-places are destroyed."

All aquatic plants, however, do not furnish protection for
mosquito larvae and pupae against fish, and some even may be
positively repellent to them. Grasses and rushes and other
plants having straight stalks and no submerged leaves afford no
protection. Areas overgrown with plants of this nature have
been repeatedly examined for breeding, but, if the water was
stocked with mosquito-destroying fish, no larvae were found.
Plants which are likely to hang over into the water after maturity
or after freshets, etc., should be removed.

PLANTS IN RELATION TO FISH CONTROL

The following plants appear to provide good protection, and
may cause considerable trouble, according to Hildebrand: 1 the
aquatic grass, Hydrochloa carolinensis; "coon-tail moss," a
species of Myriophyllum; and algae. Continuing, Hildebrand 1
says:

"The aquatic grass grows in shallow water and along the shores. It
has many slightly submerged leaves, over which the horizontally
floating or swimming Anopheles larvae hover, out of sight and out of
reach of the fish. Wherever this plant occurs, some Anopheles larvae
are almost sure to be present regardless of the abundance of Gambusia.
It, therefore, is obvious that, if this plant occurs in ponds in which
mosquito control is desired, it must be removed. This may be done
by cutting and raking it or, if growing in soft mud, it may be pulled up
by the roots.

"The plant locally (at Augusta, Ga.) known as 'coon-tail moss'
causes trouble only when it becomes detached and rises to the sur-
face. . . . This floating mass must be removed from time to time;
this can best be done on a windy day, when it drifts inshore.

"Algae often form mats which float at or near the surface. Mos-
quito larvae, particularly Anopheles, find protection from fish over and in
these mats. Copper sulphate was used in the proportion of 8 pounds
to 100,000 gallons of water for killing the algae, but this treatment
must be repeated frequently. . . . Oil, if used in moderate quantities,
is not injurious to fish; it can be quickly and conveniently applied and it

V'Fishes~in"Relation to Mosquito Control in Ponds," U. S. Bureau of
Fisheries,* 1919.

FISH CONTROL

1S9

is very effective, for the algal pads act like sponges, retaining the oil and
making them uninhabitable for the mosquito.

"Water lilies do not, as a rule, appear to furnish much protection
while growing, but some of the plants die from time to time. The leaf
then partly sinks, forming a depression over the center, while the edges

Fig. 1

furnishes
Service.)

32. — Showing growth of aquatic grass in corner of pond. Sue
excellent protection for mosquito larvae. (After U. S. Public

h grass
Health

Ml' *%£*.9*l. .jiE. *****

-, J^L

** 7Effv? ^i^^ '

MHGMOE- ^HpTT fe > f

^F-

« -fin

4t*

(U. S. Public Health Service)
Fig. 133. — Treating pond with copper sulphate to kill algae. Laborer is
dragging a small bag of the chemical through the water by means of a pole.

remain at the surface. The cup thus formed holds enough water to
support mosquito larvae, and with respect to fish the larvae contained
therein are perfectly safe. When the dead leaves drift inshore they, of
course, frequently make places inaccessible to fish."

190

MOSQUITO ERADICATION

The aquatic plant, Naias flexilis, which is common in many
ponds and lakes, forming a thick growth over the bottom, nor-
mally does not afford protection, as it does not reach the surface
of the water. During severe droughts, however, it sometimes
reaches the surface, forming a dense mass, and, in such cases, it
makes excellent protection for larvae and pupae.

he duck-weed, Spirodela polyrrhiza, sometimes forms an
almost continuous cover over a pond or a portion of it, but
observations indicate that larvae are rarely, if ever, found
therein. It is considered likely that the covering is so dense that
breeding cannot take place.

Fig. 134. — Picture showing how water-lilies furnish protection for mosquito
larvae. Note the water in the leaves with turncd-up edges, and how completely
the larvae therein are protected from fish.

The smart-weed, Polygonum, is another plant that usually does
not afford protection, and which may sometimes be obnoxious
to mosquito larvae, according to Hildebrand, 1 who says: "Many
places overgrown with this weed were repeatedly examined, but
mosquito larvae were not found, even in apparently favorable
hiding-places."

ELIMINATING LARVA-PROTECTING PLANTS

It is evident from the study of plants in relation to fish control
that to get full results, it is necessary to remove from the pond
lake, stream or other natural breeding-place algae and other

1 "Fishes in Relation to Mosquito Control in Ponds," U. S. Bureau of
Fisheries, 1919.

FISH CONTROL

191

larva-protecting plants or else to treat them in such manner as to
make them obnoxious to the larvae.

The first consideration is to get rid of the shore vegetation,
which frequently is thickest in the shallow areas where mos-
quitoes are most apt to breed. This, generally, can be done very
effectively with a hoe or shovel, the idea being to leave a clean
edge, devoid of grass, brush and other debris which may conceal
the larvae from the fish.

(Photo by E. B. Johnson, C. E.)

Fig. 135. — Breeding in this stream is controlled by means of larva-
destroying fish. Note the clean edges and the cow helping to keep
them clean.

In some cases, this cleaning of the edges may be accomplished
more cheaply by lowering the water level from 6 inches to a foot.
If the water has stood at its former level for some time, the new
shore line probably will be quite clean.

Often, there will be some shallow coves or other areas thickly
covered with algae or other aquatic growths or debris, most of
which will be beyond the reach of the man with the hoe or shovel.
In such cases, it may be sufficient to oil these areas very liberally
once every week or ten days. It should be borne in mind, how-
ever, that application of oil probably will drive away the fish,
thus making it necessary to rely solely on the use of oil to control
the area.

192

MOSQUITO ERADICATION

In oiling such growths, it sometimes happens that nearby
portions of the pond, lake or stream may be used for bathing or
other purposes for which oil would be objectionable. In such
cases, the oil required to deal with the aquatic growths must be
prevented from escaping to other parts of the water surface.

Fig. 136. Fig. 137. Fig. 138.

Fig. 136. — Section of Ziomsen subaqueous saw, slightly reduced in drawing.
Fig. 137. — Section of improvised saw of "licker-in" wire, showing method
of joining.

Fig. 138. — Section of "licker-in" wire, slightly reduced in drawing.

This is best accomplished by running a boom about the area in
which it is desired to confine the oil.

These booms may be made of logs tied together and to the shore
or of boards, which are preferable, owing to their straightness and
lesser liability to become water-logged and sink, thus allowing the
oil to get out.

FISH CONTROL 193

THE SUB-AQUEOUS SAW

Should the aquatic growths be extensive, it generally will pay
to remove them. This may be accomplished by means of
scythes and sickles from a boat, but the best method, in most
cases, is by use of a sub-aqueous saw. This saw, a pliable,
toothed strip of steel, 100 or more feet in length, will cut many
kinds of aquatic plants successfully, providing only that the water
is not studded with brush or stumps. Probably the best saw of
this kind is the Ziemsen saw. a patented article.

A somewhat similar, but not so effective, a saw, may be made
very cheaply from "licker-in" wire, which is used in a combing
process in cotton mills and which may be purchased from mill
supply houses. This wire resembles a single-edge saw. By ty-
ing two wires together firmly, back to back, at intervals of 8 to 10
inches, with the cutting edges in opposite directions, a double-
edged saw may be made, capable of cutting in either direction.
Twisting seems to improve the cutting action. In order to make
the saw follow the contour of the bottom, weights should be
attached to it at 4 or 5-foot intervals. Ropes should be tied to
each end to take hold of in sawing.

To use the saw, it should be dropped to the bottom, the ropes
stretching to either shore. If the saw is not more than 100 feet
long or so, one man at each end can handle it; if it be several
hundred feet long, however, two men at each end probably will
be required. If there are many bushes or stumps, there should
be a man ready in a boat to disengage the saw T or lift it over the
obstacle, whenever necessary. Should the span exceed the
length of the saw, one end will have to be worked from a boat.
This is tedious and difficult.

USING THE SAW

The sub-aqueous saw is worked on the principle of a cross-cut
saw, the men pulling alternately on each end. The work is
very fatiguing, and the men will have to rest frequently. Where -
there is a current, it is best to begin at the downstream end and
work upward against the current; this permits the cut-off
growths, as they rise, to float clown stream out of the way, to
be collected and hauled ashore later. If there is no current, it
is preferable to cut in the direction of the wind, if there is any.

One annoying factor in connection with the use of the sub-
aqueous saw is the frequent breaks, especially in the case of the

194 MOSQUITO ERADICATION

saw made from the "licker-in" wire. The patented article
appears to be made of better steel, and the breaks are not so
frequent. However, they are bound to occur with either type,
but either can be easily mended by overlapping the ends at the
break about 2 inches and tying them together with a strong
wire.

With labor at 30 cents an hour, the cost of sawing probably
will average about $5 an acre. However, it is likely that the cost
will vary with the type of growth, condition of the pond and many
other factors. In any event, it would appear that use of a saw
is much cheaper than doing the work by hand.

In most ca^es, one or two sawings per season should be sufficient
for most aquatic plants. It is believed that repeated sawing
will ultimately destroy many of the plants.

CHAPTER X
SCREENING

PLACE OF SCREENING IN ANTI-MOSQUITO WORK

While screening cannot, of course, be considered a method of
mosquito eradication, the fact that it is very useful under certain
circumstances in anti-mosquito work makes it desirable to include
a chapter on the subject.

These circumstances may include cases where sufficient funds
for complete drainage, oiling and fish control under a general
community organization are not available or where the breeding
areas are too extensive to be controlled economically by anti-
mosquito measures. Screening is particularly valuable for
control work in rural areas, where the population is not sufficient
to warrant the expense usually involved in eradication work.

Moreover, as it is becoming customary to screen houses,
anyway, it is well to know what the requirements for anti-
mosquito screening are, so that the screening may be as adequate
a protection against mosquitoes as against flies and other
insects.

There is no doubt that screening, where the houses are in such
condition that screening may properly be undertaken and where
the screening is done carefully and thoroughly, is one of the most
effective methods of protection against mosquitoes.

It should not be inferred, however, that screening is a satis-
factory substitute for mosquito eradication. Screening protects
only the house screened, and people do not stay in the house all
the time. Unless eradication work is carried on, therefore,
they are subject to annoyance by mosquitoes whenever they
leave it. Furthermore, screening rarely keeps out all mosquitoes.
If they are abundant outside, some will always manage to get
into the house.

It will thus be seen that screening is at best only a partial
protection. It is only one of the many phases of mosquito
control work.

195

196

MOSQUITO ERADICATION

RARITY OF GOOD SCREENING

Observations indicate that a very large percentage of the
screening ordinarily done is not 100 per cent effective. This may
be due to three general reasons, which are as follows: (1) Attempts
to screen houses that are so poorly constructed or are in such
poor condition that they cannot be effectively screened; (2)
poorly constructed or improperly fitted screens or screens having

(U. S. Public Health Service)
Fig. 139. — Tenant house in too poor a condition to warrant screening.

too large meshes; and (3) the use of sliding or easily removable
screens, which frequently result in their being left open through
carelessness or negligence.

Tarbett 1 reports that inspection of houses in the vicinity of
an aviation camp in Arkansas in 1918 revealed that not 10 per
cent of the buildings were properly screened. In this same
connection, Carter 1 says: "I do not think that 2 per cent of the

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

SCREENING 197

screened houses in the United States are perfectly screened. I
will say this, that I saw not a single cantonment that was even
well screened. "

ESSENTIALS OF GOOD SCREENING

The first consideration in good screening is to apply it only to
houses in a state of repair that justifies screening. Therefore,
in starting a screening campaign, the houses should be carefully
inspected and divided into three classes: (1) Those already in a
satisfactory condition; (2) those that can be put in such condition;
and (3) those that cannot be successfully screened. The last
class should not be touched, and the second should not be touched
cither, until the necessary repairs are made.

A No. 16 mesh cloth is sufficient for Anopheles mosquitoes,
but, if protection against all mosquitoes is desired, the cloth
should be at least 18 meshes to the inch, as Aedes calopus can
pass through a No. 16 mesh. Varying conditions may demand
the use of different kinds of screening material, but, for adequate
protection against all mosquitoes, nothing less than 18 meshes
to the inch should be considered, or, if a screening material of
less than this be used, it should be painted.

A third essential is that the work be carefully done. This
means that certain rules, evolved by experience, should be
followed, and that the work should be executed with skill and
care.

A fourth essential is that no opportunity for tampering with
the screening be afforded. This means that no easily removable
screens be used. As already pointed out, if screens of such type
are employed, they will be sure to be left open occasionally.

Finally, every opening in the house should be screened. It
will not do much good to screen the doors and windows, if the
chimneys are left unprotected and open spaces are left elsewhere.

SCREENING OF DOORS

Since screening, like the proverbial chain, is only as effective
as its weakest point, especial attention should be paid to this
weak point, which, in most cases, is the door. This is because it
is the one movable section most frequently used and, therefore,
is most subject to the carelessness of the people who use it.

As mosquitoes are prone to congregate on the sheltered or
leeward side of a building, rather than on the windward side, it is

1<)S

MOSQUITO ERADICATION

well, if a door on that side is frequently used, to build a little
vestibule of screen material about it. Prolonged observation
indicates that mosquitoes are bound to get in most single doors,
even though they be opened only for a moment. However, if
there is a vestibule in front of the door proper, so that the second
screen door is not opened until the first is closed, the chances of
entrance by mosquitoes are very much decreased.

■pilii

*^|]

1*9* ■ .

I j

1 ^^___ B i j

Fig. 140. — Vestibule to porch with double screen doors, shown on right and
extreme left, the outer doors being at the left. The screening material does
not show up very plainly.

Screen doors should always open outward, else the mos-
quitoes which settle on them will be driven into the house when-
ever they are opened, particularly when a person enters the house.
This is a point that should be kept in mind at all times.

"When the door of entrance," writes Carter, 1 "is at the top of a
flight of steps, no landing intervening, it should be so placed that the
edge of the door opposite the hinge comes as near the middle of the

^'Anti-malarial Measures for Farm-houses and Plantations," U. S.
Public Health Service, 1919.

SCREENING 199

length of the step as may be. This may be done by having folding doors
one best to stay fastened, or by moving the whole single door to the left
and fill in the space to the right by screening. The reason is that one
always goes up about the middle of the steps, and, if the door opens from
the ends of the steps, the person entering, after beginning to open the
door, steps down a couple of steps so as to get out of its way, thus open-
ing the door more widely and holding it open longer than advisable."

SOME GENERAL RULES

The following general rules in regard to construction and
installation of screen doors are given by Snidow: 1

1. "To prevent warping, the frame should be made of substantial,
carefully selected, light-weight material, well-braced with iron brackets
at the corners. In order to add a double protection against sagging, a
wire support should be drawn diagonally across the lower half. This
may be accomplished by use of a double wire attached loose, then
tightened with a turn-key until the desired tension is reached.

2. "The section of screen wire covering the frame should be cut
sufficiently large to allow a lap of Y± inch all the way around, and should
be tacked on firmly with tacks not more than 3 inches apart. After-
wards, molding strips should be nailed on, covering edges of wire and
tack heads.

3. "The lower half of the door frame should be covered on the
inside with a reinforcing section of the so-called hardware-cloth, a
coarse, substantial wire screen with about a quarter-inch opening
between the meshes. This will protect the bottom panel of the door
from kicks and the carelessness of children.

4. "A light strip of wood, about 3 inches broad, should be nailed
across the door frame at about the height of a man's shoulders. This is
to push against when opening the door.

• 5. "A satisfactory spring should be used to insure the door remaining
tightly closed against the battens when not in use.

6. "Two hooks or catches should be provided, one about half-way up
to the top section of the closing side of the frame, and the other near the
bottom. The top catch may be used alone during the day, but at night
both should be fastened. This will help to prevent warping.

7. "In fitting screen doors in the door frames, no attempt at edge-
fitting should be made. The door should be made to fit against a%-inch
batten all the way around the inside, and sufficient space should be
allowed around the edges and the frame for the door to swell in wet
weather without scraping at the bottom."

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

200

MOSQ UI TO ERA DI CA TION

The writer would supplement the provision for reinforcing the
lower half of the door (No. 3) by adding a light, wooden "kick-
board," similar to the "push-board" mentioned in No. 4, to
receive the kick with which many persons open screen doors.

Almost any substantial hinge will do. Spring hinges,, the
springs of which can be adjusted from time to time, have been
found advantageous by the writer, as they render unnecessary
the separate springs commonly used, which, as a rule, soon
weaken if a door is used very much.

SCREENING OF WINDOWS

Many of the considerations that are mentioned above in
connection with the screening of doors also apply to screening of

Fig. 141. — Close-up view of a window screen. This screen hangs from the
top and is drawn up tightly against the battens on the sides and the sill on the
bottom by a hook fitting in a ring attached to the inside of the sill.

windows. Probably the most important of these is that relating

to making the frame of the screen fit tightly up against battens.

Probably the best type of screening for windows is that in which

the top of the frame is hinged to the batten over the window with

SCREENING 201

small metallic fasteners. The parts of the fasteners attached to
the screen frame fit into the parts on the window batten. A
hook at the bottom of the screen frame, connecting with a ring in
the window ledge, draws the frame of the screen tightly against
the window battens on the sides and top and the ledge on the

bottom.

When there is no suitable batten or when the window frame is
in bad shape, as is frequently the case in negro cottages, it prob-
ably is best to tack the screen material over the whole window.

Fig. 142. — Screened porch at cantonment. The screening, which runs up
and down, is supported by 2 by 4 timbers. The edges of the screening are
covered with molding strips.

Molding strips then should be nailed over the tack heads around
the window opening.

Iron brackets should be used to strengthen the corners of
window screens as well as of door screens.

SCREENING OF PORCHES

This may be done in any way that will result in an effective
job. The screening may be put on either horizontally or ver-
tically. In either case, the framing for the screen should be
firm and substantial, the various supports being placed at such
intervals that there will be plenty of lap for tacking on the wire.
After the screening is firmly in place, the edges should all be
covered with molding.

One point that should not be overlooked in porch screening is
the importance of not leaving any open spaces where screening

202

MOSQUITO ERADICATION

connects with a sided or weather-boarded surface. The best
way of doing this probably is to cut the support to fit the surface.
If this is not practicable, the resulting spaces should be filled up
with paper pulp, pieces of wood or other material.

Sometimes the nailing of a strip along the outer edges of the
porch as a support for the bottom of the screen wire may interfere
with the draining off of rain-water that may be blown in on the
porch during storms. One way to provide for this contingency
is to bore a few holes in the floor just inside the bottom strip and
tack small pieces of screening material over or underneath them.

SCREENING OF CHIMNEYS AND FIRE-PLACES

When the house is provided with fire-places, screens are
required either at the tops of the chimneys or over the openings

Fig. 143.-

([/. S. Public Health Service)
-Chimney protection.

of the fire-places. Observations indicate that, unless the chimney
or fire-place is screened, mosquitoes will descend into the house
by this route in abundance.

As the fire-places are usually not used much during the
mosquito season, it has been found that screening the chimney
is often the easiest way of handling this matter. A section of
screen wire is placed over the chimney and held in position by a
tier of bricks around the edge of the top.

As soot soon fills the meshes of the wire, if the chimney is used,

SCREENING 203

it will be found advisable in most cases to remove the screen
from the chimney as soon as cold weather comes.

Should it be desired to screen the fire-place instead of the
chimney, this may be done. Probably the best way of doing
this is to make the frame of the screen fit exactly the fire-place
opening. If the fire-place is screened instead of the chimney, all
stove-pipe openings in the chimney should also be closed.

In some sections, it is customary to bore a hole in the floor to
permit the drip from the ice-box to escape through to the ground.
In such cases, mosquitoes may enter the house through these
holes. The best way to prevent this is either to divert the drip
to the sewer by means of a pipe or else to close the hole and put
a pan under the ice-box, emptying it whenever necessary.

THE LIFE OF A SCREEN

The life of a screen ordinarily depends upon two things — the
material of which it is made and the care it receives.

Probably the best material for screens for all-round use is
bronze or copper. This material will last a life-time, unless
torn by accident. It is so expensive, however, that but little
bronze or copper screening is seen today.

The material most commonly used is a galvanized iron. The
life of this type of screen depends upon its care and treatment.
Ordinarily, away from the sea-coast, this type of screening should
last several years— from 4 or 5 to 10 or 11. Carter 1 states that
the screening of the U. S. Marine Hospital at Baltimore— a
so-called rustless iron— put on in 1903 did not require renewal until
1914. This screening was not painted until the fourth year, and
then was painted with a very thin coat every second year. The
writer has observed galvanized iron screening, put on in 1917, in
very good condition late in 1921, and it had not been painted at

all.

Judicious treatment will undoubtedly greatly prolong the life
of a screen. It is reported that an application of banana oil each
season gives very good results. The ordinary treatment, how-
ever, is painting, a very thin coat being applied every second
year or so.

Torn wire screening may be repaired by placing a small piece

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

204 MOSQUITO ERADICATION

of screening over the torn opening and sewing it fast with a
strand of thin wire.

SCREENING NEAR THE SEA-SIDE

The economical screening of houses close to the sea and exposed
to the extreme salt atmosphere of the ocean is a problem. Houses
a few hundred yards from the water are not so difficult, but no
metal screen seems to last very long on houses close to the salt
water. Painting does not alway appear to help matters, and, in
some cases, seems to cause more rapid deterioration.

Ordinary cloth screens are objectionable on account of their
interference with ventilation, their sagging and the facility with
which they catch and hold dust, etc. Snidow, 1 however, recom-
mends a type of cloth screen which has a hard, waxed surface,
similar to that of wire.

Carter 1 reports that at the Chandelcur Islands double bob-
binet lasted a full season, while iron screen material endured only
three months.

CONDUCTING A SCREENING CAMPAIGN

In cases where it has been decided to initiate a screening
campaign in a community, the best practice seems to be more or
less as follows:

1. The area should be carefully surveyed, every house being
visited and classed, as described earlier in the chapter. Once this
is done, some idea of the cost of the campaign can be obtained.

2. The next step should be to decide upon the best way of
doing the work — that is, whether it will be preferable to let each
house owner screen his own premises or to have all screening
done by the director of the campaign. The writer strongly
recommends the latter method, since, in this way, large savings
are made possible by consolidated buying and by having a
standardized procedure, and the work will be done better and
more uniformly.

3. Owners of properties that require repair prior to screening-
should be given a certain length of time in which to make the
repairs. Those not worth repairing should be ordered vacated,
if practicable, and, if not, nothing should be done toward screening
them, as the imperfect results would only tend to discredit the
work.

4. Once the materials are procured, transportation obtained

x " Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1910.

SCREENIXC; 205

and construction gangs organized, the work should be carried on
systematically, street by street, or block by block. Careful cost
records should be made.

5. A system of monthly inspection should be organized to see
that the screening is maintained in good condition.

VALUE OF SCREENING

That screening, if properly done, is very effective in reducing
morbidity and annoyance occasioned bj r mosquitoes is certain.
Shaw 1 reports that at Lake Charles, La., the malaria rate of
screened houses, as ascertained by history index, was 50 per cent
lower than in unscreened houses.

The St. Louis & Southwestern Railway in 1917 began screen-
ing the box cars in which its bridge and building gangs sleep.
The following table 2 shows the remarkable falling off in the rate
of hospital admissions for malaria following the screening:

1915 1916 1917 1918

Hospital admissions for malaria 87 74 37 11

An interesting demonstration involving screening was carried
out on a number of plantations near Lake Village, Ark., in 1916
by the U. S. Public Health Service and the International Health
Board. Thirty-three houses were screened at a cost of $14.59
per house or SI. 76 per capita. The incidence of malaria, as
revealed in blood examinations in May and December, 1916,
both of the screened group and of a control unscreened group, is
shown in the following table. 3

May

December

Screened group, per cent infected

11.97

21.84

3.52

Unscreened group, per cent infected

19.23

COST OF SCREENING

While the cost of screening varies, of course, with the size of
the house and the number of doors, windows, porches and chim-

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

2 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Sendee, 1919.

'"Malaria Control, A Report of Demonstration Studies," U. S. Public
Health Service, 1917.

20(3

MOSQ VI TO ERA DICA TION

nej^s or fire-places in it, the cost of screening an ordinary four-
room or six-room house should not, as a rule, much exceed $25
to $50, if ordinary galvanized iron screening material is used.
An itemized table of the cost of screening 31 houses at Kress,
Va., in 1918 is given by Snidow. 1 On this job, Snidow says, it
was unnecessary to screen any chimneys. Galvanoid screen
wire, used in the work, cost $3.50 per 100 square feet, wholesale.
The table follows:

House Nuu

mbei

Number

Cost of j Cost oi

Cost of

Total

number por

c-hes

windows

doors

wire lumber

hardware

labor

cost

$ 15.26

$ 6.00

$ 2.54

$ 8.40

$ 32.20

17.22

6.50

2.64

8.40

34.76

15. 40

5.75

2.29

8.40

31.84

16.34

5.80

2.14

11.20

35. 48

15.89

4.50

2.64

11.20 34.23

4.83

3.00

2.46

5.60

15.89

4.34

2.70

2.26

5.60

14.90

4.34

2.70

2.26

5.60

14.90

4.83

3.00

2.46

5.60

15.89

11.13

3.95

2.21

7.00

24.29

10.57

4.10

2.31

7.00

23.98

9.62

3.85

1.99

7.00

22.46

9.62

3.85

1.99

7.00

22.46

9.62

3.85

1.99

7.00

22.46

22.22

6.90

2.69

14.00

45.81

16.34

6.00

2.44

8.40

33.18

21.17

5.85

1.59

11.20

39.81

15.40

4.35

2.46

7.00

29.21

15.40

4.35

2.46

7.00

29.21

15.40

4.35

2.46

7.00

29.21

17.64

6.80

3.01

11.20

38.65

3.85

1.95

2.21

2.80

10.81

0.60

0.75

1.81

2.80

5.96

4.41

2.75

2.27

4.20

13.63

2.97

1.40

1.27

2.80 8.44

3.95

1.30

1.91

2.80 9.96

3.95

1.30

1.71

2.80

9.76

3.95

1.30

1.71

2.80

9.76

1.57

0.45

0.67

1.40

4.09

1.57

0.45

0.67

1.40

4.09

4.93

2.20

1.59

5.60

14.32

Totals 2

186

$ 304. 33

$112.00

$65. 11

$200.00 $681.64

Detailed costs of the screening at Lake Village, Ark., already
referred to, with galvanized iron wire, costing $3.00 per 100
square feet, are furnished by Derivaux, Taylor and Haas, in a

1 Transactions of First Annual Conference of Sanitary Engineers, U. S.
Public Health Service.

SCREENING

207

report, 1 from which the following table has been compiled, labor
costing from 40 to 50 cents an hour; in this case, the chimneys
also were screened.

House

Number Number

Number

Cost of

Total

number

chimneys windows

doors

wire

lumber

hardware

labor

cost

$ 4.52

$ 2. 15

$ 0.90

S 11.00

$ 18.57

3.44

2.15

0.60

6.00

12. 19

2.90

2.15

0.60

8.50

14. 15

2.90

2.15

0.60

8.50

14.15

1.55

2.15

0.60

8.50

12.80

2.63

2.15

1.85

7.90

14.53

1.28

2.65

2.10

12.00

18.03

1.55

2.65

1.20

14.00

19.40

2.46

2.40

0.60

7.85

13.31

1.10

2. 4.'.

0.85

7.00

11.40

3.17

2.90

0.85

9.00

15.92

1.91

2. 15

0.70

4.00

8.76

1.91

2.15

0.70

4.00

8.76

1.91

2.15

0.70

4.00

8.76

1.66

4.90

0.60

6.90

14.06

2.66

4.90

1.10

10.40

19.06

2.66

4.90

1.10

8.80

17.46

3.86

4.90

1. 10

9.60

19.46

2.36

1.95

0.85

6.40

1 1 . 56

2.09

1.20

0.60

4.80

8.69

2.36

2.40

0.85

5.20

10.81

1.82

0.40

0.60

4.00

7.82

3.44

2.40

1.10

7.60

14.54

3.98

2.79

1. 10

10.00

17.87

1.82

2.44

0.60

7.00

1 1 . 86

• 2

1.82

3. 11

1.10

8.50

14.53

3.99

3.90

1.60

12.00

21.48

3.98

3.40

1.35

12.50

21.23

1.05

2.40

0.60

6.50

10.55

1.43

2.90

1.10

12.50

17.93

1.41

1.90

0.70

8.00

12.01

3. 16

2.80

1.10

8.00

15.06

3. 16

1.90

0.85

6.80

12.71

Totals

108

$81.93

; $88.89

$31.85

$207.75

$469.42

DOES SCREENING PAY?

It has been shown that good screening will greatly reduce the
incidence of the mosquito-borne diseases. Costs of good screen-
ing have also been discussed. The question as to whether or not
screening will pay, on a dollar-and-cent basis alone, may now be
taken up.

1 "Malaria Control: A Report of Demonstration Studies," U. S. Public
Health Service, 1917.

208

MOSQUITO ERADICATION

As a result of the screening demonstration carried on by the
U. S. Public Health Service and the International Health Board
near Lake Village, Ark., already referred to, it was found that the
incidence of malaria, as revealed by blood examination, was
reduced from 11.97 to 3.52 per cent for the screened group, but
remained virtually unchanged for the unscreened group. Study
of the cost of screening for the screened group and of the losses
arising from malaria for both groups gives the interesting results
shown in the following table:

Screened
group

Unscreened
group

Per capita loss from malaria

$0.06
1.76

$2.52

Per capita cost of screening

Totals

$1.82

$2.52

It is apparent from this that screening much more than paid
for itself, and this on the assumption that it would last only 2
years. 1 In addition, there is to be considered the freedom
enjoyed by the screened group from annoyance by mosquitoes
and also from the fly pest and its accompanying dangers of
typhoid.

1 "Malaria Control: A Report of Demonstration Studies," U. S. Public
Health Service, 1917.

CHAPTER XI

OTHER MEASURES AND EXPEDIENTS AND POINTS
REQUIRING INVESTIGATION

SCOPE OF THIS CHAPTER

In previous chapters, the standard methods of mosquito
eradication and control have been discussed at some length.
In the present chapter, it is intended to outline various auxiliary
measures in dealing with mosquitoes — some of demonstrated
value; others still under investigation — and to call attention to
points that require further study and that may lead to results of
importance.

It may be stated here definitely that we do not yet know, by
any means, all that is worth knowing about mosquitoes. There
are still many important questions that need clearing up, and it is
possible that, as they are cleared up, new and valuable methods
of procedure in eradicating mosquitoes will be developed. Also,
as our knowledge of the mosquito increases, it is not improbable
that it may be possible to effect considerable economies in
connection with present methods of control.

Despite the present limitations of our knowledge, progress is
steadily being made. The problem of the mosquito is being
studied from many different angles, and a large number of
auxiliary methods of dealing with it have been proposed. In the
following sections, a few of these will be discussed.

AUXILIARY METHODS AND EXPEDIENTS IN GENERAL

It will be noted that the standard offensive methods already
described, such as drainage, oiling and fish control, are directed
chiefly against the mosquito in its early stages; they are designed
either to prevent it from ever coming into existence, as drainage,
or to destroy it before it matures, as oiling and fish control.
While screening is directed against the adult, it is purely pro-
tective, and has no offensive aspects.

While these measures are undoubtedly based on correct
principles, nevertheless, there is no reason, theoretically, why

209

210 MOSQUITO ERADICATION

offensive measures against the adult should not be developed as a
supplementary procedure. In the plague campaigns against
rats and ground-squirrels, direct offensive measures are used
against adults with great success. The same may be said, to
some extent, in regard to flies.

Again, it may be said that there is plenty of scope for further
protective measures against adults. There are millions of homes
that are not screened, and many of these cannot be screened
effectively. Furthermore, as already pointed out, screening is
protective only in the place that is screened. For these reasons,
other protective measures should be utilized wherever and when-
ever it appears that they will be of any value.

DIRECT EXTERMINATIVE MEASURES

The following measures for attacking the adult mosquito
appear to have more or less value or to offer possibilities of
further development :

1. Direct exterminative measures, preferably by some biologi-
cal enemy.

2. Indirect methods of harassing and annoying, such as
destroying or rendering unattractive its harboring and resting
places.

The most practical application of direct exterminative meas-
sures against the adult mosquito would seem to be use of some
biological enemy. The use of fish against the earlier stages of
the mosquito is an example of the value of this procedure. There
remains only to find some animal that is adapted for destruction
of the adult mosquito.

THE BAT AS A DESTROYER OF ADULT MOSQUITOES

Doctor Campbell of San Antonio, Tex., for many years has
expounded the view that the domestic bat, Chiroptera, can be
utilized as a means of exterminating adult mosquitoes, and, as
a result of his advocacy, San Antonio and other cities have
installed bat-roosts for this specific purpose. The idea is to
encourage development of enough bats in each community greatly
to reduce, if not eliminate, the mosquito pest.

While Doctor Campbell fortifies his arguments with a mass of
resolutions and letters of approval, which apparently sustain
his conclusions, there seems to be a certain amount of doubt

OTHER MEASURES AND EXPEDIENTS 211

in scientific circles as to the general applicability of the scheme.
Hoffman 1 sums up the matter as follows:

"It is conceivable that bat-roosts may be of advantage in one loca-
tion, while entirely useless in another. It is possible that bats may
exterminate a sufficient number of Anopheles to reduce the mosquito
nuisance to a minimum. Conversely, the enormous number of bats
required for effective work may constitute an evil in itself not to be
tolerated in civilized communities. The subject has reached the
stage where, in my judgment, it is obviously the duty of the several
Government departments concerned to institute a thorough investiga-
tion and to make a full report."

Chidester 2 gives the following list of animals, other than
fishes, which are recognized as foes of the mosquito in its various
stages :

OTHER ANIMAL FOES OF THE MOSQUITO

PROTOZOA — Spirochaeta culicis, Diplocystis, Nosema stego-
myiae, Crithidia fasciculata, Herpetomonous algeriense, Try-
panosoma culicis.

COELENTERAT A— Hydra fusca, H. viridis.

PLATYHELMINTHS — Agamodislomum martiranoi.

NEMATHELMINTHS — Agamomermis culicis.

ARTHROPODA — Hydrophilus obtusatus, Dytiscus marginalis,
Acilius sulcatus, Nepa, Nolonocta, Ranatra fusca, Aeschna,
Erythemis simplicicollis, Psorophora ciliala, Megarhinus septen-
trionalis, Lutzia bigotii, Lesticocampa, Corethra, Tanypus dyari,
Lispa sinensis, Horpopeza obliterate, Tahydromia macula, Cordi-
lura haemorhoidalis, Monedula signata, Emesa longipes, Salticus,
Crangon vulgaris.

AMPHIBIA — Rana pipiens, R. palustris, Discoglossus pictus,
Triton cristatus, T. alpestris, Diemyctylus tortosus, Ambly stoma
opacum.

REPTILIA — Ptychozoon homalecephalum.

AVES — Chordeiles virginianus, Choetura pelagica, Petrochelidon
lumfrous, Iridoprocne bicolor, Hirundo erythrogasta, Progne
subis, Riparis riparia, Tachycineta thalassina lepida, Myiochanes
virens, Sayornis phoebe, Tyrannus tyr annus, Anas platyrhynches,
Aegilitis semipalmata, Pisobia pusillus.

1 Southern Medical Journal, April, 1921, page 304.

2 "A Biological Study of the More Important of the Fish Enemies of
the Salt Marsh Mosquitoes," New Jersey Agricultural Experiment Stations,
1916.

212 MOSQUITO ERADICATION

MAMMALIA — Eptesicus fuscus.

Many of these, of course, may turn out to be of no practical
value; others may be of value in destroying the earlier stages of
the mosquito, like fish: others finally, may be developed into
instruments of destruction as against the adult mosquito.

DESTRUCTION OF MOSQUITOES IN DWELLINGS

"Swat the fly" has long been a slogan in anti-fly campaigns,
in which this procedure has been recognized as a valuable
adjunct to other methods of eradication. In anti-mosquito
work "swatting" the mosquito is an equally valuable auxiliary
measure.

The importance of "swatting" the mosquito was first recog-
nized in the sanitary work of the Panama Canal Zone, where
it was found that daily, systematic killing or catching of mosqui-
toes in the laborers' barracks resulted in a noticeable reduction
in the incidence of malaria. The application of this measure
there, as an adjunct to screening, was made possible by a standard
type of screened dwelling, a population under one central control
and a trained organization to carry out the work. The procedure
under these conditions proved effective, and the possibility of
its application to other conditions should be more fully
investigated.

Repeated surveys show that the favorite hiding-places of
mosquitoes in and about homes include "garrets, bed-rooms,
on walls, under mosquito-bars, behind pictures, on clothing,
behind doors and furniture, in barns, open fire-places, privies,
chicken coops, wood and coal sheds, stables, garages, under
porches and buildings, in wind-protected corners of porches,
in empty barrels, trash-heaps, wagons, carriages, automobiles
and on spider webs." 1

For killing mosquitoes on walls, etc., probably the best device
is an ordinary fly-swatter. For attacking them on ceilings
the writer has successfully used a piece of board about a foot
square, covered with several thicknesses of gauze and attached
horizontally to the top of a pole 6 or 8 feet long.

Where it is not practicable to reach the mosquitoes with either
of these weapons, they may be driven out by burning pyrethrum
powder. This powder is not highly efficient in killing mosquitoes,

1 R. H. von Ezdorf in "Anopheline Surveys" U. S. Public Health Service,
1918.

OTHER MEASURES AND EXPEDIENTS 213

unless burned in comparatively large quantities in a tightly
closed room for a considerable period. A small amount of the
powder, however, will drive them from their hiding-places to
points where they can be reached.

LePrince 1 sums up the possibilities of systematic destruction
of mosquitoes in dwellings as follows:

"I think some very valuable experimental work can be done in this
country by applying this matter of destruction of Anopheles to houses,
where the house tenant is not in any way interested, by using the
children to do the catching ...

HARASSING THE MOSQUITO

The theory underlying this measure is that mosquitoes will be,
to some extent, dispersed and driven away if the environment is
made unfavorable to them.

It has been observed that, generally speaking, the mosquito,
when not seeking food, spends its time in some shaded and,
preferentially, damp place. It avoids the direct sunlight and,
when possible, selects a place where there is a certain amount of
moisture. This being so, it is obvious that if we can eliminate
these places or render them inaccessible or objectionable to it, the
mosquito will either have to get out and seek some new harboring
place or, at its peril, remain in an environment that has become
unfavorable to it.

The favorite harboring places of the mosquito about the aver-
age home appear to be bushes, clumps of weeds, high grass, etc.,
underneath the house, in the cellar, in the garage, under culverts,
in stables and other dark places. In each of these, a certain
amount of moisture is usually found, due to failure of the sun to
penetrate for any extended period.

In carrying out this measure, then, weeds and high grass within
a radius of several hundred feet of the dwelling, should be cut and
burned; the ground under the house, the cellar, nearby culverts,
stables and similar harboring places should be oiled thoroughly
from time to time; thick heavy foliage should be trimmed out
and, if necessary, also oiled or otherwise treated; the lawn or
garden hose should be used sparingly, so as not to cause too much
dampness about the house.

The writer has tried out this measure for several seasons; and
it is surprising what a difference its practice will make— it being
1 Southern Medical Journal, April, 1921, page 294.

214 MOSQUITO ERADICATION

understood that it is of value only in ridding the area of a brood
of mosquitoes that has settled there and is useless if new broods
are continually emerging from nearby breeding-places. It
must, therefore, be used in connection with the other standard
methods already described.

FURTHER PROTECTIVE MEASURES

When the offensive measures against the mosquito fail to bring
the desired result, defensive or protective measures may be
brought into play. In addition to screening, there are, as already
intimated in a previous section of this chapter, several other
more or less valuable protective measures that may be used
to repel the mosquito or to avert some of the consequences of its
attack.

One of the most interesting and suggestive of these is the use of
animals as a living shield between mosquito production areas and
human dwelling-places. This measure arose from the observation
that mosquitoes frequently are more numerous in stables, etc.,
than in adjoining dwellings.

Rizzi 1 records several interesting observations on the subject,
made in the vicinity of Trinitapoli, Italy, a well-known center of
malaria, which may be summarized as follows:

USE OF ANIMALS AS A PROTECTION AGAINST MOSQUITOES

1. In a locality usually non-malarious, a stable was found to
abound with Anopheles mosquitoes. Careful search led to
discovery of the breeding-place, a small basin of water still
containing larvae. Rizzi holds that the mosquitoes did not
invade surrounding areas, owing to the fact that the single beast
in the stable supplied them with sufficient blood.

2. In a village frequently attacked by malaria, only a few
mosquitoes were found; they were abundant, however, in two
large stables, each about 1,500 feet from the outlying parts of
town. No larvae were found in neighboring ponds, although
some had been found in the spring. Rizzi believes that in this
case, the mosquitoes were attracted to the stables, which, in this
way, protected the village from invasion.

1 Nuovo Indirizzo di Profilassi Anti-malarica, Ann. d'Igiene, Nov. 30,
1919. Compiled from "Public Health Engineering Abstracts," U. S.
Public Health Service, July, 2, 1921.

OTHER MEASURES AND EXPEDIENTS 215

3. At Trinitapoli itself, Rizzi records, several broods of mos-
quitoes, hatched from larvae in nearby ponds, suddenly emerged.
St ables in the vicinity of the ponds were first invaded, then stables
nearer town and, finally, some outlying houses. Anti-mosquito
measures were then pressed, and the invasion was arrested, vir-
tually no mosquitoes entering the town itself. The conclusion
seems to be that the stables attracted the mosquitoes and
detained them long enough to enable the anti-mosquito measures
to be applied.

Rizzi, however, emphasizes the fact that reliance on the attrac-
tions of stables, etc., is not sufficient in itself. He appears to
believe that the use of animals in this way is merely one factor that
may be of advantage in connection with the usual anti-mosquito
measures, and this view appears reasonable to the writer. Where
stables can be located between the dwelling and a marsh, pond or
similar breeding-place, it is believed advantageous so to locate
them. Use of land between the dwelling and the breeding-place
for a pasture might also be advantageous.

APPLICATION OF SUBSTANCES REPELLENT TO MOSQUITOES

This measure cannot be relied upon to any great extent, as
most of the substances in use at present evaporate within a few
hours, and the mosquitoes return.

These substances are generally used at night. They are either
rubbed on the face and hands or dropped on the pillow or on a
towel which is hung over the head of the bed.

Oil of citronella probably is the most efficacious of the mos-
quito-repelling substances now in use. Others employed include
spirits of camphor, oil of peppermint, oil of pennyroyal, lemon-
juice, vinegar and kerosene. Several patented preparations are
also on the market. None of these seem to last until morning,
however.

The writer has found bi-weekly or tri-weekly oiling of the floor
with kerosene is about as effective as anything else along this line.
The odor, of course, is more or less disagreeable to the person
occupying the room, but it is equally as disagreeable to the
mosquitoes, and, as a result, they usually keep out.

Another procedure that may conveniently be mentioned here is
that of making a smudge. This measure is tolerably effective,
as the mosquitoes generally flee from the smoke, but it is almost
as objectionable to the occupants of the room as the mosquitoes

216 MOSQUITO ERADICATION

are. This is a common practice in negro cabins in the malarious
districts of the South.

USE OF QUININE FOR MALARIA

Use of quinine is of value only in cases of malaria; its effect
is to destroy the malaria plasmodia, which have been injected
into the blood of the malaria patient by infected Anopheline
mosquitoes. Quinine, therefore, is of no avail, until the person
has been bitten by the mosquito. It is the last measure of
defense. Quinine is of no value, however, in the treatment of
yellow fever, dengue or filariasis.

The standard treatment for malaria recommended by the
National Malaria Committee in the hope that it would be gen-
erally adopted by practicing physicians wherever malaria pre-
vails, is as follows :

"For the acute attack, 10 grains of quinine sulphate by mouth three
times a day for a period of at least 3 or 4 days, to be followed by 10 grains
every night before retiring for a period of 8 weeks. For infected persons,
not having acute symptoms at the time, only the 8 weeks' treatment is
required.

"The proportionate doses for children are: Under 1 year, l A grain;
1 year, 1 grain; 2 years, 2 grains; 3 and 4 years, 4 grains; 5, 6 and 7
years, 5 grains; 8, 9 and 10 years, 6 grains; 11, 12, 13 and 14 years, 8
grains; 15 years or older, 10 grains."

The object of the treatment is not only to relieve the clinical
symptoms, but also to disinfect the patient in order to prevent
relapses and transmission of the disease to others.

DEMONSTRATIONS OF THE VALUE OF MASS TREATMENT BY

QUININE

Where malaria assumes an epidemic character and very large
percentages of the population are infected, mass treatment by
quinine has given excellent results. Prominent among the
successful demonstrations of this kind may be mentioned the work
in the Panama Canal Zone, the work of the Germans in Africa
and the work of the Japanese in Formosa.

In 1920, a very successful demonstration of this kind was
carried out in Georgia. In the area in question, there were
about 2,900 acres in cultivation and, according to Abercrombie, 1
the annual loss in this area due to malaria alone was something

1 Southern Medical Journal, April, 1921, page 286.

OTHER MEASURES AND EXPEDIENTS 217

over $13 an acre. In tabulating the history cards of persons
receiving the treatment, it was found that 71 per cent reported
having had malaria within the preceding 5 years; 21 per cent
reported having had malaria in 1919; and 13.5 per cent reported
having had malaria some time in 1920 before applying for
treatment.

Discussing the demonstration, Abercrombie 1 says:

"There were 600,000 doses of quinine given . . . The people who
took the treatment were 10,339, divided as follows: white people,
6,849, and colored, 3,490. There were 1,691 families. I think the
report shows that out of this total . . . there were something like
27 people who developed chills after completing the treatment. We
figured that this cost approximately 50 cents per capita over the county.
It cost probably $1.50 for each person taking the treatment, but, since
it is a county-wide proposition, we are figuring it on a per capita basis
in the county."

The campaign was started by interesting the plantation owners
and managers from an economic standpoint. Their assistance
was obtained in distributing the quinine to their tenants and
employes; in addition, 14 free dispensaries were established at
various points in the county. In all, about two-fifths of the
population of the county was treated.

QUININE VERSUS ANTI-MOSQUITO MEASURES

While quinine, as has been shown, is very valuable in coping
with malaria epidemics, use of quinine should in no sense be
considered as a satisfactory substitute for anti-mosquito measures.

In the first place, quinine is merely a remedy for but one of the
effects of mosquito bites. It has no bearing on the annoyance
caused by mosquitoes of all species and the grave effects of this
annoyance upon the health. Moreover, quinine is of no value in
coping with those other consequences of mosquito bites which
take the form of yellow fever, dengue and filariasis.

It also seems probable that over a period of years, covering
entire populations, administration of quinine would frequently
prove more costly than execution of anti-mosquito measures.

There is no doubt that quinine has its place in the mosquito
problem, but that place is necessarily a limited one.

1 Southern Medical Journal, April, 1921, page 286.

218 MOSQUITO ERADICATION

POINTS THAT REQUIRE FURTHER INVESTIGATION 1

As stated in an earlier part of this chapter, there are still
many points in connection with mosquitoes that require further
investigation. These investigations may result in improvements
in our present methods of dealing with mosquitoes or in the
development of entirely new measures of control.

Among the points that may be profitably studied, the following
may be mentioned:

1. Hibernation of adult mosquitoes of the various species.
What are the natural hibernation places? What relation have
shade, shelter, direction of prevailing winds, proximity of stand-
ing water, etc., to the hiberation places? Can any method be
devised whereby the mosquito may be successfully attacked
during the hibernation period?

2. Survival of larvae over the winter. Can any method of
attack be devised that will be of value?

3. Life of the egg. What conditions of dryness will eggs of
the various species and genera withstand? How long will eggs
of the various species and genera retain their vitality? What
circumstances result in depriving the eggs of vitality?

4. Flight distances of the various species and genera, and local
conditions influencing flight, such as moisture, wind, etc.

5. Aquatic plants influencing mosquito production. What are
they, in what manner do they influence production and how can
they be utilized in mosquito control work?

6. Factory and chemical wastes which prevent • or favor
mosquito-breeding. What are they, and can they be utilized in
mosquito control work?

7. How is it that some places, which apparently should, do not
produce mosquitoes? What is the connection between the
animal and plant life, chemical and physical properties of the
water in such pools and the absence of breeding therein?

8. Some larvicide that does not require replacement as soon as
oil and the larvicides now in use. Some larvicide that will be
cheaper than those now in use.

These are some of the maii3 r points about mosquitoes that
more light is desired on. Observation of field workers may result
in considerable progress being made.

1 Adapted from circular of Office of Field Investigations of Malaria, U. S.
Public Health Service.

CHAPTER XII

RURAL MOSQUITO AND MALARIA CONTROL

UNFAVORABLE FACTORS IN RURAL CONTROL

Mosquitoes and mosquito-borne diseases are, in general, more
troublesome in the rural regions than in the cities. Construc-
tion of water-supply and sewerage . systems eliminates a mul-
tiplicity of artificial breeding-places, while city grading and
ditching help to provide a means for rain-fall to run off, thus
largely obviating the rain-water pool as a breeding-place.

In the rural areas, there are always a number of natural breed-
ing-places. To these must be added the man-made breeding-
places, more or less necessary in the country, but not in the city,
such as cisterns, stock-troughs, stock-ponds, cesspools and a host
of others. Furthermore, a certain amount of anti-mosquito work
now is being done in most large cities that require it, while in the
country, owing to sparsity of population and the large areas
involved, community anti-mosquito measures are generally
impracticable at present, due to the heavy per capita cost. It
will be seen, therefore, that at the present time, at least, the
problem of mosquito control in rural districts is essentially an
individual one.

Towns and villages without modern sanitary conveniences and
the unsewered outlying suburbs of the cities are also more diffi-
cult to handle than the cities, for the same reasons given above.
Anti-mosquito measures in them are, however, somewhat more
practicable than in the country itself, because of the greater
density of population, which means that the cost will be spread
over a much greater number of beneficiaries per unit of area.

FAVORABLE FACTORS IN RURAL CONTROL

On the other hand, however, it may be said that, as a rule,
the rural home is better situated, from an anti-mosquito stand-
point than many urban homes. Frequently the rural home is situ-
ated on fairly high ground, where the wind can reach it and at a
respectful distance from such natural breeding-places as swamps,
etc.

219

220

MOSQ UI TO ERA DICA TION

Furthermore, the cleanly and progressive farmer need not suffer
from the sloth, ignorance and negligence of his neighbors, as is
often the case with the city or town man. Houses are usually
far enough apart to render impossible much annoyance from
mosquito-breeding in and about the homes of neighbors. Thus,
in order to be free from mosquitoes, the intelligent countryman
need only keep his own home in shape.

Sometimes, this is a comparatively easy matter; sometimes it
is almost impossible. Much depends upon the topographical

*^"^P

Wr*-

*--■

■

' ■*' :'^l

■' 1 ' 1

« - . '

* Ifl

Mr'^'T''

(Photo by E. B. Johnson, C. E.)
Fig. 144. — This ditch, in places 15 feet deep and more than a mile long, was
dug by 5 Alabama farmers as a land-improvement project. It drained a swamp
of nearly 50 acres.

and meteorological conditions of the district. Thus, in the delta
country of the Mississippi, a region of fertile, low-lying soil,
interspersed with bayous and slowly-moving streams and
having a heavy rain-fall, an individual can do but little. In a
well drained section, however, where the home is favorably
situated, there is no reason why mosquitoes should cause any
annoyance.

NEED FOR A SURVEY

In undertaking mosquito control measures about the average
rural home, probably the first consideration is cost. It would be

RURAL MOSQUITO AND MALARIA CONTROL 221

unreasonable to spend more money for mosquito control than
such control is worth. The first thing, therefore, is to ascertain
what amount is available for the work. This done, it will be
possible to determine just what measures will give the most
relief for the money.

Thus, while it may not be possible to eliminate mosquitoes
entirely from the home, it may be possible to reduce them greatly
at very slight expense. Again, it may be that, while a certain
measure, such as tile drainage, for example, might cost too much
as an anti-mosquito measure alone, the other benefits that come
from it, as improvement of the crop yield, might make the project

feasible.

The first essential, then, after determining the amount avail-
able for the work is to make a careful survey of the situation from
every angle. Doubtless, the survey will show that a consider-
able amount of breeding can be eliminated at no cost whatsoever,
other than a little care and study. .

CONTROL MEASURES ABOUT THE AVERAGE HOME

The first step to take in eliminating mosquito-breeding about
the rural home is to stop giving aid and assistance to the enemy.
This means that no breeding should be made possible by ignorance
or carelessness on the part of the farmer and his family. In
other words, cisterns, water-barrels, wells, etc., should either be
made mosquito-proof or else should be oiled weekly or stocked
with larva-eating fish. The cess-pool should be inspected and,
if necessary, made mosquito-tight. Old cans likely to hold
water should be hauled away. The roof-gutters should be
cleaned out and, if necessary, re-hung. Water-troughs should
be cleaned out weekly or stocked with fish. Every potential
breeding-place about the home should be closely watched.

The next step should be screening. This should be done pro-
perly and effectively, along the lines already described. If the
house is already screened, any repairs necessary should be made
at once. The chimneys should not be forgotten.

These two steps should suffice to prevent any considerable
annoyance by mosquitoes in most properly situated homes.

FURTHER MEASURES

Sometimes, further measures are necessary. It may be that
the home is located near borrow-pits or other depressions that

222

MOSQ UI TO ERA DICA TION

Fig. 145. — Making a concrete privy-vault mosquito-proof. All cracks are

plastered over.

(Photo by E. H. Magoon, C. E.)
Fig. 146. — While this pond was free from mosquito larvae, owing to the
activities of Gambusia, there was abundant breeding in the barrel which the fish
were unable to enter.

RURAL MOSQUITO AND MALARIA CONTROL 223

hold water for considerable periods. In this case, the holes
should be filled or drained, in accordance with the suggestions
outlined in a previous chapter.

Should the house be near a flowing stream, fish control probably
would be the best method of attack. Even though the edges of
the stream were not cleaned periodically, a certain measure
of protection would always be assured. Should the stream be
one that dries up from time to time, probably the best thing to do
would be to oil it, whenever necessary, or, if not too costly,
re-channel the stream, so that no water would stand in it for
longer than a few days.

PROTECTING HOMES IN SWAMPS, ETC.

A home situated in or near a swamp would give more trouble.
In this case, it probably would pay, in the long run, if funds
were available, to drain the swamp. If this were impracticable,
however, for any reason, there are several things that could be
done, in addition to screening and elimination of breeding about
the home, that would be of great assistance. Among them are
the following:

1. Cut down brush, tall weeds and grass that harbor mos-
quitoes. Make the yard about the house a shrubless one — open
to the sun and wind at all times. High trees may be left.

2. Plant a screen of trees some distance from the house between
the breeding-place and the house. This, according to Carter, 1
serves to hide the lights of the house from the marsh or stops the
mosquitoes brought by the breeze from their breeding-places,
or both.

3. Stock the swamp or those parts of it adjacent to the house
with larva-destroying fish.

4. Try starting a bat-roost. While some authorities are
doubtful of the efficacy of this procedure, it would cost but
little to try it out.

5. Oil nearby portions of the swamp from time to time or
install a few submerged drips therein.

6. Build the stables between the house and the swamp, at
some distance from the former. If the stables are already built
elsewhere, or there are none, pasture cattle, hogs or other domes-
tic animals between the house and the swamp.

1 "Anti-malarial Measures for Farm-houses and Plantations." U. S.
Public Health Service, 1919.

224 MOSQUITO ERADICATION

7. Make use of some mosquito-repelling substance in the home.

8. Kill all mosquitoes that succeed in penetrating the screens
or otherwise entering the house.

9. If symptoms of malaria develop, use quinine, as directed in
a previous chapter.

THE RICE-FIELD PROBLEM

An area within or near a rice-field is the worst possible site for
a home from an anti-mosquito point of view.

In the light of our present knowledge, there is no really effec-
tive means of protection in such a case. This is due to the
methods used in growing rice, which call for flooding of the culti-
vated area for several months. In the Arkansas rice section,
flooding water is first applied when the rice is 3 to 5 inches high;
the depth is increased with the growth of the rice until a depth
of 4 to 6 inches is reached, and this depth is maintained during
the growing season. It will be seen therefore, that rice-fields
constitute an ideal breeding-place, since there is quiescent water
and dense vegetation.

Some slight measure of success in reducing larvae by means of
Gambusia affinis is reported by Tarbett. 1 He states, however,
that they fail generally to penetrate the rice, remaining chiefly
in the more open water along the levees.

Tarbett 1 also reports that broad-casting oil-soaked saw-dust
appeared to give somewhat encouraging results. Dry red-oak
saw-dust was used. Thirty gallons of oil, soaked up into 10
bushels of saw-dust, sufficed for one acre. "The results obtained
were encouraging," he says, "breeding being controlled for a
period of two weeks after application, and this without an appre-
ciable effect upon the rice. In this experiment, fuel oil appeared
to give better results than did mixed oil" (mixed with kerosene).

THE RICE-FIELD PROBLEM ABROAD

According to Gunasekara, 2 little rice is raised in Ceylon because
of the increased incidence of malaria which it gives rise to and of
the vigorous methods of combatting the infection carried out
there. These include: abandonment or removal of all dwelling-
places within a mile of the rice-fields; destruction of all harboring

1 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

- Journal, Ceylon Branch, British Medical Association, 1919.

RURAL MOSQUITO AND MALARIA CONTROL 225

places for adults within the same radius; compulsory screening
of dwelling-places; exclusion of all outside labor without previous
blood-examination; the prophylactic and curative administration
of quinine; and the removal of all infective cases from the area.

Legendre reports that in Madagascar, Cellia squamosa and
C. pharoensis, local Anopheline hosts of malaria, manifest a
preference for rice-fields as breeding-places as against marshes
and swamps. He asserts that malaria is more prevalent in the
hill rice-fields than in the lowland fields, and attributes this fact
to the greater abundance of fish in the lowland rice-fields.
Recommendations made to combat malaria in Madagascar
include institution of an anti-larval service, forbidding of irriga-
tion in the vicinity of towns and compulsory culture of fish,
wherever practicable.

According to Carter, 2 attempts to control malaria about the
rice-fields of Italy have been given up. He states that cultiva-
tion of rice is now forbidden within 2 kilometers of a village.

Carter states that in 1917 it was estimated that about
$40,000,000 was invested in the production of rice in the United
States and that this investment is rapidly increasing.

COMMUNITY MEASURES IN RURAL AREAS

As has been already indicated, community offensive measures
against the mosquito at the present time are rarely carried out in
rural sections, due to the sparsity of population per unit of area
and the heavy consequent per capita cost.

Sometimes, however, considerable valuable anti-mosquito
work is clone by drainage district organizations, as the result of
measures designed primarily as agricultural improvements.
While this sort of work is not so effective, from an anti-mosquito
standpoint, as work expressly designed to rid the community of
mosquitoes, it is, nevertheless, of considerable assistance.

Again, two or more farmers may combine to carry out a tile
drainage scheme. This, likewise, has its value, from a health
viewpoint.

However, it would appear that the rural population will have 1 1 >
become much denser and land will have to increase greatly in
value before it will be practicable to carry out in most rural

i Bulletin, Soc. Path. Exot., Feb. 9, 1921.

2 Transactions of the First Annual Conference of Sanitary Engineers,
U. S. Public Health Service, 1919.

226 MOSQUITO ERADICATION

communities the direct offensive anti-mosquito campaigns that
are being waged in cities, towns and villages today.

Several community protective projects have been successfully
carried out, however. These include both screening and quinine-
treatment campaigns. Some of these have extended over com-
paratively wide areas, and have succeeded in greatly reducing the
incidence of malaria.

RURAL COMMUNITY PROTECTIVE DEMONSTRATIONS

An interesting demonstration of the efficacy of screening as a
community protective measure, carried out on a group of planta-
tions near Lake Village, Ark., is described in the chapter on
screening. In this demonstration, no other measure than
screening was employed; yet a reduction of 70.6 per cent in the
incidence of malaria was obtained at an annual per capita cost of
only $1.76.

In connection with this same demonstration, an investigation
as to the efficacy of quinine treatment was carried out on another
group of plantations. Of a total of 306 persons who received
treatment, 69 were given sterilizing doses and the remainder, 237,
were given immunizing doses. A parasite index taken in May,
1916, at the beginning of the work, and again in December of the
same year, showed a reduction of 64.45 per cent. The per
capita cost of the work, omitting overhead expenses, was 57
cents. The cost of malaria per capita for a control untreated
group was $2.52.

In 1918, a demonstration of malaria reduction by quinine
treatment of plasmodia carriers was carried out in Sunflower
County, Mississippi. The county had a population of about
9,000, about 1,000 living in the town of Ruleville and the rest
on cotton plantations. A survey showed that, of the rural
population, 40 per cent had had clinical malaria within 12
months and that, of the remaining 60 per cent, 22 per cent had the
parasites in their blood. On one plantation, having a tenant
population of 600, the average annual physicians' bill for the
preceding 10 years had been approximately $4,000, of which
$3,000 was attributed to malaria. As a result of the work, there
was no transmission of malaria in Ruleville during the year, and
the town was free from mosquitoes. In the rural area, the reduc-
tion in the incidence of malaria during the year was estimated at

RURAL MOSQUITO AND MALARIA CONTROL 227

80 per cent. The per capita cost of the work in Ruleville was 41
cents and in the rural area, $1.08.

In Chapter XI is described another extensive community
demonstration of quinine treatment in Georgia, which, at a cost
of only about $1.50 per person taking treatment, resulted in the
almost total elimination of malaria symptoms in more than
10,000 persons

APPENDIX A

TABLE TO DETERMINE SPECIES OF CERTAIN COMMON
AMERICAN MOSQUITOES

The following table, prepared by Weiss and Patterson, is reprinted from
Headlee's valuable pamphlet, "The Mosquitoes of New Jersey and Their
Control," with some abridgment and with certain changes in nomenclature
suggested by the work of Howard, Dyar and Knab :

ADULTS
Series X in Which the Wings are Spotted

PALPI UNIFORMLY DARK BROWN

Wings with two white spots on the front margin; last vein white with

black ends, Anopheles punctipennis Say.
Wings with four distinct brown spots; last vein wholly dark brown,

Anopheles quadrimaculalus Say.
PALPI WHITE MARKED AT BASE OF JOINTS

Last vein white marked with three black spots, Anopheles crucians

Wied.

Series Y in Which the Wings are not Spotted

A. IN WHICH THE FEET ARE WHITE OR YELLOWISH BANDED

I. The Beak has a More or Less Distinct White Band or
Ring at or Near its Middle.

(a) The abdomen has a yellowish stripe down its middle, and sides
of thorax are white below a black edging, Aedes sollicitans
Wlk.

(b) The abdomen has no yellowish stripe. Sides of thorax are
not white.

1. A large, blackish species with a narrow white band near
the tip of the femur; the tibia, white-spotted, Psoro-
phora (Janthinosoma) columbiae D. and K.

2. A large brown species with a lighter band near the tip
of the posterior tibia, the latter not spotted, Mansonia
perturbans Wlk.

3. A smaller, blackish species, without markings on femur
or tibia, Aedes taeniorhynchus Wied.

II. The Beak is Without Band or Ring; Uniform in Color

(a) The joints of the feet or tarsi are banded or ringed at base
only.

1. An extremely large, brownish-black species. Legs
fringed with erect black scales, Psoropliora ciliata Fabr.
228

APPENDIX 229

2. A very large species with very scaly wings, the sides of
the thorax and bands of the abdomen and feet, white,
Acdes grossbecki D. and K.

3. Wings thickly clothed with mixed yellow and brown
scales. Thorax with broad, brown central stripe.
First tarsal segment of anterior legs not banded, Aedes
fitchii Felt.

4. A small, dark species with lightly scaled wings; the
white bands of the feet narrow; those of the abdomen
nearly divided in the center, Aedes vexans Meig.

5. A good-sized brown species with the bandings yellowish
rather than white; these of the abdominal segments
only a little or not at all notched at the middle, Aedes
cantator Coq.

6. Very like the preceding; but the bands of the abdomen
and feet are broader and somewhat lighter. Breeds
only in fresh water areas, Aides stimvlans Walker.

7. Very like the two precediug, but thorax has a central
brown stripe, Aedes abfttchii Felt.

(£>) The joints of the hind feet at least are white-banded or ringed
at both base and tip, while last joint of the hind tarsi is
usually entirely white.

1. A good-sized brown species, the thorax without lines or
marks; bands of tarsal joints broad, Aedes canadensis
Theob.

2. A small, blackish species with top of thorax covered with
gray hair and a dark line down its center; bands on
tarsi are white and narrow, Aedes atropalpus Coq.

1. A large or medium-sized species, black with deep purple

reflections, Psorophora (Janthinosoma) sayi D. and K.

B. IX WHICH THE FEET ARE UNIFORM IX COLOR, XOT IX AXY
WAY MARKED OR BAXDED

I. The Thorax is Marked in Some Way With Stripes or Spots,
or the Sides are White or Golden Brown.

(a) Species with longitudinal white or blue stripes.

1. There are two white longitudinal stripes; the species
is moderate-sized and blackish, Aedes trivittatus Coq.

2. There is a well-defined broad central white band, and
the top of the head is also white, Acdes atlanticus D. and
K.

3. There is a diffuse white central stripe, not defined as
before; a very small blackish species, Aedes dupreei Coq.

4. There is a central bluish stripe, also blue spots. A
small, dark-brown species, Uranotaenia sapphirina O. S.

(b) Species in which the thorax is yellowish, white or brown,
leaving a blackish central stripe or two, usually not sharply
defined; all of moderate size.

230 MOSQUITO ERADICATION

1. The thorax is yellowish; brownish abdomen with narrow
white bands, Aedes hirsuteron Theob.

2. The thorax is golden yellow. The abdomen is almost
black, with broad, white bands, Aedes abserratus Felt.

3. The thorax is golden brown; the abdomen not banded;
the legs are black, Aedes aurifer Coq.

4. The thorax is silvery-white at the sides, not extending
much on the upper surface, most of which is black; the
abdomen is not banded, Aedes triseriatus Say.

1. There are two small, white dots on each side of the
middle and a U-shaped mark at the base; the abdomen
is banded, Culex restuans Theob.

(d) Species in which the entire under surface is silvery white or
yellowish.

1. A small form, having dorsal surface black; stripes on the
thorax are irregular. Wyeomyia smithii Coq.

II The Thorax is Without Marks or Ornamentation

(a) The segments of abdomen are narrowly banded at their
bases.

1. A small dark-brown species; abdominal bands wider in
the middle than at sides except on seventh segment,
which usually has a narrow band, broad at the sides,
Aedes fuscus O. S.

2. A moderate-sized brownish species with the bands of
abdomen of moderate width, Culex pipiens Linn.

3. A somewhat darker, longer-legged species, with very
narrow, regular abdominal bands, Culex salinarius Coq.

(b) The segments of the abdomen are narrowly banded at their
apices only.

1. A small, slight, blackish species, Culex territans, Wlk.

1. A uniformly dark-brown species of moderate size, Culex
melanurus Coq.

2. Species having thorax yellowish-brown, somewhat
polished, with a thin, bluish-gray fresting, Anopheles
barberi Coq.

LARVAE

Antennae arising from the sides of the head; antennae not pendant

1. No siphon or breathing-tube on eighth abdominal segment, Anopheles

(2).
A siphon or breathing-tube on eighth abdominal segment (3).

2. Antennae yellowish; tracheal gills moderate in size, A. punctipennis,

A. quadrimaculatus.
Antennae shorter, brownish; tracheal gills short, A. crucians.

APPENDIX 231

3. Hair tufts on thorax and abdomen simple, sparse or absent (4).
Thorax and abdomen with star-shaped or stellate hair tufts, Urano-

taenia sapphirina.

4. Abdomen with four tracheal gills at tip (5).

Abdomen with two tracheal gills only; a small whitish species, with
head rounded and thorax subquadrate, Wyeomyia smithii.

5. Antennae arise from sides of anterior part of head (6).

Antennae arise from near middle of sides of head; the mouth brushes
form a club at sides of mouth; a very large species, Psorophora
ciliata.

6. The scales of the eighth abdominal segment are separate (8).

The scales of the eighth abdominal segment, 5 to 8 in number, are

arranged on a band (7).
The scales are replaced by a series of chitinous bars, arranged in a

single row (22).

7. The anal siphon is very large and stout, dilated centrally; antennae

much longer than head, slender with an even outcurve or con-
vexity, Psorophora (J anthinasoma) sayi.
The anal siphon shorter, stout, dilated nearer the base; antennae
nearly straight slender and shorter than head, Psorophora (Janthi-
nasoma) cohmibiae.

8. The scales are not more than 16 in number and form a small patch (9).
The scales number 20 or more and form a large patch (12).

9. Anna! siphon of moderate length, three times as long as wide, or

longer (10).
Anal siphon short, less than three times as long as wide (11).

10. About 12 elongate scales in a single row; 12-16 siphonal spines, each

with one moderate-sized tooth, and sometimes a few very small

ones below it, Aedes fuscus.
Scales 10-15, in partly double row, tapering apically; siphonal spines,

14-18, simple or with 2 or 3 teeth, Aedes vexans.
Scales 7-12 in patch; a small, translucent species, feeding at bottom;

tracheal gills very long and slender, Aedes dupreei.
Scales 6-7, arranged in a curve; tracheal gills, long, slender, uniformly

tapering, Aedes abserratus.

11. A stout, black species; the thorax white-banded; antennal tuft com-

posed of many hairs; tracheal gills very long, Aedes atlanticus.
An elongate, slender, gray species; antennal tuft a single bristle;

tracheal gills short, Aedes triseriatus.
A large robust, light species; anal siphon bottle-shaped, outer half

linear; anal gills slightly longer than width of ninth segment,

Mansonia perturbans.

12. Anal siphon short, not much more than twice as long as broad (13).
Anal siphon moderate, from 2 l A to 3f£ times as long as broad (15).
Anal siphon long, not less than 4 times as long as broad (21).

13. Stout, compact larva; antennal tuft of several hairs (14).

Long, slender larva; antennal tuft of 1 or 2 hairs; 25-35 scales in
patch; 17-21 siphonal spines, with 2 or 3 long teeth at base, Aedes
atropalpus.

232 MOSQUITO ERADICATION

14. Scales 14-22, with stout apical and slender lateral spines; 13-18

siphonal spines with 2 or 3 small teeth sometimes simple; fresh

water, Aedes trivittatus.
Scales 16-22, with rounded apex and slender lateral spines; 12-16

siphonal spines with 1-4 small teeth on both sides; head maculate;

salt marsh, Aedes taeniorhynchus.
Scales 20-40, with stout apical and slender lateral spines; 16-24

siphonal spines with 1-5 small teeth; head generally immaculate;

salt marsh, Aedes sollicitans.

15. Scales rather broad (16).
Scales elongate (17).

16. Scales 35-40, with 3 stout apical and smaller lateral spines; 16-20

siphonal spines with 1-3 small teeth; head maculate; salt marsh,
Aedes cantator.
Scales 25-50, with one very stout apical and slender lateral spine;
16-22 siphonal spines, with 1-2 large and 4-6 smaller teeth on
basal half; head immaculate; fresh water form, Aedes stimulans.

17. Only the terminal segment, with a dorsal plate or ring (18).

18. Antennae not specially marked or colored (19).

Antennae prominent, white at base, dark at tip, Aedes aurifer.

19. Moderate-sized species (20).

Very large larva; scales 28-34, with long apical and slender lateral
spines; siphonal spines 17-22, with 4 or 5 large teeth basally, Aedes
grossbecki.

20. Scales 25-50 with short apical and very short lateral spines; siphonal

spines 16-20, with 1-2 teeth at base, one usually very large, Aedes
hirsuteron.
Scales 25-50, with small apical and smaller lateral spines; 16-24
siphonal spines with 4-5 serrations on basal half; antenna dark at
tip, Aedes canadensis.

21. Antennal tuft above the middle.

Anal siphon of moderate length, sides a little inflated; tracheal gills

moderately long, Culex pipiens.
Anal siphon very long, rather slender and slightly tapering to tip;

head narrower than thorax; tracheal gills short, Culex salinarius.
Anal siphon very long and slender; a little constricted centrally; head

as wide as thorax; tracheal gills moderate or long, Culex lerritans.
Antennal tuft below middle.

Scales 24-30, antenna not arising from an offset, Aedes abfitchii.
Anal siphon of moderate length; tracheal gills rather long, Culex

restuans.
Anal siphon 5 times as long as widest diameter; antennae dark at tip,

Aedes fitchii.

22. A bronzed, brown larva, with rather long, moderately stout, black

breathing tube, Culex melanurus.

APPENDIX B
APPROVED ANTI-MOSQUITO ORDINANCE

The following ordinance, prepared in connection with the joint, coop-
erative anti-malaria demonstration work of the U. S. Public Health
Service and the International Health Board, has been adopted by a large
number of cities, towns and villages in various parts of the United States,
and has proven uniformly satisfactory:

ORDINANCE FOR THE PREVENTION OF MOSQUITO BREEDING

IN THE

Section 1— It shall be unlawful to have, keep, maintain, cause or permit,

within the (incorporated) limits of

any collection of standing or flowing water in which mosquitoes breed or are
likely to breed, unless such collection of water is treated so as effectually to
prevent such breeding.

Section 2.— Any collections of water considered by Section 1 of this
ordinance shall be held to be those contained in ditches, pools, ponds,
excavations, holes, depressions, open cess-pools, privy vaults, fountains,
cisterns, tanks, shallow wells, barrels, troughs (except horse troughs in
frequent use), urns, cans, boxes, bottles, tubs, buckets, defective house roof
gutters, tanks of flush closets or other similar water containers.

Section 3.— The method of treatment of any collections of water, that are
specified in Section 2, directed toward the prevention of breeding of mos-
quitoes, shall be approved by the accredited health officer, and may be any
one or more of the following:

(a) Screening with wire netting of at least 16 meshes to the inch each
way or with any other material which will effectually prevent the ingress
or egress of mosquitoes.

(b) Complete emptying every seven (7) days of unscreened containers,
together with their thorough drying or cleaning.

(d) Covering completely the surface of the water with kerosene, petroleum
or paraffin oil once every seven (7) days.

(e) Cleaning and keeping sufficiently free of vegetable growth and other
obstructions, and stocking with mosquito-destroying fish.

(J) Filling or draining to the satisfaction of the health officer.

(<7) Proper disposal, by removal or destruction, of tin cans, tin boxes,
broken or empty bottles and similar articles likely to hold water.

Section 4.— The natural presence of mosquito larvae in standing or running
water shall be evidence that mosquitoes are breeding there, and failure to

233

234 MOSQUITO ERADICATION

prevent such breeding within three (3) days after notice by the health
officer shall be deemed a violation of this ordinance.

Section 5. — Should the person or persons responsible for conditions giving
rise to the breeding of mosquitoes fail or refuse to take necessary measures
to prevent the same, within three (3) days after due notice has been given
to them, the health officer is hereby authorized to do so, and all necessary
cost incurred by him for this purpose shall be a charge against the property-
owner or other person offending, as the case may be.

Section 6. — For the purpose of enforcing the provisions of this ordinance,
the health officer, or his duly accredited agent, acting under his authority,
may at all reasonable times enter in and upon any premises within his
jurisdiction; and any person or persons charged with any of the duties
imposed by this ordinance failing, within the time designated by this
ordinance, or within the time stated in the notice of the health officer, as the
case may be, to perform such duties, or to carry out the necessary measures
to the satisfaction of the health officer, shall be deemed guilty of a separate
violation of this ordinance.

Section 7. — Any person who shall violate any provision of this ordinance
shall on each conviction be subject to a fine of not less than One Dollar
($1.00) or more than Twenty-five Dollars ($25.00), in the discretion of the
court.

Section 8. — All ordinances or parts of ordinances in conflict with this
ordinance are hereby repealed, and this ordinance shall be in full force and

effect days after its approval.

Adopted this day of

Approved this day of .

APPENDIX C
SUGGESTED ANTI-MOSQUITO LEAFLET FOR CAMPAIGN

EDUCATIONAL WORK

The experience of the writer has been that only a very small proportion
of the inhabitants of the average American municipality have any adequate
idea as to where and in what manner mosquito-breeding takes place about
homes, and, consequently, a vast amount of mosquito production can be
eliminated if the citizens are made cognizant of a few simple facts on the
subject and persuaded to give their co-operation.

The following matter is not presented as a model essay on the subject.
It is submitted only to give some idea of the facts which, in the opinion of
the writer, ought to be given the people of a town engaging in mosquito
control work, in order to obtain their intelligent co-operation. It is believed
that the expense of printing and distributing such a leaflet will be more
than repaid by the resulting assistance of the informed citizens.

YOUR PART IN THE CITY 1 ANTI-MOSQUITO

CAMPAIGN

How to Get Rid of Mosquitoes About The Home

Mosquitoes Spread Malaria ; Mosquitoes Can Be Eliminated. — In view
of the proven fact that mosquitoes are solely responsible for the spread
of malaria and other serious diseases and of the further proven fact that
mosquitoes can be done away with in any ordinary community by intelligent
effort, the City 1 authorities have decided this year to initiate an antimos-

quito campaign in 2 and an appropriation has already

been made for the purpose.

People Must Lend Their Aid; Your Job and the City's. 1 — In order that
the campaign be a success, it is absolutely necessary that every citizen do
his part. The city is prepared to prevent mosquito-breeding in streams,
ponds, swamps and other natural breeding-places throughout the City, 1 as
well as in roads, streets, parks and other public places, but the private
citizen must prevent mosquito-breeding on his own premises, insofar as such
breeding is a result of his own activities or his own negligence. This duty
is imposed upon the citizen by City 1 ordinance.

Purpose of This Leaflet Is To Tell You How To Do Your Part.— This
leaflet is distributed by the City 1 with the object of aiding citizens in doing

1 Substitute Town or Village, where necessary.

2 Insert name of place.

235

236 MOSQUITO ERADICATION

this duty, by telling them something about the breeding-habits of mosquitoes
and about practical and easy ways to prevent such breeding.

It should be fully understood that there is absolutely no doubt that
mosquitoes spread malaria and other diseases, nor that mosquitoes can be
virtually done away with in any ordinary community. The work on the
Panama Canal Zone and in numerous other places has fully demonstrated
the truth of these statements.

Some Common Breeding-places about the Average Home. — Mosquitoes
breed only in standing or slowly running water. The belief that they
breed in grass, bushes or other such places was exploded many years ago.
Hence, if we are to do away with mosquitoes, we must either do away with
the water or else take steps to prevent them from breeding in it. These
other steps include screening, oiling, stocking with mosquito-destroying
fish, etc. Which of these measures to take in any particular case depends
upon the circumstances, as will be explained directly.

The usual breeding-places of mosquitoes about homes are: cisterns;
barrels, tubs and buckets of water; shallow wells; pools of water from rains,
leaky pipes, etc.; tin cans, bottles, etc., that hold water; water-troughs;
cess-pools that are not tightly covered; certain types of privies that mos-
quitoes can enter; stopped-up roof gutters, etc. In fact, any collection
of water that a mosquito can get to is likely to become a breeding-place.

How to Handle the Various Breeding-places.— The best measure to take
to stop breeding in any certain case depends upon the nature of the breeding-
place. Thus, where possible, pools of water should be drained; if they
cannot be drained, they should be oiled (that is, covered with a visible
film of kerosene or other light mineral oil) once a week or else stocked with
mosquito-destroying fish, which may be obtained from the City. 1 Surface
cisterns should be screened in such manner that they will be mosquito-
proof; underground cisterns should be tightly covered or else stocked with a
few mosquito-destroying fish. Barrels, tubs and buckets of water should
either be screened with burlap or netting or else oiled once a week or else
emptied and thoroughly dried out once a week. The best way to handle
shallow wells is to stock each with two or three mosquito destroying fish,
which will in no way injure the water. Tin cans, bottles, etc., should
either be buried or hauled away. Water-troughs should be emptied and
then dried out thoroughly once a week. Cess-pools, etc., should be tightly
covered and mosquito-breeding privies should be well oiled, after which the
lids should be kept closed down, whenever the privy is not in use. Stopped-
up roof gutters should be cleaned out and, where necessary, re-hung.

Make Inspection of Your Premises Once Every Week. — The City 1
expects citizens to eliminate or otherwise take care of any and all of the above-
mentioned classes of breeding-places that may be on their premises. One
of the best ways of doing this is for each citizen to make a close inspection
of his premises at least once a week, and particularly after heavy rains,
emptying all unscreened receptacles containing water or else oiling or other-
wise treating them, paying particular attention to tin cans, etc. The reason
for making the inspection weekly is that it requires only a little more than a
week for the full-fledged mosquito to develop from the egg.

1 Substitute Town or Village, where necessary.

APPENDIX 237

How the City 1 Helps You To Do Your Part. — An aquarium of mosquito-
destroying fish is kept up by the City 1 anti-mosquito forces for the purposes
of supplying all citizens who may have use for them. These fish are very
effective for cisterns, shallow wells and more or less permanent pools which
it is impracticable to drain. In order for the fish to work effectively, how-
ever, it is necessary to keep the pool free from vegetation.

The City 1 anti-mosquito forces will be glad to help willing citizens in any
other manner possible. The director of the campaign will at all times take
pleasure in advising such citizens as to the best methods of solving their
problems. Citizens who refuse or neglect to keep their premises free from
mosquito-breeding will receive scant consideration, however. Periodical
inspections will be made of every home in the City, 1 and persons who fail
to comply with the law will be prosecuted. The ordinances provide for a
fine of from SI. 00 to $25.00 for each violation.

No Fun Raising Mosquitoes; They Cost City 1 Real Money. — However, it
is the belief of the City 1 authorities that few, if any, prosecutions will be

necessary in 2 There is no pleasure to be derived

from raising mosquitoes, and mosquito-farms do not bring any profit; on
the contrary, as already stated, mosquitoes spread malaria and other
diseases, which yearly cause a vast amount of suffering and expense. It is
figured by health experts that each case of malaria costs from $15 to $20
in loss of time, loss of efficiency, medicines and physicians' bills. As it is

estimated that there were, cases of malaria in 2

last year, it will easily be seen that it is to the interest of every citizen to
help cut down this big annual community expense. In addition to the
sickness they cause, the annoyance occasioned by mosquitoes is well known
to every one, and of itself would make it well worth while to do away with
the mosquito.

Raising Mosquitoes Almost As Bad As Raising "Cooties." — But there is
another reason why each citizen should do his utmost to prevent mosquito-
breeding about his home. That is self-respect. A man who raises "cooties"
on his person is regarded as slothful and unclean. The day is not far dis-
tant when a man who raises mosquitoes on his premises will be regarded
as equally slothful and unclean.

Director,

Anti-mosquito Campaign.

1 Substitute Town or Village, where necessary.

2 Insert name of place.

APPENDIX D

BIBLIOGRAPHY

The following publications have been consulted in the preparation of this
work:

Transactions of the First Annual Conference of Sanitary Engineers and
Other Officers of the Public Health Service Directing Anti-malaria Campaign,
Public Health Bulletin No. 104, U. S. Public Health Service, Washington,
D. C, 1919.

Transactions of the Second Annual Anti-malaria Conference of Sanitary
Engineers and Others Engaged in Malaria Field Investigations and Mosquito
Control. Public Health Bulletin No. 155, U. S. Public Health Service,
Washington, D. C, 1921.

Mosquito Control About Cantonments and Ship-yards, by J. A. Le
Prince, Reprint No. 511, U. S. Public Health Service, 1919.

Anopheles Crucians Wied. As an Agent in Malaria Transmission, by
C. W. Metz., Reprint No. 536, U. S. Public Health Sen-ice, 1919.

Malaria: A Public Health and Economic Problem in the United States,
by John W. Trask, Reprint No. 382, U. S. Public Health Service, 1917.

Malaria Control: Drainage as an Anti-malarial Measure, by J. A. Le-
Prince, Reprint No. 258, U. S. Public Health Service, 1915.

Control of Malaria: Oiling as an Anti-mosquito Measure, by J. A.
LePrince, Reprint No. 260, U. S. Public Health Service, 1915.

Filariasis in Southern United States, by Edward Francis, Hygienic
Laboratory Bulletin No. 117, U. S. Public Health Service, 1919.

Field Identification of Malaria-carrying Mosquitoes, by Ernest A. Sweet,
Supplement No. 32, U. S. Public Health Service, 1918.

Anopheles Crucians: Habits of Larvae and Adults, by C. W. Metz,
Reprint No. 495, U. S. Public Health Service, 1919.

Observations on the Food of Anopheles Larvae, by C. W. Metz., Reprint
No. 549, U. S. Public Health Service, 1919.

The Malaria Problem of the South, by H. R. Carter, Reprint No. 552,
U. S. Public Health Service, 1919.

The Relations of the Railroads in the South to the Problem of Malaria and
Its Control, by R. C. DERrvAtrx, Reprint No. 480, U. S. Public Health
Service, 1918.

Use of Dynamite in Anti-malarial Drainage Operations, by J. K. Hoskins
and W. E. Hardenburg, Reprint No. 493, U. S. Public Health Service, 1919.
Malaria: Lessons on Its Cause and Prevention, by H. R. Carter, Supple-
ment No. 18, U. S. Public Health Service, 1918.

What the Farmer can do to Prevent Malaria, by R. H. Von Ezdorf,
Supplement No. 11, U. S. Public Health Service, 1914.

Demonstrations of Malaria Control, by R. H. Von Ezdorf, Reprint No.
328, U. S. Public Health Service, 1918.

238

APPENDIX 239

Some Aspects of Malaria Control Through Mosquito Eradication, by
C. W. MeTZ, Reprint No. 500, U. S. Public Health Service, 1919.

Anopheline Surveys: Methods of Conduct and Relation to Anti-malarial
Work, by R. H. Von Ezdorf, Reprint No. 272, U. S. Public Health Service,
1918.

Prevention of Malaria: Suggestions on How to Screen the Home to
Keep Out Effectively the Mosquitoes which Spread Disease, by R. H. "Von
Ezdorf, Reprint No. 170, U. S. Public Health Service, 1916.

Malaria Control: A Report of Demonstration Studies Conducted in
Urban and Rural Sections, by R. C. Derivatjx, H. A. Taylor and T. D.
Haas, Public Health Bulletin No. 88, U. S. Public Health Service, 1917.

Malaria Control: Results Obtained by a Local Community Following
Anti-mosquito Demonstration Studies by the United States Public Health
Service in co-operation with the International Health Board, by J. E.
Sparks, R. C. Derivaux and H. A. Taylor, Reprint No. 476, U. S. Public
Health Service, 1918.

Anti-malarial Measures for Farm-houses and Plantations, by H. R.
Carter, Reprint No. 105, U. S. Public Health Service, 1919.

Fishes in Relation to Mosquito Control in Ponds, by S. F. Hildebrand,
Bureau of Fisheries Document No. 874, U. S. Bureau of Fisheries, Wash-
ington, D. C, 1919.

Notes on the Life History of the Minnows, Gambusia Affinis and Cypri-
nodon Variegatus, by S. F. Hildebrand, Bureau of Fisheries Docuvu -nt
No. 857, U. S. Bureau of Fisheries, 1917.

Tile Drainage on the Farm, by A. G. Smith, Farmers' Bulletin No. 524,
U. S. Department of Agriculture, 1917.

Trenching Machinery Used for the Construction of Trenches for Tile
Drains, by D. L. Yarnell, Farmers' Bulletin No. 698, U. S. Department of
Agriculture, 1915.

The Mosquitoes of New Jersey and Their Control, by Thomas J. Headlee,
Bulletin No. 276, New Jersey Agricultural Experiment Stations, New Bruns-
wick, N. J., 1915.

Some Recent Advances in Knowledge of the Natural History and the
Control of Mosquitoes, by Thomas J. Headlee, Bulletin No. 306, New
Jersey Agricultural Experiment Stations, New Brunswick, N. J., 1916.

A Biological Study of the More Important of the Fish Enemies of the
Salt Marsh Mosquitoe's, by F. E. Chidester, Bulletin No. 300, New Jersey
Agricultural Experiment Stations, New Brunswick, N. J., 1916.

"Field Experiments in Malaria Control," by Wickliffe Rose, American
Medical Association, Chicago, 1919.

The Importance of Malaria from A Public Health and Economic Stand-
point, by W. S. Leathers, Southern Medical Journal, Birmingham, Ala.,
1918.

"Preventive Medicine and Hygiene," by Milton J. Roesnatj, D.
Appleton & Co., New York and London, 1918.

"A Plea and a Plan for the Eradication of Malaria Throughout the
Western Hemisphere," by Frederick L. Hoffman, Prudential Insurance
Company of America, Newark, N. J., 1917.

"The Use of Explosives in Making Ditches," Institute of Makers of
Explosives, New York, 1917.

240 MOSQUITO ERADICATION

"Blasters' Hand-book," E. I. duPont de Nemours & Company, Wil-
mington, Del., 1918.

"Myers' Spray Pumps," F. E. Myers & Bro., Ashland, Ohio.

"Calco Automatic Drainage Gates," California Corrugated Culvert
Company, West Berkeley, Calif.

Other publications on mosquitoes and kindred topics include:

"The Mosquitoes of North and Central America and the West Indies,"
by L. O. Howard, H. G. Dyar and Frederick Knab, Carnegie Institution,
Washington, D. C.

"A Monograph of the Culicidae of the World," by F. V. Theobald,
British Museum, London, England.

"Mosquito Control in Panama," by J. A. LePrince and A. J. Orenstein,
New York, 1916.

INDEX

Abercrombie, 216, 217
Abramis chrysolenca, 183
Acilius sulcatus, 211
Aedes calopus, 9, 34
canadensis, 42
cantator, 48
sollicitans, 44
taenierhynchus, 48
vexans, 42
Aegilitis semipalmata, 211
Aeschna, 211

Agamodistomum martiranoi, 211
Agamomermis culicis, 211
Albany, Ga., particulars of anti-
mosquito work at, 64
Alexandria, La., war anti-mosquito

work at, 59
Alexandria, Va., war anti-mosquito

work at, 59
Algae, 188

Alto, Tex., particulars of anti-
mosquito work at, 64
Amblystoma opacum, 211
Americus, Ga., war anti-mosquito

work at, 59
Anas platyrhynches, 211
Animals as protection against

mosquitoes, 214
Anniston, Ala., war anti-mosquito

work at, 59
Anopheles albimanus, 25
argyritarsis, 25
claviger, 25
costalis, 25
crucians, 25, 29
intermedium, 25
maculipennis, 25
occidentalis, 25, 32
pseudomaculipes, 25
pseudopunctipennis, 25
punctipennis, 25, 30

Anopheles albimanus, quadrima-
culatus, 25, 28

sinensis, 25

tarsimaculate, 25
Anophelinae, in general, 25

identification of, 25
Anti-mosquito campaign costs, 63

campaign leaflet, 235

ordinance, 233
Applying oil, other methods of, 1G7
Aquarium, need for, 183
Articles, texts for, 92
Ashburn, 11

Athens, Tex., particulars of anti-
mosquito work at, 64
Atlanta, Ga., war anti-mosquito

work at, 59
Augusta, Ga., war anti-mosquito
work at, 59

Bamberg, S. C, particulars of anti-
mosquito work at, 64

Barber and Hayne, 163

Barred killifish the, 176

Bastrop, La., particulars of anti-
mosquito work at, 64

Bat, the, as a mosquito-destroyer,
210

Batesville, Miss., particulars of
anti-mosquito work at, 64

Baton Rouge, La., particulars of
anti-mosquito work at, 64

Bauxite, Ark., demonstration at, 56

Beginning of mosquito control, the,
51

Bibliography, 238

Biloxi, Miss., anti-mosquito work at,
59

Bishop, 133, 162

Blasting ditches, 113

Boom, to prevent escape of oil, 192

Breeding-places about homes, 83

241

242

INDEX

British Guiana, malaria mortality
in, 7

British Honduras, malaria mortality
in, 7

Brownsville, Tenn., particulars of
anti-mosquito work at, 64

Bryan, Tex., particulars of anti-
mosquito work at, 64

Cairo, Ga., particulars of anti-
mosquito work at, 64

Calco gate, the, 153

Calvert, Tex., particulars of anti-
mosquito work at, 64

Cameron, Tex., particulars of anti-
mosquito work at, 64

Campbell, 210

Camphor, spirits of, as a mosquito
repellent, 215

Carroll, 153

Carter, 6, 7, 55, 196, 198, 203, 204,
223

Central of Georgia Railway, malaria
appropriation, 58

Ceylon, malaria mortality in, 7

methods of mosquito control in,
224

Chandeleur Islands, screening at,
204

Charleston, Miss., particulars of
anti-mosquito work at, 64

Charleston, S. C, war anti-mosquito
work at, 59

Charlotte, N. C, war anti-mosquito
work at, 59

Chattanooga, Tenn., war anti-
mosquito work at, 59

Chester, S. C, particulars of anti-
mosquito work at, 64

Chidester, 183, 211

Chiroptera, 210

Choetura pelagica, 211

Chordeiles virginianus, 211

Citronella, oil of, as a mosquito
repellent, 215

Coffeeville, Miss., particulars of
anti-mosquito work at, 64

Columbia, S. C, war anti-mosquito

work at, 59
Columbus, Ga., war anti-mosquito

work at, 59
Columbus, Miss., particulars of
anti-mosquito work at, 64
Community measures in rural areas,

225
Complaint bureau, 88
Complaint form, 90
Control measures about the home.

221
Co-operation, obtaining, 76, 93
Cordilura haemorhoidalis, 211
Corethra, 211
Corporations, aid anti-mosquito

work, 61
Cost records, 95

Costa Rica, malaria mortality in, 7
Costs of blasting ditches, 116

of hand ditching, 110, 111

of machine ditching, 119, 144

of maintenance, 124

of tile drainage, 131
Craig, 11

Crangon vulgaris, 211
Creosote, as a larvicide, 162
Crithidia fasciculata, 211
Crossett, Ark., demonstration at, 56
Cuba, malaria mortality in, 7
Culex fatigans, 11, 13, 36

pipiens, 39

restuans, 40

salinarius, 49
Culicinae, the, 32
Cyprinodon calaritanus, 183

variegatus, 180

Dallas, Tex., war anti-mosquito
work at, 59

Demopolis, Ala., particulars of anti-
mosquito work at, 64

Dengue, 10, 11, 14

Derivaux, 77, 206.

Dermott, Ark., demonstration at, 56

Diemyctylus tortosus, 211

Dikes, construction of, 145

INDEX

243

Diking, in general, 144

Diplocystis, 211

Discoglossus pictus, 211

Distribution of malaria, 5
of oil, 169

Ditch construction, 106, 140

Ditching by dynamite, 113
by hand, 107, 110, 142
by machinery, 117, 143
costs, 110, 111, 116, 124, 131,

144
required per acre of marsh, 141

Dothan, Ala., particulars of anti-
mosquito work at, 64

Drainage, in general, 99
problems, 102

Drip-cans, 165

Duck-weed, 190

Dyar, 32, 43

Dyersburg, Tenn., particulars of
anti-mosquito work at, 64

Dytiscus marginalis, 211

Eggs, mosquito, 18, 27, 28, 34, 35, 37,

42, 43, 46
Eldorado, Ark., particulars of anti-
mosquito work at, 64
Electric Mills, Miss., demonstration

at, 55
Emesa longipes, 211
Eptesicus fuscus, 212
Equipment and materials, 82
Erythemis simplicicollis, 211
Estimate of cost, the, 71
Eufala, Ala., particulars of anti-
mosquito work at, 64
Expedients, auxiliary, 209
Expenditures record, the, 96
Exterminative measures, direct, 210

Farmville, N. C, particulars of
anti-mosquito work at, 64

Fayetteville, N. C, war anti-
mosquito work at, 59

Filariae, 13

Filariasis, 11, 14

Filling, 138, 144

Finlay, 51

Fish control, in general, 172

procedure in, 183
Flight, distances of mosquitoes, 17,

29, 36, 37, 42, 44
Flint, 51
Florence, Ala., war anti-mosquito

work at, 59
Foes, animal, of mosquitoes, 211
Fordyce, Ark., particulars of anti-
mosquito work at, 64
Fort Worth, Tex., war anti-mosquito

work at, 59
Fresh- water killy, the, 179
Fuchs, 146, 149, 150, 153
Funds, raising, 74

handling of, 75
Fundulus diaphanous, 179

heteroclitus, 176

majalis, 179

notatus, 181

notii, 181

Gambusia affinis, 175

Gantt's Quarry, Ala., particulars of

anti-mosquito work at, 64
Gies, 148, 156
Girardinus caudimaculatus, 183

poeciloides, 183
Gold-fish, the, 182
Goldsboro, N. C., particulars of

anti-mosquito work at, 64
Gorgas, 51, 53
Gorman, 132
Graham, 11
Greenville, N. C., particulars of

anti-mosquito work at, 64
Greenville, S. C., war anti-mosquito

work at, 59
Guatemala, yellow fever outbreak

suppressed, 53
Gulfport, Miss., war anti-mosquito

work at, 59
Gunasekara, 224

Haas, 206

244

INDEX

Hamburg, Ark., demonstration at,
56

Haptochilus, 183

Harboring-places of the mosquito,
212, 213

Harrassing the mosquito, 213

Hartsville, S. C, particulars of anti-
mosquito work at, 64

Hattiesburg, Miss., war anti-
mosquito work at, 59

Havana, freed of yellow fever, 51

Hayne and Barber, 163

Headlee, 15, 19, 21, 24, 43, 46, 140,
141, 142, 144, 146, 150,
151

Hearne, Tex., particulars of anti-
mosquito work at 64,

Hematocytozoa, 1

Herpetomonous algeriense, 211

Hildebrand, 173, 181, 183, 184, 187,
188, 190

Hirundo erythrogasta, 211

Historical aspects of mosquito
control, 50

Hoffman, 8, 211

Horpopeza obliterate, 211

Houston, Tex., war anti-mosquito
work at, 59

Hydra fusca, 211
viridis, 211

Hydrochloa carolinensis, 188

Hydro philus obtusatus, 211

India, malaria mortality in, 6
Inspection system, 79, 85
Inspector, qualifications of, 81
Inspector's daily report, 75

procedure, 86
Instrument work in drainage, 100
International Health Board, 55, 56,

60, 63, 69, 76,205, 208
Iridoprocne bicolor, 211
Italy, malaria mortality in, 7

rice-field problem, 224

Jackson, Miss., war anti-mosquito
work at, 59

Jacksonville, Fla., war anti-mosquito

work at, 59
Jacksonville, Tex., particulars of

anti-mosquito work at, 64

Keltys, Tex., anti-mosquito work at,

57, 58
Kerosene, as mosquito repellent, 215

for oiling, 160
Knab, 25
Kress, Va., screening work at, 206

Lake Charles, La., war anti-mosquito
work at, 59, 205

Lake Village, Ark., demonstration
at, 56, 205, 206, 208, 226

Larvae, anatomy of, 24

Larvicide, the Panama, 161

Larvicides, other, 162

Laveran, 50

Leathers, 6

Legendre, 225

Lemon-juice, as a mosquito repel-
lent, 215

Lenert, 123

LePrince, 59, 60, 62, 64, 81, 93, 125,
126, 134, 160, 161, 162,
166, 170, 213

Lesticocampa, 211

Licker-in wire, 193

Life, of a mosquito, IS
of a screen, 203

Lined ditches, 125

Lispa sinensis, 211

Little Rock, Ark., war anti-mosquito
work at, 59

Livingston, Tex., particulars of anti-
mosquito work at, 64

Logs, removal from streams, 136

Lonoke, Ark., war anti-mosquito
work at, 59

Louisville, Ky., war anti-mosquito
work at, 59

Lucania parvia, 181

Lucius americanus, 183

INDEX

245

Lufkin, Tex., anti-mosquito work at,

57
Lutzia bigotii, 211

Machine ditching, 117, 14:5

Macon, Ga,, war anti-mosquito work

at, 57
Macrogametes, 2
Madagascar, mosquito control in,

225
Maintenance costs, 124

of open ditches, 120
Malaria as a labor problem, 8
census, 68
characteristics of, 4
control in United States, 53
distribution of, 5
economic significance of, 7
history of control at Panama, 52
incidence reports, 67
mortality and morbidity, 6
parasites, 1
transmission of, 1
versus yellow fever control, 10
Malvern, Ark., particulars of anti-
mosquito work at, 64
Mansonia perturbans, 42
Maps, 97
Mast, 179

Materials and equipment, 82
Mauritius, malaria mortality in, 7
Measures for attacking adult
mosquitoes, 210
exterminative, 210
protective, 214
Megarhinus septentrionalis, 211
Memphis, Tenn., war anti-mosquito

work at, 59
Methods, auxiliary, 209
Metz, 30, 103
Mierogametocytes, 2
Mignon, Ala., particulars of anti-
mosquito work at, 64
Millington, Tenn., war anti-
mosquito work at, 59
Minnow, the spotted top, 181
the star-headed, 181

Minnow, the top, 17.~>

the variegated, ISO
Mollincsia latipennia, 183
Monedula signata, 211
Montgomery, Ala., war anti-
mosquito work at, 59
Monticello, Ark., demonstration at,

56
Mosquito, anatomy of the, 21

as an annoyance, 14

breeding about homes, 83

identification of the, 20

in general, 17

life-history of the, 17

repellents, 215

why it bites, 19
Moss, coon-tail, 188
Myiochanes virens, 211
Myriophyllum, 188

Naias flexilis, 190

Nashville, Tenn., war anti-mosquito
work at, 59

National Malaria Committee, 216

Navasota, Tex., particulars of anti-
mosquito work at, 64

Negligent citizen, the, 87

Nepa, 211

Net for catching fish, 186

New Orleans yellow fever outbreaks,
52

Newport News, Va., war anti-
mosquito work at, 59

Nicaragua, malaria mortality in, 7

Niter cake as a larvicide, 162

Nosema stegomyia, 211

Notice, form of official, 88

Notonecta, 211

Oil, distribution of, 169

kind of, required, 170

storage of, 169
Oiling, costs of, 170

frequency of, 168

place of in anti-mosquito work,
15S

246

INDEX

Orange, Tex., war anti-mosquito
work at, 59

Panama Canal Zone Health Depart-
ment report, 127

Panama Canal Zone, malaria mor-
tality in, 7
progress in malaria control in,

52
"swatting" the mosquito, 212

Parallel system of ditching, 140

Parham, 86

Pass Christian, Miss., war anti-
mosquito work at, 59

Pennyroyal, oil of as a mosquito
repellent, 215

Peppermint, oil of as a mosquito
repellent, 215

Personnel, 80

Petersburg, Va., war anti-mosquito
work at, 59

Petrochelidon lumfrous, 211

Philippine Islands, malaria mortality
in, 7

Physicians, statistics from, 67

Pisobia pusillus, 211

Planning the inspection system, 85
the. work, 79

Plants in relation to fish control,
188

Plasmodia, 1

Points requiring investigation, 209.
218

Policy, questions of, 73

Polygonum, 190

Pool-connecting system of ditching,
140

Porto Rico, malaria mortality in, 7

Portsmouth, Va., war anti-mosquito
work at, 59

Progne subis, 211

Protecting homes in swamps, 223

Psorophora ciliata, 43, 211

Ptychozoon homalecephalum, 211

Publicity, 91

Pumping, 156

Pupae, 17, 18, 24, 25

Quantico, Va., war anti-mosquito

work at, 59
Quinine, for malaria, 216

treatment demonstrations, 216
versus anti-mosquito measures,
217

Railroads' contributions to malaria
hazards, 77

Rain-water fish, 181

Raleigh, N. C, war anti-mosquito
work at, 59

Rana palustris, 211
pipiens, 211

Ranatra fusca, 211

Records, 95

Reports, daily, 93

Rice-field problem, the, 224

Riparis riparia, 211

Rizzi, 214

Roanoke Rapids, N. C, demonstra-
tion at, 54

Rock Creek Lumber Company anti-
mosquito work, 64

Rose, 6

Rosenau, 4, 11, 13, 36

Ross, 6, 50

Rural mosquito control, 219

protective demonstrations, 226

Rusk, Tex., particulars of anti-
mosquito work at, 64

Salt marsh ditches, design of, 140
problem, the, 139
shrinkage, 156

Salticus, 211

San Antonio, Tex., war anti-mos-
quito work at, 59

Sayornis phoebe, 211

Schizogony, 2

Screen, life of a, 203

Screening campaign, conduct of a,
204

INDEX

247

Screening campaign, cost of, 205
of chimneys and fire-places, 202
of doors, 197
of porches, 201
of windows, 200
place of in anti-mosquito work,
195
Searcy, Ark., particulars of anti-
mosquito work at, 64
Seepage outcrops, drainage of, 104
Seine for catching fish, 186
Shaw, 123, 205
Sheffield, Ala., war anti-mosquito

work at, 59
Shelby, Ala., particulars of anti-
mosquito work at, 64
Sluice-boxes, 147
Sluices, construction of, 147

specifications for large, 150
Smart-weed, 190
Smith, A. G., 129, 130, 131
Smith, John B., 140
Smudge, to repel mosquitoes, 215
Snidow, 199, 204, 206
Sources of aid, other, 78
South Groveton, Tex., particulars of

anti-mosquito work at, 64
Spain, malaria mortality in, 7
Spartanville, S. C., war anti-
mosquito work in, 59
Spirochaeta culicis, 211
Spirodella polyrrhiza, 190
Sporozoite, 2

Spotted top minnow, the, 181
Sprayers, 163
St. Louis & Southwestern Railway,

56, 60, 205
Stables as an attraction to mos-
quitoes, 214
Star-headed minnow, the, 181
Statistics, collection of, 66
Straits Settlements, malaria mor-
tality in, 7
Stream re-channeling, 134, 135
Striped killifish, the, 179
Stromquist, 133
Sub-aqueous saw. the, 193
Substances repellent to the mosquito.
215

Sub-surface drainage, 127
Sun-fishes in anti-mosquito work, 182
Sunflower County, Miss., demon-
stration in, 226
Survey, the, 69, 220
Swamp home, protecting the, 223
Swamps, drainage of, 103, 110
"Swatting" the mosquito, 212

Table to determine species of com-
mon American mosquitoes,
228
Tachycineta thalassina, 211
Tahydromia macula, 211
Tanypus dyari, 211
Tarbett, 196, 224
Taylor, 206
Texarkana, malaria cases at hospital,

56, 57
Texts for articles, 92
Thomasville, Ga., particulars of

anti-mosquito work at, 64
Tide-gate, the Calco, 153
Tide-gates, construction of, 149
in general, 147
operation of, 155
other types of, 151
Tile drainage costs, 131

drains, 127
Tiles, placing of, 130
Tools for hand ditching, 107, 142
Top minnows, 175
Topography, need of studying the,

100
Transmission of malaria, 1

of yellow fever, 8
Trask, 5

Trenching machinery, 117, 118
Trinitapoli, Italy, observations at,

214
Trinity, Tex., particulars of anti-
mosquito work at, 64
Triton alpestris, 211

cristatus, 211
Trypanosoma culicis, 211
Tupelo, Miss., particulars of anti-
mosquito work at, 64

248

INDEX

Tuscumbia, Ala., war anti-mosquito

work at, 59
Tyler, Tex., anti-mosquito work at,

57, 58
Tyrannus tyrannus, 211

Vertical drainage, 131

Vinegar as a mosquito repellent, 215

Virginia Beach, Va., particulars of

anti-mosquito work at, 64
Von Ezdorf, 55, 212

United States anti-mosquito war
work, 58, 59
Dept. of Agriculture, 8
dengue cases and deaths in, 11
malaria morbidity and mortal-
ity in, 6
Marine hospital, screening at,

203
Public Health Service, 7, 11, 53,
54, 55, 56, 57, 59, 60, 61,
63, 69, 76, 79, 168, 205,
208

Water gas tar as a larvicide, 162

Water lilies as breeding-places, 189

West Point, Miss., war anti-
mosquito work at, 59

West Point, Va., particulars of anti-
mosquito work at, 64

Williams, 137

Wilmington, N. C, war anti-mos-
quito work at, 59

Work order, forms, 87

Van Dine, 8, 62

Variations in eggs, larvae and pupae,
18

Variegated minnow, the, 180

Vegetation, removal of for fish con-
trol, 186

Venezuela, malaria mortality in, 7

Yellow fever, mortality and
morbidity, 9
significance of, 14
transmission of, 8
versus malaria control, 10

Yarnell, 118, 131

Zygotes, 4

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