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Cornell University Library
Handbook of medical entomology
Some early medicalentomology. Athanasius Kircher's illustration of the Italian tarantula
and the music prescribed as an antidote for the poison of its bite. (1643).
HANDBOOK OF MEDICAL
ENTOMOLOGY
WM, A. RILEY, PH.D.
Professor of Insect Morphology and Parasitology, Cornell University
and
O. A. JOHANNSEN, Pu.D.
Professor of Biology, Cornell University
Mm
ITHACA, NEW YORK
THE COMSTOCK PUBLISHING COMPANY
1915
NYS 674
COPYRIGHT, I9QI5
BY THE COMSTOCK PUBLISHING COMPANY,
ITHACA, N. Y.
RA
bq
R57
IAS
Press of W. F. Humphrey
Geneva, N. Y.
PREFACE
HE Handbook of Medical Entomology is the outgrowth of a
course of lectures along the lines of insect transmission and
dissemination of diseases of man given by the senior author
in the Department of Entomology of Cornell University during the
past six years. More specifically it is an illustrated revision and
elaboration of his “‘Notes on the Relation of Insects to Disease’’
published January, 1912.
Its object is to afford a general survey of the field, and primarily
to put the student of medicine and entomology in touch with the
discoveries and theories which underlie some of the most important
modern work in preventive medicine. At the same time the older
phases of the subject—the consideration of poisonous and parasitic
forms—have not been ignored.
Considering the rapid shifts in viewpoint, and the development
of the subject within recent years, the authors do not indulge in any
hopes that the present text will exactly meet the needs of every
one specializing in the field,—still less do they regard it as complete
or final. The fact that the enormous literature of isolated articles is
to be found principally in foreign periodicals and is therefore difficult
of access to many American workers, has led the authors to hope
that a summary of the important advances, in the form of a reference
book may not prove unwelcome to physicians, sanitarians and
working entomologists, and to teachers as a text supplementing
lecture work in the subject.
Lengthy as is the bibliography, it covers but a very small fraction
of the important contributions to the subject. It will serve only to
put those interested in touch with original sources and to open up
the field. Of the more general works, special acknowledgment
should be made to those of Banks, Brumpt, Castellani and Chalmers,
Comstock, Hewitt, Howard, Manson, Mense, Neveau-Lemaire,
Nuttall, and Stiles.
To the many who have aided the authors in the years past, by
suggestions and by sending specimens and other materials, sincerest
thanks is tendered. This is especially due to their colleagues in
the Department of Entomology of Cornell University, and to Pro-
fessor Charles W. Howard, Dr. John Uri Lloyd, Mr. A. H. Ritchie,
Dr. I. M. Unger, and Dr. Luzerne Coville.
VI Preface
They wish to express indebtedness to the authors and publishers
who have so willingly given permission to use certain illustrations.
Especially is this acknowledgment due to Professor John Henry
Comstock, Dr. L. O. Howard, Dr. Graham-Smith, and Professor
G. H. T. Nuttall. Professor Comstock not only authorized the use
of departmental negatives by the late Professor M. V Slingerland
(credited as M. V. S.), but generously put at their disposal the illus-
trations from the MaNuAL FOR THE StTupy oF INseEcts and from
the SpipER Boox. Figures 5 and 111 are from Peter’s ‘Der Arzt
und die Heilkunft in der deutschen Vergangenheit.” It should be
noted that on examining the original, it is found that Gottfried’s
figure relates to an event antedating the typical epidemic of dancing
mania.
Wm. A. RILEy.
CORNELL UNIVERSITY, O. A. JOHANNSEN.
January, 1915.
18
32
47
116
136
137
145
158
212
219
266
272
281
281
284
395
309
312
313
314
315
323
328
INTRODUCTION
CONTENTS
CHAPTER I
ADDITIONS AND CORRECTIONS
line 11, for Heilkunft read Heilkunst.
line 2, for tarsi read tarsus.
line 21, and legend under fig. 23, for C. (Conorhinus)
abdominalis read Melanolestes abdominalis.
legend under figure for 33c read 34.
line 22 and 25, for sangiusugus read sanguisugus.
legend under fig. 83, for Graham-Smith read Manson.
line 10, from bottom, insert “ring’’ after ‘‘chitin’’.
line 3, for meditatunda read meditabunda.
line 7, from bottom, for Rs read R,.
line 20, for have read has.
after the chapter heading insert ‘‘continued’’.
line 10, from bottom, for Cornohinus read Conorhinus,
line 1, fig. 158j refers to the female.
line 5, insert ‘‘palpus’’ before ‘‘and leg’’.
line 6, for discodial read discoidal.
last line, insert ‘‘from’’ before ‘‘the’’.
line 5, for “‘tubercle of’’ read ‘tubercle or”’
lines 19, 28, 44, page 306 lines I, 9, 22, 27, 30, page 307 line 7,
page 309 ‘ines 8, 11, for R,+, read
ita:
legend under fig. 168 ‘add Bureau of Entomology.
line 36, for ‘‘near apex’’ read ‘‘of M,+,.”.
running head, for Muscidez read Muscoidea.
line 29, for ‘‘distal section”’ read ‘‘distally M,+,”’
legend under fig. 172, for Pseudopyrellia read Orthellia,
for Lyperosia read Hematobia, for Umbana read urbana.
and 325 legends under the figures, add ‘‘After Dr. J. H.
Stokes”.
line 7 from bottom for Apiocheta read Aphiocheta.
PARASITIC ARTHROPODS AFFECTING MAN
Acarina, or mites.
CHAPTER III
The Trombidiide, or harvest mites. ’
The Ixodoidea, or ticks.
atrodectus. Other
z or giant water-
femiptera reported
nisoning by nettling
their blood plasma.
Argaside. Ixodide. Treatment of tick bites.
The mites.
Dermanysside. Tarsonemide. Sarcoptide, the itch mites.
cide, the follicle mites.
Hexapoda, or true insects.
Siphunculata, or sucking lice.
Hemiptera.
Demode-
VII Contents
The bed-bug. Other bed-bugs.
Parasitic Diptera, or flies.
Psychodide, or moth flies. Phlebotomine. Culicide, or mosquitoes.
Simuliide, or black-flies. Chironomide, or midges. Tabanidz, or
horse-flies. Leptide or snipe-flies. Oecestride, or bot-flies. Muscide,
the stable-fly and others.
Siphonaptera, or fleas.
The fleas affecting man, the dog, cat, and rat.
‘The true chiggers, or chigoes.
CHAPTER IV
ACCIDENTAL OR FACULTATIVE PARASITES.................. 131-143
Acarina, or mites.
Myriapoda, or centipedes and millipedes.
Lepidopterous larve.
Coleoptera, or beetles.
Dipterous larve causing myiasis.
Piophila casei, the cheese skipper. Chrysomyia macellaria, the screw-
worm fly. Calliphorine, the blue-bottles. Muscine, the house or
typhoid fly, and others. Anthomyiidz, the lesser house-fly and others.
Sarcophagide, the flesh-flies.
CHAPTER V
ARTHROPODS AS SIMPLE CARRIERS OF DISEASE........... 144-163
The house or typhoid fly as a carrier of disease.
Stomoxys calcitrans, the stable-fly.
Other arthropods which may serve as simple carriers of pathogenic organisms.
CHAPTER VI
ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS 164-174
Some illustrations of direct inoculations of disease germs by arthropods.
The rdle of fleas in the transmission of the plague.
CHAPTER VII
ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGAN-
TSM 'S nascn a cieced Wala SRA OAS oo ae eae GEE See adn eee 175-185
Insects as intermediate hosts of tape-worms.
Arthropods as intermediate hosts of nematode worms. Filariasis and mosqui-
toes.
Other nematode parasites of man and animals.
CHAPTER VIII
ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PRO-
DOZOAKS 6 chad iilited Aaah Ae hep at ees aa ow aa an delves EOO-E
Mosquitoes and malaria.
Mosquitoes and yellow fever.
Contents IX
CHAPTER IX
ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PRO-
TOZOR: vise da cteic hae eo ciils Apeblsed aaa hk ge gam inne Bed eek MRED 212-229
Insects and trypanosomiases.
Fleas and lice as carriers of Trypanosoma lewisi.
Tsetse-flies and nagana.
Tsetse-flies and sleeping sickness in man.
South American trypanosomiasis.
Leishmanioses and insects.
Ticks and diseases of man and animals.
Cattle tick and Texas fever.
Ticks and Rocky Mountain Spotted fever of man.
CHAPTER X
ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC PROTO-
ZO, (Continued): 4325 ces ac kn toe sbeebs Han sada bake MESS 230-240
Arthropods and Spirochetoses of man and animals.
African relapsing fever of man.
European relapsing fever,
North African relapsing fever of man.
Other types of relapsing fever of man.
Spirochztosis of fowls.
Other spirochzte diseases of animals.
Typhus fever and lice.
CHAPTER XI
SOME POSSIBLE, BUT IMPERFECTLY KNOWN CASES OF
ARTHROPOD TRANSMISSION OF DISEASE............. 241-256
Infantile paralysis, or acute anterior poliomyelitis.
Pellagra. Leprosy. Verruga peruviana. Cancer.
CHAPTER XII
KEYS TO THE ARTHROPODS NOXIOUS TO MAN.............. 257-317
. Crustacea.
Myriapoda, or centipedes and millipedes,
Arachnida (Orders of).
Acarina or ticks.
Hexapoda (Insecta).
Siphunculata and Hemiptera (lice and true bugs).
Diptera (mosquitoes, midges, and flies).
Siphonaptera (fleas).
APPENDIX
Hydrocyanic acid gas against household insects.................0 005 318-320
Proportion of ingredients. A single room as an example. Fumigating a
large house. Precautions.
Lesions produced by the bite of the black-fly...................... 321-326
BIBLIOGRAPHY. jas od wees a alec wed eae Sa slag een Melee eas 327-340
INDE Xing orn 228 don aioe heh Rh WE Sg oR EO a eG as ae a 341-348
CHAPTER I.
INTRODUCTION *
EARLY SUGGESTIONS REGARDING THE TRANSMISSION OF DISEASE
BY INSECTS
Until very recent years insects and their allies have been considered
as of economic importance merely in so far as they are an annoyance
or direct menace to man, or his flocks and herds, or are injurious to
his crops. It is only within the past fifteen years that there has
sprung into prominence the knowledge that in another and much more
insiduous manner, they may be the enemy of mankind, that they
may be among the most important of the disseminators of disease.
In this brief period, such knowledge has completely revolutionized
our methods of control of certain diseases, and has become an import-
ant weapon in the fight for the conservation of health.
Itis nowhere truer than in the case under consideration that how-
ever abrupt may be their coming into prominence, great move-
ments and great discoveries do not arise suddenly. Centuries ago
there was suggested the possibility that insects were concerned with
the spread of disease, and from time to time there have appeared keen
suggestions and logical hypotheses along this line, that lead us to
marvel that the establishment of the truths should have been so long
delayed.
One of the earliest of these references is by the Italian physician,
Mercurialis, who lived from 1530 to 1607, during a period when
Europe was being ravaged by the dread ‘“‘black death’, or plague.
Concerning its transmission he wrote: ‘There can be no doubt that.
flies feed on the internal secretions of the diseased and dying, then,
flying away, they deposit their excretions on the food in neighboring
dwellings, and persons who eat of it are thus infected.”
It would be difficult to formulate more clearly this aspect of the
facts as we know them to-day, though it must always be borne in
mind that we are prone to interpret such statements in the light of
present-day knowledge. Mercurialis had no conception of the animate
nature of contagion, and his statement was little more than a lucky
guess.
Much more worthy of consideration is the approval which was
given to his view by the German Jesuit, Athanasius Kircher in 1658.
2 Introduction
One cannot read :carefully his works without believing that long
before Leeuwenhook’s discovery, Kircher had seen the larger species of
bacteria. Moreover, he attributed the production of disease to these
organisms and formulated, vaguely, to be sure, a theory of the animate
nature of contagion. It has taken two and a half centuries to
accumulate the facts to prove his hypothesis.
The theory of Mercurialis was not wholly lost sight of, for in the
medical literature of the eighteenth century there are scattered
references to flies as carriers of disease. Such a view seems even to
have been more or less popularly accepted, in some cases. Gudger
(1910), has pointed out that, as far back as 1769, Edward Bancroft,
in ‘‘An Essay on the Natural History of Guiana in South America,”
wrote concerning the contagious skin-disease known as ‘‘Yaws”’:
“Tt is usually believed that this disorder is communicated by the flies
who have been feasting on a diseased object, to those persons who have
sores, or scratches, which are uncovered; and from many observa-
tions, I think this is not improbable, as none ever receive this disorder
whose skins are whole.”
Approaching more closely the present epoch, we find that in 1848,
Dr. Josiah Nott, of Mobile, Alabama, published a remarkable
article on the cause of yellow fever, in which he presented “‘reasons for
supposing its specific cause to exist in some form of insect life.”’
As a matter of fact, the bearing of Nott’s work on present day ideas
of the insect transmission of disease has been very curiously overrated.
The common interpretation of his theory has been deduced from a few
isolated sentences, but his argument appears quite differently when
the entire article is studied. It must be remembered that he wrote at
a period before the epoch-making discoveries of Pasteur and before
the recognition of micro-organisms as factors in the cause of disease.
His article is a masterly refutation of the theory of ‘‘malarial” origin
of ‘‘all the fevers of hot climates,” but he uses the term ‘‘insect’’ as
applicable to the lower forms of life, and specific references to ‘“‘mos-
quitoes,” ‘‘aphids,”’ ‘‘cotton-worms,’”’ and others, are merely in the
way of similes.
But, while Nott’s ideas regarding the relation of insects to yellow
fever were vague and indefinite, it was almost contemporaneously
that the French physician, Louis Daniel Beauperthuy argued in the
most explicit possible manner, that yellow fever and various others
are transmitted by mosquitoes. In the light of the data which were
available when he wrote, in 1853, it is not surprising that he erred by
2966
Early Suggestions / 3
thinking that the source of the virus was decomposing matter which
the mosquito took up and accidentally inoculated into man. Beau-
perthuy not only discussed the réle of mosquitoes in the transmission
of disease, but he taught, less clearly, that house-flies scatter patho-
genic organisms. It seems that Boyce (1909) who quotes extensively
from this pioneer work, does not go too far when he says ‘“‘It is Dr.
Beauperthuy whom we must regard as the father of the doctrine of
insect-borne disease.’”’
In this connection, mention must be made of the scholarly article
by the American physician, A. F. A. King who, in 1883, brought
together an all but conclusive mass of argument in support of his
belief that malaria was caused by mosquitoes. At about the same
time, Finley, of Havana, was forcefully presenting his view that the
mosquito played the chief rdle in the spread of yellow fever.
To enter more fully into the general historical discussion is beyond
the scope of this book. We shall have occasion to make more
explicit references in considering various insect-borne diseases.
Enough has been said here to emphasize that the recognition of
insects as factors in the spread of disease was long presaged, and that
there were not wanting keen thinkers who, with a background of
present-day conceptions of the nature of disease, might have been in
the front rank of investigators along these lines.
THE WAYS IN WHICH ARTHROPODS MAY AFFECT THE HEALTH
OF MAN
When we consider the ways in which insects and their allies may
affect the health of man, we find that we may treat them under three
main groups:
A. They may be directly poisonous. Such, for example, are the
scorpions, certain-epiders and mites, some of the predaceous bugs,
and stinging insects. Even such forms as the mosquito deserve
some consideration from this viewpoint.
B. They may be parasitic, living more or less permanently on
or in the body and deriving their sustenance from it.
Of the parasitic arthropods we may distinguish, first, the true
parasites, those which have adopted and become confirmed in the
parasitic habit. Such are the itch mites, the lice, fleas, and the
majority of the forms to be considered as parasitic.
In addition to these, we may distinguish a group of accidental, or
facultative parasites, species which are normally free-living, feeding on
4 Introduction
decaying substances, but which when accidentally introduced into
the alimentary canal or other cavities of man, may exist there
for a greater or less period. For example, certain fly larve, or mag-
gots, normally feeding in putrifying meat, have been known to occur
as accidental or facultative parasites in the stomach of man.
C. Finally, and most important, arthropods may be trans-
mitters and disseminators of disease. In this capacity they may
function in one of three ways; as simple carriers, as direct tnoculators,
or as essential hosts of disease germs.
As simple carriers, they may, in a wholly incidental manner,
transport from the diseased to the healthy, or from filth to food,
pathogenic germs which cling to their bodies or appendages. Such,
for instance, is the relation of the house-fly to the dissemination of
typhoid.
As direct inoculators, biting or piercing species may take up from
a diseased man or animal, germs which, clinging to the mouth parts,
are inoculated directly into the blood of the insect’s next victim. It
it thus that horse-flies may occasionally transmit anthrax. Similarly,
species of spiders and other forms which are ordinarily perfectly
harmless, may accidentally convey and inoculate pyogenic bacteria.
It is as essential hosts of disease germs that arthropods play their
most important réle. In such cases an essential part of the life cycle
of the pathogenic organism is undergone in the insect. In other
words, without the arthropod host the disease-producing organism
cannot complete its development. As illustrations may be cited the
relation of the Anopheles mosquito to the malarial parasite, and the
relation of the cattle tick to Texas fever.
A little consideration will show that this is the most important of
the group. Typhoid fever is carried by water or by contaminated
milk, and in various other ways, as well as by the house-fly. Kill all
the house-flies and typhoid would still exist. On the other hand,
malaria is carried only by the mosquito, because an essential part of
the development of the malarial parasite is undergone in this insect.
Exterminate all of the mosquitoes of certain species and the dis-
semination of human malaria is absolutely prevented.
Once an arthropod becomes an essential host for a given parasite
it may disseminate infection in three different ways:
1. By infecting man or animals who ingest it. It is thus, for
example, that man, dog, or cat, becomes infected with the double-
pored dog tapeworm, Dipylidium caninum. The cysticercoid stage
Arthropods and Man 5
occurs in the dog louse, or in the dog or cat fleas, and by accidentally
ingesting the infested insect the vertebrate becomes infested. Simi-
larly, Hymenolepis diminuta, a common tapeworm of rats and mice,
and occasional in man, undergoes part of its life cycle in various meal-
infesting insects, and is accidentally taken up by its definitive host.
It is very probable that man becomes infested with Dracunculus
(Filaria) medinensis through swallowing in drinking water, the
crustacean, Cyclops, containing the larvee of this worm.
2. ‘By infecting man or animals on whose skin or mucous mem-
branes the insect host may be crushed or may deposit its excrement. .
The pathogenic organism may then actively penetrate, or may be
inoculated by scratching. The causative organism of typhus fever
is thus transmitted by the body louse.
3. By direct inoculation by its bite, the insect host may transfer
the parasite which has undergone development within it. The
malarial parasite is thus transferred by mosquitoes; the Texas fever
parasite by cattle ticks.
CHAPTER II.
ARTHROPODS WHICH ARE DIRECTLY POISONOUS
Of all the myriads of insects and related forms, a very few are of
direct use to man, some few others have forced his approbation on
account of their wonderful beauty, but the great hordes of them are
loathed or regarded as directly dangerous. As a matter of fact, only
a very small number are in the slightest degree poisonous to man or
to the higher animals. The result is that entomologists and lovers
of nature, intent upon dissipating the foolish dread of insects, are
sometimes inclined to go to the extreme of discrediting all statements
of serious injury from the bites or stings of any species.
Nevertheless, it must not be overlooked that poisonous forms do
exist, and they must receive attention in a consideration of the ways
in which arthropods may affect the health of man. Moreover, it
must be recognized that ‘‘what is one man’s meat, is another man’s
poison,” and that in considering the possibilities of injury we must not
ignore individual idiosyncrasies. Just as certain individuals may be
poisoned by what, for others are common articles of food, so some
persons may be abnormally susceptible to insect poison. Thus, the
poison of a bee sting may be of varying severity, but there are individ-
uals who are made seriously sick by a single sting, regardless of the
point of entry. Some individuals scarcely notice a mosquito bite,
others find it very painful, and so illustrations of this difference in
individuals might be multiplied.
In considering the poisonous arthropods, we shall take them up by
groups. The reader who is unacquainted with the systematic rela-
tionship of insects and their allies is referred to Chapter XII. No
attempt will be made to make the lists under the various headings
exhaustive, but typical forms will be discussed.
ARANEIDA OR SPIDERS
Of all the arthropods there are none which are more universally
feared than are the spiders. It is commonly supposed that the
majority, if not all the species are poisonous and that they are aggres-
sive enemies of man and the higher animals, as well as of lower forms.
That they really secrete a poison may be readily inferred from the
effect of their bite upon insects and other small forms. Moreover,
Araneida or Spiders 7
the presence of definite and well-developed poison glands can easily
be shown. They occur as a pair of pouches (fig. 1) lying within the
cephalothorax and connected by a delicate
duct with a pore on the claw of the chelicera,
or so-called ‘‘mandible”’ on the convex surface
of the claw in such a position that it is not
plugged and closed by the flesh of the victim.
The glands may be demonstrated by slowly
and carefully twisting off a chelicera and
pushing aside the stumps of muscles at its
1. Head of a spider showing e038 ice
poison gland (c)anditsre- base. By exercising care, the chitinous wall
‘ation to the chehicera (@)- GF the chelicera and its claw may be broken
away and the duct traced from the gland to its outlet. The inner
lining of the sac is constituted by a highly developed glandular
epithelium, supported by a basement membrane of connective
tissue and covered by a muscular layer, (fig. 2). The muscles, which
are striated, are spirally arranged (fig. 1), and are doubtless under
control of the spider, so that the amount of poison to be injected into
a wound may be varied.
The poison itself, according to Kobert (1901), is a clear, colorless
fluid, of oily consistency, acid reaction, and very bitter taste. After
the spider has bitten two or three times, its supply is exhausted and
therefore, as in the case of snakes, the poison of the bite decreases
quickly with use, until it is null. To what extent the content of the
poison sacs may contain blood serum or, at least, active principles of
serum, in addition to a specific poison formed by the poison glands
themselves, Kobert regards as an open question. He believes that
the acid part of the poison, if really present,
is formed by the glands and that,
in the case of some spiders, the
ferment-like, or better, active
toxine, comes from the blood.
But there is a wide difference
between a poison which may kill
: bao . Section through
an insect and one which is harm- * “ection,thre “Eatrodectus
i 6 if -guttat
ful to men. Certain it is that the peritoneal, muscu
8. Chelicera of there is no lack of popular belief ee a eee
and newspaper records of fatal
cases, but the evidence regarding the possibility of fatal or even very
serious results for man is most contradictory. For some years,
we have attempted to trace the more circumstantial newspaper
8 Poisonous Arthropods
accounts, which have come to our notice, of injury by North
American species. The results have served, mainly, to empha-
size the straits to which reporters are sometimes driven when
there is a dearth of news. The accounts are usually vague and lack-
ing in any definite clue for locating the supposed victim. In the
comparatively few cases where the patient, or his physician, could
be located, there was either no claim that the injury was due to
spider venom, or there was no evidence to support the belief.
Rarely, there was evidence that a secondary blood poisoning, such
as might be brought about by the prick of a pin, or by any mechani-
cal injury, had followed the bite of a spider. Such instances have
no bearing on the question of the
venomous nature of these forms.
The extreme to which unreason-
able fear of the bites of spiders
influenced the popular mind was
evidenced by the accepted explana-
tion of the remarkable dancing
mania, or tarantism, of Italy during
the Middle Ages. This was a ner-
vous disorder, supposed to be due
to the bite of a spider, the European
tarantula (fig. 4), though it was
also, at times, attributed to the
4. The Italign tarantula (Lycosa tarantula). bite of the scorpion. In its typical
form, it was characterized by so
great a sensibility to music that under its influence the victims
indulged in the wildest and most frenzied dancing, until they sank
to the ground utterly exhausted and almost lifeless. The profuse
perspiring resulting from these exertions was supposed to be the
only efficacious remedy for the disease. Certain forms of music
were regarded as of especial value in treating this tarantism, and
hence the name of ‘“‘tarantella’’ was applied to them. Our frontis-
piece, taken from Athanasius Kircher’s Magnes sive de Arte Magnetica,
1643 ed., represents the most commonly implicated spider and illus-
trates some of what Fabre has aptly designated as ‘medical
choreography.”
The disease was, in reality, a form of hysteria, spreading by sym-
pathy until whole communities were involved, and was paralleled by
the outbreaks of the so-called St. Vitus’s or St. John’s dance, which
i
Araneida or Spiders 9
swept Germany at about the same time (fig. 5). The evidence that
the spider was the cause of the first is about as conclusive as is that
of the demoniacal origin of the latter. The true explanation of the
outbreaks is doubtless to be found in the depleted physical and mental
condition of the people, resulting from the wars and the frightful
plagues which devastated all Europe previous to, and during these
times. An interesting discussion of these aspects of the question is to
be found in Hecker.
5. Dancing mania. Illustration from Johann Ludwig Gottfried‘s Chronik. 1632.
So gross has been the exaggeration and so baseless the popular fear
regarding spiders that entomologists have been inclined to discredit
all accounts of serious injury from their bites. Not only have the
most circumstantial of newspaper accounts proved to be without
foundation but there are on record a number of cases where the bite
of many of the commoner species have been intentionally provoked
and where the effect has been insignificant. Some years ago the
senior author personally experimented with a number of the largest of
our northern species, and with unexpected results. The first surprise
was that the spiders were very unwilling to bite and that it required a
considerable effort to get them to attempt to do so. In the second
10 Poisonous Arthropods
place, most of those experimented with were unable to pierce the skin
of the palm or the back of the hand, but had to be applied to the thin
skin between the fingers before they were able to draw blood. Unfor- '
tunately, no special attempt was made to determine, at the time, the
species experimented with, but among them were Theridion tepi-
dariorum, Miranda aurantia (Argiopa), Metargiope trifasciata, Marxia
stellata, Aranea trifolium, Misumena vatia, and Agelena nevia. In
no case was the bite more severe than a pin prick and though in some
cases the sensation seemed to last longer, it was probably due to the
fact that the mind was intent upon the experiment.
Similar experiments were carried out by Blackwell (1855), who
believed that in the case of insects bitten, death did not result any
6. An American tarantula (Eurypelma hentzii). Natural size. After Comstock.
more promptly than it would have from a purely mechanical injury of
equal extent. He was inclined to regard all accounts of serious
injury to man as baseless. The question cannot be so summarily
dismissed, and we shall now consider some of the groups which have
been more explicitly implicated.
The Tarantulas.—In popular usage, the term ‘‘ tarantula’”’ is
loosely applied to any one of a number of. large spiders. The famous
tarantulas of southern Europe, whose bites were supposed to cause the
dancing mania, were Lycoside, or wolf-spiders. Though various
species of this group were doubtless so designated, the one which
seems to have been most implicated was Lycosa tarantula (L.),
(fig. 4). On the other hand, in this country, though there are many
Lycosidz, the term “tarantula” has been applied to members of the
superfamily Avicularoidea (fig. 6), including the bird-spiders.
Of the Old World Lycoside there is no doubt that several species
were implicated as the supposed cause of the tarantism. In fact, as
we have already noted, the blame was sometimes attached to a scor-
The Tarantulas II
pion. However, there seems to be no doubt that most of the accounts
refer to the spider known as Lycosa tarantula.
There is no need to enter into further details here regarding the
supposed virulence of these forms, popular and the older medical
literature abound in circumstantial accounts of the terrible effects of
the bite. Fortunately, there is direct experimental evidence which
bears on the question.
Fabre induced a common south European wolf-spider, Lycosa
narbonensis, to bite the leg of a young sparrow, ready to leave the
nest. The leg seemed paralyzed as a result of the bite, and though
the bird seemed lively and clamored for food the next day, on the
third dav it died. A mole, bitten on the nose, succumbed after thirty-
six hours. From these experiments Fabre seemed justified in his
conclusion that the bite of this spider is not an accident which man
can afford to treat lightly. Unfortunately, there is nothing in the
experiments, or in the symptoms detailed, to exclude the probability
that the death of the animals was the result of secondary infection.
As far back as 1693, as we learn from the valuable account of
Kobert, (1901), the Italian physician, Sanguinetti allowed himself to
be bitten on the arm by two tarantulas, in the presence of witnesses.
The sensation was equivalent to that from an ant or a mosquito bite
and there were no other phenomena the first dav. On the second day
the wound was inflamed and there was slight ulceration. It is clear
that these later symptoms were due to a secondary infection. These
experiments have been repeated by various observers, among whom
may be mentioned Leon Dufour, Josef Erker and Heinzel, and with
the similar conclusion that the bite of the Italian tarantula ordinarily
causes no severe symptoms. In this conclusion, Kobert, though
firmly convinced of the poisonous nature of some spiders, coincides.
He also believes that striking symptoms may be simulated or arti-
ficially induced by patients in order to attract interest, or because
they have been assured that the bite, under all circumstances, caused
tarantism.
The so-called Russian tarantula, Trochosa singoriensis (fig. 7), is
much larger than the Italian species, and is much feared. Kobert
carried out a series of careful experiments with this species and his
results have such an important bearing on the question of the venom-
ous nature of the tarantula that we quote his summary. Experi-
menting first on nearly a hundred living specimens of Trochosa
singoriensis from Crimea he says that:
12 Potsonous Arthropods
“The tarantulas, no matter how often they were placed on the
skin, handled, and irritated, could not be induced to bite either myself,
the janitor, or the ordinary experimental animals. The objection
that the tarantulas were weak and indifferent cannot stand, for as
soon as I placed two of them on the shaved skin of a rabbit, instead of
an attack on the animal, there began a furious battle between the
two spiders, which did not cease until one of the two was killed.”
“Since the spiders would not
bite, I carefully ground up the
fresh animals in physiological
salt solution, preparing an extract
which must have contained, in
solution, all of the poisonous
substance of their bodies. While
in the case of Latrodectus, as we
shall see, less than one specimen
sufficed to yield an active extract,
I have injected the filtered extract
of six fresh Russian tarantulas,
of which each one was much
heavier than an average Lairo-
dectus, subcutaneously and into
the jugular vein of various cats
7. Trochosa singoriensis. After Kobert. without the animals dying or
showing any special symptoms.
On the basis of my experiments I can therefore only say that the
quantity of the poison soluble in physiological salt solution, even
when the spiders are perfectly fresh and well nourished, is very
insignificant. That the poison of the Russian tarantula is not
soluble in physiological salt solution, is exceedingly improbable.
Moreover, I have prepared alcoholic extracts and was unable to
find them active. Since the Russian spider exceeds the Italian in
size and in intensity of the bite, it seems very improbable to me that
the pharmacological test of the Italian tarantula would yield
essentially other results than those from the Russian species.”
To the Avicularoidea belong the largest and most formidable
appearing of the spiders and it is not strange that in the New World
they have fallen heir to the bad reputation, as well as to the name of
the tarantula of Europe. In this country they occur only in the
South or in the far West, but occasionally living specimens are brought
The Tarantulas 13
to our northern ports in shipments of bananas and other tropical
produce, and are the source of much alarm. It should be mentioned,
however, that the large spider most frequently found under such cir-
cumstances is not a tarantula at all, but one of the Heteropodide, or
giant crab-spiders, (fig. 8).
In spite of their prominence and the fear which they arouse there
are few accurate data regarding these American tarantulas. It has
8. The giant crab-spider or banana spider (Heteropoda venatoria).
Natural size. After Comstock.
often been shown experimentally that they can kill small birds and
mammals, though it is doubtful if these form the normal prey of any
of the species, as has been claimed. There is no question but that
the mere mechanical injury which they may inflict, and the consequent
chances of secondary infection, justify, in part, their bad reputation.
In addition to the injury from their bite, it is claimed that the body
hairs of several of the South American species are readily detached
and are urticating.
Recently, Phisalix (1912) has made a study of the physiological
effects of the venom of two Avicularoidea, Phormictopus carcerides
Pocock, from Haiti and Cientza sauvaget Rossi; from Corsica. The
glands were removed aseptically and ground up with fine, sterilized
sand in distilled water. The resultant liquid was somewhat viscid,
colorless, and feebly alkaline. Injected into sparrows and mice the
14 Poisonous Arthropods
extract of Phormictopus proved very actively poisonous, that from a
single spider being sufficient to kill ten sparrows or twenty mice. It
manifested itself first and, above all, as a narcotic, slightly lowering
the temperature and paralyzing the respiration. Muscular and
cardiac weakening, loss of general sensibility, and the disappearance
of reflexes did not occur until near the end. The extract from Cteniza
was less active and, curiously enough, the comparative effect on
sparrows and on mice was just reversed.
Spiders of the Genus Latrodectus.—While most of the popular
accounts of evil effects from the bites of spiders will not stand investi-
gation, it is a significant fact that, the world over, the best authentica-
ted records refer to a group of small and comparatively insignificant
spiders belonging to the genus Latrodectus, of the family Theridiide.
The dread ‘‘ Malmigniatte’”’ of Corsica and South Europe, the ‘‘ Kara-
kurte” of southeastern Russia, the ‘‘Katipo” of New Zealand. the
““Mena-vodi” and ‘‘ Vancoho”’ of Madagascar, and our own Latrodectus
mactans, all belong to this genus, and concerning all of these the most
circumstantial accounts of their venomous nature are given. These
accounts are not mere fantastic stories by uneducated natives but in
many cases are reports from thoroughly trained medical men.
The symptoms produced are general, rather than local. As
summarized by Kobert (1901) from a study of twenty-two cases
treated in 1888, in the Kherson (Russia) Government Hospital and
Berislaw (Kherson) District Hospital the typical case, aside from
complications, exhibits the following symptoms. The victim sud-
denly feels the bite, like the sting of a bee. Swelling of the barely
reddened spot seldom follows. The shooting pains, which quickly
set in, are not manifested at the point of injury but localized at the
joints of the lower limb and in the region of the hip. The severity
of the pain forces the victim to the hospital, in spite of the fact that
they otherwise have a great abhorrence of it. The patient is unable
to reach the hospital afoot, or, at least, not without help, for there is
usually inability to walk. The patient, even if he has ridden, reaches
the hospital covered with cold sweat and continues to perspire for a
considerable period. His expression indicates great suffering. The
respiration may be somewhat dyspneeic, and a feeling of oppression
in the region of the heart is common. There is great aversion to
solid food, but increasing thirst for milk and tea. Retention of
urine, and constipation occur. Cathartics and, at night, strong
Spiders of the Genus Latrodectus 5
narcotics are desired. Warm baths give great relief. After three
days, there is marked improvement and usually the patient is dis-
missed after the fifth. This summary of symptoms agrees well with
other trustworthy records.
It would seem, then, that Riley and Howard (1889), who discussed
a number of accounts in the entomological literature, were fully
justified in their statement that “It must be admitted that certain
spiders of the genus Latrodectus have the power to inflict poisonous
bites, which may (probably exceptionally and depending upon excep-
tional conditions) bring about the death of a human being.”’
And yet, until recently the evidence bearing on the question has
been most conflicting. The eminent arachnologist, Lucas, (1843)
states that he himself, had been repeatedly bitten by the Malmigniatte
without any bad effects. Dr. Marx, in 1890, gave before the Ento-
mological Society of Washington, anaccount of a series of experiments
to determine whether the bite of Latrodectus mactans is poisonous or
not. He described the poison glands as remarkably small* and stated
that he had introduced the poison in various ways into guinea-pigs
and rabbits without obtaining any satisfactory results. Obviously,
carefully conducted experiments with the supposed venom were
needed and fortunately they have been carried out in the greatest
detail by Kobert (rgor).
This investigator pointed out that there were two factors which
might account for the discrepancies in the earlier experiments. In
the first place, the poison of spiders, as of snakes, might be so ex-
hausted after two or three bites that further bites, following directly,
might be without visible effect. Secondly, the application of the
poison by means of the bite, is exceedingly inexact, since even after
the most careful selection of the point of application, the poison might
in one instance enter a little vein or lymph vessel, and in another case
fail to doso. Besides, there would always remain an incalculable and
very large amount externally, in the nonabsorptive epithelium.
While all of these factors enter into the question of the effect of the
bite in specific instances, they must be as nearly as possible obviated
in considering the question of whether the spiders really secrete a
venom harmful to man.
*This is diametrically opposed to the findings of Bordas (1905) in the case
of the European Latrodectus 13-guttatus, whose glands are ‘‘much larger than
those of other spiders.’ From a considerable comparative study, we should also
unhesitatingly make this statement regarding the glands of our American species,
L. mactans.
16 Poisonous Arthropods
Kobert therefore sought to prepare extracts which would contain
the active principles of the poison and which could be injected in
definite quantities directly into the blood of the experimental animal.
For this purpose various parts of the spiders were rubbed up in a mor-
tar with distilled water, or physiological salt solution, allowed to
stand for an hour, filtered, and then carefully washed, by adding water
drop by drop for twenty-four hours. The filtrate and the wash-
water were then united, well mixed and, if necessary, cleared by cen-
trifuging or by exposure to cold. The mixture was again filtered,
measured, and used, in part, for injection and, in part, for the deter-
mination of the organic materials.
Such an extract was prepared from the cephalothoraces of eight
dried specimens of the Russian Latrodectus and three cubic centimeters
of this, containing 4.29 mg. of organic material, were injected into
the jugular vein of a cat weighing 2450 grams. The previously very
active animal was paralyzed and lay in whatever position it was
placed. The sensibility of the skin of the extremities and the rump
was so reduced that there was no reaction from cutting or sticking.
There quickly followed dyspnoea, convulsions, paralysis of the
respiratory muscles and of the heart. In twenty-eight minutes the
cat was dead, after having exhibited exactly the symptoms observed
in severe cases of poisoning of man from the bite of this spider.
These experiments were continued on cats, dogs, guinea pigs and
various other animals. Not only extracts from the cephalothorax,
but from other parts of the body, from newly hatched spiders, and
from the eggs were used and all showed a similar virulence. Every
effort was made to avoid sources of error and the experiments, con-
ducted by such a recognized authority in the field of toxicology, must
be accepted as conclusively showing that this spider and, presumably,
other species of the genus Latrodectus against which the clinical evi-
dence is quite parallel, possess a poison which paralyzes the heart and
central nervous system, with or without preliminary stimulus of the
motor center. If the quantity of the poison which comes into direct
contact with the blood is large, there may occur hemolysis and
thrombosis of the vessels.
On the other hand, check experiments were carried out, using
similar extracts of many common European spiders of the genera
Tegenaria, Drassus, Agelena, Eucharia and Argyroneta, as well as
the Russian tarantula, Lycosa singoriensis. Inno other case was the
effect on experimental animals comparable to the Latrodectus extract.
Spiders of the Genus Latrodectus 17
Kobert concludes that in its chemical nature the poison is neither
an alkaloid, nor a glycoside, nor an acid, but a toxalbumen, or poison-
ous enzyme which is very similar to certain other animal poisons,
notably that of the scorpion.
Berea OM
i ee
9. Latrodectus mactans; (a) female, x 3; (b) venter of female; (c) dorsum of male.
fter Comstock.
The genus Latrodectus is represented in the United States by at
least two species, L. mactans and L. geometricus. Concerning L.
mactans there are very circumstantial accounts of serious injury and
even deathin man*. Latrodectus mactans is coal black, marked with
red or yellow or both. It has eight eyes, which are dissimilar in
*Dr. E. H. Coleman (Kellogg, 1915) has demonstrated its virulence by a series
of experiments comparable with those of Kobert.
18 Poisonous Arthropods
color and are distinctly in front of the middle of the thorax, the
lateral eyes of each side widely separate. The tarsi of the fourth
pair of legs has a number of curved sete in a single series. It has on
the ventral side of its abdomen an hour-glass shaped spot. The full-
grown female is about half an inch-in length. Its globose abdomen is
usually marked with one or more red spots dorsally along the middle
line. The male is about half as long but has in addition to the dorsal
spots, four pairs of stripes along the sides. Immature females
resemble the male in coloring (fig. 9).
Regarding the distribution of Latrodectus mactans, Comstock
states that: “Although it is essentially a Southern species, it occurs
in Indiana, Ohio, Pennsylvania, New Hampshire, and doubtless other
of the Northern States.” L. geometricus has been reported from
California.
Other Venomous Spiders—While conclusive evidence regarding
the venomous nature of spiders is meager and relates almost wholly
to that of the genus Latrodectus, the group is a large one and we are
not justified in dismissing arbitrarily, all accounts of injury from their
bites. Several species stand out as especially needing more detailed
investigation.
Chiracanthium nutrix is a common European species of the family
Clubionidee, concerning which there is much conflicting testimony.
Among the reports are two by distinguished scientists whose accounts
of personal experiences cannot be ignored. A. Forel allowed a spider
of this species to bite him and not only was the pain extreme, but the
general symptoms were so severe that he had to be helped to his
house. The distinguished arachnologist, Bertkau reports that he,
himself, was bitten and that an extreme, burning pain spread almost
instantaneously over the arm and into the breast. There were slight
chills the same day and throbbing pain at the wound lasted for days.
While this particular species is not found in the United States, there
are two other representatives of the genus and it is possible that they
possess the same properties. We are unaware of anv direct experi-
mental work on the poison.
Epetra diadema, of Europe, belongs to a wholly different group,
that of the orb-weavers, but has long been reputed venomous. Kobert
was able to prepare from it an extract whose effects were very similar
to that prepared from Latrodectus, though feebler in its action. Under
ordinary circumstances this spider is unable to pierce the skin of man
Other Venomous Spiders 19
and though Kobert’s results seem conclusive, the spider is little to
be feared.
Phidippus audax (P. tripunctatus) is one of our largest Attids,
or jumping spiders. The late Dr. O. Lugger describes a case of severe
poisoning from the bite of this spider and though details are lacking,
it is quite possible that this and other large species of the same group,
which stalk their prey, may possess a more active poison than that of
web-building species.
Summary—It is clearly established that our common spiders are
not to be feared and that the stories regarding their virulence are
almost wholly without founda-
tion. On the other hand, the
chances of secondary infection
from the bites of some of the
more powerful species are not
to be ignored.
Probably all species possess
a toxin secreted by the poison
gland, virulent for insects and
other normal prey of the
spiders, but with little or no
effect on man.
There are a very few species,
notably of the genus Latrodectus,
and possibly including the Euro-
pean Chiracanthium nutrix and
Epetra diadema, which possess,
in addition, a toxalbumen
10. A whip-scorpion (Mastigoproctus giganteus). derived from the general body
Half natural size. After Comstock. tissue, which is of great virulence
and may even cause death in man and the higher animals.
TEE PEDIPALPIDA OR WHIP-SCORPIONS
The tailed whip-scorpions, belonging to the family Thelyphonide,
are represented in the United States by the giant whip-scorpion
Mastigoproctus giganteus (fig. 10), which is common in Florida, Texas
and some other parts of the South. In Florida, it is locally known as
the ‘‘grampus”’ or ‘‘mule-killer’’ and is very greatly feared. There is
no evidence that these fears have any foundation, and Dr. Marx
states that there is neither a poison gland nor a pore in the claw of the
chelicera.
20 Poisonous Arthropods
THE SCORPIONIDA, OR TRUE SCORPIONS
The true scorpions are widely distributed throughout warm coun-
tries and everywhere bear an evil reputation. According to Comstock
(1912), about a score of species occur in the Southern United States.
These are comparatively small forms but in the tropics members of
this group may reach a length of seven or eight inches. They are
pre-eminently predaceous forms, which lie hidden during the day and
seek their prey by night.
The scorpions (fig. 11) possess large pedipalpi, terminated by
strongly developed claws, or chelae. They may be distinguished from
all other Arachnids by the fact that the dis-
tinctly segmented abdomen is divided into a
broad basal region of seven segments and a
terminal, slender, tail-lke division of five
distinct segments.
The last segment of the abdomen, or
telson, terminates in a ventrally-directed,
sharp spine, and contains a pair of highly
developed poison glands. These glands open
by two small pores near the tip of the spine.
Most of the species when running carry the
tip of the abdomen bent upward over the
back, and the prey, caught and held by the
pedipalpi, is stung by inserting the spine of
the telson and allowing it to remain for a
time in the wound.
ii, -A-4eue scorpion, “After The glands themselves have been studied
Combtog’: in Prionurus citrinus by Wilson (1904).
He found that each gland is covered by a sheet of muscle on its
mesal and dorsal aspects, which may be described as the compressor
muscle. The muscle of each side is inserted by its edge along the
ventral inner surface of the chitinous wall of the telson, close to the
middle line, and by a broader insertion laterally. A layer of fine
connective tissue completely envelops each gland and forms the
basis upon which the secreting cells rest. The secreting epithelium
is columnar; and apparently of three different types of cells.
1. The most numerous have the appearance of mucous cells,
resembling the goblet cells of columnar mucous membranes. The
nucleus, surrounded by a small quantity of protoplasm staining with
hematoxylin, lies close to the base of the cell.
The True Scorpions 21
2. Cells present in considerable numbers, the peripheral por-
tions of which are filled with very numerous fine granules, staining
with acid dyes such as methyl orange.
3. Cells few in number, filled with very large granules, or ir-
regular masses of a substance staining with hematoxylin.
The poison, according to Kobert (1893), is a limpid, acid-reacting
fluid, soluble in water but insoluble in absolute alcohol and ether.
There are few data relative to its chemical nature. Wilson (1901)
states that a common Egyptian species, Buthus quinquestriatus, has
a specific gravity of 1.092, and contains 20.3% of solids and 8.4% ash.
The venom of different species appears to differ not only quantita-
tively but qualitatively. The effects of the bite of the smaller species
of the Southern United States may be painful but there is no satis-
factory evidence that it is ever fatal. On the other hand, certain
tropical species are exceedingly virulent and cases of death of man
from the bite are common.
In the case of Buthus quinquestriatus, Wilson (1904) found the
symptoms in animals to be hypersecretion, salivation and lachryma-
tion, especially marked, convulsions followed by prolonged mus-
cular spasm; death from asphyxia. The temperature shows a
slight, rarely considerable, rise. Rapid and considerable increase
of blood-pressure (observed in dogs) is followed by a gradual fall with
slowing of the heart-beat. The coagulability of the blood is not
affected.
An interesting phase of Wilson’s work was the experiments on
desert mammals. The condition under which these animals exist
must frequently bring them in contact with scorpions, and he found
that they possess a degree of immunity to the venom sufficient at
least to protect them from the fatal effects of the sting.
As far as concerns its effect on man, Wilson found that much
depended upon the age. As high as 60 per cent of the cases of
children under five, resulted fatally. Caroroz (1865), states that in a
Mexican state of 15,000 inhabitants, the scorpions were so abundant
and so much feared that the authorities offered a bounty for their
destruction. A result was a large number of fatalities, over two
hundred per year. Most of the victims were children who had
attempted to collect the scorpions.
The treatment usually employed in the case of bites by the more
poisonous forms is similar to that for the bite of venomous snakes.
First, a tight ligature is applied above the wound so as to stop the
22 Poisonous Arthropods
4
flow of blood and lymph from that region. The wound is then
freely excised and treated with a strong solution of permanganate
of potash, or with lead and opium lotion.
In recent years there have been many attempts to prepare an
antivenom, or antiserum comparable to what has been used so
effectively in the case of snake bites. The most promising of these
is that of Todd (1909), produced by the immunization of suitable
animals. This antivenom proved capable of neutralizing the venom
when mixed zu witro and also acts both prophylactically and cura-
tively in animals. Employed curatively in man, it appears to have
a very marked effect on the intense pain following the sting, and
the evidence so far indicates that its“ prompt use greatly reduces
the chance of fatal results.
THE SOLPUGIDA, OR SOLPUGIDS
The Solpugida are peculiar spider-like forms which are distin-
guished from nearly all other
i Y, arachnids by the fact that
ee they possess no true cephalo-
W thorax, the last two leg-bear-
ing segments being distinct,
resembling those of the abdo-
men in this respect. The
Ye first pair of legs is not used
~ yx im locomotion but seemingly
WY functions as a second pair of
See pedipalpi. Figure 12 illus-
trates the striking peculiari-
ties of the group. They are
primarily desert forms and
occur in the warm zones of
all countries. Of the two
hundred or more species,
Comstock lists twelve as
occurring in our fauna.
These occur primarily in the
12. A Solptipie (Eremobates cinerea), After Com- southwest.
The Solpugida have long
borne a bad reputation and regarding virulence, have been classed
with the scorpions. Among the effects of their bites have been
Mites and Ticks 23
described painful swelling, gangrene, loss of speech, cramps, deliri-
um, unconsciousness and even death. Opposed to the numerous loose
accounts of poisoning, there are a number of careful records by
physicians and zodlogists which indicate clearly that the effects are
local and though they may be severe, they show not the slightest
symptom of direct poisoning.
More important in the consideration of the question is the fact
that there are neither poison glands nor pores in the fangs for the
exit of any poisonous secretion. This is the testimony of a number
of prominent zodlogists, among whom is Dr. A. Walter, who wrote
to Kobert at length on the subject and whose conclusions are pre-
sented by him.
However, it should be noted that the fangs are very powerful
and are used in such a manner that they may inflict especially severe
wounds. Thus, there may be more opportunity for secondary
infection than is usual in the case of insect wounds.
The treatment of the bite of the Solpugida is, therefore, a matter
of preventing infection. The wound should be allowed to bleed
freely and then washed out with a 1:3000 solution of corrosive
sublimate, and, if severe, a wet dressing of this should be applied.
If infection takes place, it should be treated in the usual man-
ner, regardless of its origin.
THE ACARINA, OR MITES AND TICKS
A number of the parasitic Acarina evidently secrete a
specific poison, presumably carried by the saliva, but in most cases
its effect on man is insignificant. There is an abundant literature
dealing with the poisonous effect of the bite of these forms, especially
the ticks, but until recently it has been confused by failure to recog-
nize that various species may transmit diseases of man, rather than
produce injury through direct poisoning. We shall therefore
discuss the Acarina more especially in subsequent chapters, dealing
with parasitism and with disease transmission.
Nevertheless, after the evidence is sifted, there can be no doubt
that the bites of certain ticks may occasionally be followed by a
direct poisoning, which may be either local or general in its effects.
Nuttall (1908) was unable to determine the cause of the toxic effect,
for, in Argas persicus, the species most often implicated, he failed to
get the slightest local or general effect on experimental animals, from
the injection of an emulsion prepared by crushing three of the ticks.
24 Poisonous Arthropods
It seems clearly established that the bite of certain ticks may
cause a temporary paralysis, or even complete paralysis, involving
the organs of respiration or the heart, and causing death. In 1912,
Dr. I. U. Temple, of Pendleton, Oregon, reported several cases of
what he called ‘‘acute ascending paralysis” associated with the occur-
rence of ticks on the head or the back of the neck.
83. Dermatobia cyaniventris (x134)._ After Graham-Smith.
as merely various stages
of the same species. It
is only very recently
that the early stage and
the method by which
man becomes infested
were made known.
About 1900, Blanch-
ard observed the pres-
ence of packets of large-
sized eggs under the
abdomen of certain mos-
quitoes from Central
America; and in 1910,
Dr. Moralés, of Costa Rica, declared that the Dermatobia deposited
its eggs directly under the abdomen of the mosquito and that they
were thus carried to vertebrates.
Dr. Nunez Tovar observed the
mosquito carriers of the eggs and
placing larve from this source on
animals, produced typical tumors
and reared the adult flies. It
remained for Surcouf (1913) to
work out the full details. He
found that the Dermatobia de-
posits its eggs in packets covered
by a very viscid substance, on
leaves. These become attached
to mosquitoes of the species
Janthinosoma lute (fig. 84) which
walk over the leaves. The eggs
which adhere to the abdomen,
remain attached and are thus
transported. The embryo de-
84.
Mosquito carrying eggs of Dermatobia
cyaniventris, After Surcouf.
velops, but the young larva (fig. 82) remainsin the egg until it has
opportunity to drop upon a vertebrate fed upon by the mosquito.
The Muscide 117
Muscidze
The following Muscidae, characterized elsewhere, deserve special
mention under our present grouping of parasitic species. Other
sites.
important species will be considered as facultative para-
Stomoxys calcitrans, the stable-fly, or the biting house-
fly, is often confused with Musca domestica and therefore
is discussed especially in our consideration of the latter
species as an accidental carrier of disease. Its possible
relation to the spread of infantile paralysis is also con-
sidered later.
The tsetse fires, belonging to the genus Glossina, are
African species of blood-sucking Muscide which have
attracted much attention because of their rédle in trans-
85. Larva of mitting various trypanosome diseases of man and animals.
Auchmero-
myia lute- They are characterized in Chapter XII and are also
ola. After
Graham- discussed in connection with the diseases which they
Smith.
convey.
Chrysomyia macellaria, (=Compsomyia), the ‘‘screw worm’’-fly
is one of the most important species of flies directly affecting man,
in North America. It is not normally parasitic, however, and hence
will be considered with other facultative parasites in Chapter IV.
Auchmeromyia lute-
ola, the Congo floor
maggot. This is a
muscid of grewsome
habits, which has a wide
distribution throughout
Africa. The fly (fig. 86)
deposits its eggs on the
ground of the huts of the
natives. The whitish
larve (fig. 85) on hatch-
ing are slightly flat-
tened ventrally, and
each .segment bears
posteriorly three foot-
86. Auchmeromyia luteola (x4). After Graham-Smith.
pads transversely arranged. At night thelarvzefind their way into the
low beds or couches of the natives and suck their blood. The adult
flies do not bite man and, as far as known, the larve do not play any
réle in the transmission of sleeping sickness or other diseases.
118 Parasitic Arthropoda
This habit of blood-sucking by muscid larve is usually referred
to as peculiar to Aucheromyia luteola but it should be noted that the
larvee of Protocalliphora frequent the
nests of birds and feed upon the
young. Mr.A.F.Coutant has studied
especially the life-history and habits
of P. agurea, whose larve he found
attacking young crowsat Ithaca, N.Y.
He was unable to induce the larve to
feed on man.
Cordylobia anthropophaga, (Ochro-
myta anthropophaga), or Tumbu-fly
(fig. 87) is an African species whose
Sit Condylebie anthropephegs (x8). Jarves ditect mat mech as do. those of
Dermatobia cyniventris, of Central and
South America. The larva (fig. 88), which is known as ‘‘ver du
Cayor’’ because it was first observed in Cayor, in Senegambia,
develops in the skin of man and of various animals, such as dogs,
cats, and monkeys. Itis about 12 mm. in length, and of the form
of the larve of other muscids. Upon the intermediate segments are
minute, brownish recurved spines which give to the larva its char-
acteristic appearance. The life-history is not satisfactorily worked
out, but Fuller (1914), after reviewing
the evidence believes that, as a rule, it
deposits its young in the sleeping places
of man and animals, whether such be a
bed, a board, the floor, or the bare ground.
In the case of babies, the maggots may
be deposited on the scalp. The minute
maggots bore their way painlessly into
the skin. As many as forty parasites
have been found in one individual and
one author has reported finding more
than three hundred in a spaniel puppy.
Though their attacks are at times ex-
tremely painful, it is seldom that any See er ee eee
serious results follow. pophaga. After Blanchard.
The Siphonaptera or Fleas 119
Tue SIPHONAPTERA OR FLEAS
The Siphonaptera, or fleas (fig. 89) are wingless insects, with
highly chitinized and laterally compressed bodies. The mouth-parts
are formed for piercing and sucking. Compound eyes are lacking
but some species possess ocelli. The metamorphosis is complete.
This group of parasites, concerning which little was known until
recently, has assumed a very great importance since it was learned
89. Xenopsylla cheopis, male (x25). After Jordan and Rothschild.
that fleas are the carriers of bubonic plague. Now over four hundred
species are known. Of these, several species commonly attack man.
The most common hominoxious species are Pulex irritans, Xenopsylla
cheopis, Ctenocephalus canis, Ctenocephalus felis, Ceratophyllus
fasciatus and Dermatophilus penetrans, but many others will feed
readily on human blood if occasion arises.
We shall treat in this place of the general biology and habits of
the hominoxious forms and reserve for the systematic section the
discussion of the characteristics of the different genera.
120 Parasitic Arthropoda
The most common fleas infesting houses in the Eastern United
States are the cosmopolitan dog and cat fleas, Ctenocephalus canis
(fig. 90) and C. felis. Their life
cycles will serve as typical.
These two species have until
recently been considered as one,
under the name Pulex serraticeps.
See figure 92.
The eggs are oval, slightly
translucent or pearly white, and
measure about .5 mm. in their
long diameter. They are de-
posited loosely in the hairs of
the host and readily drop off as the animal moves around. Howard
found that these eggs hatch in one to two days. The larve are
elongate, legless, white, worm-like creatures. They are exceed-
ingly active, and avoid the light in every way possible. They
cast their first skin in from three to seven days and their second
in from three to four days. They commenced spinning in from
seven to fourteen days after hatching and the imago appeared
five days later. Thus in summer, at Washington, the entire life
cycle may be completed in about two weeks. (cf. fig. 91, 92).
Strickland’s (1914) studies on the biology of the rat flea, Cerato-
phyllus fasciatus, have so important a general bearing that we shall
cite them in considerable detail.
He found, to begin with, that there is a marked inherent range
in the rate of development. Thus, of a batch of seventy-three eggs,
all laid in the same day and kept together under the same condi-
90. Dog flea (x15). After Howard.
91. Larva of Xenopsylla cheopis. After Bacot and Ridewood.
tions, one hatched in ten days; four in eleven days; twenty-five in
twelve days; thirty-one in thirteen days; ten in fourteen days; one
in fifteen days; and one in sixteen days. Within these limits the
duration of the egg period seems to depend mainly on the degree
of humidity. The incubation period is never abnormally prolonged
Stphonaptera, or Fleas 121
as in the case of lice, (Warburton) and varying conditions of tempera-
ture and humidity have practically no effect on the percentage of
eggs which ultimately hatch.
The same investigator found that the most favorable condition
for the larvais a low temperature, combined with a high degree of
humidity; and that the presence of rubbish in which the larva may
bury itself is essential to its successful development. When larve
are placed in a bottle containing either wood-wool soiled by excre-
ment, or with feathers or filter paper covered with dried blood they
Vertex Oceiput
dad “Labial Palpus
92. Head and pronotum of (a) dcg flea; (b) of cat flea; (c) of hen flea. After Rothschild.
(d) Nycteridiphilus (Ishnopsyllus) hexactenus. After Oudemans.
will thrive readily and pupate. They seem to have no choice be-
tween dried blood and powdered rat feces for food, and also feed
readily on flea excrement. They possess the curious habit of always
devouring their molted skins.
An important part of Strickland’s experiments dealt with the
question of duration of the pupal stage under the influence of tempera-
ture and with the longevity and habits of the adult. In October,
he placed a batch of freshly formed cocoons in a small dish that was
kept near a white rat in a deep glass jar in the laboratory. Two
months later one small and feeble flea had emerged, but no more
until February, four months after the beginning of the experiment.
Eight cocoons were then dissected and seven more found to contain
the imago fully formed but in a resting state. The remainder of
122 Parasitic Arthropoda
the batch was then placed at 70° F. for one night, near a white
rat. The next day all the cocoons were empty and the fleas were
found on the white rat.
Thus, temperature greatly influences the duration of the pupal
period, which in Ceratophyllus fasciatus averages seventeen days.
Moreover, when metamorphosis is complete a low temperature will
cause the imago to remain within the cocoon.
Sexually mature and ovipositing fleas, he fed at intervals and kept.
alive for two months, when the experiment was discontinued. In
the presence of rubbish in which they could bury themselves, unfed
rat fleas were kept alive for many months, whereas in the absence of
any such substratum they rarely lived amonth. In the former case,
it was found that the length of life is influenced to some degree by the:
temperature and humidity. In an experiment carried out at 70° F.
and 45 per cent humidity, the fleas did not live for more than four:
months, while in an experiment at 60° F. and 70 per cent humidity
they lived for at least seventeen months. There was no indication
that fleas kept under these conditions sucked moisture from surround-
ing objects, and those kept in bell jars, with an extract of flea-rubbish
on filter paper, did not live any longer than those which were not so.
supplied.
Curiously enough, although the rat is the normal host of Cerato-
phyllus fasciatus, it was found that when given the choice these fleas
would feed upon man in preference to rats. However, none of the
fleas laid eggs unless they fed on rat blood.
The experiments of Strickland on copulation and oviposition in
the rat flea showed that fleas do not copulate until they are sexually
mature and that, at least in the case of Ceratophyllus fasciatus, the
reproductive organs are imperfectly developed for some time (more
than a week) after emerging from the pupa. When mature, copula-
tion takes place soon after the fleas have fed on their true host—the
rat—but not if they have fed on a facultative host only, such as man.
Copulation is always followed by oviposition within a very short.
time.
The effect of the rat’s blood on the female with regard to egg-
laying, Strickland concludes, is stimulating rather than nutritive,
as fleas that were without food for many months were observed to
lay eggs immediately after one feed. Similarly, the male requires
the stimulus of a meal of rat’s blood before it displays any copulatory
activity.
Stphonaptera, or Fleas 123
Mitzmain (1910) has described in detail the act of biting on man,
as observed in the squirrel flea, Ceratophyllus acutus. ‘‘The flea
when permitted to walk freely on the arm selects a suitable hairy
space where it ceases abruptly in its locomotion, takes a firm hold
with the tarsi, projects its proboscis, and prepares to puncture the
skin. A puncture is drilled by the pricking epipharynx, the saw-
tooth mandibles supplementing the movement by lacerating the
cavity formed. The two organs of the rostrum work alternately,
the middle piece boring, while the two lateral elements execute a
sawing movement. The mandibles, owing to their basal attach-
ments, are, as is expressed by the advisory committee on plague
investigations in India (Journal of Hygiene, vol. 6, No. 4, p. 499),
‘capable of independent action, sliding up and down but maintaining
their relative positions and preserving the lumen of the aspiratory
channel.’ The labium doubles back, the V-shaped groove of this
organ guiding the mandibles on either side.”
‘The action of the proboscis is executed with a forward movement
of the head and a lateral and downward thrust of the entire body.
As the mouth-parts are sharply inserted, the abdomen rises simultane-
ously. The hind and middle legs are elevated, resembling oars.
The forelegs are doubled under the thorax, the tibia and tarsi resting
firmly on the epidermis serve as a support for the body during the
feeding. The maxillary palpi are retracted beneath the head and
thorax. The labium continues to bend, at first acting as a sheath
for the sawing mandibles, and as these are more deeply inserted, it
bends beneath the head with the elasticity of a bow, forcing the
mandibles into the wound until the maxille are embedded in the skin
of the victim. When the proboscis is fully inserted, the abdomen
ceases for a time its lateral swinging.”
“The acute pain of biting is first felt when the mandibles have
not quite penetrated and subsequently during each distinct move-
ment of the abdomen. The swinging of the abdomen gradually
ceases as it becomes filled with blood. The sting of the biting
gradually becomes duller and less sensitive as feeding progresses.
The movements of the elevated abdomen grow noticeably feebler
as the downward thrusts of the springy bow-like labium becomes less
frequent.”
“As the feeding process advances one can discern through the
translucent walls of the abdomen a constant flow of blood, caudally
from the pharynx, accompanied by a peristaltic movement. The
124 Parasitic Arthropoda
end of the meal is signified in an abrupt manner. The flea shakes
its entire body, and gradually withdraws its proboscis by lowering
the abdomen and legs and violently twisting the head.”’
“When starved for several days the feeding of the rat fleas is
conducted in a rather vigorous manner. As soon as the proboscis
is buried to the full length the abdomen is raised and there ensues a
gradual lateral swaying motion, increasing the altitude of the raised
end of the abdomen until it assumes the perpendicular. The flea is
observed at this point to gain a better foothold by advancing the
fore tarsi, and then, gradually doubling back the abdomen, it turns
with extreme agility, nearly touching with its dorsal side the skin
of the hand upon which it is feeding. Meanwhile, the hungry para-
site feeds ravenously.”’
“Tt is interesting to note the peculiar nervous action which the
rodent fleas exhibit immediately when the feeding process is com-
pleted or when disturbed during the biting. Even while the rostrum
is inserted to the fullest the parasite shakes its head spasmodically;
in a twinkling the mouth is withdrawn and then the flea hops away.”
A habit of fleas which we shall see is of significance in considering
their agency in the spread of bubonic plague, is that of ejecting blood
from the anus as they feed.
Fleas are famous for their jumping powers, and in control measures
it is of importance to determine their ability along this line. It is
often stated that they can jump about four inches, or, according to
the Indian Plague Commission Xenopsylla cheopis cannot hop farther
than five inches. Mitzmain (1910) conducted some careful experi-
ments in which he found that the human flea, Pulex irritans, was
able to jump as far as thirteen inches on a horizontal plane. The
mean average of five specimens permitted to jump at will was seven
and three-tenths inches. The same species was observed to jump
perpendicularly to a height of at least seven and three-fourths inches.
Other species were not able to equal this record.
The effect of the bite of fleas on man varies considerably accord-
ing to the individual susceptibility. According to Patton and Cragg,
this was borne out in a curious manner by the experiments of Chick
and Martin. ‘In these, eight human hosts were tried; in seven,
little or no irritation was produced, while in one quite severe inflam-
mation was set up around each bite.” Of two individuals, equally
accustomed to the insects, going into an infested room, one may be
literally tormented by them while the other will not notice them.
Siphonaptera, or Fleas 125
Indeed it is not altogether a question of susceptibility, for fleas seem
to have a special predilection for certain individuals. The typical
itching wheals produced by the bites are sometimes followed, especi-
ally after scratching, by inflammatory papules.
The itching can be relieved by the use of lotions of carbolic acid
(2-3 per cent), camphor, menthol lotion, or carbolated vaseline.
If forced to sleep in an infested room, protection from attacks can
be in a large measure gained by sprinkling pyrethrum, bubach, or
California insect powder between the sheets. The use of camphor,
menthol, or oil of eucalyptus, or oil of pennyroyal is also said to afford
protection to a certain extent.
In the Eastern United States the occurrence of fleas as household
pests is usually due to infested cats and dogs which have the run of
the house. We have seen that the eggs are not attached to the host
but drop to the floor when they are laid. Verrill, cited by Osborn,
states that on one occasion he was able to collect fully a teaspoonful
of eggs from the dress of a lady in whose lap a half-grown kitten had
been held for a short time. Patton and Cragg record seeing the
inside of a hat in which a kitten had spent the night, so covered with
flea eggs that it looked ‘‘as if it had been sprinkled with sugar from
a sifter.”” It is no wonder that houses in which pets live become
overrun with the fleas.
One of the first control measures, then, consists in keeping such
animals out of the house or in rigorously keeping them free from fleas.
The latter can best be accomplished by the use of strong tar soap
or Armour’s ‘‘Flesope,’’ which may be obtained from most druggists.
The use of a three per cent solution of creolin, approximately four
teaspoonfuls to a quart of warm water, has also been recommended.
While this is satisfactory in the case of dogs, it is liable to sicken cats,
who will lick their fur in an effort to dry themselves. Howard
recommends thoroughly rubbing into the fur a quantity of pyrethrum
powder. This partially stupifies the fleas which should be promptly
swept up and burned.
He also recommends providing a rug for the dog or cat to sleep
on and giving this rug a frequent shaking and brushing, afterwards
sweeping up and burning the dust thus removed.
Since the larvee of fleas are very susceptible to exposure, the use
of bare floors, with few rugs, instead of carpets or matting, is to be
recommended. Thorough sweeping, so as to allow no accumulation
of dust in cracks and crevices will prove efficient. If a house is once
126 Parasitic Arthropoda
infested it may be necessary to thoroughly scrub the floors with hot
soapsuds, or to spray them with gasoline. If the latter method is
adopted, care must be taken to avoid the possibility of fire.
To clear a house of fleas Skinner recommends the use of flake
naphthalene. In a badly infested house he took one room at a time,
scattering on the floor five pounds of flake naphthalene, and closed
it for twenty-four hours. It proved to be a perfect and effectual
remedy and very inexpensive, as the naphthalene could be swept up
and transferred to other rooms. Dr. Skinner adds, “‘so far as I am
concerned, the flea question is solved and if I have further trouble
I know the remedy. I intend to keep the dog and cat.”
The late Professor Slingerland very effectively used hydrocyanic
acid gas fumigation in exterminating fleas in houses. In one case,
where failure was reported, he found oninvestigation that the house
had become thoroughly reinfested from pet cats, which had been left
untreated. Fumigation with sulphur is likewise efficient.
The fact that adult fleas are usually to be found on the floor,
when not on their hosts, was ingeniously taken advantage of by
Professor S. H. Gage in ridding an animal room at Cornell University
of the pests. He swathed the legs of a janitor with sticky fly-paper
and had him walk back and forth in the room. Large numbers of
the fleas were collected in this manner.
In some parts of the southern United States hogs are commonly
infested and in turn infest sheds, barns and even houses. Mr. H. E.
Vick informs us that it is a common practice to turn sheep into barn-
lots and sheds in the spring of the year to collect in their wool, the
fleas which abound in these places after the hogs have been turned
out.
It is a common belief that adult fleas are attracted to fresh meat
and that advantage of this can be taken in trapping them. Various
workers, notably Mitzman (1910), have shown that there is no basis
for such a belief.
The true chiggers—The chigoes, or true chiggers, are the most
completely parasitic of any of the fleas. Of the dozen or more known
species, one commonly attacks man. Thisis Dermatophilus penetrans,
more commonly known as Sarcopsylla penetrans or Pulex penetrans.
This species occurs in Mexico, the West Indies, Central and South
America. There are no authentic records of its occurrence in the
United States although, as Baker has pointed out, there is no reason
The True Chiggers 127
why it should not become established in Florida and Texas. It is
usually believed that Brazil was its original home. Sometime about
the middle of the nineteenth century it was introduced into West
Africa and has spread across that continent.
The males and the immature females of Dermatophilus penetrans
(fig. 93) closely resemble those of other fleas. They are very active
little brown insects about 1-1.2 mm. in size, which live in the dust of
native huts and stables, and in dry, sandy soil. In such places they
‘often occur in enormous numbers and become’ a veritable plague.
They attack not only man but various animals. According to
‘Castellani and Chalmers, ‘‘ Perhaps the most noted feature is the way
93. Dermatophilus penetrans. Muchenlarged. After Karsten.
in which it attacks pigs. On the Gold Coast it appeared to be largely
kept in existence by these animals. It is very easily captured in
the free state by taking a little pig with a pale abdomen, and placing
it on its back on the ground on which infected pigs are living. After
watching a few moments, a black speck will appear on the pig’s
abdomen, and quickly another and another. These black specks are
jiggers which can easily be transferred to a test tube. On examina-
tion they will be found to be males and females in about equal
numbers.”’
Both the males and females suck blood. That which characterizes
this species as distinguished from other fleas attacking man is that
when the impregnated female attacks she burrows into the skin
and there swells until in a few days she has the size and appearance of
a small pea (fig. 94). Where they are abundant, hundreds of the
128 Parasitic Arthropoda
94. Dermatophilus penetrans, gravid female. After Moniez.
pests may attack a single individual (fig.95). Here they lie with the
apex of the abdomen blocking the opening. According to Fille-
born (1908) they do not
penetrate beneath the
epidermis. The eggs are
not laid in the flesh of
the victim, as is some-
times stated, but are
expelled through this
opening. The female
then dies, withers and
falls away or is expelled
by ulceration. Accord-
ing to Brumpt, she first
quits the skin and then,
falling to the ground,
deposits her eggs. The
subsequent develop-
ment inso far as known,
is like that of other fleas.
The chigoe usually
enters between the toes,
the skin about the roots
of the nails, or the soles
95. Chiggers in the sole of foot of man. Manson's
Tropical Diseases. Permission of Cassell and Co.
Siphonaptera, or Fleas 129
of the feet, although it may attack other parts of the body. Mense
records the occurrence in folds of the epidermis, as in the neighbor-
hood of the anus. They give rise to irritation
and unless promptly and aseptically removed
there often occurs pus formation and the
development of a more or less serious abscess.
Gangrene and even tetanus may ensue.
Treatment consists in the careful removal
of the insect, an operation more easily accom-
plished a day or two after its entrance, than
at first, when it is unswollen. The ulcerated
point should then be treated with weak car-
bolic acid, or tincture of iodine, or dusted
thoroughly with an antiseptic powder.
Castellani and Chalmers recommend as
prophylactic measures, keeping the house clean and keeping pigs,
poultry, and cattle away therefrom. ‘‘High boots should be used,
and especial care should be taken not to go to a ground floor bath-
room with bare feet. The feet, especially the toes, and under the
nails, should be carefully examined every morning to see if any black
96. Echidnophaga gallinacea,
97. Echidnophaga gallinacea infesting head of chicken. After Enderlein.
dots can be discovered, when the jigger should be at once removed,
and in this way suppuration will be prevented. It is advisable,
130 Parasitic Arthropoda
also, to sprinkle the floors with carbolic lotion, Jeyes’ fluid, or with
pyrethrum powder, or with a strong infusion of native tobacco, as
recommended by Law and Castellani.”
Echidnophaga gallinacea (fig. 96) is a widely distributed Hectopsyl-
lid attacking poultry (fig. 97). It occurs in the Southern and South-
western United States and has been occasionally reported as attack-
ing man, especially children. It is less highly specialized than
Dermatophilus penetrans, and does not ordinarily cause serious
trouble in man.
CHAPTER IV
ACCIDENTAL OR FACULTATIVE PARASITES
In addition to the many species of Arthropods which are normally
parasitic on man and animals, there isa considerable number of those
which may be classed as accidental or facultative parasites.
Accidental or facultative parasites are species which are normally
free-living, but which are able to exist as parasites when accidentally
introduced into the body of man or other animal. A wide range of
forms is included under this grouping.
ACARINA
A considerable number of mites have been reported as accidental
or even normal, endoparasites of man, but the authentic cases are
comparatively few.
In considering such reports it is well to keep in mind von Siebold’s
warning that in view of the universal distribution of mites one should
be on his guard. In vessels in which animal and other organic
fluids and moist substances gradually dry out, mites are very abund-
antly found. If such vessels are used without very careful prelimi-
nary cleaning, for the reception of evacuations of the sick, or for the
reception of parts removed from the body, such things may be readily
contaminated by mites, which have no other relation whatever to
them.
Nevertheless, there is no doubt but that certain mites, normally
free-living, have occurred as accidental parasites of man. Of these
the most commonly met with is Tyroglyphus siro, the cheese-mite.
Tyroglyphus siro is a small mite of a whitish color. The male
measures about soo long by 250% wide, the female slightly larger.
They live in cheese of almost any kind, especially such as is a little
decayed. ‘‘The individuals gather together in winter in groups or
heaps in the hollows and chinks of the cheese and there remain
motionless. As soon as the temperature rises a little, they gnaw
away at the cheese and reduce it to a powder. The powder is com-
posed of excrement having the appearance of little grayish microscopic
balls; eggs, old and new, cracked and empty; larve, nymphs, and
perfect mites, cast skins and fragments of cheese, to which must be
added numerous spores of microscopic fungi.”—Murray.
131
132 Accidental or Facultative Parasites
Tyroglyphus siro, and related species, have been found many
times in human feces, under conditions which preclude the explana-
tion that the contamination occurred outside of the body. They
have been supposed to be the cause of dysentery, or diarrhoea, and
it is probable that the Acarus dysenterie of Linnzeus, and Latreille,
was this species. However, there is little evidence that the mites
cause any noteworthy symptoms, even when taken into the body
in large numbers.
Histiogaster spermaticus (fig. 152) is a Tyroglyphid mite which
was reported by Trouessart (1902) as having been found in a cyst
in the groin, adherent to the testis. When the cyst was punctured,
it yielded about two ounces of opalescent fluid containing spermatozoa
and numerous mites in all stages of development. The evidence
indicated that a fecundated female mite had been introduced into
the urethra by means of an unclean catheter. Though Trouessart
reported the case as that of a Sarcoptid, Banks places the genus
Histiogaster with the Tyroglyphide. He states that our species
feeds on the oyster-shell bark louse, possibly only after the latter is.
dead, and that in England a species feeds within decaying reeds.
Nephrophages sanguinarius is a peculiarly-shaped, angular mite
which was found by Miyake and Scriba (1893) for eight successive
days in the urine of a Japanese suffering from fibrinuria. Males,
.I17 mm. long by .o79 mm. wide, females .36 mm. by .12 mm.,
and eggs were found both in the spontaneously emitted urine and in
that drawn by means of a catheter. All the mites found were dead.
The describers regarded this mite as a true endoparasite, but it is.
more probable that it should be classed as an accidental parasite.
MyRrIAPopDa
There are on record a number of cases of myriapods occurring as.
accidental parasites of man. The subject has been treated in detail
by Blanchard (1898 and 1902), who discussed forty cases. Since
then at least eight additions have been made to the list.
Neveau-Lamaire (1908) lists thirteen species implicated, repre-
senting eight different genera. Of the Cluilognatha there are three,
Julus terrestris, J. londinensis and Polydesmus complanatus. The
remainder are Chilopoda, namely, Lithobius forficatus, L. malenops,
Geophilus carpophagus, G. electricus, G. similis, G. cephalicus, Scutigera
coleoptrata, Himantarium gervaist, Chetechelyne vesuviana and
Stigmatogaster subterraneus.
Myriapoda 133
The majority of the cases relate to infestation of the nasal fossz,
or the frontal sinus, but intestinal infestation also occurs and there
is one recorded case of the presence of a species in Julus (fig. 13) in
the auditory canal of a child.
In the nose, the myriapods have been known to live for months
and according to some records, even for years. The symptoms
caused by their presence are inflammation, with or without increased
flow of mucus, itching, more or less intense headache, and at times
general symptoms such as vertigo, delirium, convulsions, and the
like. These symptoms disappear suddenly when the parasites are
expelled.
In the intestine of man, myriapods give rise to obscure symptoms
suggestive of infestation by parasitic worms. In a case reported by
Verdun and Bruyant (1912), a child twenty months of age had been
affected for fifteen days by digestive disturbances characterized by
loss of appetite, nausea and vomiting. The latter had been partic-
ularly pronounced for three days, when there was discovered in the
midst of the material expelled a living myriapod of the species
Chetechelyne vesuviana. Anthelminthics had been administered
without result. In some of the other cases, the administration of
such drugs had resulted in the expulsion of the parasite through the
anus.
One of the extreme cases on record is that reported by Shipley
(1914). Specimens of Geophilus gorizensis (= G. subterraneus)
‘were vomited and passed by a woman of 68 years of age. Some of
the centipedes emerged through the patient’s nose, and it must be
mentioned that she was also suffering from a round worm. One of
her doctors was of the opinion that the centipedes were certainly
breeding inside the lady’s intestines, and as many as seven or eight,
sometimes more, were daily leaving the alimentary canal.”
“According to her attendant’s statements these centipedes had
left the body in some hundreds during a period of twelve or eighteen
months. Their presence produced vomiting and some hematemesis,
and treatment with thymol, male-fern and turpentine had no effect
in removing the creatures.”
The clinical details, as supplied by Dr. Theodore Thompson were
as follows:
“Examined by me July, 1912, her tongue was dry and glazed.
There was bleeding taking place from the nose and I saw a living
centipede she had just extracted from her nostril. Her heart, lungs
134 Accidental or Facultative Parasites
and abdomen appeared normal. She was not very wasted, and did
not think she had lost much flesh, nor was there any marked degree
of anemia.”
Shipley gives the following reasons for believing it impossible
that these centipedes could have multiplied in the patient’s intestine.
“The breeding habits of the genus Geophilus are peculiar, and ill
adapted for reproducing in such a habitat. The male builds a small
web or nest, in which he places his sperm, and the female fertilizes
herself from this nest or web, and when the eggs are fertilized they
are again laid in a nest or web in which they incubate and in two or
three weeks hatch out. The young Geophilus differ but very little
from the adult, except in size. It is just possible, but improbable,
that a clutch of eggs had been swallowed by the host when eating
some vegetables or fruit, but against this is the fact that the Geophilus
does not lay its eggs upon vegetables or fruit, but upon dry wood or
earth. The egg-shell is very tough and if the eggs had been swallowed
the egg-shells could certainly have been detected if the dejecta were
examined. The specimens of the centipede showed very little signs
of being digested, and it is almost impossible to reconcile the story
of the patient with what one knows of the habits of the centipedes.”
In none of the observed cases have there been any clear indica-
tions as to the manner of infestation. It is possible that the myria-
pods have been taken up in uncooked fruit or vegetables.
Lepripoprerous Larvz
Scholeciasis—Hope (1837) brought together six records of infesta-
tion of man by lepidopterous larvee and proposed to apply the name
scholeciasis to this type of parasitism. The clearest case was that
of a young boy who had repeatedly eaten raw cabbage and who
vomited larvee of the cabbage butterfly, Pzerts brassice. Such cases
are extremely rare, and there are few reliable data relative to the
subject. In this connection it may be noted that Spuler (1906) has
described a moth whose larve live as ectoparasites of the sloth.
COLEOPTERA
Canthariasis—By this term Hope designated instances of acci-
dental parasitism by the larve or adults of beetles. Reports of
such cases are usually scouted by parasitologists but there seems no
good basis for wholly rejecting them. Cobbold refers to a half
dozen cases of accidental parasitism by the larve of Blaps mortisaga.
Dipterous Larve 135
In one of these cases upwards of 1200 larve and several perfect
insects were said to have been passed per anum. French (1908)
reports the case of a man
whoforaconsiderable period
voided adult living beetles
of the species Nitidula
bipustulata. Most of the
other cases on record relate
98. Larva of Piophila casei. Caudalaspect oflarva. to the larvee of Dermestide
Posterior stigmata.
(larder beetles et al.) or
Tenebrionide (meal infesting species). Infestation probably occurs
through eating raw or imperfectly cooked foods containing eggs or
minute larve of these insects.
Brumpt cites a curious case of accidental parasitism by a coleopter-
ous larva belonging to the genus Necrobia. This larva was extracted
from a small tumor, several millimeters long, on the surface of the
conjunctiva of the eye. The larve of this genus ordinarily live in
decomposing flesh and cadavers.
DietEerRous Larva
Myasis—By this term (spelled also myiasis, and myiosis), is
meant parasitism by dipterous larve. Such parasitism may be
normal, as in the cases already described under the heading parasitic
Diptera, or it may be facultative, due to free-living larve being
accidentally introduced
into wounds or the body-
cavities of man. Of this
latter type, there is a
multitude of cases on
record, relating to com-
paratively few species.
The literature of the sub-
‘ject, like that relating
to facultative parasitism
in general, is unsatis-
factory, for most of the :
determinations of species 99. Piophila casei. After Graham-Smith.
have been very loose.
Indeed, so little has been known regarding the characteristics of
the larvee concerned that in many instances they could not be exactly
136 Accidental or Facultative Parasites
determined. Fortunately, several workers have undertaken com-
parative studies along this line. The most comprehensive publica-
tion is that of Banks (1912), entitled ‘‘The structure of certain dip-
terous larvee, with particular reference to those in human food.”
Without attempting an exhaustive list, we shall discuss here the
more important species of Diptera whose larve are known to cause
myasis, either external or internal. The following key will serve
to determine those most likely to be encountered. The writers
would be glad to examine specimens not readily identifiable, if
accompanied by exact data relative to occurrence.
a. Body more or less flattened, depressed; broadest in the middle, each segment
with dorsal, lateral, and ventral fleshy processes, of which the laterals,
at least, are more or less spiniferous (fig. 101). Fannia (=Homalomyia).
In F. canicularis the dorsal processes are nearly as long as the laterals;
in F. scalaris the dorsal processes are short spinose tubercles.
aa. Body cylindrical, or slender conical tapering toward the head; without
fleshy lateral processes (fig. 105).
b. With the posterior stigmata at the end ofshorter or longer tubercles, or if not
placed upon tubercles, then not in pit; usually without a ‘‘marginal button’’
and without a chitinous ring surrounding the three slits; the slits narrowly
or broadly oval, not bent (fig. 171 i). Acalyptrate muscide and some species
of Anthomyude. To this group belong the cheese skipper (Piophila casei,
figs. 98, 99), the pomace-fly (Drosophila ampelophila), the apple maggot
(Rhagoletis pomonella), the cherry fruit fly (Rhagoletis cingulata), the small
dung fly (Sepsis violacea, fig. 170), the beet leaf-miner (Pegomyia vicina,
fig. 171 i), the cabbage, bean and onion maggots (Phorbia spp.) et. al.
bb. Posterior stigmata of various forms, if the slits are narrowly oval (fig. 171)
then they are surrounded by a chitin ring which may be open ventro-
mesally.
c. Integument leathery and usually strongly spinulose; larve hypodermatic or
endoparasitic.............000000e Bot flies (fig. 171, f, g, k).—Oestride
cc. Integument not leathery and (except in Protocalliphora) spinule restricted
to transverse patches near the incisures of the segments.
d. The stigmal plates in a pit; the lip-like margin of the pit with a number of
fleshy tubercles; chitin of the stigma not complete; open ventro-mesally,
button absent (fig. 171 €)...... cece cece ee eee Flesh flies —Sarcophaga
dd. Stigmata not in a pit.
e. The chitin ring open ventra-mesally; button absent (fig. 171 c). Screw-
WOET Ayis 5c sis Sa Ae Ec a La TR A Sova ae HEE dane’, PinaNe oe Chrysomyia
ee. The chitin ring closed.
f. Slits of the posterior stigmata straight; marginal ‘‘button” present (fig. 171 b);
two distinct mouth hooks, fleshy tubercles around the anal area. Phormia
(fig. 171 f), Lucila and Calliphora (fig. 172, a, b), Protocalliphora (fig. 171, j),
Cynomyia (fig. 171, a). Blow flies, bluebottle flies........ Calliphorine
Dipterous Larve 137
ff. Slits of the posterior stigmata sinuous or bent. Subfamily Muscine.
g. Slits of the posterior stigmata bent; usually two mouth hooks. Muscina
stabulans (fig. 171, 1), Muscina similis, Myiospila meditatunda (fig. 172, i),
and some of the higher Anthomyiide. ‘
ge. Slits of the posterior stigmata sinuous; mouth hooks usually consolidated
into one. The house-fly (Musca domestica fig. 171, d), the stable fly
(Stomoxys calcitrans) the horn fly (Lyperosia irritans), Pyrellia, Pseudo-
pyrellia, Morellia, Mesembrina. Polietes, et. al. (fig. 172 in part). -
Eristalis—The larvee of Eristalis are the so-called rat-tailed mag-
gots, which develop in foul water. In a few instances these larve
have been known to pass through the human alimentary canal
uninjured. Hall and Muir (1913) report the case of a boy five years
of age, who had been ailing for ten weeks and who was under treat-
ment for indigestion and chronic constipation. For some time he
had vomited everything he ate. On administration of a vermifuge
he voided one of the rat-tailed maggots of Eristalis. He admitted
having drunk water from a ditch full of all manner of rotting matter.
It was doubtless through this that he became infested. It is worth
noting that the above described symptoms may have been due to
other organisms or substances in the filthy water.
Piophila casei, the cheese-fly (fig. 99), deposits its eggs not only
in old cheeses, but on ham, bacon, and other fats. The larve (fig. 98)
are the well-known cheese skippers, which sometimes occur in great
abundance on certain kinds of cheese. Indeed, some people have
a comfortable theory that such infested cheese is especially good.
Such being the case, it is small wonder that this species has been
repeatedly reported as causing intestinal myasis. Thebault (1901)
describes the case of a girl who, shortly after consuming a large piece
of badly infested cheese, became ill and experienced severe pains
in the region of the navel. Later these extended through the entire
alimentary canal, the excrement was mixed with blood and she
suffered from vertigo and severe headaches. During the four fol-
lowing days the girl felt no change, although the excretion of the blood
gradually diminished and stopped. On the fourth day she voided
two half-digested larvee and, later, seven or eight, of which two were
alive and moving.
That these symptoms may be directly attributed to the larve,
or ‘skippers,’ has been abundantly shown by experimental evidence.
Portschinsky cites the case of a dog fed on cheese containing the
larvee. The animal suffered much pain and its excrement contained
blood. On post mortem it was found that the small intestine through-
138 Accidental or Facultative Parasites
out almost its entire length was marked by bloody bruises. The
papillae on these places were destroyed, although the walls were
not entirely perforated. In the appendix were found two or three
dead larve. Alessandri (1910) has likewise shown that the larve
cause intestinal lesions.
According to Graham-Smith, Austen (1912) has recorded a case
of myasis of the nose, attended with a profuse watery discharge of
several weeks duration and pain, due to the larve of Piophila caset.
Anthyomyiidee—The characteristic larvee of two species of Fannia
(=Homalomyia or Anthomyia, in part) (fig. 101) are the most com-
monly reported of dip-
terous larvee causing intes-
tinal myasis. Hewitt
(1912) has presented a
valuable study of the bio-
nomics and of the larve
of these flies, a type of
what is needed for all the
species concerned in my-
asis. We have seen two
cases of their having been
passed in stools, without having caused any special symptoms.
In other instances their presence in the alimentary canal has given
rise to symptoms vaguely described as those of tapeworm infestation,
or helminthiasis. More specifically, they have been described as
causing vertigo, severe headache, nausea and vomiting, severe
abdominal pains, and in some instances, bloody diarrhoea.
One of the most striking cases is that reported by Blankmeyer
(1914), of a woman whose illness began fourteen years previously
with nausea and vomiting. After several months of illness she began
passing larvee and was compelled to resort to enemas. Three years
previous to the report, she noticed frequent shooting pains in the
rectal region and at times abdominal tenderness was marked. There
was much mucus in the stools and she “‘experienced the sensation
of larve crawling in the intestine.” Occipital headaches were
marked, with remissions, and constipation became chronic. The
appetite was variable, there was a bad taste in the mouth, tongue
furred and ridged, and red at the edges. Her complexion was sal-
low, and general nervousness was marked. As treatment, there
were given doses of magnesium sulphate before breakfast and at
100. Fannia canicularis (x4). After Graham-Smith.
Anthyomyiide 139
4 P. M., with five grain doses of salol four times a day. The customary
parasiticides yielded no marked benefit. At the time of the report
the patient passed from four to fifty larve per day, and was showing
some signs of improvement. The nausea had disappeared, her
nervousness was less evident, and there was a slight gain in weight.
The case was complicated by various other disorders, but the
symptoms given above seem to be in large part attributable to the
myasis. There is nothing in the case to justify the assumption '
that larva were continuously present, for years. It seems more
reasonable to suppose that something in the habits of the patient
favored repeated infestation. Nevertheless, a study of the various
cases of intestinal myasis caused by these and
other species of dipterous larve seems to indi-
cate that the normal life cycle may be con-
siderably prolonged under the unusual conditions.
The best authenticated cases of myasis of the
urinary passage have been due to larve of
Fannia. Chevril (1909) collected and described
twenty cases, of which seven seemed beyond
doubt. One of these was that of a woman of
fifty-five who suffered from albuminuria, and
urinated with much difficulty, and finally passed
thirty to forty larve of Fannia canicularis.
It is probable that infestation usually occurs
through eating partially decayed fruit or vege-
tables on which the flies have deposited their
eggs. Wellman points out that the flies may
101. LarvaofFannia deposit their eggs in or about the anus of
persons using outside privies and Hewitt
believes that this latter method of infection is probably the common
one in the case of infants belonging to careless mothers. ‘‘Such
infants are sometimes left about in an exposed and not very clean
condition, in consequence of which flies are readily attracted to them
and deposit their eggs.”
Muscine—The larve of the common house-fly, Musca domestica,
are occasionally recorded as having been passed with the feces or
vomit of man. While such cases may occur, it is probable that in
most instances similar appearing larve of other insects have been
mistakenly identified.
140 Accidental or Facultative Parasites
Muscina stabulans is re-
garded by Portschinsky
(1913) as responsible for
many of the cases of intesti-
nal myasis attributed to other
species. He records the case
ofapeasant whosuffered from
pains in the lower part of the
breast and intestines, and
whose stools were mixed with
blood. From November until
f March he had felt particu-
102. se eeu (x4). After Graham larly ill, being troubled with
nausea and vomiting in addi-
tion to the pain in his intestines. In March, his physician prescribed
injections of a concentrated solution of tannin, which resulted in the
expulsion of fifty living larve of Muscina stabulans. Thereafter
the patient felt much better, although he suffered from intestinal
catarrh in a less severe form.
Calliphorine—Closely related to the Sarcophagide are the
Calliphoring. to which group belong many of the so-called ‘‘blue
bottle” flies. Their larvee feed upon dead animals, and upon fresh
and cooked meat. Those of Pro-
tocalliphora, already mentioned,
are ectoparasitic on living nestling
birds. Larve of Lucilia, we have
taken from tumors on living turtles.
To this sub-family belongs also
Aucheromyia luteola, the Congo
floor maggot. Some of these,
and at least the last mentioned,
are confirmed, rather than faculat-
tive parasites. Various species of
Calliphorinz are occassionally met
with as facultative parasites of
man.
Chrysomyia macellaria, the screw worm fly (fig. 107), is the fly
which is responsible for the most serious cases of human myasis in
the United States. It is widely distributed in the United States
103. Lucilia cesar, (x3). After Howard.
Chrysomyia macellaria I41
but is especially abundant in the south. While the larve breed in
decaying matter in general, they so commonly breed in the living
flesh of animals that they merit rank as true parasites. The females
are attracted to open wounds of all kinds on cattle and other animals
and quickly deposit large numbers of eggs. Animals which have
been recently castrated, dehorned, or branded, injured by barbed
wire, or even by the attacks of ticks are promptly attacked in the
tegions where the fly abounds. Even the navel of young calves or
discharges from the vulva of cows may attract the insect.
Not infrequently the fly attacks man, being attracted by an of-
fensive breath, a chronic catarrh, or a purulent discharge from the
ears. Most common are the cases where the eggs are deposited in
104. Calliphora erythrocephala, (x6). After Graham-Smith.
the nostrils. The larve, which are hatched in a day or two, are
provided with strong spines and proceed to bore into the tissues
of the nose, even down into or through the bone, into the frontal
sinus, the pharynx, larynx, and neighboring parts.
Osborn (1896) quotes a number of detailed accounts of the attacks
of the Chrysomyia on man. A vivid picture of the symptomology
of rhinal myasis caused by the larvee of this fly is given by Castellani
and Chalmers: ‘‘Some couple of days after a person suffering from
a chronic catarrh, foul breath, or ozena, has slept in the open or has
been attacked by a fly when riding or driving,—7.e., when the hands
are engaged—signs of severe catarrh appear, accompanied with
inordinate sneezing and severe pain over the root of the nose or the
frontal bone. Quickly the nose becomes swollen, and later the face
also may swell, while examination of the nose may show the presence
142 Accidental or Facultative Parasites
of the larve. Left untreated, the patient rapidly becomes worse,
and pus and blood are discharged from the nose, from which an
offensive odor issues. Cough appears as well as fever, and often
some delirium. If the patient lives long enough, the septum of the
nose may fall in, the soft and hard palates may be pierced, the wall
of the pharynx may be destroyed. By this time, however, the course
of the disease will have become quite evident by the larve dropping
out of the nose, and if the patient continues to live all the larve
may come away naturally.”
For treatment of rhinal myasis these writers recommend douch-
ing the nose with chloroform water or a solution of chloroform in
sweet milk (10-20 per cent), followed by douches of mild antiseptics.
Surgical treatment may be necessary.
105. Larva of a flesh fly (Sarcophaga).. Caudal aspect. Anterior stigmata. Pharyngeal skeleton.
Sarcophagidee—The larve (fig. 105) of flies of this family usually
feed upon meats, but have been found in cheese, oleomargerine,
pickled herring, dead and living insects, cow dung and human feces.
Certain species are parasitic in insects. Higgins (1890) reported
an instance of “‘hundreds’’ of larvee of Sarcophaga being vomited by a
child eighteen months of age. There was no doubt as to their origin
for they were voided while the physician was in the room. There
are many other reports of their occurrence in the alimentary canal.
We have recorded elsewhere (Riley, 1906) a case in which some ten
or twelve larve of Sarcophaga were found feeding on the diseased
tissues of a malignant tumor. The tumor, a melanotic sarcoma,
was about the size of a small walnut, and located in the small of the
back of an elderly lady. Although they had irritated and caused a
slight hemorrhage, neither the patient nor others of the family knew
Sarcophagide 143
of their presence. Any discomfort which they had caused had been
attributed to the sarcomatous growth. The infestation occurred
106. A flesh fly (Sarcophaga), (x4). After Graham-Smith.
in mid-summer. It is probable that the adult was attracted by the
odor of the discharges and deposited the living maggots upon the
diseased tissues.
According to Kiichenmeister, Sarcophaga carnaria (fig. 106),
attracted by the odor, deposits its eggs and larve in the vagina of
girls and women when they lie naked in hot summer days upon dirty
clothes, or when they have a discharge from the vagina. In malig-
nantinflammations of theeyes the larvee
even nestle under the eyelids and in
Egypt, for example, produce a very
serious addition to the effects of small-
pox upon the cornea, as according to
Pruner, in such cases perforation of the
‘cornea usually takes place.
Wohlfartia magnifica is another
Sarcophagid which commonly infests
man in the regions where it is abun-
dant. It is found in all Europe but is
especially common in Russia, where
Portschinsky has devoted much atten-
tion to its ravages. It deposits living
larve in wounds, the nasal fosse, the
ears and the eyes, causing injuries
even more revolting than those described for Chrysomyia.
‘107. Chrysomyia macellaria, (x3)
CHAPTER V
ARTHROPODS AS SIMPLE CARRIERS OF DISEASE
The fact that certain arthropods are poisonous, or may affect the
health of man as direct parasites has always received attention in
the medical literature. We come now to the more modern aspect
of our subject,—the consideration of insects and other arthropods
as transmitters and disseminators of disease.
The simplest way in which arthropods may function in this
capacity is as simple carriers of pathogenic organisms. It is con-
ceivable that any insect which has access to, and comes in contact
with such organisms and then passes to the food, or drink, or to the
body of man, may in a wholly accidental and incidental manner
convey infection. That this occurs is abundantly proved by the
work of recent years. We shall consider as typical the case against
the house-fly, which has attracted so much attention, both popular
and scientific. The excellent general treatises of Hewitt (1910),
Howard (1911), and Graham-Smith (1913), and the flood of bulletins
and popular literature render it unnecessary to consider the topic
in any great detail.
Tue Hovusk-riy As A CARRIER OF DISEASE
Up to the past decade the house-fly has usually been regarded as a
mere pest. Repeatedly, however, it had been suggested that it
might disseminate disease. We have seen that as far back as the
sixteenth century, Mercurialis suggested that it was the agent in the
spread of bubonic plague, and in 1658, Kircher reiterated this view.
In 1871, Leidy expressed the opinion that flies were probably a means
of communicating contagious diseases to a greater degree than was
generally suspected. From what he had observed regarding gangrene
in hospitals, he thought flies should be carefully excluded from
wounds. In the same year, the editor of the London Lancet, referring
to the belief that they play a useful réle in purifying the air said,
“Far from looking wpon them as dipterous angels dancing attendance
on Hygeia, regard them rather in the light of winged sponges spread-
ing hither and thither to carry out the foul behests of Contagion.”
These suggestions attracted little attention from medical men, for
it is only within very recent years that the charges have been sup-
ported by direct evidence. Before considering this evidence, it is
144
The House-fly as a Carrier of Disease 145
necessary that we define what is meant by “house-fly’”’ and that we
then consider the life-history of the insect.
There are many flies which are occasionally to be found in houses,
but according to various counts, from 95 per cent to 99 per cent of
these in warm weather in the Eastern United States belong to the
one species Musca domestica (fig. 108). This is the dominant house-
fly the world over and is the one which merits the name. It has been
well characterized by Schiner (1864), whose description has been
freely translated by Hewitt, as follows:
“Frons of male occupying a fourth part of the breadth of the head.
Frontal stripe of female narrow in front, so broad behind that it
entirely fills up the width of the frons. The dorsal region of the
thorax dusty grey in color with four equally broad longitudinal
stripes. Scutellum gray with black sides. The light regions of
the abdomen yellowish, transparent, the darkest parts at least at
the base of the ventral side yellow. The last segment and a dorsal
line blackish brown. Seen from behind and against the light, the
whole abdomen shimmering yellow, and only on each side of the
dorsal line on each segment a dull transverse band. The lower part
of the face silky yellow, shot with blackish brown. Median stripe
velvety black. Antenne brown. Palpi black. Legs blackish
brown. Wings tinged with pale gray with yellowish base. The
female has a broad velvety back, often reddishly shimmering frontal
stripe, which is not broader at the anterior end than at the bases of
the antenne, but become so very much broader above that the light
dustiness of the sides is entirely obliterated. The abdomen gradu-
ally becoming darker. The shimmering areas on the separate seg-
ments generally brownish. All the other parts are the same as in
the male.”
The other species of flies found in houses in the Eastern United
States which are frequently mistaken for the house or typhoid fly
may readily be distinguished by the characters of the following key:
a. Apical cell (R;) of the wide wing open,i.e., the bounding veins
parallel or divergent (fig. 100). Their larve are flattened, the
intermediate body segments each fringed with fleshy, more or
less SpINOSey “~PTOCESSESii cass veo w ay Ave re uensee eres Fannia
b. Male with the sides of the second and third abdominal seg-
ments translucent yellowish. The larva with three pairs
of nearly equal spiniferous appendages on each segment,
146 Arthropods as Simple Carriers of Disease
arranged in a longitudinal series and in addition two pairs
‘ of series of smaller processes (fig. 1oo)\ F. camnicularis
bb. Male with blackish abdomen, middle tibia with a tubercle
beyond the middle. The larva with spiniferous appen-
dages of which the dorsal and ventral series are short, the
lateral series long and feathered (fig. ror)... .F. scalaris
aa. Apical cell (R) of the wing more or less narrowed in the
margin; i. e., the bounding veins more or less converging
(fig. 108).
b. The mouth-parts produced and pointed, fitted for piercing.
c. Palpi much shorter than the proboscis; a brownish gray
fly, its thorax with three rather broad whitish stripes;
on each border of the middle stripe and on the mesal
borders of the lateral stripes is a blackish brown line.
Abdomen yellowish brown; on the second, third and
fourth segments are three brown spots which may be
faint or even absent. The larve live in dung. The
stable-fly (ig. 110)... «eee Stomoxys calcitrans
cc. Palpi nearly as long as the proboscis. Smaller species
than the house-fly. The horn-fly (fig. 167)
Hematobia trritans
bb. Mouth-parts blunt, fitted for lapping.
c. Thorax, particularly on the sides and near the base of the
wings with soft golden yellow hairs among the bristles.
This fly is often found in the house in very early spring
or even in the winter. The cluster-fly, Pollenia rudis
cc. Thorax without golden yellow hairs among the bristles.
d. The last segment of the vein M with an abrupt
angle. (fig. 108). The larve live in manure,
etc. ... .... .House-fly, Musca domestica
dd. The last segment of vein M with a broad, gentle
curve (fig. 102).
e. Eyes microscopically hairy; each abdominal
segment with two spots. Larve in dung.
Myiospila meditabunda
ee. Eyes bare; abdomen gray and brown marbled.
Muscina
f. With black legs and palpi. M. assimilis
The House-fly as a Carrier of Disease 147
ff. With legs more or less yellowish; palpi
yellow. Larve in decaying vegetable
substances, dung, etc. M. stabulans
It is almost universally believed that the adults of Musca domestica
hibernate, remaining dormant throughout the winter in attics,
around chimneys, and in sheltered but cold situations. This belief
has been challenged by Skinner (1913), who maintains that all the
adult flies die off during the fall and early winter and that the species
is carried over in the pupal stage, and in no other way. The cluster-
fly, Pollenia rudis, undoubtedly does hibernate in attics and similar
108. The house or typhoid fly (Musca domestica (4x)). After Howard.
situations and is often mistaken for the house-fly. In so far as
concerns Musca domestica, the important question as to hibernation
in the adult stage is an open one. Many observations by one of the
writers (Johannsen) tend to confirm Dr. Skinner’s conclusion, in so
far as it applies to conditions in the latitude of New York State.
Opposed, is the fact that various experimentors, notably Hewitt
(1910) and Jepson (1909) wholly failed to carry pupe through the
‘winter.
The house-fly breeds by preference in horse manure. Indeed,
Dr. Howard, whose extensive studies of the species especially qualify
him for expressing an opinion on the subject, has estimated that under
ordinary city and town conditions, more than ninety per cent of the
flies present in houses have come from horse stables or their vicinity.
They are not limited to such localities, by any means, for it has been
found that they would develop in almost any fermenting organic
substance. Thus, they have been bred from pig, chicken, and cow
148 Arthropods as Simple Carriers of Disease
manure, dirty waste paper, decaying vegetation, decaying meat,
slaughter-house refuse, sawdust-sweepings, and many other sources.
A fact which makes them especially dangerous as disease-carriers
is that they breed readily in human excrement.
The eggs are pure white, elongate ovoid, somewhat broader at
the anterior end. They measure about one millimeter (1-25 inch)
in length. They are deposited in small, irregular clusters, one
hundred and twenty to one hundred and fifty from a single fly. A
female may deposit as many as four batches in her life time. The
eggs hatch in from eight to twenty-four hours.
The newly hatched larva, or maggot (fig. 108), measures about two
millimeters (1-12 inch) in length. It is pointed at the head end and
blunt at the opposite end, where the spiracular openings are borne.
It grows rapidly, molts three times and reaches maturity in from six
to seven days, under favorable conditions.
The pupal stage, like that of related flies, is passed in the old
larval skin which, instead of being molted, becomes contracted and
heavily chitinized, forming the so-called puparium (fig. 108). The
pupal stage may be completed in from three to six days.
Thus during the warm summer months a generation of flies may
be produced in ten to twelve days. Hewitt at Manchester, England,
found the minimum to be eight days but states that larve bred in
the open air in horse manure which had an average daily temperature
of 22.5 C., occupied fourteen to twenty days in their development,
according to the air temperature.
After emergence, a period of time must elapse before the fly is
capable of depositing eggs. This period has been termed the pre-
oviposition period. Unfortunately we have few exact data regarding
this period. Hewitt found that the flies became sexually mature in
ten to fourteen days after their emergence from the pupal state and
four days after copulation they began to deposit their eggs; in other
words the preoviposition stage was fourteen days or longer. Griffith
(1908) found this period to be ten days. Dr. Howard believes that
the time “‘must surely be shorter, and perhaps much shorter, under
midsummer conditions, and in the freedom of the open air.’”’ He
emphasizes that the point is of great practical importance, since it is
during this period that the trapping and other methods of destroying
the adult flies, will prove most useful.
Howard estimates that there may be nine generations of flies a
year under outdoor conditions in places comparable in climate to
The House-fly as a Carrier of Disease 149
Washington. The number may be considerably increased in warmer
climates.
The rate at which flies may increase under favorable conditions is
astounding. Various writers have given estimates of the numbers of
flies which may develop as the progeny of a single individual, provid-
ing all the eggs and all the individual flies survived. Thus, Howard
estimates that from a single female, depositing one hundred and
twenty eggs on April isth, there may be by September roth,
5,598,720,000,000 adults. Fortunately, living forms do not produce
in any such mathematical manner and the chief value of the figures
is to illustrate the enormous struggle for existence which is con-
stantly taking place in nature.
Flies may travel for a considerable distance to reach food and
shelter, though normally they pass to dwellings and other sources
of food supply in the immediate neighborhood of their breeding
places. Copeman, Howlett and Merriman (1911) marked flies by
shaking them in a bag containing colored chalk. Such flies were °
repeatedly recovered at distances of eight to one thousand yards
and even at a distance of seventeen hundred yards, nearly a mile.
Hindle and Merriman (1914) continued these experiments on a
large scale at Cambridge, England. They ‘“‘do not think it likely
that, as a rule, flies travel more than a quarter of a mile in thickly-
housed areas.’’ In one case a single fly was recovered at a distance
of 770 yards but a part of this distance was across open fen-land.
The surprising fact was brought out that flies tend to travel either
against or across the wind. The actual direction followed may be
determined either directly by the action of the wind (positive anemo-
tropism), or indirectly owing to the flies being attracted by any odor
that it may convey from a source of food. They conclude that it is
likely that the chief conditions favoring the disposal of flies are fine
weather and a warm temperature. The nature of the locality is
another considerable factor. Hodge (1913) has shown that when
aided by the wind they may fly to much greater distances over the
water. He reports that at Cleveland, Ohio, the cribs of the water
works, situated a mile and a quarter, five miles, and six miles out in
Lake Erie are invaded by a regular plague of flies when the wind
blows from the city. Investigation showed that there was absolutely
nothing of any kind in which flies could breed on the crib.
The omnivorous habits of the house-fly are matters of everyday
observation. From our view point, it is sufficient to emphasize
150 Arthropods as Simple Carriers of Disease
that from feeding on excrement, on sputum, on open sores, or on
putrifying matter, the flies may pass to the food or milk upon the table
or to healthy mucous membranes, or uncontaminated wounds.
There is nothing in its appearance to tell whether the fly that comes
blithely to sup with you is merely unclean, or whether it has just
finished feeding upon dejecta teeming with typhoid bacilli.
109. Pulvillus of foot of house-fly, showing glandular hairs.
The method of feeding of the house-fly has an important bearing
on the question of its ability to transmit pathogenic organisms.
Graham-Smith (1910) has shown that when feeding, flies frequently
moisten soluble substances with ‘‘vomit”’ which is regurgitated from
the crop. This is, of course, loaded with bacteria from previous
food. When not sucked up again these drops of liquid dry, and pro-
duce round marks with an opaque center and rim and an intervening
less opaque area. Fly-specks, then, consist of both vomit spots
and feces. Graham-Smith shows a photograph of a cupboard window
where, on an area six inches square, there were counted eleven hundred
and two vomit marks and nine fecal deposits.
The House-fly as a Carrier of Disease 151
From a bacteriologist’s viewpoint a discussion of the possibility
of a fly’s carrying bacteria would seem superfluous. Any exposed
object, animate or inanimate, is contaminated by bacteria and will
transfer them if brought into contact with suitable culture media,
whether such substance be food, or drink, open wounds, or the sterile
culture media of the laboratory. A needle point may convey enough
germs to produce disease. Much more readily may the house-fly
with its covering of hairs and its sponge-like pulvilli (fig. 109) pick
up and transfer bits of filth and other contaminated material.
For popular instruction this inevitable transfer of germs by the
house-fly is strikingly demonstrated by the oft copied illustration
of the tracks of a fly on a sterile culture plate. Two plates of gela-
tine or, better, agar medium are prepared. Over one of these a fly
(with wings clipped) is allowed to walk, the other is kept as a check.
Both are put aside at room temperature, to be examined after twenty-
four to forty-eight hours. At the end of that time, the check plate
is as clear as ever, the one which the fly has walked is dotted with
colonies of bacteria and fungi. The value in the experiment consists
in emphasizing that by this method we merely render visible what is
constantly occurring in nature.
A comparable experiment which we use in our elementary labora-
tory work is to take three samples of clean (preferably, sterile) fresh
milk in sterile bottles. One of them is plugged with a pledget of
cotton, into the second is dropped a fly from the laboratory and into
the third is dropped a fly which has been caught feeding upon gar-
bage or other filth. After a minute or two the flies are removed and
the vials plugged as was number one. The three are then set aside
at room temperature. When examined after twenty-four hours
the milk in the first vial is either still sweet or has a‘‘clean”’ sour odor;
that of the remaining two is very different, for it has a putrid odor,
which is usually more pronounced in the case of sample number
three.
Several workers have carried out experiments to determine the
number of bacteria carried by flies under natural conditions. One
of the most extended and best known of these is the series by Esten
and Mason (1908). These workers caught flies from various sources
in a sterilized net, placed them in a sterile bottle and poured over
them a known quantity of sterilized water, in which they were shaken
so as to wash the bacteria from their bodies. They found the number
of bacteria on a single fly to range from 550 to 6,600,000. Early in
152 Arthropods as Simple Carriers of Disease
the fly season the numbers of bacteria on flies are comparatively
small, while later the numbers are comparatively very large. The
place where flies live also determines largely the numbers that they
carry. The lowest number, 550, was from a fly caught in the
bacteriological laboratory, the highest number, 6,600,000 was the
average from eighteen swill-barrel flies. Torrey (1912) made exami-
nation of ‘wild’ flies from a tenement house district of New York
City. He found “that the surface contamination of these ‘wild’
flies may vary from 570 to 4,400,000 bacteria per insect, and the
intestinal bacterial content from 16,000 to 28,000,000.”
Less well known in this country is the work of Cox, Lewis, and
Glynn (1912). They examined over four hundred and fifty naturally
infected house-flies in Liverpool during September and early October.
Instead of washing the flies they were allowed to swim on the surface
of sterile water for five, fifteen, or thirty minutes, thus giving natural
conditions, where infection occurs from vomit and dejecta of the
flies, as well as from their bodies. They found, as might be expected,
that flies from either insanitary or congested areas of the city contain
far more bacteria than those from the more sanitary, less congested,
or suburban areas. The number of aerobic bacteria from the former
varied from 800,000 to 500,000,000 per fly and from the latter from
21,000 to 100,000. The number of intestinal forms conveyed by
fliesfrom insanitary or congested areas was from 10,000 to 333,000,000
as compared with from 100 to 10,000 carried by flies from the more
sanitary areas.
Pathogenic bacteria and those allied to the food poisoning group
were only obtained from the congested or moderately congested
areas and not from the suburban areas, where the chances of infesta-
tion were less.
The interesting fact was brought out that flies caught in milk
shops apparently carry and obtain more bacteria than those from
other shops with exposed food in a similar neighborhood. The
writers explained this as probably due to the fact that milk when
accessible, especially during the summer months, is suitable culture
medium for bacteria, and the flies first inoculate the milk and later
reinoculate themselves, and then more of the milk, so establishing a
vicious circle.
They conclude that in cities where food is plentiful flies rarely
migrate from the locality in which they are bred, and consequently
the number of bacteria which they carry depends upon the general
The House-fly as a Carrier of Disease 153
standard of cleanliness in that locality. Flies caught in a street of
modern, fairly high class, workmen’s dwellings forming a sanitary
oasis in the midst of a slum area, carried far less bacteria than those
caught in the adjacent neighborhood.
Thus, as the amount of dirt carried by flies in any particular
locality, measured in the terms of bacteria, bears a definite relation
to the habits of the people and to the state of the streets, it demon-
strates the necessity of efficient municipal and domestic cleanliness,
if the food of the inhabitants is to escape pollution, not only with
harmless but also with occasional pathogenic bacteria.
The above cited work is of a general nature, but, especially in
recent years, many attempts have been made to determine more
specifically the ability of flies to transmit pathogenic organisms.
The critical reviews of Nuttall and Jepson (1909), Howard (1911),
and Graham-Smith (1913) should be consulted by the student of
the subject. We can only cite here a few of the more striking experi-
ments.
Celli (1888) fed flies on pure cultures of Bacillus typhosus and de-
clared that he was able to recover these organisms from the intestinal
contents and excrement.
Firth and Horrocks (1902), cited by Nuttall and Jepson, ‘‘kept
Musca domestica (also bluebottlés) in a large box measuring 4 x 3 x 3
feet, with one side made of glass. They were fed on material
contaminated with cultures of B. typhosus. Agar plates, litmus,
glucose broth and a sheet of clean paper were at the same time
exposed in the box. After a few days the plates and broth were
removed and incubated with a positive result.” Graham-Smith
(1910) ‘‘carried out experiments with large numbers of flies kept
in gauze cages and fed for eight hours on emulsions of B. typhosus
in syrup. After that time the infested syrup was removed and the
flies were fed on plain syrup. B. typhosus was isolated up to 48
hours (but not later) from emulsions of their feces and from plates
over which they walked.”
Several other workers, notably Hasilton (1903), Ficker (1903),
Bertarelli (1910) Faichnie (1909), and Cochrane (1912), have iso-
lated B. typhosus from “wild” flies, naturally infected. The papers
of Faichnie and of Cochrane we have not seen, but they are quoted
in extenso by Graham-Smith (1913).
On the whole, the evidence is conclusive that typhoid germs not
only may be accidentally carried on the bodies of house-flies but
154 Arthropods as Simple Carriers of Disease
may pass through their bodies and be scattered in a viable condition
in the feces of the fly for at least two days after feeding. Similar,
results have been reached in experiments with cholera, tuberculosis
and yaws, the last-mentioned being a spirochete disease. Darling
(1913) has shown that murrina, a trypanosome disease of horses
and mules in the Canal zone is transmitted by house-flies which feed
tupon excoriated patches of diseased animals and then pass to cuts
and galls of healthy animals.
Since it is clear that flies are abundantly able to disseminate
viable pathogenic bacteria, it is important to consider whether they
have access to such organisms in nature. A consideration of the
method of spread of typhoid will serve to illustrate the way in which
flies may play an important réle.
Typhoid fever is a specific disease caused by Bacillus typhosus,
and by it alone. The causative organism is to be found in the excre-
ment and urine of patients suffering from the disease. More than
that, it is often present in the dejecta for days, weeks, or even months
and years, after the individual has recovered from the disease.
Individuals so infested are known as “typhoid carriers’’ and they,
together with those suffering from mild cases, or ‘walking typhoid,”
are a constant menace to the health of the community in which they
are found.
Human excrement is greedily visited by flies, both for feeding and
for ovipositing. The discharges of typhoid patients, or of chronic
“carriers,” when passed in the open, in box privies, or camp latrines,
or the like, serve to contaminate myriads of the insects which may
then spread the germ to human food and drink. Other intestinal
diseases may be similarly spread. There is abundant epidzmiologi-
cal evidence that infantile diarrhoea, dysentery, and cholera may be
so spread.
Stiles and Keister (1913) have shown that spores of Lamblia
intestinalis, a flagellate protozoan living in the human intestine,
may be carried by house-flies. Though this species is not normally
pathogenic, one or more species of Entameba are the cause of a type
of a highly fatal tropical dysentery. Concerning it, and another
protozoan parasite of man, they say, “If flies can carry Lamblia
spores measuring 10 to 7y, and bacteria that are much smaller, and
particles of lime that are much larger, there is no ground to assume
that flies may not carry Eniameba and Trichomonas spores.
The House-fly as a Carrier of Disease I55
Tuberculosis is one of the diseases which it is quite conceivable
may be carried occasionally. The sputum of tubercular patients
is very attractive to flies, and various workers, notably Graham-
Smith, have found that Musca domestica may distribute the bacillus
for several days after feeding on infected material.
A type of purulent opthalmia which is very prevalent in Egypt
is often said to be carried by flies. Nuttall and Jepson (1909)
consider that the evidence regarding the spread of this disease by
flies is conclusive and that the possibility of gonorrhceal secretions
being likewise conveyed cannot be denied.
Many studies have been published, showing a marked agreement
between the occurrence of typhoid and other intestinal diseases
and the prevalence of house-flies. The most clear-cut of these are
the studies of the Army Commission appointed to investigate the
cause of epidemics of enteric fever in the volunteer camps in the
Southern United States during the Spanish-American War. Though
their findings as presented by Vaughan (1909), have been quoted
very many times, they are so germane to our discussion that they
will bear repetition:
“Flies swarmed over infected fecal matter in the pits and fed
upon the food prepared for the soldiers in the mess tents. In some
instances where lime had recently been sprinkled over the contents
of the pits, flies with their feet whitened with lime were seen walking
over the food.’”” Under such conditions it is no wonder that ‘‘ These
pests had inflicted greater loss upon American soldiers than the arms
of Spain.”
Similar conditions prevailed in South Africa during the Boer War.
Seamon believes that very much of the success of the Japanese in
their fight against Russia was due to the rigid precautions taken to
prevent the spread of disease by these insects and other means.
Veeder has pointed out that the characteristics of a typical fly-
borne epidemic of typhoid are that it occurs in little neighborhood
epidemics, extending by short leaps from house to house, without
regard to water supply or anything else in common. It tends to
follow the direction of prevailing winds (cf. the conclusions of Hindle
and Merriman). It occurs during warm weather. Of course, when
the epidemic is once well under way, other factors enter into its spread.
In general, flies may be said to be the chief agency in the spread of
typhoid in villages and camps. In cities with modern sewer systems
they are less important, though even under the best of such condi-
156 Arthropods as Simple Carriers of Disease
tions, they are important factors. Howard has emphasized that in
such cities there are still many uncared-for box privies and that, in
addition, the deposition of feces overnight in uncared-for waste lots
and alleys is common.
Not only unicellular organisms, such as bacteria and protozoa,
but also the eggs, embryos and larvee of parasitic worms have been
found to be transported by house-flies. Ransom (1911) has found
that Habronema musce, a nematode worm often found in adult flies,
is the immature stage of a parasite occurring in the stomach of the
horse. The eggs or embryos passing out with the feces of the horse,
are taken up by fly larve and carried over to the imago stage.
Grassi (1883), Stiles (1889), Calandruccio (1906), and especially
Nicoll (1911), have been the chief investigators of the ability of
house-flies to carry the ova and embryos of human intestinal parasites.
Graham-Smith (1913) summarizes the work along this line as follows:
“Tt is evident from the investigations that have been quoted that
house-flies and other species are greatly attracted to the ova of
parasitic worms contained in feces and other materials, and make
great efforts to ingest them. Unless the ova are too large they often
succeed, and the eggs are deposited uninjured in their feces, in some
cases up to the third day at least. The eggs may also be carried on
their legs or bodies. Under suitable conditions, food and fluids
may be contaminated with the eggs of various parasitic worms by flies,
and in one case infection of the human subject has been observed.
Feces containing tape-worm segments may continue to be a source of
infection for as long as a fortnight. Up to the present, however,
there is no evidence to show what part flies play in the dissemination
of parasitic worms under natural conditions.”’
Enough has been said to show that the house-fly must be dealt
with as a direct menace to public health. Control measures are
not merely matters of convenience but are of vital importance.
Under present conditions the speedy elimination of the house-fly
is impossible and the first thing to be considered is methods of pro-
tecting food and drink from contamination. The first of these
methods is the thorough screening of doors and windows to prevent
the entrance of flies. Inthe case of kitchen doors, the flies, attracted
by odors, are likely to swarm onto the screen and improve the first
opportunity for gaining an entrance. This difficulty can be largely
avoided by screening-in the back porch and placing the screen door
at one end rather than directly before the door.
The House-fly as a Carrier of Disease 157
The use of sticky fly paper to catch the pests that gain entrance
to the house is preferable to the various poisons often used. Of the
latter, formalin (40 per cent formaldehyde) in the proportion of two
tablespoonfuls to a pint of water is very efficient, if all other liquids
are removed or covered, so that the flies must depend on the formalin
for drink. The mixture is said to be made more attractive by the
addition of sugar or milk, though we have found the plain solution
wholly satisfactory, under proper conditions. It should be em-
phasized that this formalin mixture is not perfectly harmless, as so
often stated. There are on record cases of severe and even fatal
poisoning from the accidental drinking of solutions.
When flies are very abundant in a room they can be most readily
gotten rid of by fumigation with sulphur, or by the use of pure
pyrethrum powder either burned or puffed into the air. Herrick
(1913) recommends the following method: ‘‘At night all the doors
and windows of the kitchen should be closed; fresh powder should
be sprinkled over the stove, on the window ledges, tables, and in the
air. In the morning flies will be found lying around dead or stupified.
They may then be swept up and burned.” This method has proved
very efficaceous in some of the large dining halls in Ithaca.
The writers have had little success in fumigating with the vapors
of carbolic acid, or carbolic acid and gum camphor, although these
methods will aid in driving flies from a darkened room.
All of these methods are but makeshifts. As Howard has so well
put it, “‘the truest and simplest way of attacking the fly problem
is to prevent them from breeding, by the treatment or abolition of
all places in which they can breed. To permit them to breed un-
disturbed and in countless numbers, and to devote all our energy to
the problem of keeping them out of our dwellings, or to destroy them
after they have once entered in spite of all obstacles, seems the
wrong way to go about it.”
We have already seen that Musca domestica breeds in almost any
fermenting organic material. While it prefers horse manure, it
breeds also in human feces, cow dung and that of other animals,
and in refuse of many kinds. To efficiently combat the insect,
these breeding places must be removed or must be treated in some
such way as to render them unsuitable for the development of the
larve. Under some conditions individual work may prove effective,
but to be truly efficient there must be extensive and thorough co-
operative efforts. :
158 Arthropods as Simple Carriers of Disease
Manure, garbage, and the like should be stored in tight receptacles
and carted away at least once a week. The manure may be carted
to the fields and spread. Even in spread manure the larve may con-
tinue their development. Howard points out that ‘‘it often happens
that after a lawn has been heavily manured in early summer the
occupants of the house will be pestered with flies for a time, but
finding no available breeding place these disappear sooner or later.
Another generation will not breed in the spread manure.”
Hutchinson (1914) has emphasized that the larve of house-
flies have deeply engrained the habit of migrating in the prepupal
stage and has shown that this offers an important point of attack
in attempts to control the pest. He has suggested that maggot
traps might be developed into an efficient weapon in the warfare
against the house-fly. Certain itis that thehabit greatly simplifies the
problem of treating the manure for the purpose of killing the larve.
There have been many attempts to find some cheap chemical
which would destroy fly larve in horse manure without injuring the
bacteria or reducing the fertilizing values of the manure. The litera-
ture abounds in recommendations of kerosene, lime, chloride of lime,
iron sulphate, and other substances, but none of them have met the
situation. The whole question has been gone into thoroughly by
Cook, Hutchinson and Scales (1914), who tested practically all of the
substances which have been recommended. They find that by far
the most effective, economical, and practical of the substances is
borax in the commercial form in which it is available throughout the
country.
“Borax increases the water-soluble nitrogen, ammonia and alkali-
nity of manure and apparently does not permanently injure the
bacterial flora. The application of manure treated with borax at the
rate of 0.62 pound per eight bushels (10 cubic feet) to soil does not
injure the plants thus far tested, although its cumulative effect, if
any, has not been determined.”
As their results clearly show that the substances so often recom-
mended are inferior to borax, we shall quote in detail their directions
for treating manure:so as to kill fly eggs and maggots.
“Apply 0.62 pound borax or 0.75 pound calcined colemanite to
every ro cubic feet (8 bushels) of manure immediately on its removal
from the barn. Apply the borax particularly around the outer
edges of the pile with a flour sifter or any fine sieve, and sprinkle two
or three gallons of water over the borax-treated manure.
The House-fly as a Carrier of Disease 159
“The reason for applying the borax to the fresh manure immedi-
ately after its removal from the stable is that the flies lay their eggs
on the fresh manure, and borax, when it comes in contact with the
eggs, prevents their hatching. As the maggots congregate at the
outer edge of the pile, most of the borax should be applied there.
The treatment should be repeated with each addition of fresh manure,
but when the manure is kept in closed boxes, less frequent applica-
tions will be sufficient. When the calcined colemanite is available,
“at may be used at the rate of 0.75 pound per ro cubic feet of manure,
and is a cheaper means of killing the maggots. In addition to the
application of borax to horse manure to kill fly larve, it may be
applied in the same proportion to other manures, as well as to refuse -
and garbage. Borax may also be applied to the floors and crevices in
barns, stables, markets, etc., as well as to street sweepings, and water
should be added as in the treatment of horse manure. After estimat-
ing the amount of material to be treated and weighing the necessary
amount of borax, a measure may be used which will hold the proper
arrount, thus avoiding the subsequent weighings.
‘While it can be safely stated that no injurious action will follow
the application of manure treated with borax at the rate of 0.62
pound for eight bushels, or even larger amounts in the case of some
plants, nevertheless the borax-treated manure has not been studied
in connection with the growth of all crops, nor has its cumulative
effect been determined. It is therefore recommended that not more
than 15 tons per acre of the borax-treated manure should be applied
to the field. As truckmen use considerably more than this amount,
it is suggested that all cars containing borax-treated manure be so
marked, and that public-health officials stipulate in their directions
for this treatment that not over 0.62 pound for eight bushels of manure
be used, as it has been shown that larger amounts of borax will
injure most plants: It is also recommended that all public-health
officials and others, in recommending the borax treatment for kill-
ing fly eggs and maggots in manure, warn the public against the
injurious effects of large amounts of borax on the growth of plants.”’
“The amount of manure from a horse varies with the straw or
other bedding used, but 12 or 15 bushels per week represent the
approximate amount obtained. As borax costs from five to six
cents per pound in roo-pound lots in Washington, it will make the
cost of the borax practically one cent per horse, per day. And if
calcined colemanite is purchased in large shipments the cost should
be considerably less.”
160 Arthropods as Simple Carriers of Disease
Hodge (1910) has approached the problem of fly extermination
from another viewpoint. He believes that it is practical to trap
flies out of doors during the preoviposition period, when they are
sexually immature, and to destroy such numbers of them that the
comparatively few which survive will not be able to lay eggs in suffi-
cent numbers to make the next generation a nuisance. To the end
of capturing them in enormous numbers he has devised traps to be
fitted over garbage cans, into stable windows, and connected with the
kitchen window screens. Under some conditions this method of
attack has proved very satisfactory.
One of the most important measures for preventing the spread
of disease by flies is the abolition of the common box privy.. In
villages and rural districts this is today almost the only type to be
found. It is the chief factor in the spread of typhoid and other
intestinal diseases, as well as intestinal parasites. Open and ex-
posed to myriads of flies which not only breed there but which feed
upon the excrement, they furnish ideal conditions for spreading con-
tamination. Even where efforts are made to cover the contents
with dust, or ashes, or lime, flies may continue to breed unchecked.
Stiles and Gardner have shown that house-flies buried in a screened
stand-pipe forty-eight inches under sterile sand came to the surface.
Other flies of undetermined species struggled up through seventy-
two inches of sand.
So great is the menace of the ordinary box privy that a number of
inexpensive and simple sanitary privies have been designed for use
where there are not modern sewer systems. Stiles and Lumsden
(1911) have given minute directions for the construction of one of the
best types, and their bulletin should be obtained by those interested.
Another precaution which is of fundamental importance in
preventing the spread of typhoid, is that of disinfecting all discharges
from patients suffering with the disease. For this purpose, quick-
lime is the cheapest and is wholly satisfactory. In chamber vessels
it should be used in a quantity equal to that of the discharge to be
treated. It should be allowed to act for two hours. Air-slaked
lime is of no value whatever. Chloride of lime, carbolic acid, or
formalin may be used, but are more expensive. Other intestinal
diseases demand similar precautions.
Stomoxys calcitrans, the stable-fly—It is a popular belief that
house-flies bite more viciously just before a rain. As a matter of
Stomoxys calcitrans, the Stable-fly 161
fact, the true house-flies never bite, for their mouth-parts are not
fitted for piercing. The basis of the misconception is the fact that a
true biting fly, Stomoxys calcitrans (fig. 110), closely resembling the
house-fly, is frequently found in houses and may be driven in in
greater numbers by muggy weather. From its usual habitat this
fly is known as the ‘‘stable-fly” or, sometimes as the “biting house-
fly.”
Stomoxys calcitrans may be separated from the house-fly by the use
of the key on p. 145. It may be more fully characterized as follows:
The eyes of the male are separated by a distance equal to one-
fourth of the diameter of the head, in the female by one-third. The
110. Stomoxys calcitrans; adult, larva, puparium and details, (xs). After Howard.
frontal stripe is black, the cheeks and margins of the orbits silvery-
white. The antenne are black, the arista feathered on the upper
side only. The proboscis is black, slender, fitted for piercing and
projects forward in front of the head. The thorax is grayish, marked
by four conspicuous, more or less complete black longitudinal stripes;
the scutellum is paler; the macrochetz are black. The abdomen is
gray, dorsally with three brown spots on the second and third seg-
ments and a median spot on the fourth. These spots are more
pronounced in the female. The legs are black, the pulvilli distinct.
The wings are hyaline, the vein M:+z2 less sharply curved -than in
the house-fly, the apical cell being thus more widely open (cf. fig.
z10). Length 7 mm.
This fly is widely distributed, being found the world over. It was
probably introduced into the United States, but has spread to all
162 Arthropods as Simple Carriers of Disease
parts of the country. Bishopp (1913) regards it as of much more
importance as a pest of domestic animals in the grain belt than else-
where in the United States. The life-history and habits of this
species have assumed a new significance since it has been suggested
that it may transmit the human diseases, infantile paralysis and
pellagra. In this country, the most detailed study of the fly is that
of Bishopp (1913) whose data regarding the life cycle are as follows:
The eggs like those of the house-fly, are about one mm.
‘in length. Under a magnifying glass they show a distinct furrow
along one side. When placed on any moist substance they hatch
in from one to three days after being deposited.
The larve or maggots (fig. 110) have the typical shape and actions
of most maggots of the Muscid group. They can be distinguished
from those of the house-fly as the stigma-plates are smaller, much
further apart, with the slits less sinuous. Development takes place
fairly rapidly when the proper food conditions are available and
the growth is completed within eleven to thirty or more days.
The pupa (fig. 110), like that of related flies, undergoes its develop-
ment within the contracted and hardened last larval skin, or pu-
parium. This is elongate oval, slightly thicker towards the head end,
and one-sixth to one-fourth of an inch in length. The pupal stage
requires six to twenty days, or in cool weather considerably longer.
The life-cycle of the stable-fly is therefore considerably longer
than that of Musca domestica. Bishopp found that complete
development might be undergone in nineteen days, but that the
average period was somewhat longer, ranging from twenty-one to
twenty-five days, where conditions are very favorable. The longest
period which he observed was forty-three days, though his finding
of full grown larve and pupe in straw during the latter part of
March, in Northern Texas, showed that development may require
about three morths, as he considered that these stages almost cer-
tainly developed from eggs deposited the previous December.
The favorite breeding place, where available, seems to be straw or
manure mixed with straw. It also breeds in great numbers in horse-
manure, in company with Musca domestica.
Newstead considers that in England the stable-fly hibernates in
the pupal stage. Bishopp finds that in the southern part of the
United States there is no true hibernation, as the adults have been
found to emerge at various times during the winter. He believes
that in the rorthern United States the winter is normally passed
Other Arthropods as Simple Carriers 163
in the larval and pupal stages, and that the adults which have been
observed in heated stables in the dead of winter were bred out in
refuse within the warm barns and were not hibernating adults.
Graham-Smith (1913) states that although the stable-fly fre-
quents stable manure, it is probably not an important agent in
distributing the organisms of intestinal diseases. Bishopp makes the
important observation that ‘it has never been found breeding in
human excrement and does not frequent malodorous places, which
are so attractive to the house-fly. Hence it is much less likely to
carry typhoid and other germs which may be found in such places.”’
Questions of the possible agency of Stomoxys calcitrans inthe trans-
mission of infantile paralysis and of pellagra, we shall consider later.
Other arthropods which may serve as simple carriers of patho-
genic organisms—It should be again emphasized that any insect which
has access to, and comes in contact with, pathogenic organisms
and then passes to the food, or drink, or the body of man, may serve
as a simple carrier of disease. In addition to the more obvious
illustrations, an interesting one is the previously cited case of the
transfer of Dermatobia cyaniventris by a mosquito (fig. 81-84).
Darling (1913) has shown that in the tropics, the omnipresent ants
may be important factors in the spread of disease.
CHAPTER VI
ARTHROPODS AS DIRECT INOCULATORS OF DISEASE GERMS
We have seen that any insect which, like the house-fly, has access
to disease germs and then comes into contact with the food or drink
of man, may serve to disseminate disease. Moreover, it has been
clearly established that a contaminated insect, alighting upon
wounded or abraded surfaces, may infect them. These are instances
of mere accidental, mechanical transfer of pathogenic organisms.
Closely related are the instances of direct inoculation of disease
germs by insects and other arthropods. In this type, a blood-
sucking species not only takes up the germs but, passing to a healthy
individual, it inserts its contaminated mouth-parts and thus directly
inoculates its victim. In other words, the disease is transferred
just as blood poisoning may be induced by the prick of a contami-
nated needle, or as the laboratory worker may inoculate an experi-
mental animal.
Formerly, it was supposed that this method of the transfer of
disease by arthropods was a very common one and many instances
are cited in the earlier literature of the subject. It is, however,
difficult to draw a sharp line between such cases and those in which,
on the one hand, the arthropod serves as a mere passive carrier or,
on the other hand, serves as an essential host of the pathogenic
organism. More critical study of the subject has led to the belief
that the importance of the réle of arthropods as direct inoculators
has been much overestimated.
The principalreason for regarding this phase of the subject as
relatively unimportant, is derived from a study of the habits of the
blood-sucking species. It is found that, in general, they are inter-
mittent feeders, visiting their hosts at intervals and then abstaining
from feeding for a more or less extended period, while digesting their
meal. In the meantime, most species of bacteria or of protozoan
parasites with which they might have contaminated their mouth-
parts, would have perished, through inability to withstand drying.
In spite of this, it must be recognized that this method of transfer
does occur and must be reckoned with in any consideration of the
relations of insects to disease. We shall first cite some general
illustrations and shall then discuss the réle of fleas in the spreading
of bubonic plague, an illustration which cannot be regarded as typi-
cal, since it involves more than mere passive carriage.
Some Illustrations of Direct Inoculation 165
Some IL.Lustrations or Direct INocuLATION oF DisEASE GERMS
By ARTHROPODS
In discussing poisonous arthropods, we have already emphasized
that species which are of themselves innocuous to man, may occasion-
ally introduce bacteria by their bite or sting and thus cause more or
less severe secondary symptoms. That such cases should occur, is
no more than is to be expected. The mouth-parts or the sting of
the insect are not sterile and the chances of their carrying pyogenic
organisms are always present..
More strictly falling in the category of transmission of disease
germs by direct inoculation are the instances where the insect, or
related form, feeds upon a diseased animal and passes promptly to a
healthy individual which it infects. Of such a nature are the follow-
ing:
Various species of biting flies are factors in the dissemination of
anthrax, an infectious and usually fatal disease of animals and,
occasionally, of man. That the bacteria with which the blood of
diseased animals teem shortly before death might be transmitted
by such insects has long been contended, but the evidence in support
of the view has been unsatisfactory. Recently, Mitzmain (1914)
has reported a series of experiments which show conclusively that the
disease may be so conveyed by a horse-fly, Tabanus striatus, and by
the stable-fly, Stomoxys calcttrans.
Mitzmain’s experiments were tried with an artificially infected
guinea pig, which died of the disease upon the third day. The flies
were applied two and one-half hours, to a few minutes, before the
death of the animal. With both species the infection was success-
fully transferred to healthy guinea pigs by the direct method, in
which the flies were interrupted while feeding on the sick animal.
The evidence at hand does not warrant the conclusion that insect
transmission is the rule in the case of this disease.
The nagana, or tsetse-fly disease of cattle is the most virulent
disease of domestic animals in certain parts of Africa. It is caused
by a protozoan blood parasite, Trypanosoma brucei, which is con-
veyed to healthy animals by the bite of Glossina morsitans and possi-
bly other species of tsetse-flies. The flies remain infective for
forty-eight hours after feeding on a diseased animal. The insect
also serves as an essential host of the parasite.
Surra, a similar trypanosomiasis affecting especially horses and
mules, occurs in southern Asia, Malaysia, and the Philippines where
166 Arthropods as Direct Inoculators of Disease Germs
the tsetse-flies are not to be found. It is thought to be spread by
various species of blood-sucking flies belonging to the genera Stomoxys,
Hematobia, and Tabanus. Mitzmain (1913) demonstrated that in
the Philippines it is conveyed mechanically by Tabanus striatus.
The sleeping sickness of man, in Africa, has also been supposed
to be directly inoculated by one, or several, species of tsetse-flies.
It is now known that the fly may convey the disease for a short
time after feeding, but that there is then a latent period of from
fourteen to twenty-one days, after which it again becomes infectious.
This indicates that in the meantime the parasite has been under-
going some phase of its life-cycle and that the fly serves as an inter-
mediate host. We shall therefore consider it more fully under that
grouping.
These are a few of the cases of direct inoculation which may be
cited as of the simpler type. We shall next consider the réle of the
flea in the dissemination of the bubonic plague, an illustration
complicated by the fact that the bacillus multiples within the insect
and may be indirectly inoculated.
Tue ROLE or FLEAS IN THE TRANSMISSION OF THE PLAGUE
The plague is a specific infectious disease caused by Bacillus pestis.
It occurs in several forms, of which the bubonic and the pneumonic
are the most common. According to Wyman, 80 per cent df the
human cases are of the bubonic type. It is a disease which, under
the name of oriental plague, the pest, or the black death, has ravaged
almost from time immemorial the countries of Africa, Asia, and
Europe. The record of its ravages are almost beyond belief. In 542
A. D. it caused in one day ten thousand deaths in Constantinople.
In the r4th century it was introduced from the East and prevailed
throughout Armenia, Asia Minor, Egypt and Northern Africa and
Europe. Hecker estimates that one-fourth of the population of
Europe, or twenty-five million persons, died in the epidemic of that
century. From then until the 17th century it was almost constantly
present in Europe, the great plague of London, in 1665 killing 68,596
out of a population of 460,000. Such an epidemic would mean for
New York City a proportionate loss of over 600,000 in a single year.
It is little wonder that in the face of such an appalling disaster sus-
picion and credulity were rife and the wildest demoralization ensued.
During the 14th century the Jews were regarded as responsible
for the disease, through poisoning wells, and were subjected to the
Réle of Fleas in the Transmission of Plague 167
111. A contemporaneous engraving of the pest hospital in Vienna in 1679,
After Peters.
most incredible persecution and torture. In Milan the visitation
of 1630 was credited to the so-called anointers,—men who were
supposed to spread the plague by anointing the walls with magic
ointment—and the most horrible tortures that human ingenuity
could devise were imposed on scores of victims, regardless of rank
or of public service (fig. 112,a). Manzoni’s great historical novel,
“The Betrothed”’ has well pictured conditions in Italy during this
period.
In modern times the plague is confined primarily to warm climates,
a condition which has been brought about largely through general
improvement in sanitary conditions.
At present, the hotbed of the disease is India, where there were
1,040,429 deaths in 1904 and where in a period of fifteen years,
ending with January 1912, there were over 15,000,000 deaths. The
reported deaths in that country for 1913 totaled 198,875.
During the winter of 1910-11 there occurred in Manchuria and
North China a virulent epidemic of the pneumonic plague which
caused the death of nearly 50,000 people. The question as to its
origin and means of spread will be especially referred to later.
Until recent years, the plague had not been known to occur in
the New World but there were outbreaks in Brazil and Hawaii in
1899, and in 1900 there occurred the first cases in San Francisco.
Arthropods as Direct Inoculators of Disease Germs
168
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‘anaeld ay} BuljequrIod jo poyjel [eAdIpsu VW
OLOI Ul UEP UI SIazUIOUe ayy Jo UOIyNoesIOd ay],
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Réle of Fleas in the Transmission of Plague 169
In California there were 125 cases in the period 1900-04; three cases
in the next three years and then from May 1907 to March 1908,
during the height of the outbreak, 170 cases. Since that time there
have been only sporadic cases, the last case reported being in May
t914. Still more recent were the outbreaks in the Philippine Islands,
Porto Rico, and Cuba.
On June 24, 1914, there was recognized a case of human plague
in New Orleans. The Federal Health Service immediately took
charge,and measures for the eradication of the disease were vigor-
ously enforced. Up to Otcober 10, 1914 there had been reported
30 cases of the disease in man, and 181 cases of plague in rats.
112b. The modern method of combating the plague. A day’s catch of rats in the fight
against plague in San Francisco. Courtesy of Review of Reviews.
The present-day methods of combating bubonic plague are well
illustrated by the fight in San Francisco. Had it not been for the
strenuous and radical anti-plague campaign directed by the United
States Marine Hospital Service we might have had in our own
country an illustration of what the disease can accomplish. On what
newly acquired knowledge was this fight based?
The basis was laid in 1894, when the plague bacillus was first
discovered. All through the centuries, before and during the Christian
era, down to 1894, the subject was enveloped in darkness and there
had been a helpless, almost hopeless struggle in ignorance on the part
of physicians, sanitarians, and public health officials against the
ravages of this dread disease, Now its cause, method of propaga-
tion and means to prevent its spread are matters of scientific cer-
tainty.
170 Arthropods as Direct Inoculators of Disease Germs
After the discovery of the causative organism, one of the first.
advances was the establishment of the identity of human plague
and that of rodents. It had often been noted that epidemics of the
human disease were preceded by great epizootics among rats and
mice. So well established was this fact that with the Chinese,
unusual mortality among these rodents was regarded as foretelling
a visitation of the human disease. That there was more than an
accidental connection between the two was obvious when Yersin,
the discoverer of Bacillus pestis,announced that during an epidemic
the rats found dead in the houses and in the streets almost always
contain the bacillus in great abundance in their organs, and that many
of them exhibit veritable buboes.
Once it was established that the diseases were identical, the atten-
tion of the investigators was directed to a study of the relations
between that of rats and of humans, and evidence accumulated to
show that the bubonic plague was primarily a disease of rodents
and that in some manner it was conveyed from them to man.
There yet remained unexplained the method of transfer from rat
to man. As long ago as the 16th century, Mercuralis suggested
that house-flies were guilty of disseminating the plague but modern
investigation, while blaming the fly for much in the way of spreading
disease, show that it is an insignificant factor in this case.
Search for blood-sucking insects which would feed on both rodents
and man, and which might therefore be implicated, indicated that
the fleas most nearly met the conditions. At first it was urged that
rat fleas would not feed upon man and that the fleas ordinarily attack-
ing man would not feed upon rats. More critical study of the habits
of fleas soon showed that these objections were not well-founded.
Especially important was the evidence that soon after the death of
their host, rat fleas deserted its body and might then become a pest
in houses where they had not been noticed before.
Attention was directed to the fact that while feeding, fleas are in
the habit of squirting blood from the anus and that in the case of those
which had fed upon rats and mice dying of the plague, virulent plague
bacilli were to be found in such blood. Liston (1905) even found,
and subsequent investigations confirmed, that the plague bacilli
multiply in the stomach of the insect and that thus the blood ejected
was richer in the organisms than was that of the diseased animal.
It was found that a film of this infected blood spread out under the
body of the flea and that thus the bacilli might be inoculated by the
bite of the insect and by scratching.
Réle of Fleas in the Transmission of Plague 171
Very recently, Bacot and Martin (1914) have paid especial
attention to the question of the mechanism of the transmission of
the plague bacilli by fleas. They believe that plague infested fleas
regurgitate blood through the mouth, and’ that under conditions
precluding the possibility of infection by dejecta, the disease may be
thus transmitted. The evidence does not seem sufficient to establish
that this is the chief method of transmission. :
Conclusive experimental proof that fleas transmit the disease is
further available from a number of sources. The most extensive
series of experiments is that of the English Plague Commission in
India, which reported in 1906 that:
On thirty occasions a healthy rat contracted plague in sequence
of living in the neighborhood of a plague infected rat under cir-
cumstances which prevented the healthy rat coming in contact with
either the body or excreta of the diseased animal.
In twenty-one experiments out of thirty-eight, healthy rats living
in flea-proof cages contracted plague when exposed to rat fleas
(Xenopsylla cheopis), collected from rats dead or dying of septiceemic
plague.
Close contact of plague-infected with healthy animals, if fleas
are excluded, does not give rise to an epizootic among the latter.
As the huts were never cleaned out, close contact included contact
with feces and urine of infected animals, and contact with, and eat-
ing of food contaminated with feces and urine of infected animals,
as well as pus from open plague ulcers. Close contact of young,
even when suckled by plague-infected mothers, did not give the
disease to the former.
If fleas are present, then the epizootic, once started, spreads from
animal to animal, the rate of progress being in direct proportion to
the number of fleas.
Aerial infection was excluded. Thus guinea-pigs suspended in a
cage two feet above the ground did not contract the disease, while
in the same hut those animals allowed to run about and those placed
two inches above the floor became infected. It had previously
been found that a rat flea could not hop farther than about five
inches.
Guinea pigs and monkeys were placed in plague houses in pairs,
both protected from soil contact infection and both equally exposed
to aerial infection, but one surrounded with a layer of tangle-foot
paper and the other surrounded with a layer of sand. The follow-
ing observations were made:
172 Arthropods as Direct Inoculators of Disease Germs
(a) Many fleas were caught in the tangle-foot, a certain pro-
portion of which were found on dissection to contain in their stomachs
abundant bacilli microscopically identical with plague bacilli. Out
of eighty-five human fleas dissected only one contained these bacilli,
while out of seventy-seven rat fleas twenty-three were found thus
infected.
(b) The animals surrounded with tangle-foot in no instance
developed plague, while several (24 per cent) of the non-protected
animals died of the disease.
Thus, the experimental evidence that fleas transmit the plague
from rat to rat, from rats to guinea pigs, and from rats to monkeys
is indisputable. There is lacking direct experimental proof of its
transfer from rodents to man but the whole chain of indirect evi-
dence is so complete that there can be no doubt that such a transfer
does occur so commonly that in the case of bubonic plague it must
be regarded as the normal method.
Rats are not the only animals naturally attacked by the plague
but as already suggested, it occurs in various other rodents. In
California the disease has spread from rats to ground squirrels
(Otospermophilus beecheyi), a condition readily arising from the
frequency of association of rats with the squirrels in the neighbor-
hood of towns, and from the fact that the two species of fleas found
on them are also found on rats. While the danger of the disease
being conveyed from squirrels to man is comparatively slight, the
menace in the situation is that the squirrels may become a more or
less permanent reservoir of the disease and infect rats, which may
come into more frequent contact with man.
The tarbagan (Arctomys bobac), is a rodent found in North Man-
churia, which is much prized for its fur. It is claimed that this ani-
mal is extremely susceptible to the plague and there is evidence to
indicate that it was the primary source of the great outbreak of
pneumonic plague which occurred in Manchuria and North China
during the winter of 1910-11.
Of fleas, any species which attacks both rodents and man may be
an agent in the transmission of the plague. We have seen that in
India the species most commonly implicated is the rat flea, Xenopsylla
cheopis, (= Lemopsylla or Pulex cheopis) (fig. 89). This species has
also been found commonly on rats in San Francisco. The cat flea,
Ctenocephalus felis, the dog flea, Ctenocephalus canis, the human flea,
Pulex irritans, the rat fleas, Ceratophyllus fasciatus and Ctenopsyllus
muscult have all been shown to meet the conditions.
Réle of Fleas in the Transmission of Plague 173
But, however clear the evidence that fleas are the most important
agent in the transfer of plague, it is a mistake fraught with danger
to assume that they are the only factor in the spread of the disease.
The causative organism is a bacillus and is not dependent upon any
insect for the completion of its development.
Therefore, any blood-sucking insect which feeds upon a plague
infected man or animal and then passes to a healthy individual,
conceivably might transfer the bacilli. Verjbitski (1908) has shown
experimentally that bed-bugs may thus convey the disease. Hertzog
found the bacilli in a head-louse, Pediculus humanus, taken from a
child which had died from the plague, and McCoy found them in a
louse taken from a plague-infected squirrel. On account of their
stationary habits, the latter insects could be of little significance in
spreading the disease.
Contaminated food may also be a source of danger. While this
source, formerly supposed to be the principal one, is now regarded as
unimportant, there is abundant experimental evidence to show that
it cannot be disregarded. It is believed that infection in this way
can occur only when there is some lesion in the alimentary canal. q
Still more important is the proof that in pneumonic plague the
patient is directly infective and that the disease is spread from man
to man without any intermediary. Especially conclusive is the
evidence obtained by Drs. Strong and Teague during the Manchurian
epidemic of 1910-11. They found that during coughing, in pneu-
monic plague cases, even when sputum visible to the naked eye is
not expelled, plague bacilli in large numbers may become widely
disseminated into the surrounding air. By exposing sterile plates
before patients who coughed a single time, very numerous colonies
of the baccilus were obtained.
But the great advance which has been made rests on the dis-
covery that bubonic plague is in the vast majority of cases transmitted
by the flea. The pneumonic type forms a very small percentage
of the human cases and even with it, the evidence indicates that the
original infection is derived from a rodent through the intermediary
of the insect.
So modern prophylactic measures are directed primarily against
the rat and fleas. Ships coming from infected ports are no longer
disinfected for the purpose of killing the plague germs, but are fumi-
gated to destroy the rats and the fleas which they might harbor.
When anchored at infected ports, ships must observe strenuous
174 Arthropods as Direct Inoculators of Disease Germs
precautions to prevent the ingress of rats. Cargo must be inspected
just before being brought on board, in order to insure its freedom from
rats. Even lines and hawsers must be protected by large metal discs
or funnels, for rats readily run along a rope to reach the ship. Once
infested, the ship must be thoroughly fumigated, not only to avoid
carrying the disease to other ports but to obviate an outbreak on
board.
When an epidemic begins, rats must be destroyed by trapping
and poisoning. Various so-called biological poisons have not proved
practicable. Sources of food supply should be cut off by thorough
cleaning up, by use of rat-proof garbage cans and similar measures.
Hand in hand with these, must go the destruction of breeding places,
and the rat-proofing of dwellings, stables, markets, warehouses, docks
and sewers. All these measures are expensive, and a few years ago
would have been thought wholly impossible to put into practice
but now they are being enforced on a large scale in every fight against
the disease.
Rats and other rodents aré regularly caught in the danger zone
and examined for evidence of infection, for the sequence of the epi-
zootic and of the human disease is now understood. In London, rats
are regularly trapped and poisoned in the vicinity of the principal
docks, to guard against the introduction of infected animals in ship-
ping. During the past six years infected rats have been found
yearly, thirteen having been found in 1912. In Seattle, Washington,
seven infected rats were found along the water front in October, 1913,
and infected ground squirrels are still being found in connection with
the anti-plague measures in California,
The procedure during an outbreak of the human plague was well
illustrated by the fight in San Francisco. The city was districted,
and captured rats, after being dipped in some fluid to destroy the fleas,
were carefully tagged to indicate their source, and were sent to the
laboratory for examination. If an infected rat was found, the officers
in charge of the work in the district involved were immediately
notified by telephone, and the infected building was subjected to a
thorough fumigation. In addition, special attention was given to
all the territory in the four contiguous blocks.
By measures such as these, this dread scourge of the human race
is being brought under control. Incidentally, the enormous losses
due to the direct ravages of rats are being obviated and this alone
would justify the expenditure many times over of the money and
labor involved in the anti-rat measures.
CHAPTER VII
ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC ORGANISMS
We now have to consider the cases in which the arthropod acts
as the essential host of a pathogenic organism. In other words,
cases in which the organism, instead of being passively carried or
merely accidentally inoculated by the bite of its carrier, or vector, is
taken up and undergoes an essential part of its development within
the arthropod.
In some cases, the sexual cycle of the parasite is undergone in the
arthropod, which then serves as the definitive or
primary host. In other cases, it is the asexual stage
of the parasite which is undergone, and the arthropod
then acts as the zntermediate host. This distinction
is often overlooked and all the cases incorrectly
referred to as those in which the insect or other
arthropod acts as intermediate host.
We have already emphasized that this is, the most
important way in which insects may transmit disease,
for without them the particular organisms concerned
could never complete their development. Exter-
minate the arthropod host and the life cycle of the
parasite is broken, the disease is exterminated.
As the phenomenon of alternation of generations,
as exhibited by many of the parasitic protozoa, is a
complicated one and usually new to the student, we
_~..,_ Shall first take wp some of the grosser cases illustrated
113. Dipylidium A es é eas
caninum. The by certain parasitic worms. There is the additional
double pored
iavewores ofthe reason that these were the first cases known of arthro-
pod transmission of pathogenic organisms.
InsrEcts as INTERMEDIATE Hosts or TAPEWORMS
A number of tapeworms are known to undergo their sexual stage
in an insect or other arthropod. Of these at least two are occasional
parasites of man.
Dipylidium caninum (figs. 113 and 114), more generally known as |
Taenia cucumerina or T. elliptica, is the commonest intestinal parasite
of. pet dogs and cats. It is occasionally found as a human parasite,
70 per cent of the cases reported being in young children.
175
176 Arthropods as Essential Hosts of Pathogenic Organisms
In 1869, Melnikoff found in a dog louse, Trichodectes canis, some
peculiar bodies which Leuckart identified as the larval form of this
tapeworm. The worm is, however, much more
common in dogs and cats than is the skin para-
site, and hence it appears that the Trichodectes
could not be the only intermediate host. In
1888, Grassi found that it could also develop
in the cat and dog fleas, Ctenocephalus felis
and C. canis, and in the human flea, Pulex
\ trritans.
114. Dipylidium caninum. The eggs, scattered among the hairs of the
Rostrum evaginated and i z
invaginated. After dog or cat, are ingested by the insect host and
in its body cavity they develop into pyriform
bodies, about 300u. in length, almost entirely destitute of a bladder,
but in theimmature stage provided with a caudal appendage (fig. 115).
Within the pear-shaped body (fig. 116) are the invaginated head and
suckers of the future tapeworm. This larval
form is known as a cysticercoid, in contradis-
tinction to the bladder-like cysticercus of many
other cestodes. It is often referred to in liter-
ature as Cryptocystis trichodectis Villot.
As many as fifty of the cysticercoids have
been found in the body cavity of a single flea. 415. Dipytiaium caninum.
When the dog takes up an infested flea or louse, — FRmAauure,_cystigercoid.
by biting itself, or when the cat licks them up, the
larvee quickly develop into tapeworms, reaching sexual maturity in
about twenty days in the intestine of their host. Puppies and
kittens are quickly infested when suckling a flea-infested mother, the
developing worms having been found in the intestines of puppies not
more than five or six days old.
Infestation of human beings occurs only
through accidental ingestion of an infested flea.
It is natural that such cases should occur largely
Ss : in children, where they may come about in
116. Dipylidium caninum. 5 3
Cysticercoid. After. SOME such way as illustrated in the accompany-
ing figures 117 and 118.
Hymenolepis diminuta, very commonly living in the intestine
of mice and rats, is also known to occur in man. Its cysticercoid
develops in the body cavity of a surprising range of meal-infesting
insects. Grassi and Rovelli (abstractin Ransom, 1904) found it in the
Insects as Intermediate Hosts of Tapeworms 177
larvee and adult of a moth, Asopia farinalis, in the earwig, Anisolabis
annulipes, the Tenebrionid beetles Akis spinosa and Scaurus striatus.
Grassi considers that the lepi-
dopter is the normal inter-
mediatehost. The insect takes
up the eggs scattered by rats
and mice. It has been experi-
mentally demonstrated that
man may develop the tape-
worm by swallowing infested
insects. Natural infection
probably occurs by ingesting
HT. Ope way in which Digyidiym infecvon in such insects with cereals, ‘or
imperfectly cooked foods.
Hymenolepis lanceolata, a parasite of geese and ducks, has been
reported once for man. The supposed cysticercoid occurs in various
small crustaceans of the family Cyclopide.
118. The probable method by which Dipylidium infection usually occurs,
178 Arthropods as Essential Hosts of Pathogenic Organisms
Several other cestode parasites of domestic animals are believed
to develop their intermediate stage in certain arthropods. Among
these may be mentioned:
Choanotenia infundibulformis, of chickens, developing in the house-
fly (Grassi and Rovelli) ;
Davainea cesticillus, of chickens, in some lepidopter or coleopter
(Grassi and Rovelli) ;
Hymenolepis anatina, H. gracilis, H. sinuosa, H. coronula and
Fimbriaria fasciolaris, all occurring in ducks, have been reported as
developing in small aquatic crustaceans. In these cases, cysticer-
coids have been found which, on account of superficial characters,
have been regarded as belonging to the several species, but direct
experimental evidence is scant.
Arturopops Aas InTeERMEDIATE Hosts or NeEmatopE Worms
Filariasis and Mosquitoes—A number of species of Nematode
worms belonging to the genus Filaria, infest man and other verte-
brates and in the larval condition are to be found in the blood.
Such infestation is known as filariasis. The sexually mature worms
are to be found in the blood, the lymphatics, the mesentery and sub-
cutaneous connective tissue. In the cases best studied it has been
found that the larval forms are taken up by mosquitoes and undergo
a transformation before they can attain maturity in man.
The larve circulating in the blood are conveniently designated
as microfilarie. In this stage they are harmless and only one species,
Filaria bancrofti, appears to be of any great pathological significance
at any stage.
Filaria bancrofti in its adult state, lives in the lymphatics of man.
Though often causing no injury it has been clearly established that
they and their eggs may cause various disorders due to stoppage
of the lymphatic trunks (fig.tr9). Manson lists among other effects,
abscess, varicose groin glands, lymph scrotum, chyluria, and ele-
phantiasis.
The geographical distribution of this parasite is usually given as
coextensive with that of elephantiasis, but it is by no means certain
that it is the only cause of this disease and so actual findings of the
parasites are necessary. Manson reports that it is ‘‘an indigenous
parasite in almost every country throughout the tropical and sub-
tropical world, as far north as Spain in Europe and Charlestown in
Filariasts and Mosquitoes 179
the United States, and as far south as Brisbane in Australia.’”’ In
some sections, fully 50 per cent of the natives are infested. Labredo
(z910) found 17.82 per cent infestation in Havana.
The larval forms of Filaria bancrofti were first discovered in 1863,
by Demarquay, in a case of chylous dropsy. They were subse-
quently noted under similar conditions, by several workers, and by
Wicherer in the urine of twenty-eight cases of tropical chyluria,
but in 1872 Lewis found that the blood of man was the normal
habitat, and gave them the name Filaria sanguinis hominis. The
adult worm was found in 1876
by Bancroft, and in 1877,
Cobbold gave it thename Filaria
bancroftt. It has since been
found repeatedly in various parts
of the lymphatic system, and its
life-history has been the subject
of detailed studies by Manson
(1884), Bancroft (1899), Low
(1900), Grassi and Noé (1900),
Noé (1901) and Fulleborn (1910).
The larvee, as they exist in
the circulating blood, exhibit a
very active wriggling movement,
without material progression.
They may exist in enormous
119. Elephantiasis in Man. From ‘New numbers, as Many as five or
Sydenham Society’s Atlas.” six hundred swarming in a
single drop of blood. This is the more surprising when we con-
sider that they measure about 300n x 8y, that is, their width is
equal to the diameter of the red blood corpuscle of their host and
their length over thirty-seven times as great.
Their organs are very immature and the structure obscure. When
they have quieted down somewhat in a preparation it may be seen
that at the head end there is a six-lipped and very delicate prepuce,
enclosing a short ‘‘fang’’ which may be suddenly exserted and
retracted. Completely enclosing the larva is a delicate sheath,
which is considerably longer than the worm itself. To enter into
further details of anatomy is beyond the scope of this discussion
and readers interested are referred to the work of Manson and of
Fiilleborn.
Ne
180 Arthropods as Essential Hosts of Pathogenic Organisms
One of the most surprising features of the habits of these larvee
is the periodicity which they exhibit in their occurrence in the peri-
pheral blood. If a preparation be made during the day time there
may be no evidence whatever of filarial infestation, whereas a prep-
aration from the same patient taken late in the evening or during
the night may be literally swarming with the parasites. Manson
quotes Mackenzie as having brought out the further interesting
fact that should a ‘‘filarial subject be made to sleep during the day
and remain awake at night, the periodicity is reversed; that is to say,
the parasites come into the blood during the day and disappear from
it during the night.”” There have been numerous attempts to explain
this peculiar phenomenon of periodicity but in spite of objections
which have been raised, the most plausible remains that of Manson,
who believes that it is an adaptation correlated with the life-habits
of the liberating agent of the parasite, the mosquito.
The next stages in the development of Filaria nocturna occur in
mosquitoes, a fact suggested almost simultaneously by Bancroft
and Manson in 1877, and first demonstrated by the latter very soon
thereafter. The experiments were first carried out with Culex
quinquetasciatus (= fatigans) as a host, but it is now known that a
number of species of mosquitoes, both anopheline and culicine, may
serve equally well.
When the blood of an intested individual is sucked up and reaches
the stomach of such a mosquito, the larve, by very active movements,
escape from their sheaths and within a very few hours actively mi-
grate to the body cavity of their new host and settle down primarily
in the thoracic muscles. There in the course of sixteen to twenty
days they undergo a metamorphosis of which the more conspicuous
features are the formation of a mouth, an alimentary canal and a
trilobed tail. At the same time there is an enormous increase in
size, the larvee which measured .3 mm. in the blood becoming 1.5 mm.
in length. This developmental period may be somewhat shortened
in some cases and on the other hand may be considerably extended.
The controlling factor seems to be the one of temperature.
The transformed larve then reenter the body cavity and finally
the majority of them reach the interior of the labium (fig. 120). A
few enter the legs and antenne, and the abdomen, but these are
wanderers which, it is possible, may likewise ultimately reach the
labium, where they await the opportunity to enter their human host.
Filariasis and Mosquitoes 181
It was formerly supposed that when the infested mosquito punc-
tured the skin of man, the mature larve were injected into the cir-
culation. The manner in which this occurred was not obvious, for
when the insect feeds it inserts only the stylets, the labium itself
remaining on the surface of the skin. Fulleborn has cleared up the
question by showing that at this time the filarie escape and, like
the hookworm, actively bore into the skin of their new host.
Once entered, they migrate to the lymphatics and there quickly
become sexually mature. The full grown females measure 85—go mm.
in length by .24-.28 mm. in diameter, while the males are less than
Gras
Le
120. Filaria in the muscles and labiumof Culex. After Blanchard.
half this size, being about 40 mm. by .t mm. Fecundation occurs
and the females will be found filled with eggs in various stages of
development, for they are normally viviparous.
Filaria philippinensis is reported by Ashburn and Craig (1907) as
a common blood filaria in the Philippine Islands. As they describe
it, it differs from Filaria bancrofti primarily in that it does not exhibit
periodicity. Its development has been found to occur in Culex
quinquefasciatus, where it undergoes metamorphosis in about fourteen
or fifteen days. There is doubt as to the species being distinct from
bancroftt.
Several other species occur in man and are thought to be trans-
ferred by various insects, among which have been mentioned Taba-
nidze and tsetse-flies, but there is no experimental proof in support
of such conjectures.
182 Arthropods as Essential Hosts of Pathogenic Organisms
Filaria immitis is a dangerous parasite of the dog, the adult worm
living in the heart and veins of this animal. It is one of the species
which has been clearly shown to undergo its development in the
mosquito, particularly in Anopheles maculipennis and Aedes calopus
(= Stegomyia). The larval form occurs in the peripheral blood,
especially at night. When taken up by mosquitoes they differ from
Filaria bancrofti in that they undergo their development in the
Malpighian tubules rather than in the thoracic muscles. In
about twelve days they have completed their growth in the tubules,
pierce the distal end, and pass to the labium. This species occurs
primarily in China and Japan, but is also found in Europe and in the
United States. It is an especially favorable species for studying
the transformations in the mosquito.
Filarig are also commonly found in birds, and in this country
this is the most available source of laboratory material. We have
found them locally (Ithaca, N. Y.) in the blood of
over sixty per cent of all the crows examined, at
any season of the year, and have also found them
in English sparrows.
In the crows, they often occur in enormous
numbers, as many as two thousand having been
found in a single drop of the blood of the most
heavily infested specimen examined. For study, a
small drop of blood should be mounted on a clean
slide and the coverglass rung with vaseline or oil
to prevent evaporation. In this way they can
121. Dracunculus
medinensis; female; be kept for hours.
mouth; embryo. ‘
After Bastian and Permanent preparations may be made by
Leuckart.
spreading out the blood in a film on a perfectly
clean slide and staining. This is easiest done by touching the fresh
drop of blood with the end of a second slide which is then held at
an angle of about 45° to the first slide and drawn over it without
pressure. Allow the smear to dry in the air and stain in the usual
way with hematoxylin.
OrnEer Nematove Parasites or Man AND ANIMALS DEVELOPING
IN ARTHROPODS
Dracunculus medinensis (fig. 121), the so-called guinea-worm, is
a nematode parasite of man which is widely distributed in tropical
Africa, Asia, certain parts of Brazil and is occasionally imported
into North America.
Other Nematodes Developing in Arthropods 183
The female worm is excessively long and slender, measuring nearly
three feet in length and not more than one-fifteenth of an inch in
diameter. It is found in the subcutaneous connective tissue and when
mature usually migrates to some part of the leg.
Here it pierces the skin and there is formed a small
superficial ulcer through which the larve reach the
exterior after bursting the body of the mother.
Fedtschenko (1879) found that when these larvee
reach the water they penetrate the carapace of the
little crustacean, Cyclops (fig.122). Here they molt
several times and undergo ametamorphosis. Fedts-
chenko,in Turkestan, found that these stages required
about five weeks, while Manson who confirmed these
general results, found that eight or nine weeks were gnteediee Py ne
required in the cooler climate of Engand. een
Infection of the vertebrate host probably occurs through swallow-
ing infested cyclops in drinking water. Fedtschenko was unable to
demonstrate this experimentally and objection has been raised against
the theory, but Leiper (1907), and Strassen (1907) succeeded in infest-
ing monkeys by feeding them on cyclops containing the larve.
Habronema musce is a worm which has long been known in its
larval stage, as a parasite of the house-fly. Carter found them in
33 per cent of the house-flies examined in Bombay during July, 1860,
and since that time they have been shown to be very widely distrib-
uted. Italian workers reported them in 12 per cent to 30 per cent
of the flies examined. Hewitt reported finding it rarely in England.
In this country it was first reported by Leidy who found it in about
20 per cent of the flies examined at Philadelphia, Pa. Since then it
has been reported by several American workers. We have found it
at Ithaca, N. Y., but have not made sufficient examinations to justify
stating percentage. Ransom (1913) reports it in thirty-nine out of
one hundred and thirty-seven flies, or 28 per cent.
Until very recently the life-history of this parasite was unknown
but the thorough work of Ransom (1911, 1913) has shown clearly
that the adult stage occurs in the stomach of horses. The embryos,
produced by the parent worms in the stomach of the horse, pass
out with the feces and enter the bodies of fly larvae which are develop-
ing in the manure. In these they reach their final stage of larval
development at about the time the adult flies emerge from the pupal
stage. Im the adult fly they are commonly found in the head,
184 Arthropods as Essential Hosts of Pathogenic Organisms
124. June beetle (Lachnosterna). Larva
frequently in the proboscis, but they occur also in the thorax and
abdomen. Infested flies are accidentally swallowed by horses and
the parasite completes its development to maturity in the stomach of
its definitive host.
Other Nematodes developing in Arthropods 185
Gigantorhynchus hirudinaceus (=Echinorhynchus gigas) is a com-
mon parasite of the pig and has been reported as occurring in man.
~The adult female is 20-35 cm. long and 4-9 mm. in diameter.
It lacks an alimentary canal and is provided with a strongly spined
protractile rostrum, by means of which it attaches to the intestinal
mucosa of its host. -
The eggs are scattered with the feces of the host and are taken
up by certain beetle larvee. In Europe the usual intermediate hosts
are the larve of the cockchafer, Melolontha vulgaris, or of the flower
beetle, Cetonia aurata. Stiles has shown that in the United States
the intermediate host is the larva of the June bug, Lachnosterna
(fig. 124). It is probable that several of the native species serve in
this capacity.
A number of other nematode parasites of birds and mammals
have been reported as developing in arthropods but here, as in the
case of the cestodes, experimental proof is scant. The cases above
cited are the better established and will serve as illustrations.
\
CHAPTER VIII
ARTHROPODS AS ESSENTIAL HOSTS OF PATHOGENIC
PROTOZOA
MosquiTroEs AND MALARIA
Under the name of malaria is included a group of morbid symp-
toms formerly supposed to be due to a miasm or bad air, but now
known to be caused by protozoan parasites of the genus Plasmodium,
which attack the red blood corpuscles. It occurs in paroxysms,
each marked by a chill, followed by high fever and sweating. The
fever is either intermittent or remittent.
There are three principal types of the disease, due to different
species of the parasite. They are:
1. The benign-tertian, caused by Plasmodium vivax, which under-
goes its schizogony or asexual cycle in the blood in forty-eight hours
or even less. This type of the disease,—characterized by fever
every two days, is the most wide-spread and common.
2. The quartan fever is due to the presence of Plasmodium
malarie, which has an asexual cycle of seventy-two hours, and there-
fore the fever recurs every three days. This type is more prevalent
in temperate and sub-tropical regions, but appears to be rare every-
where.
3. The sub-tertian “estivo-autumnal,” or ‘pernicious’ fever
is caused by Plasmodium falciparum. Schizogony usually occurs
“in the internal organs, particularly in the spleen, instead of in the
peripheral circulation, as is the case of the tertian and quartan forms.
The fever produced is of an irregular type and the period of schizogony
has not been definitely determined. It is claimed by some that the
variations are due to different species of malignant parasites.
It is one of the most wide-spread of human diseases, occurring
in almost all parts of the world, except in the polar regions and in
waterless deserts. It is most prevalent in marshy regions.
So commonplace is malaria that it causes little of the dread
inspired by most of the epidemic diseases, and yet, as Ross says,
it is perhaps the most important of human diseases. Figures regard-
ing its ravages are astounding. Celli estimated that in Italy it
caused an average annual mortality of fifteen thousand, representing
about two million cases. In India alone, according to Ross (1910)
186
Mosquitoes and Malaria 187
“it has been officially estimated to cause a mean annual death-rate
of five per thousand; that is, to kill every year, on the average, one
million one hundred and thirty thousand.’ In the United States
it is widespread and though being restricted as the country develops,
it still causes enormous losses." During the year 1011, ‘‘in Alabama
alone there were seventy thousand cases and seven hundred and
seventy deaths.” The weakening effects of the disease, the invasion
of other diseases due to the attacks of malaria, are among the very
serious results, but they cannot be estimated.
Not only is there direct effect on man, but the disease has been one
of the greatest factors in retarding the development of certain regions.
Everywhere pioneers have had to face it, and the most fertile regions
have, in many instances been those most fully dominated by it.
Herrick (1903) has presented an interesting study of its effects on
‘the development of the southern United States and has shown that
some parts, which are among the most fertile in the world, are
rendered practically uninhabitable by the ravages of malaria. How-
ard (1909) estimates that the annual money loss from the disease
in the United States is not less than $100,000,000.
It was formerly supposed that the disease was due to a miasm,
to a noxious effluvia, or infectious matter rising in the air from
swamps. In other words its cause was, as the name indicated
“‘mal aria,” and the deep seated fear of night air is based largely on
the belief that this miasm was given off at night. Its production
was thought to be favored by stirring of the soil, dredging operations
and the like.
The idea of some intimate connection between malaria and
mosquitoes is not a new one. According to Manson, Lancisi noted
that in some parts of Italy the peasants for centuries have believed
that malaria is produced by the bite of mosquitoes. Celli states
that one not rarely hears from such peasants the statement that
“Tn such a place, there is much fever, because it is full of mosquitoes.”
Koch points out that in German East Africa the natives call malaria
and the mosquito by the same name, Mbz. The opinion was not
lacking support from medical men. Celli quotes passages from the
writings of the Italian physician, Lancisi, which indicate that he
favored the view in 1717.
Dr. Josiah Nott is almost universally credited with having sup-
ported the theory, in 1848, but as we have already pointed out
his work has been misinterpreted. The statements of Beauperthuy,
(1853) were more explicit.
188 Arthropods as Hosts of Pathogenic Protozoa
The clearest early presentation of the circumstantial evidence in
favor of the theory of mosquito transmission was that of A. F. A.
King, an American physician, in 1883. He presented a series of
epidemiological data and showed “how they may be explicable by
the supposition that the mosquito is the real source of the disease,
rather than the inhalation or cutaneous absorption of a marsh vapor.”
We may well give the space to summarizing his argument here for
it has been so remarkably substantiated by subsequent work:
t. Malaria, like mosquitoes, affects by preference low and moist
localities, such as swamps, fens, jungles, marshes, etc.
2. Malaria is hardly ever developed at a lower temperature
than 60° Fahr., and such a temperature is necessary for the develop-
ment of the mosquito.
3. Mosquitoes, like malaria, may both accumulate in and be
obstructed by forests lying in the course of winds blowing from
malarious localities.
4. By atmospheric currents malaria and mosquitoes are alike
capable of being transported for considerable distances.
5. Malaria may be developed in previously healthy places by
turning up the soil, as in making excavations for the foundation of
houses, tracks for railroads, and beds for canals, because these opera-
tions afford breeding places for mosquitoes.
6. In proportion as countries, previously malarious, are cleared
up and thickly settled, periodical fevers disappear, because swamps
and pools are drained so that the mosquito cannot readily find a place
suitable to deposit her eggs.
7. Malaria is most dangerous when the sun is down and the
danger of exposure after sunset is greatly increased by the person
exposed sleeping in the night air. Both facts are readily explicable
by the mosquito malaria theory.
8. In malarial districts the use of fire, both indoors and to those
who sleep out, affords a comparative security against malaria, because
of the destruction of mosquitoes.
g. It is claimed that the air of cities in some way renders the
poison innocuous, for, though a malarial disease may be raging out-
side, it does not penetrate far into the interior. We may easily
conceive that mosquitoes, while invading cities during their nocturnal
pilgrimages will be so far arrested by walls and houses, as well as
attracted by lights in the suburbs, that many of them will in this
way be prevented from penetrating ‘‘far into the interior.”’
Mosquitoes and Malaria 189
to. Malarial diseases and likewise mosquitoes are most prevalent
toward the latter part of summer and in the autumn.
11. Various writers have maintained that malaria is arrested by
canvas curtains, gatize veils and mosquito nets and have recom-
mended the use of mosquito curtains, “through which malaria can
seldom or never pass.” It can hardly be conceived that these
intercept marsh-air but they certainly do protect from mos-
quitoes,
12. Malaria spares no age, but it affects infants much less
frequently than adults, because young infants are usually carefully
housed and protected from mosquito inoculation.
Correlated with the miasmatic theory was the belief that some
animal or vegetable organism which lived in marshes, produced
malaria, and frequent searches were made for it. Salisbury (1862)
thought this causative organism to be an alga, of the genus Palmejla;
others attributed it to certain fungi or bacteria.
In 1880, the French physician, Laveran, working in Algeria,
discovered an amoeboid organism in the blood of malarial patients
and definitely established the parasitic nature of this disease. Pig-
mented granules had been noted by Meckel as long ago as 1847, in
the spleen and blood of a patient who had died of malaria, and his
observations had been repeatedly verified, but the granules had been
regarded as degeneration products, and the fact that they occurred
in the body of a foreign organism had been overlooked.
Soon after the discovery of the parasites in the blood, Gerhardt
(1884) succeeded in transferring the disease to healthy individuals
by inoculation of malarious blood, and thus proved that it is a true
infection. This was verified by numerous experimenters and it
was found that inoculation with a very minute quantity of the dis-
eased blood would not only produce malaria but the particular type
of disease.
Laveran traced out the life cycle of the malarial parasite as it
occurs in man. The details as we now know them and as they are
illustrated by the accompanying figure 125, are as follows:
The infecting organism or sporozoite, is introduced into the cir-
culation, penetrates a red blood corpuscle, and forms the amoeboid
schizont. This lives at the expense of the corpuscle and as it develops
there are deposited in its body scattered black or reddish black
particles. These are generally called melanin granules, but are
much better referred to as hemozoin, as they are not related to
190 Arthropods as Hosts of Pathogenic Protozoa
melanin. The hemozoin is the most conspicuous part of the para-
site, a feature of advantage in diagnosing from unstained prepara-
tions.
‘As the schizont matures, its nucleus breaks up into a number of
daughter nuclei, each with a rounded mass of protoplasm about it,
and finally the corpuscles are broken down and these rounded bodies
125. Life cycle of the malaria parasite. Adapted from Leuckart’s chart,
by Miss Anna Stryke.
are liberated in the plasma as merozoites. These merozoites infect
new corpuscles and thus the asexual cycle is continued. The malarial
paroxysm is coincident with sporulation.
As early as Laveran’s time it was known that under conditions
not yet determined there are to be found in the blood of malarious
patients another phase of the parasite, differing in form according
to the type of the disease. In the pernicious type these appear as
large, crescent-shaped organisms which have commonly been called
““crescents.’’ We now know that these are sexual forms.
Mosquitoes and Malaria IgI
When the parasite became known there immediately arose specu-
lations as to the way in which it was transferred from man to man.
It was thought by some that in nature it occurred as a free-living
amoeba, and that it gained access to man through being taken up
with impure water. However, numerous attempts to infect healthy
persons by having them drink or inhale marsh water, or by injecting
it into their circulation resulted in failure, and influenced by Leuckart’s
and Melnikofi’s work on Dipylidium, that of Fedtschenko on Dracun-
culus, and more especially by that of Manson on Filaria, search was
made for some insect which might transfer the parasite.
Laveran had early suggested that the réle of carrier might be
played by the mosquito, but Manson first clearly formulated the
hyopthesis, and it was largely due to his suggestions that Ross in
India, undertook to solve the problem. With no knowledge of the
form or of the appearance in this stage, or of the species of mosquito
concerned, Ross spent almost two anda half years of the most arduous
work in the search and finally in August, 1897, seventeen years
after the discovery of the parasite in man, he obtained his first
definite clue. In dissecting a ‘“‘dappled-winged mosquito,” ‘every
cell was searched and to my intense disappointment nothing what-
ever was found, until I came to the insect’s stomach. Here, however,
just as I was about to abandon the examination, I saw a very delicate
circular cell, apparently lying amongst the ordinary cells of the organ
and scarcely distinguishable from them. On looking further,
another and another similar object presented itself. I now focused
the lens carefully on one of these, and found that it contained a few
minute granules of some black substance, exactly like the pigment of
the parasite of malaria. I counted altogether twelve of these cells
in the insect.”
Further search showed that ‘‘the contents of the mature pigment
cells did not consist of clear fluid but of a multitude of delicate,
thread-like bodies which on the rupture of the parent cell, were poured
into the body cavity of the insect. They were evidently spores.’
With these facts established, confirmation and extension of
Ross’s results quickly followed, from many different sources. We
cannot trace this work in detail but will only point out that much
of the credit is due to the Italian workers, Grassi, Bignami, and
Bastianelli, and to Koch and Daniels.
It had already been found that when fresh blood was mounted and
properly protected against evaporation, a peculiar change occurred
192 Arthropods as Hosts of Pathogenic Protozoa
in these crescents after about half an hour’s time. From certain
of them there were pushed out long whip-like processes which moved
with a very active, lashing movement. The parasite at this stage
is known as the “‘flagellated body.’’ Others, differing somewhat in
details of structure, become rounded but do not give off “‘flagella.’””
The American worker, MacCallum (1897), in studying bird
malaria as found in crows, first recognized the true nature of these
bodies. He regarded them as sexual forms and believed that the
so-called flagella played the part of spermatozoa. Thus, the ‘‘flagel-
lated body” is in reality a microgametoblast, producing muicrogametes,
or the male sexual element, while the others constitute the macro-
gametes, or female elements.
It was found that when blood containing these sexual forms was
sucked up by an Anopheline mosquito and taken into its stomach, a
microgamete penetrated and fertilized a macrogamete in a way
analogous to what takes place in the fertilization of the egg in higher
forms. The resultant, mobile organism is known as the migratory
ookinete. In this stage the parasite bores through the epithelial
lining of the “‘stomach”’ (mid-intestine) of the mosquito and becomes
encysted under the muscle layers. Here the oocyst, as it is now
known, matures and breaks up into the body cavity and finally
its products come to liein the salivary glands of the mosquito. Ten
to twelve days are required for these changes, after which the mos-
quito is infective, capable of introducing the parasite with its saliva,
when feeding upon a healthy person.
Thus the malarial parasite is known to have a double cycle, an
alternation of generations, of which the asexual stage is undergone in
man, the sexual in certain species of mosquitoes. The mosquito is
therefore the definitive host rather than the intermediate, as usually
stated.
The complicated cycle may be made clearer by the diagram of
Miss Stryke (1912) which, by means of a double-headed mosquito
(fig. 126) endeavors to show how infection takes place through the
biting of the human victim, (at A), in whom asexual multiplication
then takes place, and how the sexual stages, taken up at B in the
diagram, are passed in the body of the mosquito.
The experimental proof that mosquitoes of the Anopheline group
are necessary agents in the transmission of malaria was afforded in
1900 when two English physicians, Drs. Sambon and Low lived for
the three most malarial months in the midst of the Roman Campagna,
Mosquitoes and Malaria 193
a region famous for centuries as a hot-bed of malaria. The two
experimenters moved about freely throughout the day, exposed
126. Life cycle of the malarial parasite. After Miss Anna Stryke.
themselves to rains and all kinds of weather, drank marsh water,
slept exposed to the marsh air, and, in short, did everything which
was supposed to cause malaria, except that they protected them-
selves thoroughly from mosquito bites, retiring at sunset to a mosquito-
194 Arthropods as Hosts of Pathogenic Protozoa
proof hut. Though they took no quinine and all of their neighbors
suffered from malaria, they were absolutely free from the disease.
To complete the proof, mosquitoes which had fed in Rome on
malarious patients were sent to England and allowed to bite two
volunteers, one of them Dr. Manson’s own son, who had not been
otherwise exposed to the disease. Both of these gentlemen con-
tracted typical cases of malaria and the parasites were to be found in
abundance in their blood.
Since that time there have been many practical demonstrations
of the fact that malaria is transmitted exclusively by the bite of
mosquitoes and that the destruc-
tion of the mosquitoes means the
elimination of the disease.
We have said that the malarial
parasite is able to undergo its
development only in certain
species of mosquitoes belonging
to the Anopheline group. It is
by no means certain that all of
this group even, are capable of
acting as the definitive host of
the parasites, and much careful
experiment work is still needed
along this line. In the United
States, several species have been
found to be implicated, Anopheles
quadrimaculatus and Anopheles
crucians being the most common. The characteristics of these species
and the distinctions between them and other mosquitoes will be
discussed in Chapter XII.
In antimalarial work it is desirable to distinguish the anopheline
mosquitoes from the culicine species in all stages. The following
tabulation presents the more striking distinctions between the groups
as represented in the United States.
127. Eggs of Anopheles. After Howard.
Anopheles
Eggs: Laid singly in small
numbers upon the surface of the
water. Eggs lie upon their sides
and float by means of lateral
expansions (fig. 127).
Culex, Aedes, etc.
Deposited in clumps in the
form of a raft (Culex group) or
deposited singly in the water or
on the ground in places which
may later be submerged.
Mosquitoes and Malaria
Larva: When at rest floats in
a horizontal position beneath the
surface film. No respiratory
tube but instead a flattened
area on the eighth abdominal
segment into which the two
spiracles open (fig. 128).
Adults: Palpi in both sexes
nearly or quite as long as the
proboscis. Proboscis projecting
forward nearly on line with the
axis of the body. When at rest
on a vertical wall the body is
usually held at an angle with the
vertical (fig. 128). Wings fre-
quently spotted (fig. 130).
195
When at rest (with few excep-
tions) floats suspended in an
oblique or vertical position, or
more rarely nearly horizontal,
with the respiratory tube in
contact with the surface film
(fig. 128).
Palpi short in the female, in
the male usually elongate. Pro-
boscis projects forward at an
angle with the axis of the body.
When at rest on a vertical wall
the body is usually held parallel
or the tip of the abdomen in-
clined towards the wall (fig. 128).
Wings usually not spotted.
Culex pupa,
These malarial-bearing species are essentially domesticated
mosquitoes. They develop in any accumulation of water which
stands for a week or more.
Re eae Go Ponds, puddles, rain barrels,
horse troughs, cess-pools, cans,
198: Mavof Culer and Anopielesin. EVen. the foot-prints of ani-
Ad Ore ee er dics Cues ote” «mals in marshy ground may
ming Haniel Bre afford them breeding places.
It is clear from what has been said regarding the life cycle of the
malarial parasite that the mosquito is harmless if not itself diseased.
Hence malarial-bearing species may abound in the
neighborhood where there is no malaria, the disease
being absent simply because the mosquitoes are unin-
fected. Such a locality is potentially malarious and
needs only the introduction of a malarial patient who is
exposed to the mosquitoes. Itis found that such patients
may harbor the parasites in their blood long after they
are apparently well and thus may serve as a menace,
just as do the so-called typhoid carriers. In some //
malarious regions as high as 80-90 per cent of the natives
are such malaria-carriers and must be reckoned with in \
antimalaria measures. 128, (6) Norma
Based upon our present day knowledge of the lifecycle Rosition, of
of the malarial parasite the fight against the disease
Anopheles on
the wall.
196 Arthropods as Hosts of Pathogenic Protozoa
becomes primarily a problem in economic entomology,—it is a ques-
tion of insect control, in its broadest interpretation.
The lines of defence and offence
against the disease as outlined by
Boyce (1909) are’
t. Measures to avoid the reser-
voir (man):
Segregation.
Screening of patients.
2. Measures to avoid Anopheles:
Choice of suitable locality,
when possible.
Screening of houses and
porches.
Sleeping under mosquito nets.
3. Measures to exterminate the
Anopheles:
Use of natural enemies.
Use of culicides, oiling ponds,
etc.
Drainage and scavenging to
destroy breeding places.
Enforcement of penalties for
\ harboring larve or keeping
129. Larva of Anopheles. After Howard. stagnant water.
Educational methods.
4. Systematic treatment with quinine to exterminate the parasites.
MosquItorEs AND YELLOW FEVER
Yellow fever was until recently one of the most dreaded of epi-
demic diseases. It is an acute, specific and infectious disease, non-
contagious in character but occurring in epidemics, or endemics,
within a peculiarly limited geographical area. It is highly fatal,
but those who recover are generally immune from subsequent at-
tacks.
It is generally regarded as an American disease, having been
found by Cortez, in Mexico, and being confined principally to the
American continents and islands. It also occurs in Africa and at-
tempts have been made to show that it was originally an African
disease but there is not sufficient evidence to establish this view.
Mosquitoes and Yellow Fever 197
There have been many noted outbreaks in the United States.
Boston suffered from it in 1691 and again in 1693; New York in
1668 and as late as 1856; Baltimore in 1819. In 1793 occurred the
great epidemic in Philadelphia, with a death rate of one in ten of the
population. In the past century it was present almost every year in
some locality of our Southern States, New Orleans being the greatest
sufferer. In the latter city there were 7848 deaths from the disease
in 1853, 4854 in 1858, and 4046 in 1878. The last notable outbreak
130. Anopheles quadrimaculatus, male and female, (x3!4). After Howard.
was in 1905. Reed and Carroll (1901) estimated that during the
period from 1793 to 1900 there had not been less than 500,000 cases
in the United States.
As in the case of the plague, the most stringent methods of con-
trol proved ineffective and helplessness, almost hopelessness marked
the great epidemics.
tion by trans-
verse divisson
Multiplication of
Ucoccord hodres in
cells of Argas
~\s
formation of
coccoid bodies
in blood
Formation of |
coceora. bodies in
cells of Argus £.,
143. Spirochseta gallinarum, After Hindle.
then elongate and redevelop into ordinary spirochetes in the blood
of the fowl, and the cycle may be repeated.
Hindle’s account is clear cut and circumstantial, and is quite in
line with the work of Balfour, and of Leishman. Radically different
is the interpretation of Marchoux and Couvy (1913). These investi-
gators maintain that the granules localized in the Malpighian tubules
in the larvee and, in the adult, also in the ovules and the genital ducts
of the male and female, are not derived from spirochetes but that they
exist normally in many acariens. They interpret the supposed
Typhus Fever and Pediculide 237
disassociation of the spirochete into granules as simply the first
phase, not of a process of multiplication, but of a degeneration
ending in the death of the parasite. The fragmented chromatin
has lost its affinity for stains, remaining always paler than that of
the normal spirochetes. On the other hand, the granules of Leish-
man stain energetically with all the basic stains.
Further, according to Marchoux and Couvy, infection takes
place without the emission of the coxal fluid and indeed, soiling of the
host by the coxal fluid diluting the excrement is exceptional. All
of the organs of the Argasid are invaded by the parasites, but they
pass from the ccelom into the acini of the salivary glands and collect
im its efferent canal. The saliva serves as the vehicle of infection.
Thus, the question of the life cycle of Spirocheta gallinarum, and
of spirocheetes in general, is an open one.
It should be noted that Argas persicus, the carrier of Spirocheta
gallinarum, is a common pest of poultry in the southwestern United
States. Though the disease has not been reported from this country,
conditions are such that if accidentally introduced, it might do great
damage.
Other Spirochete Diseases of Animals—About a score of other
blood inhabiting spirochetes have been reported as occurring in
mammals, but little is known concerning their life-histories. One
of the most important is Sprrocheta theilert which produces a spiro-
cheetosis of cattle in the Transvaal. Theiler has determined that it
is transmitted by an Ixodid tick, Margaropus decoloratus.
Tyenus Fever anp PEpDICULIDa
Typhus is an acute, and continued fever, formerly epidemically
prevalent in camps, hospitals, jails, and similar places where persons
were crowded together under insanitary conditions. It is accom-
panied by a characteristic rash, which gives the disease the common
name of “spotted” or “lenticular” fever. The causative organism
is unknown.
Typhus fever has not generally been supposed to occur in the
United States, but there have been a few outbreaks and sporadic
cases recognized. According to Anderson and Goldberger (1912a),
it has been a subject of speculation among health authorities why,
in spite of the arrival of occasional cases in this country and of many
persons from endemic foci of the disease, typhus fever apparently
does not gain a foothold in the United States. These same workers
238 Arthropods as Essential Hosts of Pathogenic Protozoa
showed that the so-called Brill’s disease, studied especially in New
York City, is identical with the typhus fever of Mexico and of
Europe.
The conditions under which the disease occurs and under which
it spreads most rapidly are such as to suggest that it is carried by
some parasitic insect. On epidemiological grounds the insects most
open to suspicion are the lice, bed-bugs and fleas.
In 1909, Nicolle, Comte and Conseil, succeeded in transmitting
typhus fever from infected to healthy monkeys by means of the
body louse (Pediculus corporis). Independently of this work,
Anderson and Goldberger had undertaken work along this line in
Mexico, and in 1910 reported two attempts to transmit the disease
to monkeys by means of body lice. The first experiment resulted
negatively, but the second resulted in a slight rise in temperature,
ard in view of later results it seems that this was due to infection
with typhus.
Shortly after, Ricketts and Wilder (1910) succeeded in transmitt-
ing the disease to the monkey by the bite of body lice in two experi-
ments, the lice in one instance deriving their infection from a man
and in another from the monkey. Another monkey was infected
by typhus through the introduction of the feces and abdominal
contents of infested lice into small incisions. Experiments with
fleas and bed-bugs resulted negatively.
Subsequently, Goldberger and Anderson (1912b) indicated that
the head louse (Pediculus humanus) as well, may become infected
with typhus. In an attempt to transmit typhus fever (Mexican
virus) from man to monkey by subcutaneous injection of a saline
suspension of crushed head lice, the monkeys developed a typical
febrile reaction with subsequent resistance to an inoculation of
virulent typhus (Mexican) blood. In one of the three experiments
to transmit the disease from man to monkey by means of the bite
of the head louse, the animal bitten by the presumably infected head
lice proved resistant to two successive immunity tests with viru-
lent typhus blood.
In 1910, Ricketts and Wilder reported an experiment undertaken
with a view to determining whether the young of infected lice were
themselves infected. Young lice were reared to maturity on the
bodies of typhus patients, so that if the eggs were susceptible to
infection at any stage of their development, they would have every
opportunity of being infected within the ovary. The eggs of these
infected lice were obtained, they were incubated, and the young lice
Typhus Fever and Pediculide 239
of the second generation were placed on a normal rhesus monkey.
The experimenters were unable to keep the monkey under very
close observation during the following three or four weeks, but from
the fact that he proved resistant to a subsequent immunity test
they concluded that he probably owed this immunity to infection
by these lice of the second generation.
Anderson and Goldberger (1912b) object that due consideration
was not given to the possibility of a variable susceptibility of the
monkey to typhus. Their similar experiment was “frankly nega-
tive.”
Prophylaxis against typhus fever is, therefore, primarily a ques-
tion of vermin extermination. A brief article by Dr. Goldberger
(1914) so clearly shows the practical application of his work and that
of the other investigators of the subject, that we abstract from it
the following account:
“In general terms it may be stated that association with a case of
typhus fever in the absence of the transmitting insect is no more
dangerous than is association with a case of yellow fever in the
absence of the yellow fever mosquito. Danger threatens only when
the insect appears on the scene.”
““We may say, therefore, that to prevent infection of the indi-
vidual it is necessary for him only to avoid being bitten by the louse.
In theory this may readily be done, for we know that the body louse
infests and attaches itself almost entirely to the body linen, and that
boiling kills this insect and its eggs. Individual prophylaxis is
based essentially, therefore, on the avoidance of contact with indi-
viduals likely to harbor lice. Practically, however, this is not
always as easy as it may seem, especially under the conditions of
such intimate association as is imposed by urban life. Particularly
is this the case in places such as some of the large Mexican cities,
where a large proportion of the population harbors this vermin.
Under such circumstances it is well to avoid crowds or crowded places,
such as public markets, crowded streets, or public assemblies at
which the ‘peon’ gathers.”
“Community prophylaxis efficiently and intelligently carried out
is, from a certain point of view, probably easier and more effective
in protecting the individual than is the individual’s own effort to
guard himself. Typhus emphasizes, perhaps better than any other
disease, the fact that fundamentally, sanitation and health are
economic problems. In proportion as the economic condition of the
masses has improved—that is, in proportion as they could afford
240 Arthropods as Essential Hosts of Pathogenic Protozoa
to keep clean—the notorious filth disease has decreased or dis-
appeared. In localities where it still prevails, its further reduction
or complete eradication waits on a further improvement in, or exten-
sion of, the improved economic status of those afflicted. Economic
evolution is very slow process, and, while doing what we can to hasten
it, we must take such precautions as existing conditions permit,
looking to a reduction in or complete eradication of the disease.”’
“When possible, public bath houses and public wash houses,
where the poor may bathe and do their washings at a minimum or
without cost, should be provided. Similar provision should be
made in military and construction camps. Troops in the field should
be given the opportunity as frequently as possible to wash and scald
or boil their body linen.”
“Lodging houses, cheap boarding houses, night shelters, hospitals,
jails and prisons, are important factors in the spread and frequently
constitute foci of the disease. They should receive rigid sanitary
supervision, including the enforcement of measures to free all inmates
of such institutions of lice on admission.”
“So far as individual foci of the disease are concerned these
should be dealt with by segregating and keeping under observation
all exposed individuals for 14 days—the period of incubation—from
the last exposure, by disinfecting (boiling or steaming) the suspected
bedding, body linen, and clothes, for the destruction of any possible
vermin that they may harbor, and by fumigating (with sulphur)
the quarters that they may have occupied.”
“Tt will be neted that nothing has been said as to the disposition
of the patient. So far as the patient is concerned, he should be
removed to ‘clean’ surroundings, making sure that he does not
take with him any vermin. This may be done by bathing, treating
the hair with an insecticide (coal oil, tincture of larkspur), and a
complete change of body linen. Aside from this, the patient may
be treated or cared for in a general hospital ward or in a private house,
provided the sanitary officer is satisfied that the new surroundings
to which the patient has been removed are ‘clean,’ that is, free
from vermin. Indeed, it is reasonably safe to permit a ‘clean’
patient to remain in his own home if this is ‘clean,’ for, as has al-
ready been emphasized, there can be no spread in the absence of lice.
This is a common experience in native families of the better class
and of Europeans in Mexico City.”
“Similarly the sulphur fumigation above prescribed may be
dispensed with as unnecessary in this class of cases.”
CHAPTER XI
SOME POSSIBLE, BUT IMPERFECTLY ESTABLISHED CASES OF
ARTHROPOD TRANSMISSION OF DISEASE
INFANTILE PaRAuysis oR AcuTE ANTERIOR POLIOMYELITIS
The disease usually known in this country as infantile paralysis
or, more technically, as acute anterior poliomyelitis, is one which
has aroused much attention in recent years.
The causative organism of infantile paralysis is unknown, but
it has been demonstrated that it belongs to the group of filterable
viruses. It gives rise to a general infection, producing characteristic
lesions in the central nervous system. The result of the injury to
the motor nerves is a more or less complete paralysis of the corres-
ponding muscle. This usually manifests itself in the legs and arms.
The fatal cases are usually the result of paralysis of the muscles
of respiration. Of the non-fatal cases about 60 per cent remain
permanently crippled in varying degrees.
Though long known, it was not until about 1890 that it was
emphasized that the disease occurs in epidemic form. At this time
Medin reported his observations on an epidemic of forty-three cases
which occurred in and around Stockholm in 1887. Since then,
according to Frost (1911), epidemics have been observed with increas-
ing frequency in various parts of the world. The largest recorded
epidemics have been those in Vermont, 1894, 126 cases; Norway and
Sweden, 1905, about 1,500 cases; New York City, 1907, about
2,500 cases. Since 1907 many epidemics have been reported in the
United States, and especially in the Northern States east of the
Dakotas. In 1912 there were over 300 cases of the disease in Buffalo,
N. Y., with a mortality of somewhat over 11 per cent.
In view of the sudden prominence and the alarming spread of
infantile paralysis, there have been many attempts to determine
the cause, andthe manner in which the disease spreads and develops
in epidemic form. In the course of these studies, the question of
possible transmission by insects was naturally suggested.
C. W. Howard and Clark (1912) presented the results of studies
in this phase of the subject. They dealt especially with the house-
fly, bedbug, head, and body lice, and mosquitoes. It was found
that the house-fly (Musca domestica) can carry the virus of poliomye-
litis in an active state for several days upon the surface of the body
241
242 Arthropod Transmission of Disease
and for several hours within the gastro-intestinal tract. Mosquitoes
and lice were found not to take up or maintain the virus. On the
other hand, the bedbug (Cimex lectularius) was found to take the
virus from the infected monkeys and to maintain it in a living state
within the body for a period of seven days. This was demonstrated
by grinding up in salt solution, insects which had fed on poliomyeletic
animals and injecting the filtrate into a healthy monkey. The experi-
menters doubted that the bedbug is a carrier of the virus in nature.
Earlier in the same year, Brues and Sheppard published the results
of an intensive epidemiological study of the outbreak of ro11z, in
Massachusetts. Special attention had been paid to the possibility
of insect transfer and the following conclusion was reached:
“Field work during the past summer together with a consideration
of the epidemiology of the disease so far as known, points strongly
toward biting flies as possible carriers of the virus. It seems probable
that the common stable-fly (Stomoxys calcitrans L.) may be responsi-
ble to a certain extent for the spread of acute epidemic poliomyelitis,
possibly aided by other biting flies, such as Tabanus lineola. No
facts which disprove such a hypothesis have as yet been adduced,
and experiments based upon it are now in progress.’’
As stated by Brues (1913), especial suspicion fell upon the stable-
fly because:
1. The blood-sucking habits of the adult fly suit it for the transfer
of virus present in the blood.
2. The seasonal abundance of the fly is very closely correlated
with the incidence of the disease, rising rapidly during the summer
and reaching a maximum in July and August, then slowly declining
in September and October.
3. The geographical distribution of the fly is, so far as can be
ascertained, wider, or at least co-extensive with that of poliomyelitis.
4. Stomoxys is distinctly more abundant under rural conditions,
than in cities and thickly populated areas.
5. While the disease spreads over districts quickly and in a
rather erratic way, it often appears to follow along lines of travel,
and it is known that Stomoxys flies will often follow horses for long
distances along highways.
6. Ina surprisingly large number of cases, it appeared probable
that the children affected had been in the habit of frequenting places
where Stomoxys is particularly abundant, i.e., about stables, barn-
yards, etc.
Infantile Paralysis or Acute Anterior Poliomyelites 243
The experiments referred to were carried on during the summer of
zg12 and in September Dr. Rosenau announced that the disease was
transferred by the bite of the stable-fly.
A monkey infected by inoculation was exposed to the bites of
upwards of a thousand of the Stomoxys flies daily, by stretching it
at full length and rolling it in a piece of chicken wire, and then placing
it on the floor of the cage in which the flies were confined. The flies
fed freely from the first, as well as later, after paralysis had set in.
Alternating with the inoculated monkey, healthy monkeys were
similarly introduced into the cage at intervals. New monkeys were
inoculated to keep a supply of such infectedanimals and additional
healthy ones were exposed to the flies, which fed willingly and in
considerable numbers on each occasion. ‘‘Thus the flies were given
every opportunity to obtain infection from the monkeys, since the
animals were bitten during practically every stage of the disease
from the time of the inoculation of the virus till their death follow-
ing the appearance of paralysis. By the same arrangement the
healthy monkeys were likely to be bitten by flies that had previously
fed during the various stages of the disease on the infected monkeys.
The flies had meanwhile enjoyed the opportunity of incubating the
virus for periods varying from the day or two which usually elapses
between consecutive feedings, to the two or three-week period for
which at least some (although a very small percentage) of the flies
lived in the cage.”
“In all, twelve apparently healthy monkeys of a small Japan
species were exposed to the flies in the manner described for the in-
fected monkeys. Some were placed in the cage only once or twice
and others a number of times after varying intervals. These ex-
posures usually lasted for about half an hour, but were sometimes
more protracted. No results were apparent until two or three
weeks after the experiment was well under way, and then in rather
rapid succession six of the animals developed symptoms of poliomye-
litis. In three, the disease appeared in a virulent form, resulting
in death, while the other three experienced transient tremblings,
diarrhoea, partial paralysis and recovery.’’—Brues, 1913.
Very soon after the announcement of the results of experiments
by Rosenau and Brues, they were apparently conclusively confirmed
by Anderson and Frost (1912), who repeated the experiments, at
Washington. They announced that through the bites of the Stomoxys
flies that had previously fed on infected monkeys, they had succeeded
in experimentally infecting three healthy monkeys.
244 Arthropod Transmission of Disease
The results of these experiments gained much publicity and in
spite of the conservative manner in which they had been announced,
it was widely proclaimed that infantile paralysis was conveyed in
nature by the stable-fly and by it alone.
Serious doubt was cast on this theory by the results of further
experiments by Anderson and Frost, reported in May of 1913.
Contrary to the expectations justified by their first experience, the
results of all the later, and more extended, experiments were wholly
negative. Not once were these investigators again able to transmit
the infection of poliomyelitis through Stomoxys. They concluded that
it was extremely doubtful that the insect was an important factor
in the natural transmission of the disease, not only because of their
series of negative results, “‘but also because recent experiments have
afforded additional evidence of the direct transmissibility or con-
tagiousness of poliomyelitis, and because epidemiological studies
appear to us to indicate that the disease is more likely transmitted
largely through passive human virus carriers.”
Soon after this, Kling and Levaditi (1913) published their detailed
studies on acute anterior poliomyelitis. They considered that the
experiments of Flexner and Clark (and Howard and Clark), who fed
house-flies on emulsion of infected spinal cord, were under conditions
so different from what could occur in nature that one could not
draw precise conclusions from them regarding the epidemiology of
the disease. They cited the experiments of Josefson (1912), as
being under more reasonable conditions. He sought to determine
whether the inoculation of monkeys with flies caught in the wards of
the Hospital for Contagious Diseases at Stockholm, where they had
been in contact with cases of poliomyelitis, would produce the
disease. The results were completely negative.
Kling and Lavaditi made four attempts of this kind. The flies
were collected in places where poliomyelitics had dwelt, three, four
and twenty-four after the beginning of the disease in the family and
one, three, and fifteen days after the patient had left the house.
These insects were for the greater part living and had certainly been
in contact with the infected person. In addition, flies were used
which had been caught in the wards of the Hospital for Contagious
Diseases at Séderkoping, when numbers of poliomyelitics were con-
fined there. Finally, to make the conditions as favorable as possible,
the emulsions prepared from these flies were injected without previous
filtering, since filtration often causes a weakening of the virus. In
Infantile Paralysis or Acute Anterior Poliomyelitis 245
spite of these precautions, all their results were negative, none of the
inoculated animals having contracted poliomyelitis. They also
experimented with bedbugs which had fed upon infected patients at
various stages of the disease, but the results in these cases also were
wholly negative.
Kiing and Levaditi considered at length the possibility of trans-
mission of the disease by Stomoxys. Asa result of their epidemiologi-
cal studies, they found that infantile paralysis continued to spread
in epidemic form in the dead of winter, when these flies were very
rare and torpid, or were even completely absent. Numerous cases
developed in the northern part of Sweden late in October and
November, long after snow had fallen. On account of the rarity
of the Stomoxys flies during the period of their investigations they
were unable to conduct satisfactory experiments. In one instance,
during a severe epidemic, they found a number of the flies in a stable
near a house inhabited by an infected family, though none was
found in the house itself. These flies were used in preparing an
emulsion which, after filtering, was injected into the peritoneal
cavity of a monkey. The result was wholly negative.
As for the earlier experiments, Kling and Levaditi believe if the
flies were responsible for the transmission of the disease in the cases
reported by Rosenau and Brues, and the first experiments of Ander-
son and Frost, it was because the virus of infantile paralysis is elimi-
nated with the nasal secretions of paralyzed monkeys and the flies,
becoming contaminated, had merely acted as accidental carriers.
Still further evidence against the hypothesis of the transmission
of acute anterior poliomyelitis by Stomoxys calcitrans was brought
forward by Sawyer and Herms (1913). Special precautions were
used to prevent the transference of saliva or other possibly infectious
material from the surface of one monkey to that of another, and to
avoid the possibility of complicating the experiments by intro-
ducing other pathogenic organisms from wild flies, only laboratory-
bred flies were used. Ina series of seven carefully performed experi-
ments, in which the conditions were varied, Sawyer and Herms were
unable to transmit poliomyelitis from monkey to monkey through
the agency of Stomoxys, or to obtain any indication that the fly is the
usual agent for spreading the disease in nature.
The evidence at hand to date indicates that acute anterior polio-
myelitis, or infantile paralysis, is transmitted by contact with in-
fected persons. Under certain conditions insects may be agents in
spreading the disease, but their réle is a subordinate one.
246 Arthropod Transmission of Disease
Pellagra
Pellagra is an endemic and epidemic disease characterized by a
peculiar eruption or erythema of the skin (figs 144 and 14 5), digestive
disturbances and nervous trouble.
Insanity is a common result, rather
than a precursor of the disease.
The manifestations of pellagra are
periodic and its duration indeter-
minate.
The disease is one the very name
of which was almost unknown in the
United States until within the past
decade. It hasusually been regarded
as tropical, though it occurs commonly
in Italy and in various parts of Europe.
Now it is known that it not only
occurs quite generally in the United
States but that it isspreading. Lav-
inder (1911) says that ‘‘There are
certainly many thousard cases of the
disease in this country, and the pres-
144. Pellagrous eruption on the face. =» ent situation must be looked upon
with grave concern.”
It is not within the scope of this book to undertake a general
discussion of pellagra. The subject is of such importance to every
medical man that we cannot do better than refer to Lavinder’s
valuable précis. We can only touch briefly upon the entomological
phases of the problems presented.
The most commonly accepted theories regarding the etiology
of the disease have attributed it to the use of Indian corn as an article
of diet. This supposed relationship was explained either on the
basis of, (a) insufficiency of nutriment and inappropriateness of
corn as a prime article of food; (b) toxicity of corn or, (c) parasitism
of, certain organisms—fungi or bacteria—ingested with either sound
or deteriorated corn.
In 1905, Sambon proposed the theory of the protozoal origin’ of
pellagra and in 1910 he marshalled an imposing array of objections
to the theory that there existed any relationship between corn and
the disease. He presented clear evidence that pellagra existed in
Europe before the introduction of Indian corn from America, as an
Pellagra 247
article of diet, and that its spread wasnot part passu with that of the
use of corn. Cases were found in which the patients had apparently
never used corn, though that is obviously difficult to establish. He
showed that preventive measures based on the theory had been a
failure. Finally, he believed that the recurrence of symptoms of
the disease for successive springs, in patients who abstained absolutely
from the use of corn, militated against the theory.
On the other hand, Sambon believed that the periodicity of the
symptoms, peculiarities of distribution and seasonal incidence, and
analogies of the symptoms to those of other parasitic diseases indi-
145. Pellagrous eruption on the hand. After Watson.
cated that pellagra was of protozoal origin, and that it was insect-
borne.
The insect carriers, he believed to be one or more species of
Simuliide, or black-flies. In support of this he stated that Simulium
appears to effect the same topographical conditions as pellagra,
that in its imago stage it seems to present the same seasonal incidence,
that it has a wide geographical distribution which seems to cover
that of pellagra, and that species of the genus are known to cause
severe epizootics. Concluding from his studies in Italy, that pel-
lagra was limited almost wholly to agricultural laborers, he pointed
out that the Simulium flies are found only in rural districts, and as a
rule do not enter towns, villages, or houses.
When Sambon’s detailed report was published in 1910, his theory
was seized upon everywhere by workers who were anxious to test it
248 Arthropod Transmission of Disease
146. A favorite breeding place of Simulium. Ithaca, N. Y.
Pellagra 249
and who, in most cases, were favorably disposed towards it because
of the wonderful progress which had been made in the understanding
of other insect-borne diseases. In this country, the entomological
aspects of the subject have been dealt with especially by Forbes
(1912), and by King and Jennings, under the direction of W. D.
Hunter, of the Bureau of Entomology, and in co-operation with
the Thompson-McFadden Pellagra Commission of the Department
of Tropical Medicine of the New York Post-Graduate Medical
School. An important series of experiments with monkeys has
been undertaken by S.J. Hunter, of Kansas, but unfortunately wehave
as yet no satisfactory evidence that these animals are susceptible
to the disease—a fact which renders the whole problem difficult.
The accumulated evidence is increasingly opposed to Sambon’s
hypothesis of the transmission of pellagra by Simulium. This has
been so clearly manifested in the work of the Thompson-McFadden
Commission that we quote here from the report by Jennings (1914):
‘‘Our studies in 1912 convinced us that there was little evidence
to support the incrimination of any species of Simulium in South
Carolina in the transmission of pellagra. Reviewing the group as a
whole, we find that its species are essentially ‘‘wild’’ and lack those
habits of intimate association with man which would be expected
in the vector of such a disease as pellagra. Although these flies are
excessively abundant in some parts of their range and are moderately
so in Spartanburg County, man is merely an incidental host, and no
disposition whatever to seek him out or to invade his domicile seems
to be manifested. Critically considered, it is nearer the fact that
usually man is attacked only when he invades their habitat.”
“As our knowledge of pellagra accumulates, it is more and more
evident that its origin is in some way closely associated with the
domicile. The possibility that an insect whose association with man
and his immediate environment is, at the best, casual and desultory,
can be active in the causation of the disease becomes increasingly
remote.”
“Our knowledge of the biting habits of Simulium is not complete,
but it is evident, as regards American species at least, that these are
sometimes not constant for the same species in different localities.
Certain species will bite man freely when opportunity offers, while
others have never been known to attack him. To assume that the
proximity of a Simulium-breeding stream necessarily implies that
persons in its vicinity must be attacked and bitten is highly fal-
250 Arthropod Transmission of Disease
lacious. In Spartanburg County attacks by Simulium seems to be
confined to the immediate vicinity of the breeding-places. Our
records and observations, exceedingly few in number, refer almost
exclusively to such locations. Statements regarding such attacks,
secured with much care and discrimination from a large number of
persons, including many pellagrins, indicate conclusively that these
insects are seldom a pest of man in this county. A certain number
of the persons questioned were familiar with the gnats in other
localities, but the majority were seemingly ignorant of the existence
of such flies with biting habits. This is especially striking, in view
of the fact that the average distance of streams from the homes of
the pellagra cases studied was about 200 yards, many being at a
distance of less than 100 yards, and that 78 per cent of these streams
were found to be infested by larval Stmulium. Such ignorance in a
large number of persons cannot be overlooked and indicates strongly
that our belief in the negligible character of local attacks by Simulium
is well founded.”
“In localities infested by ‘sand-flies,’ mosquitoes, etc., these
pests are always well known and the ignorance described above is
very significant.”
“Such positive reports as we received nearly always referred to
bites received in the open, along streams, etc., and observations made
of their attack were of those on field laborers in similar situations.
Males engaged in agricultural pursuits are almost exempt from
pellagra in Spartanburg County. During the season of 1913, in
some two or three instances, observations were made of the biting
of Simulium and some additional and entirely creditable reports
were received. These observations and reports were under condi-
tions identical with those referred to in the reports of 1912 and con-
firm the conclusions based on the observations of that year. I
would repeat with emphasis that it is inconceivable that a fly of the
appearance and habits of the prevalent species of Simulium could be
present in such a region, especially about the haunts of man and
attack him with sufficient frequency and regularity to satisfactorily
account for so active and prevalent a disease as pellagra without
being a well-known and recognized pest.”
“In connection with the conditions in the Piedmont region of
South Carolina, it may be well to cite the results of a study of those
in the arid region of western Texas.”
Pellagra 251
“In May, 1913, in company with Capt. J. F. Siler of the Thomp-
son-McFadden Pellagra Commission, I visited the region of which
Midland in Midland County is the center. This region is very dry
and totally devoid of running water for a long distance in every
direction. The only natural source of water-supply, a few water
holes and ponds, were visited and found to be of such a nature that
the survival of Simulium, far less its propagation in them, is abso-
lutely impossible. The nearest stream affording possibilities as a
source of Szmulium is 60 miles away, while the average distance of
such possibility is not less than 100 miles.”
‘‘Artificial sources of water-supply were also investigated care-
fully and were found to offer no opportunity for the breeding of
Simulium.”
“At Midland the histories of five cases of pellagra were obtained,
which gave clear evidence that this place or its immediate vicinity
was the point of origin. Persons of long residence in the country
were questioned as to the occurrence of such flies as Simulium and
returned negative answers. These included a retired cattle owner,
who is a man of education and a keen observer, an expert veterinarian
stationed in the country who has the cattle of the country under
constant observation, and a practical cattle man, manager of a ranch
and of wide experience. The latter had had experience with ‘Buf-
falo gnats’ in other localities (in the East) and is well acquainted
with them. His close personal supervision of the cattle under his
charge, makes it practically certain that he would have discovered
these gnats had they been present in the country.”
“At the time the study was made, Simulium was breeding and
active in the adult state in the vicinity of Dallas, Texas, in the
eastern part of the state. We have here a region in which cases of
pellagra have originated, yet in which Simulium does not and cannot
breed.”’
Other possible insect vectors of pellagra have been studied in
great detail and the available evidence indicates that if any insect
plays a réle in the spread of the disease, Stomoxys calcitrans most
nearly fills the conditions. This conclusion was announced by
Jennings and King in 1912, and has been supported by their subse-
quent work.
Yet, after all the studies of the past decade, the old belief that
pellagra is essentially of dietary origin is gaining ground. Gold-
berger, Waring and Willets (1914) of the United States Public Health
252 Arthropod Transmission of Disease
Service summarize their conclusions in the statement, (1) that it is
dependent on,some yet undetermined fault in a diet in which the
animal or leguminous protein component is disproportionately large
and (2) that no pellagra develops in those who consume a mixed,
well-balanced, and varied diet, such, for example, as that furnished
by the Government to the enlisted men of the Army, Navy, and
Marine Corps.
Leprosy
Leprosy is a specific, infectious disease due to Bacillus lepre, and
characterized by the formation of tubercular nodules, ulcerations,
and disturbances of sensation. In spite of the long time that the
disease has been known and the dread with which it is regarded,
little is known concerning the method of transfer of the causative
organism or the means by which it gains access to the human body.
It is known that the bacilli are to be found in the tubercles, the
scurf of the skin, nasal secretions, the sputum and, in fact in prac-
tically all the discharges of the leper. Under such conditions it is
quite conceivable that they may be transferred in some instances
from diseased to healthy individuals through the agency of insects
and other arthropods. Many attempts have been made to demon-
strate this method of spread of the disease, but with little success.
Of the suggested insect carriers none seem to meet the conditions
better than mosquitoes, and there are many suggestions in literature
that these insects play an important réle in the transmission of
leprosy. The literature has been reviewed and important experi-
mental evidence presented by Currie (1910). He found that mosqui-
toes feeding, under natural conditions, upon cases of nodular leprosy
so rarely, if ever, imbibe the lepra bacillus that they cannot be
regarded as one of the ordinary means of transference of this bacillus
from lepers to the skin of healthy persons. He believes that the
reason that mosquitoes that have fed on lepers do not contain the
lepra bacillus is that when these insects feed they insert their probos-
cis directly into a blood vessel and thus obtain bacilli-free blood,
unmixed with lymph.
The same worker undertook to determine whether flies are able
to transmit leprosy. He experimented with five species found in
Honolulu,p—Musca domestica, Sarcophaga pallinervis, Sarcophaga
barbata, Volucella obesa and an undetermined species of Lucilia.
The experiments with Musca domestica were the most detailed.
Leprosy 253
From these experiments he concluded, first, that all of the above-
named flies, when given an opportunity to feed upon leprous fluids,
will contain the bacilli in their intestinal tracts and feces for several .
days after such feeding. Second, that considering the habits of
these flies, and especially those of Musca domestica, it is certain that,
given an exposed leprous ulcer, these insects will frequently convey
immense numbers of lepra bacilli, directly or indirectly, to the skins,
nasal mucosa, and digestive tracts of healthy persons. Additional
evidence along this line has recently been brought forward by
Honeij and Parker (1914), who incriminate both Musca domestica
and Stomoxys calcitrans. Whether or not such insect-borne bacilli
are capable of infecting persons whose skin and mucosa are thus
contaminated, Currie was unwilling to maintain, but he concludes
that until we have more accurate knowledge on this point, we are
justified in regarding these insects with grave suspicion of being
one of the means of disseminating leprous infection.
Various students of the subject have suggested that bed-bugs
may be the carriers of leprosy and have determined the presence of
acid-fast bacilli in the intestines of bed-bugs which had fed on leprous
patients. Opposed to this, the careful experiments of Thompson
(1913) and of Skelton and Parkham (1913) have been wholly nega-
tive.
Borrel has recently suggested that Demodex, may play a réle in
spreading the infection in families. Many other insects and acariens
have been suggested as possible vectors, but the experimental data
are few and in no wise conclusive. The most that can be said is that
it is quite possible that under favorable conditions the infection
might be spread by any of the several blood-sucking forms or by
house-flies.
Verruga peruviana
Verruga peruviana is defined by Castellani and Chalmers as “a
chronic, endemic, specific, general disorder of unknown origin, not
contagious, but apparently inoculable, and characterized by an ir-
regular fever associated with rheumatoid pains, anemia, followed
by granulomatous swellings in the skin, mucous membranes, and
organs of the body.” It has been generally believed by medical
men interested that the comparatively benign eruptive verruga is
identical with the so-called Oroya, or Carrion’s fever, a malignant
type. This view is not supported by the work of Strong, Tyzzer
and Brues, (1913).
.
254 Arthropod Transmission of Disease
The disease is confined to South America and to definitely limited
areas of those countries in which it does occur. It is especially
prevalent in some parts of Peru.
The causative organism and the method of transfer of verruga
are unknown. Castellani and Chalmers pointed out in 1910 that the
study of the distribution of the disease in Peru would impress one
with the similarity to the distribution of the Rocky Mountain fever
and would lead to the conclusion that the etiological cause must in
some way be associated with some blood-sucking animal, perhaps an
arachnid, and that this is supported by the fact that the persons
most prone to the infection are those who work in the fields.
More recently, Townsend (1913), in a series of papers, has main-
tained that verruga and Carrion’s disease are identical, and that they
are transmitted to man by the bites of the Psychodid fly, Phlebotomus
verrucarum. He succeeded in producing the eruptive type of the
disease in experimental animals by injecting a physiological salt
trituration of wild Phlebotomus flies. A cebus monkey was exposed
from October 10 to November 6, by chaining him to a tree in the
verruga zone, next to a stone wall from which the flies emerged in
large numbers every night. Miliar eruption began to appear on the
orbits November 13 and by November 21, there were a number of
typical eruptions, with exudation on various parts of the body
exactly like miliar eruptive sores commonly seen on legs of human
cases.
An assistant in the verruga work, George E. Nicholson, contracted
the eruptive type of the disease, apparently as a result of being bitten
by the Phlebotomus flies. He had slept in a verruga zone, under a
tight net. During the night he evidently put his hands in contact
with the net, for in the morning there were fifty-five unmistakable
Phlebotomus bites on the backs of his hands and wrists.
Townsend believes that in nature, lizards constitute the reservoir
of the disease and that it is from them that the Phlebotomus flies
receive the infection.
Cancer
There are not wanting suggestions that this dread disease is
carried, or even caused, by arthropods. Borrel (1909) stated that
he had found mites of the genus Demodex in carcinoma of the face
and of the mamme. He believed that they acted as carriers of the
virus.
Cancer 285
Saul (1910) and Dahl (1910) go much further, since they attribute
the production of the malignant growth to the presence of mites
which Saul had found incancers. These Dahl described as belonging
to a new species, which he designated Tarsonemus hominis. These
findings have since been confirmed by several workers. Neverthe-
less, the presence of the mite is so rare that it cannot be regarded as
an important factor in the causation of the disease. The theory
that cancer is caused by an external parasite is given little credence
by investigators in this field.
In conclusion, it shouldbe noted that themedical and entomolog-
ical literature of the past few years abounds in suggestions, and in
unsupported direct statements that various other diseases are insect-
borne. Knab (1912) has well said ‘‘Since the discovery that certain
blood-sucking insects are the secondary hosts of pathogenic para-
sites, nearly every insect that sucks blood, whether habitually or
occasionally, has been suspected or considered a possible transmitter
of disease. No thought seems to have been given to the conditions
and the characteristics of the individual species of blood-sucking
insects, which make disease transmission possible.”’
He points out that “in order to be a potential transmitter of human
blood-parasites, an insect must be closely associated with man and
normally have opportunity to suck his blood repeatedly. It is not
sufficient that occasional specimens bite man, as, for example, is the
case with forest mosquitoes. Although a person may be bitten by a
large number of such mosquitoes, the chances that any of these
mosquitoes survive to develop the parasites in question, (assuming
such development to be possible), and then find opportunity to bite
and infect another person, are altogether too remote. Applying
this criterion, not only the majority of mosquitoes but many other
blood-sucking insects, such as Tabanide and Simuliide, may be
confidently eliminated. Moreover, these insects are mostly in
evidence only during a brief season, so that we have an additional
difficulty of avery long interval during which there could be no prop-
agation of the disease in question.’””’ He makes an exception of
tick-borne diseases, where the parasites are directly transmitted from
the tick host to its offspring and where, for this reason, the insect
remains a potential transmitter for a very long period. He also
cites the trypanosome diseases as possible exceptions, since the causa-
tive organisms apparently thrive in a number of different vertebrate
hosts and may be transmitted from cattle, or wild animals, to man.
256 Arthropods Transmission of Disease
Knab’s article should serve a valuable end in checking irrespon-
sible theorizing on the subject of insect transmission of disease.
Nevertheless, the principles which he laid down cannot be applied
to the cases of accidental carriage of bacterial diseases, or to those
of direct inoculation of pyogenic organisms, or of blood parasites
such as the bacillus of anthrax, or of bubonic plague. Accumulated
evidence has justified the conclusion that certain trypanosomes
pathogenic to man are harbored by wild mammals, and so form an
exception. Townsend believes that lizards constitute the natural
reservoir of verruga; and it seems probable that field mice harbor
the organism of tsutsugamushi disease. Such instances are likely to
accumulate as our knowledge of the relation of arthropods to disease
broadens.
‘CHAPTER XII
HOMINOXIOUS ARTHROPODS
The following synoptic tables are presented in the hope that they
may be of service in giving the reader a perspective of the relation-
ships of the Arthropoda in general and enabling him to identify the
more important species which have been found noxious to man.
Though applicable chiefly to the arthropods found in the United
States, exotic genera and species which are concerned in the trans-
mission of disease are also included. For this reason the keys to the
genera of the Muscids of the world are given. As will be seen, the
tables embrace a number of groups of species which are not injurious.
This was found necessary in order that the student might not be
lead to an erroneous determination which would result were he to
attempt to identify a species which heretofore had not been considered
noxious, by means of a key containing only the noxious forms. The
names printed in bold faced type indicate the hominoxious arthropods
which have been most commonly mentioned in literature.
CRUSTACEA
Arthropods having two pairs of antennz which are sometimes
modified for grasping, and usually with more than five pairs of legs.
With but few exceptions they are aquatic creatures. Representatives
are: Crabs, lobsters, shrimps, crayfish, water-fleas, and woodlice.
To this class belongs the Cyclops (fig. 122) a genus of minute aquatic
crustaceans of which at least one species harbors Dracunculus medi-
nensis, the Guinea worm (fig. 121).
MYRIAPODA
Elongate, usually vermiform, wingless, terrestrial creatures having
one pair of antenne, legs attached to each of the many intermediate
body segments. This group is divided into two sections, now usually
given class rank: the Diplopoda or millipeds (fig. 13), commonly
known as thousand legs, characterized by having two pairs of legs
attached to each intermediate body segment, and the Chilopoda
or centipeds (fig. 14) having only one pair of legs to each body seg-
ment.
257
258 Hominoxious Arthropods
ARACHNIDA
In this class the antennz are apparently wanting, wings are never
present, and the adults are usually provided with four pairs of legs.
Scorpions, harvest-men, spiders, mites, etc.
HEXAPODA (Insects)
True insects have a single pair of antenne, which is rarely vestigial,
and usually one or two pairs of wings in the adult stage. Familiar
examples are cockroaches, crickets, grasshoppers, bugs, dragonflies,
butterflies, moths, mosquitoes, flies, beetles, ants, bees and wasps.
ORDERS OF THE ARACHNIDA
a. Abdomen distinctly segmented. A group of orders including scorpions,
(fig. 11), whip-scorpions (fig. 10), pseudo-scorpions, solpugids (fig. 12)
harvest-men (daddy-long-legs or harvestmen), etc........ ARTHROGASTRA
aa. Abdomen unsegmented, though sometimes with numerous annulations
RS Rael eat lt aes gee cat pat haves oh toads le ul GEE LE Sok aaa eee te eA SPHZROGASTRA
b. A constriction between cephalothorax and abdomen (fig. 7). True Spiders
she oct A MN e A a Mn LR nae ty Manica tinue cess aes ARANEIDA
bb. No deep constriction between these parts.
c. Legs usually well developed, body more.or less depressed (fig. 49). Mites
Fu sauabota paececinoisas ot BslantoB yooh ease Bio eebee a: aheg Ban ghedarat enduey shin aud sy Maesliah seis ends fex ACARINA
cc. Legs stumpy or absent, body more or less elongate or vermiform, or if
_ shorter, the species is aquatic or semi-aquatic in habit.
d. Four pairs of short legs; species inhabiting moss or water. Water-
BOATS: Wis nyata uiemis'a ay ais ehin gi owe ats ehh yam Saw c Pa NTN TARDIGRADA
dd. Two pairs of clasping organs near the mouth, instead of legs, in the
adult; worm-like creatures parasitic within the nasal passages,
lungs, etc. of mammals and reptiles (fig. 148). Tongue worms.
a sehr ah aay nate WBiper BA ARTS. AS LSA saa tLe Tg ae SN AOR GieHe GOREN RAS LINGUATULINA
148. Linguatula, (a) larva; (enlarged). (6) adult; (natural size).
Acarina 259
ACARINA*
a. Abdomen annulate, elongate; very minute forms, often with but four legs
(88562) 35 sonhacire Ghee nea Cee Oe Cues eR wae: DEMODICOIDEA
b. With but four legs of five segments each. Living on plants, often forming
ANS sg ks te i Leo “ars ines Ortega aha er ink Heal wb aude dow a hab dies bk ERIOPHYIDE
bb. With eight legs, of three segments each. Living in the skin of mammals
eo sih Galehee he tik tee Sri dorset ve wy aah BOR HES RATES fesey te Re eV DEMODICIDE
To this family belongs the genus Demodex found in the sebaceous glands
and hair follicles of various mammals, including man. D. phylloides
Csokor has been found in Canada on swine, causing white tubercles
on the skin. D. bovis Stiles has been reported from the United States
on cattle, upon the skin of which they form swellings. D. folliculorum
Simon is the species found on man. See page 78.
aa. Abdomen not annulate nor prolonged behind; eight legs in the adult stage.
b. With a distinct spiracle upon a stigmal plate on each side of the body (usu-
ally ventral) above the third or fourth coxe or a little behind (fig. 50);
palpi free; skin often coriaceous or leathery; tarsi often with a sucker.
c. Hypostome large (fig. 50), furnished below with many recurved teeth;
venter with furrows, skin leathery; large forms, usually parasitic
iy Shy Senne Oe we auceh ob Ail AlareIR BBR ba oa vege se a RB IxopoIDEA
d. Without scutum but covered by a more or less uniform leathery integu-
ment; festoons absent; coxe unarmed, tarsi without ventral spurs;
pulvilli absent or vestigial in the adults; palpi cylindrical; sexual
dimorphisim: Slight 25.40 224 A344 ses ss Bo bs BESO S ways LE ARGASIDE
e. Body flattened, oval or rounded, with a distinct flattened margin
differing in structure from the general integument; this margin
gives the body a sharp edge which is not entirely obliterated even
when the tick is full fed. Capitulum (in adults and nymphs)
entirely invisible dorsally, distant in the adult by about its own
length from the anterior border. Eyes absent...... Argus Latr.
f. Body oblong; margin with quadrangular cells; anterior tibie and
metatarsi each about three times as long as broad. On poultry,
southwest United States................ A. persicus miniatus
A. brevipes Banks, a species with proportionately shorter legs has
been recorded from Arizona.
ff. With another combination of characters. About six other species
of Argas from various parts of the world, parasitic on birds and
mammals.
ee. Body flattened when unfed, but usually becoming very convex on
distention; anterior end more or less pointed and hoodlike;
margin thick and not clearly defined, similar in structure to the
rest of the integument and generally disappearing on distention;
capitulum subterminal, its anterior portions often visible dorsally
in the adult; eyes present in some species.
f. Integument pitted, without rounded tubercles; body provided
with many short stiff bristles; eyes absent. On horses, cattle
Ani AMAT CAP AB) io sca US son gies eect thes dead Otiobius Banks.
O. megnini, a widely distributed species, is the type of this genus.
*Adapted from Banks, Nuttall, Warburton, Stiles, et. al.
260 Hominoxious Arthropods
ff, Integument with rounded tubercles or granules; body without stiff
PHISHIES!. codes hse SR RTA Ree Ea Ae eR ENs Ornithodoros Koch.
g. Two pairs of eyes; tarsi IV with a prominent subterminal spur
above; leg I strongly roughened. On cattle and man.
2 wiplabed ce cee aia aes a Sa a arate Aco hciya Saree ae See O. coriaceus
gg. No eyes; no such spur on the hind tarsi.
h. Tarsi I without humps above............+-+++- O. talaje.
hh. Tarsi I with humps above.
i. Tarsi IV without distinct humps above. On hogs, cattle
ANGAMAN): We cand gus ioe eee Se AAs Fe eons see O. turicata
ii. Tarsi IV with humps nearly equidistant (fig. 142). Africa.
O. moubata
— : Ay ys
one bade frosl.anal praeve P
149. Hemaphysalis wellingtoni. Note short palpi. After Nuttall and Warburton.
dd. With scutum or shield (fig. 50); festoons usually present; cox
usually armed with spurs, tarsi generally with one or two ventral
spurs; pulvilli present in the adults; sexual dimorphism pronounced
SSS CRRA SED SES WE See Oe ecg epee hea es dea ae eee ae IXODIDZ
e. With anal grooves surrounding anus in front; inornate; without eyes;
no posterior marginal festoons; venter of the male with non-
salient plates. Numerous species, 14 from the United States,
among them I. ricinus (fig. 49 and 50), scapularis, cookei, hexa-
gonus, bicornis. Ixodes Latr. (including Ceratixodes).
ee. With anal groove contouring anus behind, or groove faint or obsolete.
f. With short palpi (fig. 149).
g. Without eyes, inornate, with posterior marginal festoons; male
without ventral plates. Numerous species. H. chordeilis
and leporis-palustris from the United States ..............
ATiahoce Sai tensa atcaicen tipsy dened Steins ate si Hemaphysalis Koch.
Acarina 261
150. Stigmal plate of Dermacentor andersoni; (@) of male, (b) of female. After Stiles.
(c) Dermacentor variabilis, male- (d) Glyciphagus obesus; (e) Otodectes
cynotis; (f) Tyroglyphus lintneri; (g) Tarsonemus pallidus; (kh) anal plate
and mand ble of Liponyssus; (c) to (h) after Banks.
262 Hominoxious Arthropods
gg. With eyes.
h. Anal groove distinct; posterior marginal festoons present.
i. Base of the capitulum (fig. 150c) rectangular dorsally;
usually ornate............0-.0000- Dermacentor Koch.
j. Adults with four longitudinal rows of large denticles on
each half of hypostome; stigmal plate nearly circular,
without dorso-lateral prolongation, goblets very large,
attaining 43H to 115¢ in diameter; not over 40 per
plate, each plate surrounded by an elevated row of
regularly arranged supporting cells; white rust want-
ing; base of capitulum distinctly broader than long,
its postero-lateral angles prolonged slightly, if at all;
coxe I with short spurs; trochanter I with small
dorso-terminal blade. Texas, Arizona, etc. D.nitens
151. Rhipicephalus bursa, male.
After Nuttall and Warburton.
jj. Adults with three longitudinal rows of large denticles on
each half of hypostome; goblet cells always more
than 40 per plate; whitish rust usually present.
k. Dorso-lateral prolongation of stigmal plate small or
absent; plates of the adults distinctly longer than
broad; goblet cells large, usually 30u to 85m in
diameter, appearing as very coarse punctations on
untreated specimens, but on specimens treated
with caustic potash they appear very distinct in
outline; base of capitulum distinctly (usually about
twice) broader than long, the postero-lateral angles
distinctly produced caudad; spurs of coxe I long, |
lateral spur slightly longer than median; tro-
chanter I with dorso-terminal spur. D. albipictus,
= variegatus), salmont, nigrolineatus.
Acarina 263
kk. Dorso-lateral prolongation of stigmal plate distinct.
1. Body of plate distinctly longer than broad; goblet
cells of medium size, usually 17.54 to 354 or 40m in
diameter, appearing as medium sized punctua-
tions on untreated specimens, but on the speci-
mens treated with caustic potash they appear
very distinct in outline, which is not circular;
base of capitulum usually less than twice as broad
as long, the postero-lateral angles always dis-
tinctly prolonged caudad.
m. Trochanter I with distinct dorso-subterminal
retrograde sharp, digitate spur; postero-
lateral angles of capitulum pronouncedly
prolonged caudal, 112% to 160 long; goblet
cells attain 134 to 4ou in diameter; type
locality California........... D. occidentalis
mm. Trochanter I with dorso-terminal blade; postero-
lateral angles of capitulum with rather short
prolongations.
n. Stigmal plate small, goblet cells not exceeding
45 inthe male or 100 in the female; scutum
with little rust, coxa I with short spurs, the
inner distinctly shorter than the outer
teen och tne ee D. parumapertus-marginatus
nn. Stigmal plate larger; goblet cells over 70 in
the male and over 100 in the female; coxa I
with longer spurs, inner slightly shorter
than the outer; scutum with considerable
TUS tia son yooh Seas eae ease D. venustus*
tl. Goblet cells small, rarely exceeding 17.64, occasional-
ly reaching 194 in diameter; on untreated speci-
mens they appear as very fine granulations, and on
specimens treated with caustic potash they may
be difficult to see, but their large number can
be determined from the prominent stems of the
goblets; surface of outline of the goblets dis-
tinctly circular; base of the capitulum usually less
than twice as broad as long, the postero-lateral
angle distinctly prolonged caudad; spurs of
CORB LIONS soci w chavs nanos eae Manas aaeioaes
sina oS D. reticulatus and electus (= partubais?)
ii. Base of the capitulum (fig. 151) tisually hexagonal (except
in the male of puchellus); and usually inornate.
*Dr. C. W. Stiles considers the species which is responsible for spotted fever distinct from the
venustus of Banks, separating it as follows:
Goblet cells about 75 in the male or 105 in the female. Texas. D. venustus.
Goblet cells 157 in the male, or 120 in the female; stigmal plate shaped as shown in the figure
(figs. 150 a,b). Montana, etc. D. andersoni.
264 Hominoxious Arthropods
j. No ventral plate or shield in either sex (fig. 153). R.
bicornis from the United States ....Rhipicentor Nuttall
jj. Males with a pair of adanal shields, and usually a pair of
accessory adanal shields. Numerous species, among
them R. sanguineus (fig. 154) and texanus, the latter
from the United States...... Rhipicephalus Koch
hh. Anal grooves faint or obsolete; no marginal festoons.
i. Short palpi; highly chitinized; unfed adults of large size;
coxee conical; male with a median plate prolonged in two
long spines projecting caudad; segments of leg pair IV
greatly swollen (fig. 155, 156). M. winthemi..........
Margaropus Karsch
152, Monieziella (Histiogaster) emtomophaga~spermatica, ventral aspect,
male and female. After Trouessart,
ii. Very short palpi, ridged dorsally and laterally; slightly
chitinized; unfed adults of smaller size; coxe I bifid;
male with adanal and accessory adanal shields (fig. 139).
B. annulatus........................ Boophilus Curtis
ff. Palpi longer than broad (fig. 157).
g. Male with pair of adanal shields, and two posterior abdominal
protrusions cappéd by chitinized points; festoons present or
absent. Several species, among them H. egypticum (fig. 140)
from the old world.................... Hyalomma Koch
gg. Male without adanal shields but small ventral plaques are
occassionally present close to the festoons. Many species, a
few from the Unted States (fig. 157).... Amblyomma Koch
h. Coxa I with but one spine; metatarsi (except I) with two
thickened spurs at tips................ A. maculatum
hh. Coxa I with two spines; metatarsi without stout spurs at
tips, only slender hairs.
Acarina 265
1, Projections of coxa I blunt and short. Large species on the
gopher tortoise in Florida.......... A. tuberculatum
ii. Projections of coxa I longer, and at least one of them sharp
pointed; second segment of palpus twice as long as the
third; coxa IV of the male with a long spine.
j. Porose areas nearly circular; shield of both sexes pale
yellowish, with some silvery streaks and marks, and
some reddish spots; shield of female as broad as long.
Jauiirerivsnemany some ee ts A. cayennense ( =mixtum).
jj. Porose areas elongate, shield brown, in the female with
an apical silvery mark, in the male with two small
and two or four other silvery spots; shield of the fe-
male longer than broad (fig 158 e)..A. americanum.
Internal Spur
External Sper
Genclul
Ovifree- Coxa In
Coxe AT
Coca zr.
Coxa€ Spurs
2 Soiracle—
JSestoo 2S
153. Rhipicentor bicornis, ventral aspect, male. After Nuttall and
Warburton.
ec. Hypostome small, without teeth, venter without furrows; body often
with coriaceous shields, posterior margin of the body never crenulate
(i.e. without festoons); no eyesS.............. GAMASOIDEA.
d. Parasitic on vertebrates; mandibles fitted for piercing; body sometimes
Constricted): wes soem ote cds eee tales DERMANYSSIDA.
e, Anal plate presenti... gcscccne se csaneceins antes eames DERMANYSSINE.
f. Body short; legs stout, hind pair reaching much beyond the tip of
the body. On bats..............00 eens Pteroptus Dufour.
ff. Body long; hind legs not reaching beyond the tip of the body.
g. Peritreme on the dorsum, very short; body distinctly con-
SETICTEG wi. - < as ascqe ned agers oes Carpoglyphus Robin.
ll. The bristle on the penultimate segment of the legs
arise from near the tip; a suture between cephalo-
thorax and abdomen.
m. Cephalothorax with four distinct and long bristles
in a transverse row; tarsi I and II about twice
as long as the preceding segment (fig. 150 f)
sa ae cng salgnatagya NG nie aes $e peer Tyroglyphus Latr.
n. Some bristles on tarsi I and II near middle,
distinctly spine-like; the sense hair about its
length from the base of the segment. Several
species in the United States belong to this
group.
nn. No spine-like bristles near the middle of the
tarsi; sense hair not its length from the base
of the segment.
o. Of the terminal abdominal bristles, only two
are about as long as the abdomen; leg I
of the male greatly thickened and with a
spine at apex of the femur below. .T. farinz.
oo. Of the terminal abdominal bristles at least
six or more are very long, nearly as long
as the body.
p. Bristles of the body distinctly plumose or
pectinate; tarsi very long..T. longior.
pp. Bristles of the body not pectinate.
q. In mills, stored foods, grains, etc. Third
and fourth joints of hind legs scarcely
twice as long as broad; abdominal
bristles not unusually long; legs I
Acarina 269
and II of the male not unusually
SPOUT ig 5 anneal aastnetins T. americanus.
qq. With other characters and habits.
T. lintneri (fig. 150 f£) the mushroom
mite, and several other species.
mm. Cephalothorax with but two long distinct
bristles (besides the frontal pair), but some-
times a very minute intermediate pair;
tarsi I and II unusually short and not twice
as long as the preceding segment.
n. Tarsi with some stout spines. Rhizoglyphus Clap.
The species of this genus are vegetable feed-
ers. Several occur in the United States.
R. parsiticus and R. spinitarsus have been
recorded from the old world, attacking human
beings who handle affected plants.
nn. Tarsi with only fine hairs. .Monieziella Berl.
The species of this genus, as far as known,
are predaceous or feed on recently killed
animal matter. Several species occur
in the United States. M. (=Histiogaster)
entomophaga (fig. 152) from the old
world has been recorded as injurious
to man.
ge. Genital suckers absent; integument with fine parallel lines.
Parasitic on birds and mammals.
h. Possessing a specially developed apparatus for clinging to
hairs of mammals..................4. LISTROPHORIDE.
hb. Without such apparatus.
ji. Living on the plumage of birds........ ANALGESIDZ.
ii. In the living tissues of birds and mammals.
j. Vulva longitudinal. In the skin and cellular tissues of
birds ....... repheesinse Beguis dyteenda inane CYTOLEICHIDE.
This family contains two species, both occurring in the
United States on the common fowl. Laminosioptes
cysticola occurs on the skin and also bores into the
subcutaneous tissue where it gives rise to a cal-
careous cyst. Cytoleichus nudus is most commonly
found in the air passages and air cells.
jj. Vulva transverse. In the skin of mammals and birds
Lah dada sabre needs Bakes Ree yee wae SARCOPTIDE
k. Anal opening on the dorsum.
1. Third pair of legs in the male without apical suckers.
On cats and rabbits.............. Noteedres Rail.
The itch mite of the cat, N. cati (fig. 61) has been
recorded on man.
ll. Third leg in the male with suckers. On bats....
eile (aidan eas pie nuatetsel Miah adhe Prosopodectes Can.
270 Hominoxtous Arthropods
kk. Anal opening below.
1. Pedicel of the suckers jointed; mandibles styliform
and serrate near the tip........ Psoroptes Gerv.
P. communis ovis is the cause of sheep scab.
ll. Pedicel of the suckers not jointed; mandibles
chelate.
m. No suckers on the legs of the females; parasitic
on birds, including chickens. C. mutans is
itch mite of chickens. Cnemidocoptes Faurst.
mm. Suckers at least on legs I and II; parasitic on
mammals.
n. Legs very short; in the male the hind pairs
equal in size; body usually short..........
tA Ghied elon 4 Peal hn sui acateyreals oe Sarcoptes Latr.
S. scabiei is the itch mite of man (fig. 56).
“* Sfuare =
claw bulithas fauna
157. Amblyomma, female. After Nuttall
and Warburton.
nn, Legs more slender; in the male the third pair
is much larger than the fourth; body more
elongate.
o. Female with suckers on the fourth pair of
legs. Species do not burrow in the skin,
but produce a scab similar to sheep scab.
They occur in the ox, horse, sheep and goat
Hep aa Palle 24 HG Be eeu Chorioptes Gerv.
C. symbiotes bovis of the ox has been
recorded a few times on man.
oo. Female without suckers to the fourth legs.
p. Hind part of the male abdomen with two
lobes. On a few wild animals........
Acarina 271
pp. Hind part of the male abdomen without
lobes. Live in ears of dogs and cats
eed eee Wa) te Kee a Otodectes Canestr.
O. cynotis Hering (fig. 150 e) has been
taken in the United States.
ee. Palpi usually of four or five segments, free; rarely with ventral
suckers near genital or anal openings; eyes often present; tarsi
never end in suckers; body usually divided into cephalothorax
and abdomen; rod-like epimera rarely visible; adults rarely
parasitic.
f. Last segment of the palpi never forms a thumb to the preceding
segment; palpi simple, or rarely formed to hold prey; body
with: ‘but: few -hairsy. . ecace ca ex oae exe oad ee EUPODOIDEA.
g. Palpi often geniculate, or else fitted for grasping prey; mandi-
bles large and snout like; cephalothorax with four long
bristles above, two in front, two behind; last segment of leg I
longer than the preceding segment, often twice as long.....
ear Rees aed CDER AE aOR oe ea Des eee ee Me OTE BDELLID.
gg. Palpi never geniculate (fig. 158a), nor fitted for grasping prey:
beak small; cephalothorax with bristles in different arrange-
ment; last segment of leg I shorter or but little longer than
the preceding joint; eyes when present near posterior
border a2 ere eened Gers ope eee eure ee edeNes EUPODIDZ
Moniez has described a species from Belgium (Tydeus
molestus) which attacks man. It is rose colored; eye-
less; its legs are scarcely as long as its body, the hind
femur is not thickened; the mandibles are small and the
anal opening is on the venter. The female attains a
length of about 0.3 mm.
ff. Last segment of the palpus forms a thumb to the preceding, which
ends in a claw (with few exceptions); body often with many
Ihaits: (ig: 158: Myer. naccnesg awd iaeune caries TROMBIDOIDEA.
g. Legs I and II with processes bearing spines; skin with several
shields; coxe contiguous...............-..000-- CACULIDE.
gg. Legs I and II without such processes; few if any shields.
h. Palpi much thickened on the base, moving laterally, last
joint often with two pectinate bristles; no eyes; legs I
ending in several long hairs; adult sometimes parasitic
i, Siti a KI spe way a SIGE S aie win eee Ne iene wate carat CHEYLETIDE
Cheyletus eruditus, which frequents old books, has once
been found in pus discharged from the ear of man.
hh. Palpi less thickened, moving vertically; eyes usually present;
leg I not ending in long hairs.
i. Coxze contiguous, radiate; legs slender, bristly; body with
few hairs; no dorsal groove; tarsi not swollen..........
sidassosicd deitesn, soabiutheva, sane tts ped RMA RE WRASSE ERYTHREIDA.
ii. Coxe more or less in two groups; legs less bristly.
272 Hominoxious Arthropods
yl
158. (a) Tydeus, beak and leg from below; (b) Cheyletus pyriformis, beak and palpus;
(c) beak and claw of Pediculoides; (d) leg of Sarcoptes; (e) scutum of
female of Amblyomma americana; (f) leg I and tip of mandible of Histio-
stoma americana; (g) Histiogaster malus, mandible and venter; (hk) Aleuro-
bius faring, and leg 1 of male; (4) Otodectes cynotis, tip of abdomen of male,
(j) beak and anal plate of Dermanyssus galling; (Rk) palpus of Allothrom-
bium. (a) to (7) after Banks.
Acarina 273
j. Body with fewer, longer hairs; often spinning threads;
no dorsal groove; tarsi never swollen; mandibles
styliform (for piercing).............. TETRANYCHIDE
The genus Tetranychus may be distinguished from the
other genera occurring in the United States by the
following characters: No scale-like projections on
the
front of the cephalothorax; legs I as long or
longer than the body; palp ends in a distinct thumb;
the
body is about 1.5 times as long as broad. T.
molestissimus Weyenb. from South America, and
T. telarius from Europe and America ordinarily
infesting plants, are said also to molest man.
jj. Body with many fine hairs or short spines; not spinning
threads; often with dorsal groove; tarsi often
swollen.
k. Mandibles styliform for piercing. ... RHyYCHOLOPHID.
kk. Mandibles chelate, for biting.......... TROMBIDIDE
The genus Trombidium has recently been sub-
divided by Berlese into a number of smaller
ones, of which some five or six occur in the
United States. The mature mite is not para-
sitic but the larvee which are very numerous in
certain localities will cause intense itching,
soreness, and even more serious complications.
They burrow beneath the skin and produce
inflammed spots. They have received the
popular name of ‘‘red bug,’”” The names Leptus
americanus and L. irritans have been applied to
them, although they are now known to be im-
mature stages. (Fig. 44.)
HEXAPODA (Insecta)
The Thysanura (springtails and bristletails), the Neuropteroids
(may-flies, stone-flies, dragon-flies, caddis-flies, etc.), Mallophaga
(bird lice), Physopoda (thrips), Orthoptera (grasshoppers, crickets,
roaches), are of no special interest from our viewpoint. The remain-
ing orders are briefly characterized below.
SIPHUNCULATA (page 275)
Mouth parts suctorial;
parasitic upon mammals.
beak fleshy, not jointed; insect wingless;
Metamorphosis incomplete. Lice.
HEMIPTERA (page 275)
Mouth parts suctorial;
beak or the sheath of the beak jointed;
in the mature state usually with four wings. In external appearance
274 Hominoxious Arthropods
the immature insect resembles the adult except that the immature
form (i.e. nymph) never has wings, the successive instars during
the process of growth, therefore, are quite similar; and the meta-
morphosis is thus incomplete. To this order belong the true bugs,
the plant lice, leaf hoppers, frog hoppers, cicadas, etc.
LEPIDOPTERA
The adult insect has the body covered with scales and (with the
rare exception of the females of a few species) with four wings also
covered with scales. Proboscis, when present, coiled, not seg-
mented, adapted for sucking. Metamorphosis complete, i.e. the
young which hatches from the egg is quite unlike the adult, and after
undergoing several molts transforms into a quiescent pupa which is
frequently enclosed in a cocoon from which the adult later emerges.
The larve are known as caterpillars. Butterflies and moths.
DIPTERA (page 285)
The adult insect is provided with two, usually transparent,
wings, the second pair of wings of other insects being replaced by a
pair of halteres or balancers. In a few rare species the wings, or
halteres, or both, are wanting. The mouth parts, which are not
segmented, are adapted for sucking. The tarsi are five-segmented.
Metamorphosis complete. The larve, which are never provided
with jointed legs, are variously known as maggots, or grubs, or
wrigglers. Flies, midges, mosquitoes.
SIPHONAPTERA (page 316)
Mouth parts adapted for sucking; body naked or with bristles
and spines; prothorax well developed; body compressed; tarsi
with five segments; wings absent. Metamorphosis complete.
The larva is a wormlike creature. Fleas.
COLEOPTERA
Adult with four wings (rarely wanting), the first pair horny or
leathery, veinless, forming wing covers which meet in a line along
the middle of the back. Mouth parts of both immature stages and
adults adapted for biting and chewing. Metamorphosis complete.
The larve of many species are known as grubs. Beetles.
Siphunculata and Hemiptera 275
HYMENOPTERA
Adult insect with four, usually transparent, wings, wanting in
some species. Mouth parts adapted for biting and sucking; palpi
small; tarsi four or five-segmented. Metamorphosis complete.
Parasitic four-winged flies, ants, bees, and wasps.
SIPHUNCULATA AND HEMIPTERA
a. Legs with claws fitted for clinging to hairs; wings wanting; spiracles of the
abdomen on the dorsal surface. (=ANOPLURA=PARASITICA).....
Sidbts oases ca blalenbeake ditch Gale atch: ois nesneeheA voce oe ace Nastaaraone wate SIPHUNCULATA.
b. Legs not modified into clinging hooks; tibia and tarsus very long and
slender; tibia without thumb-like process; antenne five-segmented
Ase Mal LONE St Rane HERE eo ee Mer Sa DEL RAE H#MATOMYZID& Endr.
Hematomyzus elephantis on the elephant.
bb. Legs modified into clinging hooks; tibia and tarsus usually short and
stout; tibia with a thumb-like process; head not anteriorly pro-
longed, tube-like.
c. Body depressed; a pair of stigmata on the mesothorax, and abdominal
segments three to eight; antennz three to five-segmented.
d. Eyes large, projecting, distinctly pigmented; pharynx short and
broad; fulture (inner skeleton of head) very strong and broad,
with broad arms; proboscis short, scarcely attaining the thorax.
‘9 24 4O SS 4 OPER SS ERS OO EA See Red Ee HERO E BER es PEDICULIDA
e. Antenne three-segmented. A few species occurring upon old
WOrld MONKEYS... coe scecsse sn wile dn teslocdcs eemnws eiw ers Pedicinis Gerv.
ee. Antenne five -segmented.
f. All legs stout; thumb-like process of the tibia very long and
slender, beset with strong spines, fore legs stouter than the
others; abdomen elongate, segments without lateral pro-
cesses; the divided telson with a conical process posteriorly
upon the ventral side...................05. Pediculus L.
g. Upon man,
h. Each abdominal segment dorsally with from one to three
more or less regular transverse rows of small sete;
antenna about as long as the width of the head. Head
16TSE (ASS, G5) ciagicna screea eee eS P, humanus.
hh. ‘‘No transverse rows of abdominal sete; antenna longer
than the width of the head; species larger.’ Piaget.
Body louse ‘of mati.ee gi se cain vas nes P. corporis.
gg. Upon apes and other mammals.......... P. pusitatus (?).
ff. Fore legs delicate, with very long and slender claws; other legs
very stout with short and stout claws; thumb-like process of
the tibia short and stout; abdomen very short and broad;
segment one to five closely crowded, thus the stigmata of seg-
ments three to five apparently lying in one segment; segments
five to eight with lateral processes; telson without lateral
conical appendages (fig. 69). Crab louse of man............
Phthirus pubis.
276 Hominoxious Arthropods
dd. Eyes indistinct or wanting; pharynx long and slender, fulture very
slender and closely applied to the pharynx; proboscis very long.
Several genera found upon various mammals.....HA#MATOPINIDA.
cc. Body swollen; meso- and metathorax, and abdominal segments two to
eight each with a pair of stigmata; eyes wanting; antenne four or
five-segmented; body covered with stout spines. Three genera found
upon marine mammals...................... EcHINOPHTHIRIIDA
aa. Legs fitted for walking or jumping; spiracles of abdomen usually ventral;
beak segmented. s
b. Apex of head usually directed anteriorly; beak arising from its apex; sides
of the face remote from the front cox; first pair of wings when present
thickened at base, with thinner margins.......... HETEROPTERA
aN
JYwryr0Lu,
aertguay
159. Taxonomic details of Hemiptera—Heteroptera. (@) Dorsal aspect; (b) seta from
bedbug; (c) wing of Heteropteron; (d) leg; (e) wing of Sinea.
c. Front tarsi of one segment, spade-form (paleformes); beak short, at
most two-segmented; intermediate legs long, slender; posterior pair
adapted for swimming. 2.6.60) ccc ce eee een deweee bus CorixID&
cc. Front tarsi rarely one-segmented, never spade-form; beak free, at least
three-segmented.
d. Pulvilli wanting.
e. Hemelytra usually with a distinct clavus (fig. 159), clavus always
ends behind the apex of the scutellum, forming the commissure.
(Species having the wings much reduced or wanting should be
sought for in both sections.)
f. Antenne very short; meso- and metasternum composite; eyes
always present.
Siphunculata and Hemiptera 277
g. Ocelli present; beak four-segmented. OcHTERID# and
NERTHRIDA.
gg. Ocelli wanting; antenne more or less hidden in a groove.
h. Anterior coxe inserted at or near anterior margin of the
prosternum; front legs raptorial; beak three-segmented.
BELOSTOMID& (with swimming legs), NEpID#, NAUCORIDA.
i, Metasternum without a median longitudinal keel; antennz
always four -segmented.
j. Beak short, robust, conical; the hairy fleck on the corium
elongate, large, lying in the middle between the inner
angle of the membrane and the outer vein parallel to
the membrane margin; membrane margin S-shaped.
k. The thick fore femur with a relatively deep longitudinal
furrow to receive the tibia. Several American
species (fig. 19f.). .. Belostoma (= Lethocerus Mayer)
kk. The less thickened fore femur without such a furrow
sudhidssushanslaanenipe mbar slarcen B. griseus. Benacus Stal.
jj. Beak slender, cylindrical; the hairy spot on the corium
rounded lying next to the inner angle of the membrane.
k. Membrane large, furrow of the embolium broadened.
Z. aurantiacum, fluminea, etc............ Zaitha
kk. Membrane very short; furrow of embolium not
broadened. Western genus.......... Pedinocoris
ii. Metasternum with a long median longitudinal keel. South-
western forms..... Abedus ovatus and Deniostoma dilatato
hh. Anterior coxz inserted at the posterior margin of the
prosternum; legs natatorial. Back swimmers (fig. 19 b.)
Bs Od cs oh det lao eda (iecletees Ce toa \..... NOTONECTIDZ
1. Apices of the hemelytra entire; the three pairs of legs
similar in shape; beak three-segmented; abdomen not
keeled ‘or hairyins oovenes ch eeenesepaeee war 6 Plea Leach
il. Apices of hemelytra notched; legs dissimilar; beak four-
segmented; abdomen keeled and hairy.
j. Hemelytra usually much longer than the abdomen;
fourth segment of the antenna longer than the third
segment; hind tarsi with claws......... Bueno Kirk.
jj. Hemelytra but little longer than the abdomen; fourth
segment of the antenna shorter than the third seg-
ment; hind tarsi without claws (fig. 19b). . Notonecta L.
ff. Antenne longer than the head; or if shorter, then the eyes and
ocelli absent.
g. Eyes, ocelli, and scutellum wanting; beak three-segmented;
head short; hemelytra always short; membrane wanting.
Insects parasitic on bats.................000. POLYCTENIDA
gg. Eyes present.
h. First two antennal segments very short, last two long, pilose,
third thickened at the base; ocelli present, veins of the
hemelytra forming cells. D1ipsocorip& (=CERATOCOMBI-
D#) including ScHIZOPTERIDA.
278 Hominoxious Arthropods
hh. Third segment of the antenna not thickened at the base,
second as long or longer than the third, rarely shorter.
i. Posterior coxe hinged (cardinate), if rarely rotating, the
cuneus is severed, the membrane is one or two-celled,
and the meso- and metasternum are composite.
j. Ocelli absent, clypeus dilated toward the apex; hemelytra
always short, membrane wanting. Species parasitic.
Béd Bugs), 666. 6c s0c cca Sawa aeeek ewe wd CIMICIDZ
k. Beak short, reaching to about the anterior coxe;
scutellum acuminate at the apex; lateral margin of
the elytra but little reflexed, apical margin more or
less rounded; intermediate and posterior coxe
very remote.
1. Body covered with short hairs, only the sides of the
pronotum and the hemelytra fringed with longer
hairs; antenne with the third and fourth seg-
ments very much more slender than the first and
second; pronotum with the anterior margin very
deeply Sinuaee vo decane sco h veins oe E4 Cimex L.
m. Sides of the pronotum widely dilated, broader
than the breadth of one eye, and densely
fringed with backward curved hairs; apical
margin of the hemelytra nearly straight, rounded
toward the interior or exterior angles.
n. Body covered with very short hairs; second
segment of the antenna shorter than the third;
sides of the pronotum feebly reflexed, fringed
with shorter hairs than the breadth of one
eye; hemelytra with the commissural (inner)
margin rounded and shorter than the scutel-
lum, apical margin rounded towards the
interior angle. The common bed bug (fig.
TOM) salt A d.aateinraenat age came C. lectularius Linn
nn. Body covered with longer hairs; second and
third segments of the antenna of equal
length; side of the pronotum narrowly, but
distinctly, reflexed, fringed with longer
hairs than the breadth of oneeye; hemelytra
with the commissural margin straight and
longer than the scutellum, apical margin
rounded towards the exterior angle. Species
found on bats in various parts of the United
DlALES,< ntAk ce wlalecicmaamen C. pillosellus Hov.
mm. Sides of the pronotum neither dilated, nor
reflexed, fringed with less dense and nearly
straight hairs; hemelytra with the apical
margin distinctly rounded. Parasitic on
man, birds and bats. Occurs in the old
world, Brazil and the West Indies........
oti ees C. hemipterus Fabr. (=rotundatus)
Siphunculata and Hemiptera 279
Il. Body clothed with rather longer silky hairs; third
and fourth segments of the antenna somewhat
more slender than the first and second; anterior
margin of the pronotum very slightly sinuate or
nearly straight in the middle, produced at the
lateral angles. This is the species which in Ameri-
can collections is known as C. hirundinis, the
latter being an old world form. It is found in
swallows nests. O. vicarius....Oeciacus Stal
kk. Beak long, reaching to the posterior coxze; scutellum
rounded at the apex; lateral margins of the elytra
strongly reflexed, apical margin slightly sinuate
toward the middle; intermediate and posterior
cox sub-contiguous. This species infests poultry
in southwest United States and in Mexico. H.
inodorus................ Hematosiphon Champ.
160. Pselliopsis (Milyas)
cinctus. (x2). After
C. V. Riley.
jj. Ocelli present, if rarely absent in the female, then the
tarsus has two segments; or if with three tarsal seg-
ments, the wing membrane with one or two cells.
k. Beak four-segmented, or with two-segmented tarsi.
. ISOMETOPIDZ, MICROPHYSID# and some CapsID&.
kk. Beak three-segmented.
1. Hemelytra with embolium; head horizontal, more
or less conical; membrane with one to four veins,
fately wanting .o....3 05 ehand vee ANTHOCORIDZE
Several species of this family affecting man have
been noted, Anthocoris kingi and congolense,
from Africa and Lyctocoris campestris from
various parts of the world. Lyctocoris fitchii
Reuter (fig. 19 j), later considered by Reuter as
a variety of L. campestris, occurs in the United
States:
ll. Hemelytra without embolium. Superfamily Acan-
THIOIDEA (=SALD#& Fieber and L&EpTOPODa
Fieber)
280 Hominoxious Arthropods
ii. Posterior coxe rotating.
j. Claws preapical; aquatic forms. GERRID# and VELIADA
jj. Claws apical.
k. Prosternum without stridulatory sulcus (notch for
beak).
l. Tarsus with three segments; membrane with two or
three longitudinal cells from which veins radiate;
rarely with free longitudinal veins (Arachnocoris)
or veins nearly obsolete (Arbela); clavus and
corium coriaceous; ocelli rarely absent. .NABIDZE
Reduviolus (=Coriscus) subcoleoptratus (fig. 19 g),
a species belonging to this family, occurring in
the United States, has been accused of biting
man. This insect is flat, of a jet black color,
bordered with yellow on the sides of the abdomen,
and with yellowish legs. It is predaceous,
feeding on other insects.
ll. With other combinations of characters. Hypro-
METRIDZ, HENICOCEPHALID, N2ZOGEIDZ, MEso-
VELIAD&, JOPPEICIDE
kk. Prosternum with stridulatory sulcus (notch for beak);
with three segments, short, strong.
1. Antennz filiform or sometimes more slender apically,
geniculate; wing membrane with two or three
large basal cells; scutellum small or moderate
For a key to the genera and species see next page.
ll. Last antennal segment clavate or fusiform; wing
membrane with the veins often forked and ana-
stomosing; scutellum large; tarsi each with two
segments; fore legs strong. (=PHYMATID#)
ata Nee bia as opiates a aS ta Sahl MACROCEPHALIDA
ee. Clavus noticeably narrowed towards the apex, never extending
beyond the scutellum, the two not meeting to form a commissure;
head horizontal, much prolonged between the antennz, on each
side with an antennal tubercle, sometimes acute; ocelli absent;
meso- and metasternum simple; tarsi each with two segments;
body flattened (fig. 19c), ARADID#, including Dysopip#.
dd. Pulvilli present (absent in one Australian family THAUMATOCORIDZ
in which case there is a membranous appendage at the tip of the
tibia). CAPSIDZ (=MIRIDZ&),* Eotrechus (in family GERRIDZ),
N#ocaip#, TINGITID#, PIESMID#, MyopocHID#, CorIzID#,
CorEIDA, ALYDID®, PENTATOMID#, SCUTELLERIDE, etc.
bb. Apex of head directed ventrally, beak arising from the hinder part of the
lower side of the head; sides of face contiguous to the front cox; first
_ *Professor C. R, Crosby who has been working upon certain capsids states that he and his
assistant have been bitten by Lygus pratensis, the tarnished plant bug, by Chlamydatus associatus
and by Orthotylus flavosparsus, though without serious results.
Reduviide of ‘the United States 281
pair of wings, when present, of uniform thickness, Cicadas, scale
insects, plant lice (Aphids), spittle-insects, leaf hoppers, etc...........
Aehiad SHEae Ane oak RU Se eee eee ae Ree dee te Bars HOMOPTERA
REDUVIIDZ OF THE UNITED STATES
(Adapted from a key given by Fracker).
a. Ocelli none; wings and hemelytra always present in the adults; no discodial
areole in the corium near the apex of the clavus. Orthometrops decorata,
Oncerotrachelus acuminatus, etc., Pennsylvania and south...... Sarcine
aa. Ocelli present in the winged individuals; anterior coxe not as long as the
femora.
b. Hemelytra without a quadrangular or discoidal areole in the corium near
the apex of the clavus.
c. Ocelli not farther cephalad than the caudal margins of the eyes; segment
two of the antenna single.
d. Thorax usually constricted caudad of the middle; anterior coxe ex-
ternally flat or concavVes; outs deaveensstmnarenreeweads PIRATINE
e. Middle tibiae without spongy fossa, head long, no lateral tubercle
on neck. SS. stria, Carolina, Ill., Cal........ Sirthenia Spinola
ee. Middle tibie with spongy fossa; fore tibie convex above; neck
with a small tubercle on each side.
f. Apical portion of anterior tibie angularly dilated beneath, the
spongy fossa being preceded by a small prominence..........
ML ay ets earn te siner earn clu een ag tel fale cheeeaattita owed ea Na Melanolestes Stal
g. Black, with piceous legs and antenne. N. E. States (fig. 19a)
acai y Raa any ade RO Sph git st x Fe ere P tiake Nata ea ahi at M. picipes
gg. Sides, and sometimes the whole dorsal surface of the abdomen
red. Ill.,andsouthward.................. M. abdominalis
ff. Tibize not dilated as in ‘‘f’’; spongy fossa elongate; metapleural
sulci close to the margin. R. biguttatus (fig. 22). South
de ivseiriguiale wiies Qainis angie Raw taro. idgwa ReR aL Rasahus A. and S.
dd. Thorax constricted in the middle or cephalad of the middle; anterior
tarsi each three-segmented.
e. Apex of the scutellum narrow, without spines or with a single spine
eB Airs s Ria Sanaa hE RANGA AR LI GEO iy Red ene DS aude dae ik REDUVONA
f. Antennz inserted in the lateral or dorso-lateral margins of the head;
antenniferous tubercles slightly projecting from the sides of the
head; head produced strongly cephalad; ocelli at least as far
apart as the eyes.
g. Antenne inserted very near the apex of the head; segments
one and three of the beak short, segment two nearly four
times as long as segment one. R. prolixus. W.I.........
gg. Antenne inserted remote from the vertex of the head.
h. Body slightly hairy; pronotum distinctly constricted; angles
distinct; anterior lobe four-tuberculate, with the middle
tubercles large and conical. M. phyllosoma, large species
the southwestxccv. ex vegaens gh tes wea kees ass Meccus Stal
282 Hominoxious Arthropods
hh. Body smooth, margin of the pronotum sinuous, scarcely
constricted; anterior lobe lined with little tubercles
dir ips vielen ores aaah Saito puerta Conorhinus Lap.
i. Surface of the pronotum and prosternum more or less
grandular.
j. Eyes small, head black; body very narrow, a fifth as
wide as long; beak reaches the middle of the proster-
num. Califormia. ioc... 66sec ves eae es C. protractus
jj. Eyes large, head fuscous; body at least a fourth as wide
as long. Southern species........ C. rubrofasciatus
ii. Pronotum and prosternum destitute of granules.
j. Border of abdomen entirely black except for a narrow
yellowish spot at the apex of one segment. Texas
rae ape Sucre GMA Ga ove BRD Aue el ecalteedel aed C. gerstaeckeri
jj. Border of abdomen otherwise marked.
k. Beak slender, joints one and two slightly pilose, two
more than twice as long as one; tubercles at the
apical angles of the pronotum slightly acute, conical.
Md. to Ill. and south. The masked bed bug hunter
EU ZT) 2 GH eRe Selaltnedg oar nnis: atm C. sanguisugus
kk. Beak entirely pilose, joint two a third longer than
joint one; joint one much longer than three;
tubercles at the apical angles of pronotum slightly
elevated, obtuse. Ga., Ill., Tex., Cal. .C. variegatus
ff. Antenna inserted on top of the head between margins, close to the
eyes; antenniferous tubercles not projecting from the side of the
head.
g. Anterior lobe of the pronotum with a bispinous or bituberculate
disc; femora unarmed. SS. arizonica, S.° bicolor. South-
WESTETNSPECIES n25 2 od ncwaae wou cad bee win ees Spiniger Burm.
gg. Disc of pronotum unarmed; apex of scutellum produced into
a spine; ocelli close to the eyes; eyes large and close to-
POLED sn2taea 3 au day unserer vas dasy 9 RMS ES Reduvius Lamarck
h. Color piceous. Widely distributed in the United States.
(Bigs 20) thls on aie oa x toate Ves eee eels R. personatus
hh. More or less testaceous in color. Southwestern states
eats tail ag ta eA nctas Aemehaalae A ca elsaies a SONOMA. eH esey aie as R. senilis
ee. Apex of scutellum broad, with two or three spines. . ECTRICHODIINE
f. First segment of the antenna about as long asthe head. E. cruciata
Pa. and south; E. cinctiventris, Tex. and Mex ................
ff. First segment of the antenne short. P. @neo-nitens. South
ese ots a Sach Se Shas A Saat eee ee Gas ARs capa es LAC Ego Pothea A. et 8.
ec. Ocelli cephalad of the hind margins of the eyes; first segment of the
antenne stout, second segment divided into many smaller segments.
South and west. Homalocoris maculicollis, and Hammatocerus
PULCUS ph teed sare aindan aaNet a ea ences eta ree ae ssa e OR Sete HAMMATOCERINE
Reduviide of the United States 283
bb. Hemelytra with a quadrangular or discoidal areole in the corium near the
apex of the clavus (fig. 159e).
c. Anal areole of the membrane not extending as far proximad as the costal
areole; basal segment of the antenna thickened, porrect; the other
segments slender, folding back beneath the head and the first segment
ugpadlsata Ree ya Rs cee Paulas Raum he Mae} widlalds « wantbaananid STENOPODINE
d. Head armed with a ramous or furcate spine below each side, caudad
of the eyes.
e. First segment of the antenna thickened, apex produced in a spine
beyond the insertion of the second segment. Species from Va.,
Uiand: southis s sacieaaaheceuieed cinaiy main ad bucanilea es Pnirontis Stal.
ee. First segment of the antenna not produced beyond the insertion
of the second segment. Pygolampis, N. E. states and south;
Gnathobleda, S. W. and Mex.
dd. Head unarmed below or armed with a simple spine; rarely with a
subfurcate spine at the side of the base. Carolina, Missouri and
south. Stenopoda, Schumannia, Diaditus, Narvesus, Oncocephalus
ce. Anal areole of membrane extending farther proximad than the costal
areole.
d. Ocelli farther apart than the eyes. A. crassipes, widely distributed
in the United States; other species occur in the southwest......
pastiahitan eae ESA Casino ge rttcL ete A cece seeatineshs mash ea Apiomerus Hahn.
dd. Ocelli not so far apart as the eyes................0.005. ZELINZ
e. Sides of mesosternum without a tubercle or fold in front.
f{. Fore femur as long as or longer than the hind femur; first segment
of the beak much shorter than the second. Z. audax, in the
north eastern states; other species south and west. .Zelus Fabr.
ff. Fore femur shorter than the hind femur, rarely of equal length,
in this case the first segment of the beak as long or longer than
the second.
g. First segment of the beak shorter than the second; fore femur
a little shorter than the hind femur; the first segment of the
beak distinctly longer than the head before the eyes. P.
cinctus a widely distributed species (fig. 160). P. punctipes,
P. spinicollis, Cal., Mex..... (= Milyas) Pselliopus Berg.
gg. First segment of the beak as long or longer than the second.
h. Pronotum armed with spines on the disc.
i. Juga distinctly prominent at the apex and often acute or
subacute; fore femur distinctly thickened; hemelytra
usually not reaching the apex of the abdomen. Fitchia
aptera, N. Y., south and west; F. spinosula, South;
Rocconata annulicornis, Texas, etc.
ii. Juga when prominent, obtuse at apex; eyes full width of
the head; fore femur not thickened; pronotum with four
spines on posterior lobe. R. taurus, Pa., south and west
ip Suwieh datas POEMS De ORCA RAMA LS ES Repipia Stal.
hh. Pronotum unarmed on the disc.
284 Hominoxious Arthropods
i. Spines on each apical angle of the penultimate abdominal
segment. A. cinereus, Pa., and south. .Atrachelus A.et S.
ii. Apical angle of the penultimate abdominal segment un-
armed. Fitchia (in part); Castolus ferox, Arizona.
ee. Sides of the mesosternum with a tubercle of fold in front at the hind
angles of the prosternum; first segment of the beak longer than
the part of the head cephalad of the eyes.
f. Fore femur thickened, densely granulated; hind femur unarmed.
Sy
161. Taxonomic details of Diptera. (a) Ventral aspect of abdomen of Cynomyia;
(b) antenna of Tabanus; (c) ventral aspect of abdomen of Chortophila; (d)
ventral aspect of abdomen of Stomoxys; (e) claw of Aedes (Culex) sylves-
tris, male; (f) claw of Hippoboscid; (g) foot of dipterous insect showing
empodimm developed pulvilliform; (h) hind tarsal segment of Simulium
vittatum, female; (7) foot of dipterous insect showing bristle-like empodium.
g. Fore tibie each with three long spines on the ventral side.
S. diadema (fig. 159e), a widely distributed species; and
several southwestern species................4: Sinea A. et S.
gg. Fore tibize unarmed. A. multispinosa, widely distributed;
Asctabida,? Cale vaivek ate de 4 needs ee aay en we hoy Acholla Stal.
ff. Fore femur unarmed, rarely a little thickened, a little granulated.
g. Pronotum produced caudad over the scutellum, with a high
mesal tuberculate ridge (fig. t9e). A. cristatus. N. Y. to
Cali atic SOuthiacs cack aon ees nace nen ates Arilus Hahn.
gg. Caudal lobe of the pronotum six sided, neither elevated nor
produced caudad. H. americanus, Southwest; also several
W. I. and Mexican genera.............. Harpactor Lap.
Diptera 285
DIPTERA (Mosquitoes, Midges, Flies)
a. Integument leathery, abdominal segments indistinct; wings often wanting;
PAFASICIS TOL UTS ists csee Aa adevactut-siad ator auehiries ee tie psaies Sindy we eeu te euewuet a PUPIPARA
b. Head folding back on the dorsum of the thorax; wingless flies parasitic
on bats. Genus Nycteribia....... 0000000 NYcCTERIBIIDE
bb. Head not folding back upon the dorsum of the thorax; flies either winged
or wingless; parasitic on birds and on bats and other mammals.
c. Antenne reduced, wings when present, with distinct parallel veins and
outer crossveins; claws simple; palpi leaf-like, projecting in front of
the head. Flies chiefly found on bats. Several genera occur in North
America STREBLIDA
162. Hippobosca equina. x4. After Osborn.
cc. Antenne more elongate, segments more or less distinctly separated;
head sunk into an emargination of the thorax; wings when present
with the veins crowded toward the anterior margin; palpi not leaf-
RE oth Heats coe Be cee a eche ERAT Se eee ERE SAEs HIPPOBOSCIDA
d. Wings absent or reduced and not adapted for flight.
e. Wings and halteres (balancers) absent. M. ovinus, the sheep tick
riba tes ei tte eept Doms ibd estes Medal oh att DSA sSesecte drat angst Melophagus Latr.
ee. Wing reduced (or cast off), halteres present.
f. Claw bidentate; ocelli present. On deer after the wings are cast
Of. “Be Gepressa@s «oi acsag sts saiee ta eee Lipoptena Nitsch
ff. Claw tridentate (fig. 161 f). ....On Macropis. B. femorata
a enea Ath ho ANG STR SHS Ge ENG San ARE sae ag Brachypteromyia , Will.
dd. Wings present and adapted for flight.
e. Claws bidentate.
f. Ocelli present; head flat; wings frequently cast off. On birds
before casting of the wing.............. Lipoptena Nitsch.
ff. Ocelli absent; head round; wings present. The horse tick
H. equina may attack man (fig. 162)........ Hippobosca L.
ee. Claws tridentate (fig. 161 f.).
f, Anal cell closed at apical margin by the anal crossvein.
@. Océlli, absénitucs.cossameveaun sens eawee Stilbometopa Coq.
gg. Ocelli present. :
286 Hominoxious Arthropods
h. R4y+5 does not form an angle at the crossvein. On birds.
There is a record of one species of this genus attacking man
SGN ds ee YeA i tacbe Sted a colo attests sik cea hegnty state Be Ornithomyia Latr.
hh. Ry+; makes an angle at the crossvein. O. confluens,
iy aap lsten hn ane ae aiitaiians lea wicreyaas eae enemas Ornithoica Rdi.
ff, Anal cell not closed by an anal crossvein. Lynchia, Pseudolfersia,
and Olfersia are chiefly bird parasites. The first mentioned
genus is said to be the intermediate host of Hemoproteus columbe.
aa. Abdominal segments chitinous; not parasitic in the adult stage.
b. Antennz with six or more segments and empodium not developed pulvilli-
form; palpi often with four segments.
c. Ocelli present. BLEPHAROCERIDZE, RHYPHID#, BIBIONID#, MyYcerTo-
PHILIDA, besides some isolated genera of other families.
cc. Ocelli absent.
d. Dorsum of the thorax with a V-shpaed suture; wings usually with
numerous veins; legs often very long and slender. Crane flies.
Aah schon 58 Bocgeiine Ree an tdals ® iets d Wie eay tor, aaitand tos Resta ade du rem e TIPULIDZ
dd. Dorsum of the thorax without a V-shaped suture.
e. Not more than four longitudinal veins ending in the wing margin;
wing usually hairy: antenne slender; coxe not long; tibie with-
out spurs, legs long and slender. Small, delicate flies often called
Gall Oma tS isin Kev casvanie adeamarcemat a Gsaieiaeeaye aud Sauaunneienses CECIDOMYIIDE
ee. More than four longitudinal veins ending in the wing margin.
f. The costal vein is not produced beyond the tip of the wing; radius
with not more than three branches.
g. Antenne short, composed of ten or eleven closely united seg-
ments; legs stout; body stout; abdomen oval; anterior
veins stout, posterior ones weak (fig. 163 b); eyes of the male
contiguous over the antenne. Black flies, buffalo flies,
turkey gnats. Many North American species, several of
them notorious for their blood sucking propensities......
Ue eda wire ids attees iene hits Satine cae ata crs aA ee heed | SIMULODE
h. Second joint of the hind tarsus with basal scale-like process and
dorsal excision (fig. 161 h); radial sector not forked; no
small cell at the base of the wing. S. forbesi, jenningsi,
johannseni, meridionale, piscicidium, venustum, vittatum,
etc. Widely distributed species..................0005.
Si HAO gaeetieleies wiih dasy Senay (=Eusimulium) Simulium Latr.
hh. No basal scale-like process on the second joint of the hind
tarsus; radial sector usually forked (fig. 163 b).
i, Face broad, small basal cell of the wing present. P. fuluum,
hirtipes, mutatum, pecuarum, pleurale. .Prosimulium Roub.
ii. Face linear; small basal cell of the wing absent. One
species, P. furcatum, from California................
NOGA aie at daine nade a eee ee kel Parasimulium Malloch
gg. Flies of a different structure.
h, Antenne composed of apparently two segments and a terminal
arista formed of a number of closely united segments.
Rare flies with aquatic larve........ ORPHNEPHILIDE
Diptera 287
hh. Antenne of six to fifteen segments, those of the male usually
plumose; legs frequently slender and wings narrow
figs ia a seh Sctonay vu ts ald Or eetda Bees ees SA CHIRONOMIDZ
i, Media forked (except in the European genus Brachypogon);
thorax without longitudinal fissure and not produced over
the head (except in four exotic genera); antennz usually
fourteen-jointed in both sexes; fore tibia with a simple
comb of setule, hind tibia with two unequal combs,
middle tibia without comb.......... CERATOPOGONINE
j. Thorax produced cap-like over the head, wing narrow
and very long. Jenkinsia, Macroptilum and Caly-
ptopogon, eastern hemisphere; Paryphoconus, Brazil.
jj. Thorax not produced over the head,
k. Eyes pubescent, empodium well developed, or if short
then R2+3 distinct and crossvein-like or the
branches of R coalescent; r-m crossvein present;
fore femora not thickened; wing either with ap-
pressed hairs or with microscopic erect setule
sositbudlve2Gua idee bachiy uae, isu Intoauatiis ADL GS Dasyhelea Kieff.
kk. Eyes bare, or otherwise differing from the foregoing.
1. Empodium well developed, nearly as long as the
claws and with long hairs at the base; femora and
fifth tarsal segments unarmed, i.e. without spines
or stout sete; fourth tarsal segment cylindrical.
m. Wing with erect and microscopic setule. Widely
GiStHibUted: crac Sonn aces oaaane at go penaetracdivaa ia
etait ae (=Atrichopogon) Ceratopogon Meig.
mm, Wing with long and depressed hairs. Widely
distributed...........-..000005 Forcipomyia
n. Hind metatarsus shorter or not longer than the
& following (i. the second tarsal) segment
erie torattl in thenalis aunts Subgenus Prohelea Kieft
nn. Hind metatarsus longer than the following
segment....Subgenus Forcipomyia Meig.
ll. Empodium short, scarcely reaching the middle of
the claws, or vestigial.
m. R-m crossvein wanting.
n. Palpi four segmented; inferior fork of the media
obliterated at the base. Australia.........
etfs yeva havent ibarba cag icionr Sateen Lepioconops Skuse
nn. Palpi three-segmented.
o. Legs spinulose, tarsal claws of the female
with a basal tooth or strong bristle, those
of the male unequal, the anterior with a
long sinuous tooth, the posterior with a
short arcuate tooth. Italy............
epee ai bh crane, AS Laer oaeaceci ts Mycterotypus Noé
288 Hominoxious Arthropods
oo. Legs unarmed; no crossvein between the
branches of the radius (fig. 163e). New
MEXI1C6) o.5. sc eee cies Tersesthes Townsend
mm. R-m crossvein present.
n. Fore femora very much swollen, armed with
spines below, fore tibia arcuate and applied
closely to the inferior margin of the femur.
o. Ra+3 present, therefore cell Ry and R2 both
present; wing usually fasciate. United
Stalesiciowa hovered reek Heteromyia Say.
oo. R243 not distinct from R4+5, hence cell
R3 obliterated. South America........
giiate Nido y oe Pachyleptus Arrib. (Walker)
nn. Fore femur not distinctly swollen.
o. Ra+3 present therefore cells Rr and R3
both present, or if not, then the branches
of the radius more or less coalescent,
obliterating the cells.
p. At least the tip of the wing with erect
setule; tip of Ry+5 scarcely attaining
the middle of the wing, empodium rather
indistinct, not reaching the middle of the
claws, the claws not toothed, equal, with
long basal bristle; legs without stout
sete. Widely distributed............
Satlete gs be hae eee ea acs Culicoides Latr.
Hematomyidium and Oecacta are prob-
able synonyms of this.
pp. Wings bare, if rarely with hair, then the
radius reaches beyond two-thirds the
length of the wing, or the femur or
fifth tarsal segment with stout black
spines.
q. Media unbranched. Europe..........
sin pet TR aeghed nue ate Brachypogon Kieft
qq. Media branched.
r. Hind femur much swollen and spined.
America and Europe. Serromyia Meg.
tr. Hind femur not distinctly swollen.
s. Cell Ry not longer than high; fork
of the media distad of the cross-
vein; wing with microscopic setu-
LB etsawe eased Stilobezzia Kieff
ss. Cell Ry elongate.
t. Femora unarmed. Widely dis-
tributed. (= Sphaeromias Kieff.
1913 not Curtis?)............
Rete Ricigea bes Johannseniella Will.
Diptera 289
tt. Femora, at least in part, with
strong black spines. Widely
distributed . Palpomyia Megerle
00. Re+3 coalescent with Rais hence cell Rg
is obliterated.
p. In the female the lower branch of the
media with an elbow near its base pro-
jecting proximad, the petiole of the
media coalescent with the basal section
of the radius, wing long and narrow,
radial sector ending near the tip of the
wing; venation of the male as in Bezzia;
front concave. United States........
pgs ilies ete tree tear pee cnn Stenoxenus Coq.
pp. Venation otherwise, front not concave.
q. Subcosta and R; more or less coalescent
with the costa; wing pointed at the
apex, much longer than the body;
antenne fourteen segmented, not plu-
mose. India........ Haasiella Kieft,
qq. Subcosta and radius distinct from the
costa.
tr. Abdomen petiolate...Dibezzia Kieff.
tr. Abdomen not petiolate.
s. Head semi-globose; hind tarsi un-
usually elongate in the female;
antenne of the male not plumose.
Europe...... Macropeza Meigen.
ss. Head not globose, more or less
flattened in front; antenne of
the male plumose. Widely dis-
tributediy on veseues Bezzia Kieff.
t. Fore femora, at least, armed with
stout spines below............
shied wine Subgenus Bezzia Kieff,
tt. Femora unarmed..............
....subgenus Probezzia Kieff.
ii. Media of the wing simple, and otherwise not as in ‘1’. To
this group belong numerous Chironomid genera, none of
which are known to be noxious to man.
ff. The costal vein apparently is continued around the hind margin of
the wing; radius with at least four branches.
g. Wing ovate pointed, with numerous veins; crossveins, if evi-
dent, before the basal third of the wing; veins very hairy;
very small moth-like flies.................... PsYCHODIDE
h. With elongate biting proboscis; the petiole of the anterior
forked cell of the wing (R2) arises at or beyond the middle of
the: wing: (fig: 1630) e100 ge-sas eases sitas Phlebotomus Rdi.
290 Hominoxious Arthropods
a
4
! Rees
Miss
%
Cur
Cu A
163. Wings of Diptera. (@) Anopheles; (b) Prosimulium; (c) Johannseniella; (d) Phle-
botomus (After Doerr and Russ); (e) Tersesthes (after Townsend); (f) Ta-
banus; (g) Symphoromyia; (h) Aphiochaeta; @) Eristalis; (j) Gastrophilus;
(k) Fannia; () Musca.
Diptera 291
hh. With shorter proboscis; the petiole of the anterior forked
cell arises near the base of the wing....................
ioc ste lent oa ene ae ea an Soh Beant pe Psychoda, Pericoma, etc.
gg. The r-m crossvein placed at or beyond the center of the wing;
wings not folded roof-like over the abdomen.
h. Proboscis short, not adapted for piercing; wings bare (Drx1-
D#); or wings scaled (CuLicip™, Subf. CoRETHRIN).
hh. Proboscis elongate, adapted for piercing; wings scaled,
fringed on the hind margin; antenne of the male bushy
plumose. Mosquitoes....... 0.0... 0.0.02 cece eee eee
Spi gvncoueiad wigan CULICIDZ (exclusive of CORETHRIN#&)
i, Metanotum without sete.
j. Proboscis strongly decurved; body with broad, ap-
pressed, metalescent scales; cell Rz less than half as
long as its petiole; claws of female simple, some of the
claws of the male toothed. Several large southern
species believed to feed only on nectar of flowers
i weg lg alte Pal eg (etd psa ears aletgin a lbalahie # acter Megarhinus R. D.
jj. Proboscis straight or nearly so, or otherwise different.
k. Scutellum evenly rounded, not lobed; claws simple in
BOE) SEXES) wisn cla aianes wee Anopheles Meig.
1. Abdomen with clusters of broad outstanding scales
along the sides; outstanding scales on the veins of
the wing rather narrow, lanceolate; upper side of
the thorax and scutellum bearing many appressed
lanceolate scales. Florida and southward (Cellia).
m. Hind feet from the middle of the second segment
largely or wholly snow white.
n. With a black band at the base of the last seg-
ment of each hind foot..................
ee A. albimanus* and tarsimaculata*
nn. Without such a band....A. argyritarsis*
mm. Hind feet black, mottled with whitish and with
bands of the same color at the sutures of the
segments. W. I.....:...... A. maculipes
ll. Abdomen without such a cluster of scales; outstand-
ing scales of the wing veins rather narrow, lanceo-
late; tarsi wholly black.
m. Deep black, thorax obscurely lined with violace-
ous, especially posteriorly; head, abdomen and
legs black; no markings on the pleura; ab-
domen without trace of lighter bandings;
wing scales outstanding, uniform, not forming
spots, though little thicker at the usual points
indicating the spottings. Florida..A. atropus
*Species marked with an * are known to transmit malaria. Species found only in tropical
North America and not known to carry malaria have been omitted from this table, but all found
in the United States are included.
2092 Hominoxious Arthropods
mm. Otherwise marked when the wings are unspotted.
n. Wings unspotted.
o. Petiole of the first forked cell (R2) more than a
third the length of the cell. Mississippi
VAM EY. joc. din dob eas ak oa a ee ee A. walkeri
oo. Petiole of the first forked cell a third the
length of the cell. Md...... A. barberi
nn. Wings spotted.
o. Front margin of the wings with a patch of
whitish and yellow scales at a point about
two-thirds or three-fourths of the way from
base to apex of wing.
p. Veins of the wing with many broad obovate
outstanding scales; thorax with a black
dot near the middle of each side. W. I.
sth bth BONES as wee tor, 8 REE A. grabhami*
pp. The outstanding scales of the wings rather
narrow, lanceolate.
q. Scales of the last vein of the wings white,
those at each end black; Rais black
scaled, the extreme apex white scaled.
Widely distributed north and south
(figs I3T)baseveacss A. punctipennis
A dark variety from Pennsylvania has
been named A. perplexens.
qq. Scales of the last vein of the wing white,
those at its apex black; R445 white
scaled and with two patches of
black scales. South and the tropics.
A. franciscanus and pseudopunctipen-
nis*
oo. Front margin of the wings wholly black
scaled.
p- Last (anal) vein of the wings white scaled
with three patches of black scales (fig.
132). New Jersey to Texas. . A. crucians*
pp. Last vein of the wings wholly black
scaled.
q. Widely distributed north and south
(fig. 130), (=maculipennis)..........
2 eeecer a a eee a A. quadrimaculatus*
qq. Distributed from Rocky Mountains
westward............ A. occidentalis
kk. Scutellum distinctly trilobed.
1, Cell Rz less than half as long as its petiole; thorax
with metallic blue scales; median lobe of the
scutellum not tuberculate; few small species which
are not COMMON... 25.4 ches vw: Uranotenia Arrib.
Diptera 293
ll. Cell Rz nearly or quite as long as its petiole, or
otherwise distinct.
m. Femora with erect outstanding scales; occiput
broad and exposed. Large species. P. ciliata.
P.howardi................ Psorophora R. D.
mm. Femora without erect scales.
u. Clypeus bearing several scales or hairs, scutel-
lum with broad scales only; back of head
with broad scales; scales along the sides of the
mesonotum narrow; some or the claws
toothed; thorax marked with a pair of
silvery scaled curved stripes; legs black
with white bands at the bases of some of the
segments (fig. 134). Yellow Fever mosquito
eee te cated A soa Aedes (=Stegomyia) calopus.
nn. With another combination of characters.
Numerous species of mosquitoes belonging
to several closely related genera, widely
distributed over the country. (Culex, Aedes,
Ochlerotatus, etc.). Culex in the wide sense.
li. Metanotum with sete. Wyeomyia (found in the United
States); and related tropic genera.
bb. Antenne composed of three segments with a differentiated style or bristle;
third segment sometimes complex or annulate, in which case the empo-
dium is usually developed like the pulvilli, ie., pad-like (fig. 161 g).
ce. Empodium developed pad-like (pulvilliform) i.e., three nearly equal
membranous appendages on the underside of the claws (fig. 161g).
d. Squamez, head, and eyes large; occiput flattened or concave; third
segment of the antenne with four to eight annuli or segments,
proboscis adapted for piercing; body with fine hairs, never with
bristles; middle tibia with two spurs; wing venation as figured
(fig. 163f); marginal vein encompasses the entire wing. Horse
flies, greenheads, deer flies, gad flies.................. TABANIDE*
e. Hind tibia with spurs at tip; ocelli usually present (PANGONINZ)
f. Third joint of the antennze with seven or eight segments; probo-
cis usually prolonged.
g. Each section the the third antennal segment branched. Central
American species, P. fest@..............05 Pityocera G. T.
gg. Sections of the third antennal segment not branched.
h. Upper corner of the eyes in the female terminating in an acute
angle; wings of both sexes dark anteriorly. G. chrysocoma,
a species from the eastern states.......... Goniops Ald.
hh. Upper corner of the eye in the female not so terminating;
wings nearly uniform in color, or hyaline.
i. Proboscis scarcely extending beyond the palpi; front of the
female wide; much wider below than above. S. W.
SHALES sie cuss dais tice amresciuantl alte ae A patolestes Will.
*This table to the North American genera of the Tabanide is adapted from one given by
Miss Ricardo.
204 Hominoxious Arthropods
ii. Proboscis extending beyond the palpi.
j. Wing with cell M3 closed. Tropic America ..........
sda nie Gt east Ek orn Bae ae tN Te ear (=Diclisa) Scione Wik.
jj. Cell M3 open; ocelli present or absent. Two or three
eastern species; many south and west. .Pangonia Rdi.
ff. Third segment of the antenna with five divisions; ocelli present.
g. First and second segments of the antenna short, the second only
half as long as the first, three western species... .Silvius Rdi.
gg. First and second segments of the antenna long, the second
distinctly over half as long as the first. Deer flies. Many
species, widely distributed.............. Chrysops Meig.
ee. Hind tibia without spurs; ocelli absent.
f. Third segment of antenna with four divisions, no tooth or angula-
tion; wings marked with rings and circles of darker coloring;
front of the female very wide. Widely distributed. H. ameri-
cana, H. punctulata.............0005. Hematopota Meig.
ff. Third segment of the antenna with five divisions (fig. 161b).
g. Third segment of the antenna not furnished with a tooth or
distinct angular projection.
h. Body covered with metallic scales; front of female of normal
width; front and middle tibie greatly dilated. L.
VO DUOEE. se. icccsous Bi Soar nie sae AE BE BSS Lepidoselaga Macq.
hh. Body without metallic scales; antenne not very long, the
third segment not cylindrical, not situated on a projecting
tubercle; front of the female narrow. South. D.
ferrugaius, 1.06... eee eee (=Diabasis) Diachlorus O. 8.
gg. Third segment of the antenna furnished with a tooth or a
distinct angular projection.
h. Hind tibie ciliate with long hairs. S. W. and tropics.
as aiasiei ena Ueius AAO arch iy, wages eae aged Snowiella and Shbasoma.
hh. Hind tibie not ciliate.
i. Species of slender build, usually with a banded thorax and
abdomen; third segment of the antenna slender, the
basal prominence long; wings mostly with brownish
markings. Tropic America........ Dichelacera Macq.
li. Species of a stouter build; third segment of the antenna
stout, its basal process short (fig. 161b). Many species,
widely distributed...................--05. Tabanus L.
dd. With another group of characters.
e. Squamz small, antennz variable, thinly pilose or nearly bare species,
without distinct bristles; wing veins not crowded anteriorly, R4 and
Rs both present, basal cells large; middle tibiz at least with spurs
SEE eed Svc Ae Say hee ihash SR eh AE ak GOMES OE Yen aah be eee ake ad LEPTIDE
f. Flagellum of the antenna more or less elongated, composed of
numerous more or less distinct divisions.................00005
miktcgge eee eens aoeget, ys XYLOPHAGINE and ARTHROCERATINE.
ff. Antenne short, third segment simple, with arista or style; face
small, proboscis short ............ 0c ccc eee eens LEPTINE
Diptera 205
g. Front tibiz each with one or two spurs, or if absent, then no
discal cell. Tviptotricha, Pheneus, Dialysis, Huilarimorpha.
gg. Front tibe without terminal spurs, discal cell present.
h. Hind tibe each with a single spur.
i. Anal cell open (fig. 163g); third antennal segment kidney-
shaped with dorsal or subdorsal arista; first antennal
segment elongate and thickened. About a dozen species
have been described from the United States, of which at
least one (S. pachyceras) is known to be a vicious blood
SUCKERS, eGo Rarer sommaae ined Hee Symphoromyia Frauenf.
ii. Anal cell closed; third antennal segment not kidney-
Shaped asexosr ga uege tes Chrysopila, Ptiolina, Spania.
hh. Hind tibise each with two spurs.
i. Third segment kidney-shaped, the arista subdorsal; anal
CED CLOSE ae. eerste carin oe ise prandniva ts actiisnas anime ee Atherix Meig.
ui. Third segment of the antenna short and with terminal
arista; anal cell open. ..........-.00-005- Leptis Fabr.
Two European species of this genus have been accused of
blood sucking habits, but the record seems to have
been based upon error in observation.
ee. With another combination of characters..................0000.
echt raee secant oer areas cre iy hopterstana STRATIOMYIIDZ, CYRTID&, etc.
ec. Empodium bristlelike or absent.
d. Antenne apparently two-segmented, with three-segmented arista,
wings (rarely wanting) with several stout veins anteriorly, the
weaker ones running obliquely across the wing (fig. 163h); small,
quick running, bristly, humpbacked flies. Several genera; Aphio-
cheeta, Phora, Trineura, etc............... 20.000 eee PHORIDE
dd. Flies with other characters.
e. No frontal lunule above the base of the antenne; both R4 and Rs
often present; third segment of the antenna often with a terminal
bristle. ASILIDZ, Mypaip#, APIOCERIDH, THEREVIDZ, SCENO-
PINIDZ, BOMBYLIID#, Empipip&, DoLicHorpopip®, LONCcHOP-
TERIDZ.
ee. A frontal lunule above the base of the antenne; third segment of the
antenna always simple, i.e., not ringed, usually with a dorsal
arista; R4 and Rs coalesced into a simple vein.
f. A spurious vein or fold between the radius and the media, rarely
absent; the cell R445 closed at the apex by vein Mi; few or no
bristles on the body, none on the head; flies frequently with
yellow markings. Eristalis (fig. 163i), Helophilus, and many
Other EMC abe gto ais sinp,.46, 5, aieaerstrenctin em NRA oaeueNee NS SYRPHIDE
ff. No spurious vein present.
g. Body without bristles; proboscis elongate and slender, often
folding; front of both male and female broad... .CONOPIDE
gg. Bristles almost always present on head, thorax, abdomen and
legs.
296 Hominoxious Arthropods
h. Arista terminal; hind metatarsus enlarged, sometimes orna-
mented, hind tarsus more or less flattened beneath......
i aig eee Page He RES E SHALES TH SET Rah Tee ws PLATYPEZIDZ
hh. Flies having a different combination of characters.
i. Head large, eyes occupying nearly the entire head; cell
R4+5 narrowed in the margin; small flies .. PIPUNCULIDZ
ii. Head and eyes not unusually large.
j. Squame (tegule, or calyptre, or alule) not large, often.
quite small, the lower one lacking, or at most barely
projecting from below the upper one (antisquama);
front of both male and female broad, the eyes therefore
widely separated; posthumeral and intraalar macro-
cheta not simultaneously present; thorax usually
without a complete transverse suture; postalar callus
usually absent; the connectiva adjoining the ventral
sclerites always visible; hypopleural macrochete
absent; last section of Rais and Mi+2 with but few
exceptions nearly parallel; subcostal vein often wanting
or vestigial or closely approximated to Ri; the latter
often short, basal cells small, the posterior ones often
indistinct or wanting; vibrisse present or absent
apices id ate ahah wae SR ee Rais dae 2 ACALYPTRATE MUSCOIDEA
k. Subcosta present, distinctly separated from R; at the
tip; Ri usually ends distad of the middle of the
wing; the small basal cells of the wing distinct.
1. A bristle (vibrissa) on each side of the face near the
margin of the mouth. CORDYLURIDZ, SEPSIDZ,
PHYCODROMID2, HETERONEURID&, HELOMYZID&.
ll. No vibrisse present.
m. Head nearly spherical, cheeks broad and re-
treating; proboscis short; the cell Rs closed or
narrowed in the margin; legs very long; tarsi
shorter than the tibie. Calobata and other
PNET 4 ts vie das art db dukin wan ak OS MICROPEZIDE
mm. Flies with another combination of characters.
RHOPALOMERIDZ, TRYPETIDE, ORTALIDA,
SCIOMYZID&.
kk. Subcosta absent or vestigial, or if present, then
apparently ending in the costa at the point where
Rj joins it; Ry usually ends in the costa at or before
the middle of the wing.
1, Arista long plumose, or pectinate above; oral vibris-
se present; anal cell complete; costa broken at
the apex of Ry. Drosophila, Phortica, and other
EMO TAI i hie iic nel Sus altel tees sueess eda aa DROSOPHILIDE
i. With another combination of characters.
m. The cell M and first Me not separated by a cross-
vein; anal cell absent; front bare or only
Diptera 297
bristly above; usually light colored flies.
Hippelates, Oscinus, and other genera. (See
ALSO; MM MIs ice canes Hedge die vay OSCINIDE
mm. Cell M and cell first Me often separated by a
crossvein; anal cell present, complete, though
frequently small; scutellum without spines
or protuberances; oral vibrisse present;
arista bare or short plumose; front bristly at
vertex only; small dark flies. Piophila
(fig. 99), Sepsis and other genera. . .SEPSIDE
mmm. The Gromyzip#, AGRoMyzID#, PSsILID&,
TRYPETIDZ, RHOPALOMERIDH, BORBORIDE
and Driopsip# differ in various particulars
from either the OSCINIDE and the SEPSIDE
noted above.
jj. Squamz well developed, usually large, the lower one
frequently projecting from below the upper one; both
posthumeral and intraalar macrochete present;
thorax with a complete transverse suture; postalar
callus present and separated by a distinct suture from
the dorsum of the thorax; front of the female broad,
of the male frequently narrow, the eyes then nearly or
quite contiguous; the connectiva adjoining the ventral
sclerites either visible or not; hypopleural macro-
cheetz present or absent; subcosta always distinct in
its whole course, Ri never short.................00.
setdud-coma Hint a5 adele UA See ca CALYPTRATE MUSCOIDEA*
k. Oral opening small, mouth parts usually much reduced
or vestigial. This family is undoubtedly of poly-
phyletic origin but for convenience it is here con-
sidered as a single family.............. OESTRIDZ.
l. The costal vein ends at the tip of Rats, Mi+se
straight, not reaching the wing margin, hence
cell Rs wide open (fig. 163}); squamz small;
arista bare; ovipositor of the female elongate.
Larve in the alimentary canal of horses, etc.
PENG Sts Ahead BON hk OV len AIOE ra Deen ae Gastrophilus
m. Posterior crossvein (m-cu) wanting; wings
smoky or with clouds. Europe..G. pecorum
mm. Posterior crossvein (m-cu) present, at least in
part.
*The classification of the Muscoidea as set forth by Schiner and other earlier writers has
long been followed, although it is not satisfactory, being admittedly more or less artificial. With-
in the last two or three decades several schemes have been advanced, that of Brauer and Bergen-
stamm and of Girschner, with the modifications of Schnabl and Dziedzicki having obtained most
favor in Europe. Townsend, in 1908, proposed a system which differs from Girschner’s in some
respects, but unfortunately it has not yet been published in sufficient detail to permit us to adopt
it. From considerations of expediency we use here the arrangement given in Aldrich’s Cata-
logue of North American Diptera, though we have drawn very freely upon Girschner’s most excel-
lent paper for taxonomic characters to separate the various groups. .
t may sometimes be found that a species does not agree in all the characters with the synop-
sis; in this case it must be placed in the group with which it has the most characters in common.
298 Hominoxious Arthropods
n. Wing hyaline with smoky median cross band,
and two or three spots; posterior trochanters
with hook in the male and a prominence in
thefemale. World wide distribution. G. equi.
nn. Wings without spots.
o. Posterior crossvein (m-cu) distad of the
anterior crossvein (r-m); legs, particularly
the femora, blackish brown. Europe and
North America........ G. hemorrhoidalis
oo. Posterior crossvein opposite or proximad of
the anterior crossvein. Europe and North
ll. The costal vein ends at the tip of M1 2, Mite witha
bend, the cell Rs hence much narrowed in the
margin, or closed.
m. Proboscis geniculate, inserted in a deep slit;
female without extricate ovipositor; arista
either bare or plumose; squame large; facial
grooves approximated below.
n. Arista bare, short. Larve in rodents. Tropic
America. B. princeps...... Bogeria Austen
nn. Arista pectinate above.
o. Tarsi broadened and flattened, hairy, anal
lobe of the wing large. Larve in rodents.
A number of American species. Cuterebra.
oo. Tarsi slender, not hairy; anal lobe of the
wing moderate. Larve in man and other
mammals. TropicAmerica. D.cyaniven-
TIS Sie ik caer etng ecs dd doe Dermatobia Br.
mm. Mouth parts very small, vestigial; arista bare.
n. Facial grooves approximated below, leaving a
narrow median depression or groove.
o. Cell Rs closed and petiolate, body nearly
bare. Larve in the nasal cavities of the
smaller Ungulates. The sheep bot fly.
O. ovis. Widely distributed. .Oestrus L.
oo. Cell Rs narrowly open, body hairy. Larve
parasitic on deer. Europe and America
ied ears ite ao Gti ergs Cephenomyia Latr.
nn. Facial grooves far apart, enclosing between
them a broad shield-shaped surface; squamz
large; female with elongate ovipositor.
Larve hypodermatic on Ungulates......
yey WER SAE NER sais Gaus ae Hypoderma Clark
9. Palpi wanting; tibie thickened in the middle.
p. Hair at apex of the abdomen yellow; legs
including femora yellowish brown... .
selene ora Shep Sips isan aes hut aud ae H. diana
Diptera 299
pp. Hair at the apex of the abdomen reddish
yellow. Europe and America,
q. Tibiz and tarsi yellow; femora black
Rt AR gia chy sie Susy on ig dace Bee H. lineata
qq. Legs black with black hair; tips of
hind tibia and tarsi yellowish brown
Mvubhws Swe MEY eMaRE WS H. bovis
oo. Palpi small, globular; tibie cylindrical,
straight. On reindeer. ....0. tarandi
SeShaaAs ein Aik and se shay a lyre Oedemagena Latr.
kk. Oral opening of the usual size; mouth parts not
vestigial.
1. Hypopleurals wanting; if three sternopleurals are
present the arrangement is 1:2; conjunctiva
(fig. 161c) of the venter usually present; if the
terminal section of Mi+2 is bent it has neither fold
nor appendage (ANTHOMYIID of Girschner).
m. Sternopleurals wanting; Mi+s straight toward
the apex, costa ends at or slightly beyond the
tip of Ra+s; mouth parts vestigial.........
ce er ees GASTROPHILINE. See OESTRIDE
mm. Sternopleurals present, if rarely absent then
differing in other characters.
n. Caudal margin of the fifth ventral abdominal
sclerite of the male deeply notched on the
median line usually to beyond the middle;
abdomen often cylindrical or linear; abdomen
often with four to eight spots; eyes of the
male usually widely separated; sterno-
pleurals three, arranged in an equilateral
triangle; subapical seta of the hind tibia
placed very low; My straight; anal vein
abbreviated; wings not rilled. Cenosia,
Caricea, Dexiopsis, Hoplogaster, Scheno-
myia, etc. (CGNOSINA)*.............000.
spoaavane Satoh nusbengu sen lemeek asueet ANTHOMYIID in part
nn. Caudal margin of the fifth ventral abdominal
sclerite of the male incurved, rarely deeply
cleft, rarely entire, in a few genera
deeply two or three notched; M142 straight
*There are several genera of flies of the family Cordyluride (i.e. Acalypirate) which might be
placed with the Anthomyiide@ (i.e. Calyptrate), owing to the relatively large size of their squamz.
As there is no single character which will satisfactorily separate all doubtful genera of these two
groups we must arbitrarily fix the limits. In general those forms on the border line having a
costal spine, or lower squama larger than the upper, or the lower surface of the scutellum more
or less pubescent, or the eyes of the male nearly or quite contiguous, or the eyes hairy, or the
frontal sete decussate in the female; or any combination of these characters may at once be
placed with the Anthomyiide. Those forms which lack these characteristics and have at least
six abdominal segments (the first and second segments usually being more or less coalescent)
are placed with the Acalyptrates. There are other acalyptrates with squame of moderate size
which have either no vibrissz, or have- the subcosta either wholly lacking or coalescent in large
part with R,, or have spotted wings; they, therefore will not be confused with the calyptrates.
300 Hominoxious Arthropods
or curved; abdomen usually short or elongate
oval; sternopleurals, if three are present,
arranged in the order 1:2 in a right triangle.
....(Muscin@&-ANTHOMYIIN of Girschner)
o. Mj+2 straight, hence cell Rs not narrowed in
the margin........ ANTHOMYUDZ in part
p. Underside of the scutellum more or less
sparsely covered with fine hairs; anal
vein nearly always reaches the hind
margin of the wing; extensor surface of
the hind tibize with a number of stout
sete; squame often small and equal.
Anthomyia, Chortophila, Eustalomyia,
Hammomyia, Hylemyia, Prosalpia, Pego-
myia, etc.... HYLEMYINZ-PEGOMYINE
pp. Underside of the scutellum bare; anal
vein does not reach the wing margin.
q. First anal vein short, second anal sud-
denly flexed upwards; hind tibie each
with one or two strong sete on the
extensor surface. Fannia (=Homalo-
myia), Caelomyia, Choristoma, Eur-
yomma, Azeliu, etc. FANNINE-AZELINE
qq. Anal veins parallel or divergent.
r. Setz on the exterior surface of the hind
tibie wanting (except in Limnaricia
and Cenosites), lower squama not
broadened to the margin of the
scutellum. Leucomelina, Limno-
phora, Limnospila, Lispa, Mydaea,
Spilogaster, ete. 2... eee eee eee
Era stiiy a pia Myb1n&-LIMNOPHORINE
tr. One (rarely more) seta on the extensor
surface of the hind tibia; squame
usually large and unequal. Hydro-
taea, Aricia, Drymeta, Ophyra,
Phaonia (=Hyetodesia), Pogono-
myia, Trichophthicus, etc. ARICINE
oo. Mi+e2 curved or bent, hence the cell Rs more
or less narrowed in the margin.
(MUSCINZ). MuUSCIDZ in part. See
page 303 for generic synopsis.
ll. Hypopleurals present; when three sternopleurals
are present the arrangement is 2:1 or I:1:1.
s Aes Sak deci a Set Aca nado bapa (TACHINID& of Girschner)
m. Conjunctiva of the ventral sclerites of the ab-
domen present, frequently well developed,
surrounding the sclerites.
Diptera 301
n. Mouth parts vestigial. OESTRIDZ, See page
297 for generic synopsis.
nn. Mouth parts well developed.
0. Mite straight, hence cell Rs wide open in
the margin; costa ending at the tip of R;;
three sternopleurals present; antennal
arista plumose. Syllegopiera. Europe.
....(SYLLEGOPTERINZ)..DEXIIDZ in part
00. Mi+2 bent, hence cell Rs narrowed in the
margin; sternopleurals rarely wanting,
usually 1:1 or 0:1; facial plate strongly
produced below vibrissal angle like the
bridge of the nose; antennal arista bare.
Parasitic on Hemiptera and Coleoptera.
Allophora, Cuistogaster, Clytia; Phasia,
etc. (PHASIINH)..TACHINIDZ in part.
mm. Conjunctiva of the ventral sclerites invisible
(fig. 161a).
n. Second ventral sclerite of the abdomen lying
with its edges either upon or in contact with
the ventral edges of the corresponding
dorsal sclerite.
o. Outermost posthumeral almost always lower
(more ventrad) in position than the pre-
sutural macrocheta; fifth ventral abdomi-
nal sclerite of the male cleft beyond the
middle, often strongly developed; body
color very frequently metallic green or
blue, or yellow; arista plumose. (CALLI-
PHORINE) ............ MUSCID& in part.
See page 303 for generic synopsis.
oo. Outermost posthumeral macrocheta on
level or higher (more dorsad) than the
presutural macrocheta; arista bare, pube-
scent, or plumose only on the basal two-
thirds; body coloring usually grayish
(fig. 106)...........,.. SARCOPHAGIDE
p. Fifth ventral sclerite of the male either
wanting or with the caudal margin
straight; presutural intraalar rarely
present............. (SARCOPHAGINZE)
q. Fifth ventral abdominal sclerite of the
male much reduced, the remaining
segments with straight posterior mar-
gin, overlapping scale-like; in the
female only segment one and two scale-
like, the others wholly or in part
covered; sternopleurals usually three
or more. Sarcophaga and _ related
genera.
302 Hominoxious Arthropods
qq. Fifth ventral sclerite of the male plainly
visible; sternopleurals usually two.
Sarcophila, Wohlfahrtia, Brachycoma,
Hilarella, Miliogramma, Metopia,
Macronychia,, Nyctia, Paramacrony-
chia, Pachyphthalmus, etc.
pp. Fifth ventral abdominal sclerite of the
male cleft to beyond the middle; ventral
sclerites usually visible, shield-like.
Rhinophora, Phyto, Melanophora....
SS tert noah Gat Sania aes RHINOPHORINA
164. Glossina palpalis. (x4.) After Austen.
nn. Second ventral abdominal sclerite as well as
the others more or less covered, sometimes
wholly, by the edges of the dorsal sclerite.
o. The presutural intraalar wanting; ventral
sclerites two to five nearly or quite covered
by the edges of the corresponding dorsal
sclerites; base of the antenne usually at or
below the middle of the eye; arista usually
plumose; legs usually elongate; abdomi-
nal segments with marginal and often
discal macrochete............. DEXIDZ
oo. Presutural intraalar present, if absent, then
the ventral sclerites broadly exposed
or the fifth ventral sclerite vestigial;
Muscide 303
base of the antenne usually above the
middle of the eye; arista bare; at least
two posthumerals and three posterior
intraalars present. Parasitic on cater-
Pillars, ClO re dnc siding «alec TACHINIDA
SYNOPSIS OF THE PRINCIPAL GENERA OF THE MUSCIDZ OF THE WORLD
a. Proboscis long, directed forward, adapted for piercing, or oral margin much
produced, snout-like.
b. Oral margin produced snout-like; vibrissa placed high above the oral
margin; antennal arista either pectinate or more or less plumose.
c. Antennal arista short or long-plumose; neither sex with distinct
orbital bristles.
d. No facial carina between the antenne ............ RHYNCHOMYIINE
e. Arista short-plumose. R.speciosa. Europe....Rhynchomyia R.D.
ee. Arista long-plumose. I. phasina. Europe and Egypt. Idiopsis. B.B.
dd. With flattened carina, the bases of the antennz separated; no abdom-
IMAL MA CTOCH PE 5 + einctaiialn a Aceiiey whedon 4 dudiees a eg eae a saus COSMININE
C. fuscipennis. South Africa............. ih cms ean Cosmina
ce. Antennal arista pectinate; bases of the antenne separated by a flat-
tened! carina: ::.cseeeadeaceiiet Meee veomheeews Eee Ruinun# R. D.
d. Cell Rs open, or closed at the margin.
e. Third segment of the antenna twice as long as the second; claws of
both sexes short; cell Rs open. J. /unata. Eastern Hemisphere.
asa lvl ca teen een Ieee ens alin iE p aS roNn ai a Sisk ade Idia Meigen
ee. Third segment of the antenna three times as long as the second;
cell Rs open or closed; claws of the male long and slender, of the
female shorter than the last tarsal joint. J. mandarina, China.
seth tar daw nev etree Spe EAA Ne poses ape naeaD SEL Idiella B. B.
dd. Cell Rs petiolate................0065 Rhinia; and Beccarimyia Rdi.
bb. Proboscis long, directed forward, adapted for piercing....... STOMOXINE
c. Arista flat, pectinate above with plumose rays; sternopleurals 1:2;
bases of the veins R; and R445 without sete; base of the media bowed
down; apical cell opens before the apex of the wing. African species
seg sh de Set ein tah tac eco eset Soe aero ec ne isla eer aeee Glossina Wied.
d. Species measuring over twelve mm. in length. G. longipennis and fusca.
dd. Species less than twelve mm. in length.
e. All segments of the hind tarsi black.
f. The fourth and fifth segments of the fore tarsi black; antenne
black (igs TOA) wacinunteaneca ani acmunid G. palpalis R. D.
ff. Otherwise marked. ............ G. bocagei, tachinoides, pallicera.
ee. First three segments of the hind tarsi are yellow, the fourth and
fifth segments are black.
f. Fourth and fifth segments of the first and second pair of tarsi are
black.
g. The yellow bands of the abdominal segments occupy a third of
the segment (fig. 165)............ G. morsitans Westw.
gg. The yellow band on each segment of the abdomen occupies a
sixth of the segment...............66- G. longipalpis Wied.
304 Hominoxious Arthropods
ff. Tarsi of the first and second pairs of legs wholly yellow..........
cialis bot Gia ARE Sead EM eeelee eS G. pallidipes Austen
cc. Rays of the arista not plumose; only one or two sternopleurals; base of
the media not strongly bowed down; apical cell opens at or very near
the apex of the wing.
d. Vein Rats without setz at the base; palpi about as long as the pro-
boscis.
e. Arista pectinate (i. e. rays on one side only), the rays often undulate;
two yellow sternopleurals often difficult to detect; vein M i+
only slightly bent, the apical cell hence wide open. The horn fly,
H. irritans (=Lyperosia serrata) and related species. Widely dis-
tributed (figs. 167, 168) ............ Hematobia R. D. not B. B.
165. Glossina morsitans. (x4.) After Austen.
ee. Arista also with rays below; vein Mj42 more strongly bent, the
apical cell hence less widely open.
f. Palpi strongly spatulate at the tips, lower rays of the arista about
six in number, B. sanguinolentus. South Asia..............
Sie Mea Be nates S DRE ee ORR RE A eRe Seen Bdellolarynx Austen
ff. Palpi feebly spatulate; apical cell of the wing narrowly open
slightly before the tip; sternopleurals black, anterior bristle
sometimes absent. H. atripalpis. Europe................
reailineaee Heatoees env quip izantel AE agaatin geet atin een meds Hematobosca Bezzi
dd. Vein Rais with seta at the base.*
*Pachymyia Maca. is closely related to Stomoxys. It differs in having the arista rayed both
above and below. P. vexans, Brazil.
Muscide 305
e. Veins Ri and Rais with sete at the base; two equally prominent
sternopleural macrochete; arista with rays both above and be-
low; palpi as long as the proboscis; apical cell of the wing wide
open. L. tibialis. (Hematobia B. B. not R.D.)...............
a dE OS GUS gute nro Gaara carla ehe Ge ATE EY Lyperosiops Town.
ee. Only vein Rais with basal sete; anterior sternopleural macro-
cheta wanting; arista pectinate.
f. Palpi as long as the proboscis, the latter stout, with fleshy termi-
nal labelle; apical cell narrowly open; sternopleural macro-
chete black. S. maculosa from Africa and related species
fromiy ASIA gan a yp ge hee Bm oe Bed ae ee Be Stygeromyia Austen
ff. Palpi much shorter than the proboscis, the latter pointed at the
apex, without fleshy labelle; apical cell of the wing wide open.
S. calcitrans, the stable fly and related species. Widely dis-
tributed in both hemispheres (fig. 110) ........ Stomoxys Geof.
aa. Proboscis neither slender nor elongate, the labelle fleshy and not adapted for
piercing.
b. Hypopleure without a vertical row of macrochete............ MUSCINE
ce. Arista bare; distal portion of Rg1s5 broadly curved at the end; hypop-
pleurae with a sparse cluster of fine hairs. S. braziliana, Southern
States:and southward ss. ciepcsvarsswadaamy sane Synthesiomyia B. B.
ec. Arista pectinate or plumose.
d. Arista pectinate. H. vittigera, with the posterior half of the abdomen
metallic blue. Mexico..................4. Hemichlora V. d. W.
dd. Arista plumose.
e. Middle tibia with one or more prominent sete on the inner (flexor)
surface beyond the middle, or inner surface very hairy.
f. Ri ends distad of the m-cu crossvein; R445 with a broad curve
near its apical end. (=Neomesembrina Schnabl, = Metamesem-
brina Town). M. meridiana. Europe.... Mesembrina Meigen
ff. Ry ends proximad of the m-cu crossvein.
g. Eyes pilose, sometimes sparsely in the female.
h. Female with two or three stout orbital sete; the hind metatar-
sus of the male thickened below at the base and penicillate.
D. pratorum. Europe............ Dasyphora R. D.*
hh. Neither sex with orbital sete.
i. Abdomen without macrochete; arista plumose. C.
asiatica. Eastern Hemisphere... Cryptolucilia B. B.
ii. Abdomen with strong macrochete; arista very short-
plumose, nearly bare. 3B. tachinina. Brazil..........
ere re eee eT ee eee ee oe Reinwardtia B. B.
gg. Eyes bare.
h. Body densely pilose; thoracic macrochete wanting; middle
tibize much elongate and bent; last section of Rats with a
gentle curve. H. (Mesembrina) mystacea, et al., Europe
and H. solitaria, N. America....Hypodermodes Town.
hh. Body not densely pilose.
*The genus Eudasyphora Town. has recently been erected to contain D. lasiophthalma.
306 Hominoxious Arthropods
i. Dorsocentrals six; last section of Rats with a gentle curve.
j. Inner dorsocentrals (‘‘acrostichals’’) wanting; sterno-
.pleurals arranged 1:3. P. cyanicolor, cadaverina, etc.
Europeand America................. , Pyrellia R. D.
jj. Inner dorsocentrals (‘‘acrostichals”) present; sterno-
pleurals arranged 1:2. E. Jatreillii. North America.
inate fin ee asaeeta deca ete et aes Eumesembrina Town.
ii. Dorsocentrals five; inner dorsocentrals present; last
section of R445 with a rounded angle; sternopleurals
arranged 1:2. P. cornicina Europe and America,
(Pseudopyrellia Girsch.)..........00000+ Orthellia R. D.
ee. Middle tibia without a prominent bristle on the inner surface beyond
the middle.
166. Pycnosoma marginale. (x4.) After Graham—Smith.
f Squamula thoracalis broadened mesad and caudad as far as the
scutellum.
g. Sternopleural macrochete arranged in an equilateral triangle;
front of both sexes broad; gene bare; dorsocentrals six,
small; wing not rilled. (To CoENosIN#). Atherigona Rdi.
gg. Sternopleural macrochete when three are present, arranged
in a right triangle.
h, Last section of R4is with a more or less rounded angle
(fig. 1631).
i. Eyes of the male pilose or pubescent, of the female nearly
bare; m-cu crossvein usually at or proximad of the mid-
distance between the r-m crossvein and the bend of
Rais. P. (= Placomyia R. D.) vitripennis............
eects Meh ka ieaueoni saya ice mathe y eats ae Bisere eas Plaxemyia R. D.
li. Eyes bare; the m-cu crossvein always nearer to the bend of
Rg+s than to the r-m crossvein.
j. Apex of the proboscis when extended reveals a circlet of
stout chitinous teeth. P. insignis Austen, of India,
bites both man and animals. (= Pristirhynchomyia)
pba ati aR LS wet dee We CS Sn Philematomyia Austen
Muscide 307
jj. Apex of the proboscis without black teeth.
k. Eyes of male separated by a distance equal to a fourth
the width of the head. House or typhoid fly.
M. domestica L. Widely distributed... Musca L.
kk. Eyes of the male contiguous. E.corvina. Europe.
Se HUNAN th ah astern de Gries Eumusca Town
hh. Last section of R445 with a gentle curve (fig. 102).
i. Eyes pilose.
j. Claws in the male somewhat elongated; no orbitals in
either sex; antenne separated at the base by a flat
carina; abdomen marked with red or yellow. G.
maculata. Europe and America....Graphomyia R. D.
jj. Claws short and equal in the two sexes; two or three
stout orbital macrochetz in the female; Ry scarcely
produced beyond the r-m crossvein; eyes contiguous
in the male. P. obsoleta. Brazil ..Phasiophana Br.
ii. Eyes bare; fronto-orbital macrochete in a double row,
antenne contiguous at the base.
j. One or more pairs of well developed anterior inner dorso-
central (acrostichal) macrochetze; seta on extensor
surface of hind tibia. M. assimilis, stabulans, etc.
Europe and America.............. Muscina R. D.
jj. Anterior inner dorsocentrals and the setz on the ex-
tensor surface of the hind tibia wanting. M. micans,
etc. Europe and North America....Morellia R. D.
ff. Squamula thoracalis not broadened mesad and caudad, not
reaching the margin of the scutellum; macrochete on extensor
surface of the hind tibia wanting.
g. Eyes pubescent. M. meditabunda. Europe and America.
Boe oe Baaaataehs sat ote WON LA Ah A ewier N Ae Myiospila Rdi.
gg. Eyes bare; R, ends before the middle of the wing. A number
of species from the tropics of both hemispheres. ..........
pea gh aga dearshaese lee ae yee an yeshxyed Clinopera V. d. W.
bb. Hypopleure with a vertical row of macrochete.
c. Eyes pubescent.
d. Ri ends about opposite the r-m crossvein; basal section of Rg+ts bristly
nearly to the crossvein; S. enigmatica. Africa. Somalia Hough
dd. Ry ends distad of the r-m crossvein.
e. Eastern hemisphere. Australasia. N. ochracea, dasypthalma.
s desat Wha duad Ht Seacb ase Gag ele chads d-auatcane hud. sh es ble eon oBionsl SEG Neocalliphora Br.
ee. Western Hemisphere. T. muscinum. Mexico.. Tyreomma V.d. W.
ce. Eyes bare.
d. The vibrissal angle situated at a noticeable distance above the level of
\ the margin of the mouth.
e. Sternopleural macrochete arranged in the order 1:1.
f. Gene with microchete.
g. Body grayish, with depressed yellow woolly hair among the
macrochetz; wings folded longitudinally over the body when
308 Hominoxious Arthropods
at rest. Cluster flies. P. rudis and related species, widely
GiStHBUtEd: ous eauelead Ba es SRR ea COR eS Pollenia R. D.*
gg. Body metallic blue or green. Eastern Hemisphere.
h. Vibrissal angle placed very high above the oral margin; a
catina between the antenne; outer posthumeral wanting;
anterior intraalar present. YT. viridaurea. Java ......
Thelycheta Br.
Manda
167. Horn fly. (a) egg; (b) larva; (c) puparium; (d) adult. (x4). Bureau of Entomology
hh. Vibrissal angle moderately high above the oral margin;
carina small or wanting; no post humeral macrocheta;
lower squame hairy above. (=Paracompsomyia
Hough): Ge. 166) 2s odin ee pe ca es oe aw dS Pycnosoma Br.
ff. Gene bare. S. terminaia. Eastern Hemisphere..............
Hath eA Catalase it fond aed het ray ent Slay Baa G Strongyloneura Bigot
ee. Sternopleurals arranged 2:1.
f. Body metallic green or blue, with gray stripes; gene hairy to the
lower margin; post humerals often wanting; lower squame bare
above. (=Compsomyia Rdi.) ............ Chrysomyia R. D.
g. With one or two orbitals; height of bucca less than half the
height of the eye. South and east U.S. (fig. 107).........
Seeeshitaria et dtehte are seated Sees fA tne NA shart ee. atl ster ots Ets C. marcellaria
gg. No orbitals; height of bucca about a third less than height of
eye. West Us Sinctcisccs goken ayeiede we C. wheelert Hough
*Nitellia, usually included in this genus has the apical cell petiolate. A pollenia Bezzi, has
recently been separated from Pollenia to contain the species P. nudiuscula. Both genera belong
to the Eastern hemisphere.
Muscide 309
ff. Body black or sordidly metallic greenish gray, usually yellow pol-
linose or variegate; genz at most hairy above. WN. stygia.
Eastern Hemisphere................020.000 Neopollenia Br.
dd. Vibrissal angle situated nearly on a level of the oral margin.
e. Species wholly blackish, bluish, or greenish metallic in color.
f. First section of R445 with at most three or four small bristles at
the immediate base.
g. The bend of Ruts a gentle curve; costal spine present; cell Rs
closed, ending before the apex of the wing. S. cuprina.
JAVA Act ved eb eR are BONE ee Sa Selnd bane Synamphoneura Bigot
gg. Bend of R445 angular; or the insect differs in other characters;
dorsal surface of the squamula thoracalis hairy (except in
Melinda); arista plumose only on the basal two-thirds
(except usually in Calliphora and Eucalliphora).
168. Head of horn-fly (Lyperosia irritans); (@) female; (6) male; (c) lateral aspect of female.
h. Arista plumose only on the basal two-thirds.
ji. Base of the antennz ventrad of the middle of the eye; eyes
of the male nearly contiguous; gene hairy; second
abdominal segment with median marginal macrochate;
two, rarely three, postsutural intraalar macrochete.
j. Squamula thoracalis dorsally with long black hairs; male
hypopgium two-segmented, large, projecting; claws
and pullvilli of the male elongate; three strong sterno-
pleural macrochetz; gene at least half the width of the
eye; bucce (cheeks) half the height of the eyes; ovivi-
parous. O. sepulcralis. Europe...... Onesia R. D.
jj. Dorsal surface of the squamula thoracalis bare; male
hypopygium small, scarcely projecting below; claws
and pulvilli not elongate; two stout sternopleural
macrochetz, sometimes with a delicate one below the
anterior; genz nearly linear in the male; bucce about
a third of the eye height; oviparous. M. cerulea.
Euro p@tcss eicewies cae ean S89 SES Melinda. R. D.
310 Hominoxious Arthropods
: ec Teansielee Sle Past alar callus
Front coxa -->
Ss , ade antertor dorsocentrals
aide «inner ww
fee a dea tec vsap ees aia « intraalar
wbure Aumerals ;*
yas ph post « .
ps. presutural
p.lde p-de posterior dorse centrals
SOS ORES GaN SERS pide « inner « z
fa. nlraalar
pra prealarzanterior sa
Ja supra alar
lower sQuaria = :
al { squeccrnyeda thoracalis
upper Squama,=
i Lepuenula alaris
-Probisers
169. Lateral and dorsal aspects of the thorax, and frontal aspect of the head of a muscoidean
fly, with designations of the parts commonly used in taxonomic work.
Muscide 311
ii. Base of the antennz dorsad of the middle of the eye; eyes
of both sexes distinctly separated; dorsal surface of
the squamula thoracalis with black hairs; two post
sutural intraalar macrochete.
j. Hypopygium of the male large, with a pair of slightly
curved forceps whose ends are concealed in a longi-
tudinal slit in the fifth ventral sclerite; third posterior
inner dorso-central (acrostichal) macrochete absent;
anterior intraalar rarely present; abdomen usually not
pollinose; the second segment without median marginal
macrochete; face yellow. C. mortuorum, cadaverina,
and related species. Both hemispheres.
rat Batata mee gp anatase ae i hui uce a dp de deunwa barton Cynomyia R. D.*
170. Sepsis violacea; puparium and adult. (See page 297.) After Howard.
jj. Three pairs of posterior inner dorsocentrals (acrostichals)
present; second abdominal segment with a row of
marginal macrochete; gene hairy, at least above.
k. Hypopygium of the male with a projecting style.
S. stylifera. Europe............ Steringomyia Pok.
*The following three genera are not sufficiently well defined to place in this synopsis. In
color and structural characters they are closely related to Cynomyia from which they may be
distinguished as follows. Catapicephala Macq.. represented by the species C. splendens from
Java, has the sete on the facial ridges rising to the base of the antennz and has median mar,
nal macrochete on the abdominal segments two to four: Blepharicnema Macq., represented
B. splendens from Venezuela has bare genz, oral sete not ascending; tibie villose; claws Hore.
in both sexes; Sarconesia Bigot with the species S. chlorogaster from Chile, setose gene; legs
slender, not villose; claws of the mae! elongate.
312 Hominoxious Arthropods
kk. Hypopygium of the male without style. A. steluiana
TB TB sedi etae a de sts bet a aud weet ¥ ow BE Acrophaga B. B.
hh. Arista usually plumose nearly to the tip; posterior dorso-
centrals and inner dorsocentrals (acrostichals) well
developed; dorsal surface of the squamula thoracalis
hairy; abdomen metallic and usually pollinose; gene
hairy.
i, With one pair of ocellar macrochete. C. vomitoria,
erythrocephala, viridescens, and related species. Both
hemispheres.............0 0000s eee Calliphora R. D.
2 ii. With two strong pairs of ocellar macrochete. .£. latifrons.
Pacific slope of the U. S........ Eucalliphora Town.
ff. First section of R445 bristly near or quite half way to the small
crossvein; dorsal surface of the squamula thoracalis is bare;
the hypopygium of the male is inconspicuous.
g. Gene bare; posterior inner and outer dorsocentrals distinct
and well developed. JL. cesar, sericata, syluarum, and
related species. Widely distributed in both hemispheres
igs 108 ek sSs, Meco e a erags Seite ae Uk Lucilia R. D.
gg. Genz with microchete, at least down to the level of the base
of the arista.
h. Mesonotum flattened behind the transverse suture.
i, Posterior dorsocentrals inconstant and unequally developed;
one pair of posterior inner dorsocentrals. P. terraenove.
North America..............+..- Protophormia Town.
ii. Posterior dorsocentrals well developed, the inner dorso-
centrals (acrostichals) unequally developed. P. azurea,
chrysorrhea, etc. Europe and America..............
ay cisy acaba MBrecceS guitt guts ace Wade eee aa ale Protocalliphora Hough
hh. Mesonotum not flattened behind the transverse suture;
posterior inner and outer dorsocentrals inconstant
and unequally developed. P. regina. Europe and
Amienicn's asin oh Meee tag eden ths al ae Phormia R. D.
ee. Species more or less rufous or yellow in color.
f. Anterior dorsocentrals wanting; first section of the Ru+5 at most
only bristly at the base, bend near apex rectangular, Ri ends over
the crossvein; fronto-orbital macrocheta absent; eyes of the
male contiguous. C. semiviridis. Mexico. .Chloroprocta V. d. W
ff. With another combination of characters.
g. Body robust, of large size, abdomen elongate, not round; gene
with several ranges of microchetz; vibrissal ridges strongly
convergent; abdomen with well developed macrochete;
costal spine usually absent; eyes of the male widely separated.
h. Peristome broad, pteropleural macrochetz distinct; one or
two sternopleurals; in the female a single orbital macro-
cheta; last abdominal segment without discal macro-
chete; hypopygial processes of the male with a long
stylet; second abdominal segment of the female sometimes
313
Muscide
171, Stigmata of the larve of Muscoidea. Thirdinstar, (a) Cynomyia cadavarina; (b) Phormia regina; (c) Chrysomyia macel-
laria; (d) Musca domestica; (e) Sarcophaga SP; (f) Oestris ovis; (g) Gastrophilus equi; (hk) Sarcophaga sp; (4) Pegomyia
e
vicina; (j) Protocalliphora azurea; (k) Hypoderma lineata; (J) Muscina stabulans. Magnification for f, g, and k, x 25;
all others, x 50.
314 Hominoxious Arthropods
much elongate. A. luteola (fig. 86). Africa. The sub-
genus Cheromyia Roub. is included here. Auchmeromyia B.B.
hh. Peristome narrow; no pteropleurals, two sternopleurals;
two orbitals in the female; second segment not elongate;
the fourth with two well developed discal macrochete.
B. depressa. Africa...............05. Bengalia R. D
gg. With another combination of characters.
h. Costal spine present; body in part black; antenne notice-
ably shorter than the epistome, inserted above the middle
of the eye and separated from each other by a carina;
abdominal segments with marginal macrochete; sterno-
PleGials 22h OF Ut cca ieee ees tee RE Paratricyclea Villen.
hh. Costal spine not distinct, or if present, insect otherwise
different.
i. Genz with several ranges of microchete; vibrissal ridges
strongly converging; peristome broad; arista moderately
plumose; sternopleurals usually 1:1; color entirely
testaceous. C. anthropophaga (fig. 87) and grunbergi.
ATHCAe eia-¢y pee ees te Sea ees Cordylobia Griinb.
ii. Genz bare or with but one range of sete; vibrissal ridges
less converging; peristome narrow; arista long plumose.
j. Genz with a single row of microchete.
k. Sternopleurals 2:1; color entirely testaceous.........
fit GAS PERLE Be Oey BARA ONS Ochromyia Macq.*
kk. Sternopleurals 1:1. P. varia Hough. Africa.......
Seng ko nah ya ae ctNn Rares iC ite Parochromyia Hough
jj. Gene bare.
k. Basal section of Rats bristly only at the immediate
base, distal section with a broad curve; distal
portion of the abdomen metallic; sternopleurals
usually 1:1, rarely 2:1. M. eneiventris Wd. Tropic
ATHOTICA ret a aiinn sess ogee Mesembrinella. G. T.
kk. Rats bristly at least nearly half way to the small
crossvein; sternopleurals 1:1.
1, Macrochetz of the abdomen marginal; neither sex
with orbitals; no carina between the base of the
antenne; three pairs of presutural inner dorso-
centrals. Eastern hemisphere. T. ferruginea.
Tricyclea V. d. W. (= Zonochroa B. B. according
to Villeneuve I914).
Il Abdomen without macrochete; wing usually with
a marginal streak and gray markings. Brazil
i fete tonto ots aah a Won Gna alu aes ae Hemilucilia B. B.
*Plinthomyia Rdi. and Hemigymnochata Corti are related to Ochromyia, though too briefl
described to place in the key. a . ee
Muscoidea 315
eg OS oe oe age
&
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a3
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Oo
Median line
Median line
7%
a3 ot \oF
172, Left hand stigmata of the larvae of muscoidea. Third instar. (a) Lucilia cesar;
(b) Calliphora vomitoria; (c) Stomoxys calcitrans; (d) Pseudopyrellia cornicina;
(e) Pyrellia cadavarina; (f) Lyperosia irritans; (g) Mesembrina mystacea; (h)
Mesembrina meridiana; (i) Myospila meditabunda; (7) Mydea umbana; (k)
Polietes albolineata; (2) Polietes lardaria; (m) Morellia hortorum; (7) Hydrotea
dentipes; 0) Hebecnema umbratica; (p) H. vespertina; (g) Limnophora sep-
temnotata; (r) Muscina stabulans. (@ and b) after MacGregor; (d) after Banks;
all others after Portchinsky. Magnification varies. The relative distance to the
median line is indicated in each figure.
316 Hominoxitous Arthropods
SIPHONAPTERA. Fleas
Adapted from a table published by Oudemans.
a. Elongated fleas, with jointed (articulated) head, with combs (ctenidia) on
head and thorax; with long, oval, free-jointed flagellum of the antenna
(GES O20) oars: seats es aussie wn Ree ioe one Suborder FRACTICIPATA
b. With ctenidia in front of the antennz and on the genz (cheeks); maxille
with acute apices; labial palpi five-segmented, symmetrical; eyes poorly
developed or wanting. On rodents.............. HysTRICHOPSYLLID
c. Abdominal segments without ctenidia.
d. Post-tibial spines in pairs and not in a very close set row; head with
Cteni dia ian ac caccs aeeet hea ee ete a oes Ctenophthalmus Kol.
dd. Post-tibial spines mostly single and in a close set row. Ctenopsyllus
and Leptopsyllus. The last genus has recently been erected for
L. musculi, a widely distributed species occurring on rats and mice.
ce. Abdominal segments with one or more ctenidia; post-tibial spines in
numerous, short, close-set transverse rows on posterior border with
about four spines in each row. H. americana. .Hystrichopsylla Taschenb.
bb. With only two pairs of subfrontal ctenidia; labial palpi five-segmented,
symmetrical; eyes vestigial or wanting. On bats. (=ISCHNOPSYL-
DID) es eye eadin see cle du ee yes OH EE GE eRe aE ME NYCTERIDIPSYLLIDE
With more or less blunt maxilla; all tibie with notch; a single antepygi-
dial bristle; metepimeron without ctenidium. N. crosby: from
Missouri was found on bats. Rothschild suggests that this is probably
the same as N. insignis.
i epeEL OVE eeeNeS (=Ischnopsyllus = Ceratopsyllus), Nycteridiphilus
aa. Head not jointed, ie. the segments coalescent, traces of the segmentation
still being visible in the presence of the vertex tubercle, the falx (sickle-
shaped process), and a suture............ Suborder INTEGRICIPITA
b. Flagellum of the antenne long and oval.
c. Usually elongate fleas, with a free-segmented flagellum of the antenna;
thorax not shorter than the head, longer than the first tergite.
d. Gene of the head and the pronotum with ctenidia....NEOPSYLLIDZ
e. Labial palpi four or five-segmented; symmetrical; hind coxe with
patch of spines inside; row of six spatulate spines on each side in
front of the antenne. C. ornata found on a California mole
Grier a chabert ate tities ga nad genre ave taghs se Sede Sirens BE sheen ANE Corypsylla
ee. Labial palpi two-segmented, transparent, membranous. On
ATES ts se hie cath aetrpan inn ceion ase en oe ES Spilopsyllus Baker
dd. No ctenidium on the head.
e. Pronotum with ctenidium.................... DOLICHOPSYLLIDZ
f. Labial palpi five-segmented, symmetrical.
g. Antepygidial bristles one to three; eyes present.
h. Inner side of hind coxe distally with a comb of minute teeth;
falx present. On rodents and carnivores..............55
Aug seed Gh pe vant oe Ss x4 GPSS Chee eas Odontopsyllus Baker
hh. Inner side of hind coxa without comb or teeth. Many
North American species on rodents..............2+2.-.
Stphonaptera 317
gg. Antepygidial bristles five on each side; eyes absent; suture
white. D. stylosus on rodents........ Dolichopsyllus Baker
ff. Labial palpi four or five-segmented; asymmetrical (membranous
behind), apex acute. Hoplopsyllus anomalus found on Spermo-
philes in Colorado.......... 0.0.0.0... 00 HOPLOpPSYLLIDE
ee. Pronotum without ctenidium. Anomiopsyllus californicus and
nudatus on rodents..............00 0c e eee ANOMIOPSYLLID&
cc. Very short fleas; flagellum of the antenna with pseudo-segments coales-
cent; thorax much shorter than the head and than the first tergite
BER Ge ita NS Rake cate ia Svaccensdonn ayachaarase dvs pcuyast Suis esau bd epdevbonsoonGaud Basal Gees HECTOPSYLLIDA
Flagellum of the antenna with six coalescent pseudo-segments; maxilla
blunt. The chigger on man (fig. 93). D. penetrans................
proton eeeiRunee (=Rhynchoprion = Sarcopsylla) Dermatophilus Guérin
bb. Flagellum short, round, free portion of the first segment shaped like a
mandolin.
c. Thorax not shorter than the head, longer than the first tergite; flagellum
either with free segments or in part with the segments coalescent.
d. Head and pronotum with ctenidium; labial palpi asymmetrical... .
Sioa eh Ca SOW See Bn ete ew ES Ener cae aid Gig aoe NS ARCHZOPSYLLIDE
With four subfrontal, four genal, and one angular ctenidia. Widely
GISTHIDUEER 3 i. atid ae eae eschamaday aeace eee Ctenocephalus Kol.
e. Head rounded in front (fig. 92a). Dog flea.............. C. canis
ee. Head long and flat (fig. 92b). Cat flea...............4.. C. felis
dd. Neither head nor pronotum with ctenidium. Labial palpi asym-
metrical, membranous behind.................. ssn ee PULICIDA
e. Mesosternite narrow, without internal rod-like thickening from the
insertion of the coxe upwards. Human flea, etc...... Pulex L.
ee. Mesosternite broad with a rod-like internal thickening from the
insertion of the coxe upwards (fig. 89). X. (Leemopsylla) cheopis,
Plague Or. Tat Mes: 2 es id cesac aud Raed weahbat’y waded need ndeeo Xenopsylla
cc. Thorax much shorter than the head and than the first tergite. Echi-
dnophagide. E. gallinacea, the hen flea also attacks man (fig. 96).
be di aeons dae i (=Argopsylla = Xestopsylla) Echidnophaga Olliff,
APPENDIX
HYDROCYANIC ACID GAS AGAINST HOUSEHOLD INSECTS
The following directions for fumigating with hydrocyanic acid
gas are taken from Professor Herrick’s circular published by the
Cornell Reading Course:
Hydrocyanic acid gas has been used successfully against house-
hold insects and will probably be used more and more in the future.
It is particularly effective against bed-bugs, and cockroaches, but
because it is such a deadly poison 1t must be used very carefully.
The gas is generated from the salt potassium cyanid, by treating
it with sulfuric acid diluted with water. Potassium cyanid is a
most poisonous substance and the gas emanating from it is also
deadly to most, if not all, forms of animal life. The greatest care
must always be exercised in fumigating houses or rooms in buildings
that are occupied. Before fumigation a house should be vacated.
It is not necessary to move furniture or belongings except brass or
nickel objects, which may be somewhat tarnished, and butter, milk,
and other larder supplies that arelikely to absorb gas. If the nickel
and brass fixtures or objects are carefully covered with blankets
they will usually be sufficiently protected.
There may be danger in fumigating one house in a solid row of
houses if there is a crack in the walls through which the gas may find
its way. It also follows that the fumigation of one room in a house
may endanger the occupants of an adjoining room if the walls be-
tween the two rooms are not perfectly tight. It is necessary to keep
all these points in mind and to do the work deliberately and thought-
fully. The writer has fumigated a large college dormitory of 253
rooms, once a year for several years, without the slightest accident
of any kind. In order to fumigate this building about 340 pounds
of cyanid and the same amount of sulfuric acid were used each time.
In addition to this, the writer has fumigated single rooms and smaller
houses with the gas. In one instance the generating jars were too
small; the liquid boiled over and injured the floors and the rugs.
Such an accident should be avoided by the use of large jars and by
placing old rugs or a quantity of newspapers beneath the jars.
318
The Proportions of Ingredients 319
Tue Proportions or INGREDIENTS
Experiments and experience have shown that the potassium
cyanid should be ninety-eight per cent pure in order to give satis-
factory results. The purchaser should insist on the cyanid being of
at least that purity, and it should be procurable at not more than
forty cents per pound. The crude form of sulfuric acid may be used.
It is a thickish, brown liquid and should not cost more than four or
five cents a pound. Ifa room is made tight, one ounce of cyanid for
every one hundred cubic feet of space has been shown to be sufficient.
It is combined with the acid and water in the following proportions:
Potassium cyanid..............0 00.0000. I ounce
Commercial sulfuric acid .... 2... 002... 1 fluid ounce
AMAL OR oct tnucniea lam pico ueMs bbvee Aten eee 3 fluid otinces
A Srnete Room as an ExamMpiEe
Suppose a room to be 12 by 15 by 8 feet. It will contain
12x 15x 8, or 1440 cubic feet. For convenience the writer always
works on the basis of complete hundreds; in this case he would
work on the basis of 1500 cubic feet, and thus be sure to have enough.
The foregoing room, then, would require 15 ounces of cyanid, 15
ounces of sulfuric acid, and 45 ounces of water. The roomshould
be made as tight as possible by stopping all the larger openings,
such as fireplaces and chimney flues, with old rags or blankets.
Cracks about windows or in other places should be sealed with narrow
strips of newspaper well soaked in water. Strips of newspaper two
or three inches wide that have been thoroughly soaked in water may
be applied quickly and effectively over the cracks around the window
sash and elsewhere. Such strips will stick closely for several hours
and may be easily removed at the conclusion of the work.
While the room is being made tight, the ingredients should be
measured according to the formula already given. The water should
be measured and poured first into a stone jar for holding at least two
gallons. The jar should be placed in the middle of the room, with
an old rug or several newspapers under it in order to protect the floor.
The required amount of sulfuric acid should then be poured
rather slowly into the water. This process must never be reversed;
that is, the acid must never be poured into the jar first. The cyanid
should be weighed and put into a paper bag beside the jar. All hats,
coats, or other articles that will be needed before the work is over
320 Hydrocyanic Acid Gas Against Household Insects
should be removed from the room. When everything is ready the
operator should drop the bag of cyanid gently into the jar, holding
his breath, and should walk quickly out of the room. The steam-
like gas does not rise immediately under these conditions, and ample
time is given for the operator to walk out and shut the door. If
preferred, however, the paper bag may be suspended by a string
passing through a screw eye in the ceiling and then through the key-
hole of the door. In this case the bag may be lowered from the out-
side after the operator has left the room and closed the door.
The writer has most often started the fumigation toward evening
and left it going all night, opening the doors in the morning. The
work can be done, however, at any time during the day and should
extend over a period of five or six hours at least. It is said that bet-
ter results will be obtained in a temperature of 70° F., or above, than
at a lower degree.
At the close of the operation the windows and doors may be opened
from the outside. In the course of two or three hours the gas should
be dissipated enough to allow a person to enter the room without
danger. The odor of the gas is like that of peach kernels and is easily
recognized. The room should not be occupied until the odor has
disappeared.
Fumicating a Larce House
The fumigation of a large house is merely a repetition, in each room
and hall, of the operations already described for a single room. All
the rooms should be made tight, and the proper quantities of water
and sulfuric acid should be measured and poured into jars placed
in each room with the cyanid in bags besides the jars. When all
is ready, the operator should go to the top floor and work downward
because the gas is lighter than air and tends to rise.
PRECAUTIONS
The cyanid should be broken up into small pieces not larger than
small eggs. This can best be done on a cement or brick pavement.
It would be advantageous to wear gloves in order to protect the hands,
although the writer has broken many pounds of cyanid without any
protection on the hands. Wash the hands thoroughly at frequent
intervals in order to remove the cyanid.
The operations ot the work must be carried out according to
directions.
Precautions 321
The work should be done by a calm, thoughtful and careful
person—best by one who has had some experience.
Conspicuous notices of what has been done should be placed on
the doors, and the doors should be locked so that no one can stray
into the rooms.
The gas is lighter than air, therefore one should always begin in the
rooms at the top of the house and work down.
After fumigation is over the contents of the jar should be emptied
into the sewer or some other safe place. The jars should be washed
thoroughly before they are used again.
It must be remembered that cyanid is a deadly poison; but it is
very efficient against household insects, if carefully used, and is not
particularly dangerous when properly handled.
LESIONS PRODUCED BY THE BITE OF THE BLACK-FLY
While this text was in press there came to hand an important paper
presenting a phase of the subject of black fly injury so different from
others heretofore given that we deem it expedient to reproduce here
the author’s summary. The paper was published in The Journal
of Cutaneous Diseases, for November and December, 1914, under the
title of ‘‘A Clinical, Pathological and Experimental Study of the
Lesions Produced by the Bite of the Black Fly’ (Simulium venus-
tum),”’ by Dr. John Hinchman Stokes, of the University of Michigan.
ResumME anp Discussion or EXPERIMENTAL FINDINGS
The principal positive result of the work has been the experimental
reproduction of the lesion produced by the black-fly in characteristic
histological detail by the use of preserved flies. The experimental
lesions not only reproduced the pathological pictures, but followed
a clinical course, which in local symptomatology especially, tallied
closely with that of the bite. This the writer interprets as satis-
factory evidence that the lesion is not produced by any living infec-
tive agent. The experiments performed do not identify the nature
of the toxic agent. " Tentatively they seem to bring out, however,
the following characteristics.
1. The product of alcoholic extraction of flies do not contain
the toxic agent.
2. The toxic agent is not inactivated by alcohol.
3. The toxic agent is not destroyed by drying fixed flies.
4. The toxic agent is not affected by glycerin, but is, if anything,
more active in pastes made from the ground fly and glycerin, than
in the ground flies as such.
322 Lesions Produced by the Bite of the Black-fiy
5. The toxic agent is rendered inactive or destroyed by hydro-
chloric acid in a concentration of 0.25%.
6. The toxic agent is most abundant in the region of the ana-
tomical structures connected with the biting and salivary apparatus
(head and thorax).
7. The toxic agent is not affected by a 0.5 % solution of sodium
bicarbonate.
8. The toxic agent is not affected by exposure to dry heat at
100° C. for two hours.
9. The toxic agent is destroyed or rendered inactive in alkaline
solution by a typical hydrolytic ferment, pancreatin.
to. Incomplete experimental evidence suggests that the activity
of the toxic agent may be heightened by a possible lytic action of
the blood serum of a sensitive individual, and that the sensitive serum
itself may contain the toxic agent in solution.
These results, as far as they go (omitting No. ro), accord with
Langer’s except on the point of alcoholic solubility and the effect
of acids. The actual nature of the toxic agent in the black-fly is
left a matter of speculation.
The following working theories have suggested themselves to
the writer. First, the toxin may be, as Langer believes in the case
of the bee, an alkaloidal base, toxic as such, and neutralized after
injection by antibodies produced for the occasion by the body. In
such a case the view that a partial local fixation of the toxin occurs,
which prevents its immediate diffusion, is acceptable. Through
chemotactic action, special cells capable of breaking up the toxin
into harmless elements are attracted to the scene. Their function
may be, on the other hand, to neutralize directly, not by lysis.
This would explain the réle of the eosinophiles in the black-fly lesion.
If their activities be essential to the destruction or neutralization
of the toxin, one would expect them to be most numerous where
there was least reaction. This would be at the site of a bite in an
immune individual. A point of special interest for further investiga-
tion, would be the study of such a lesion.
Second, it is conceivable that the injected saliva of the fly does
not contain an agent toxic as such. It is possible, that like many
foreign proteins, it only becomes toxic when broken down. The
completeness and rapidity of the breaking down depends on the
number of eosinophiles present. In such a case immunity should
again be marked by intense eosinophilia.
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Lesions
Produced by the Bite of the Black-fly 323
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324 Lesions Produced by the Bite of the Black-fly
Third, lytic agents in the blood serum may play the chief rédle
in the liberation of the toxic agent from its non-toxic combination.
An immune individual would then be one whose immunity was not
the positive one of antibody formation, but the negative immunity
of failure to metabolize. An immune lesion in such a case might
be conceived as presenting no eosinophilia, since no toxin is liberated.
If the liberation of the toxin is dependent upon lytic agents present
in the serum rather than in any cellular elements, a rational explana-
tion would be available for the apparent results (subject to con-
firmation) of the experiment with sensitive and immune sera. In
this experiment it will be recalled that the sensitive serum seemed to
bring out the toxicity of the ground flies, and the serum itself seemed
even to contain some of the dissolved or liberated toxin. The
slowness with which a lesion develops in the case of the black-fly
bite supports the view of the initial lack of toxicity of the injected
material. The entire absence of early subjective symptoms, such
as pain, burning, etc., is further evidence for this view. It would
appear as if no reaction occurred until lysis of an originally non-
toxic substance had begun. Regarding the toxin itself as the chemo-
tactic agent which attracts eosinophiles, its liberation in the lytic
process and diffusion through the blood stream attracts the cells
in question to the point at which it is being liberated. Arriving
upon the scene, these cells assist in its neutralization.
The last view presented is the one to which the author inclines
as the one which most adequately explains the phenomena.
A fourth view is that the initial injection of a foreign protein by
the fly (1.e., with the first bite) sensitizes the body to that protein.
Its subsequent injection at any point in the skin gives rise to a
local expression of systematic sensitization. Such local sensitization
reactions have been described by Arthus and Breton, by Ham-
burger and Pollack and by Cowie. The description of such a lesion
given by the first named authors, in the rabbit, however, does not
suggest, histopathologically at least, a strong resemblance to that
of the black-fly. Such an explanation of many insect urticarie
deserves further investigation, however, and may align them under
cutaneous expressions of anaphylaxis to a foreign protein injected
by the insect. Depending on the chemical nature of the protein
injected, a specific chemotactic reaction like eosinophilia may or
may not occur. Viewed in this light the development of immunity
to insect bites assumes a place in the larger problem of anaphylaxis.
Lesions Produced by the Bite of the Black-fly 325
174. Experimental lesion produced from alcohol-fixed flies, dried and ground into a
paste with glycerin.
326 Lesions Produced by the Bite of the Black-fly
SUMMARY
In order to bring the results of the foregoing studies together,
the author appends the following résumé of the clinical data pre-
sented in the first paper.
The black-fly, Simuléum venustum, inflicts a painless bite, with
ecchymosis and hemorrhage at the site of puncture. A papulo-
vesicular lesion upon an urticarial base slowly develops, the full
course of the lesion occupying several days to several weeks. Marked
differences in individual reaction occur, but the typical course in-
volves four stages. These are, in chronological order, the papular
stage, the vesicular or pseudovesicular, the mature vesico-papular or
weeping papular stage and the stage of involution terminating in a
scar. The papule develops in from 3 to 24 hours. The early pseudo-
vesicle develops in 24 to 48 hours. The mature vesico-papular lesion
develops by the third to fifth day and may last from a few days to
three weeks. Involution is marked by cessation of oozing, subsidence
of the papule and scar-like changes at the site of the lesion. The
symptoms accompanying this cycle consist of severe localized or
diffused pruritus, with some heat and burning in the earlier stages
if the cedema is marked. The pruritus appears with the pseudo-
vesicular stage and exhibits extraordinary persistence and a marked
tendency to periodic spontaneous exacerbation. The flies tend to
group their bites and confluence of the developing lesions in such
cases may result in extensive oedema with the formation of oozing
and crusted plaques. A special tendency on the part of the flies
to attack the skin about the cheeks, eyes and the neck along the
hair line and behind the ears, is noted. In these sites inflammation
and oedema may be extreme.
A distinctive satellite adeonpathy of the cervical glands develops
in the majority of susceptible persons within 48 hours after being
bitten in the typical sites. This adenopathy is marked, discrete
and painful, the glands often exquisitely tender on pressure. It
subsides without suppuration.
Immunity may be developed to all except the earliest manifesta-
tions, by repeated exposures. Such an immunity in natives of an
infested locality is usually highly developed. There are also ap-
parently seasonal variations in the virulence of the fly and variations
in the reaction of the same individual to different bites.
Constitutional effects were not observed but have been reported.
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Culex pipiens. ... 00.06 ce eee 35, 98
Culex quinquefasciatus.......... 180
Culex sollicitans................ 200
Culex territans................. 101
Culicides 2. gcse psoas sees asad 33, 97
Cats sieve das. d cet ees Chae aged 34
Culicoides scssi vase we cabs 109, 288
CYyClopsies bvaneseegegeusce 183, 257
Cynomyia.................. 136, 311
Dance, St. Vitus ............... 8
Dancing mania................ 8
Meer fies: aie aes sce Get cal ee en a 5 IIo
Definitive host................. 192
Demodecide .................. 78
Demo ext 0.0 cis Se cr Reds Miles wren 259
Demodex folliculorum.......... 78
Dermacentor .................. 262
Dermacentor andersoni....... 67, 228
Dermacentor occidentalis........ 227
Dermacentor variabilis.......... 67
Dermacentor venustus........ 24, 228
Dermanysside ................ 68
Dermanyssus ................. 266
Dermanyssus galline........... 68
Dermatitis..........0.00.. 72, 77, 85
Dermatobia................ II5, 298
Dermatobia cyaniventris........ 163
Dermatophilus................. 317
Dermatophilus penetrans...... 60, 126
Index
Diamphidia simplex............ 55
Dimorphismt a.0-¢0-6 sce avaces 65
Direct inoculators.............. 4
Diplopoda..............00.. 25, 257
Dipterancndi. emcee cusses 33, 94, 274
Dipterous Larve............... 135
Dipylidium................. 175, 221
Dipylidium canium........ 4, 175-176
DOS! NEB eidiccs caro watounssonots 172
Dracunculust ca vegeu.ecwaracenee ds 257
Dracunculus medinensis......... 182
Drosophila .................... 296
Dum-dum fever................ 220
TOV SOMCCEY secters arcercrve Seed criatient cian 154
Har-Mes! olives gusateueene eset 110
RAR WAGE ase ceicecciansisydce SceoanePareue recesses 177
Echidnophaga ................. 317
Echinorynchus................. 185
Elephantiasis .............. 178-179
Empoasca mali................ 33
FMIpretiay s jc.032-saceastaukes Mwaaeon 46
English Plague Commission...... 171
Epeira diadema................ 18
PUDIZOOUC® centre: gto mine agrann aA 170
Hristalis! . ois vecpadeyecdenc 137, 295
Essential hosts................ 4, 165
PUTTS Cal ss sac: a Susieucr i euateadeeedt busi 307
European Relapsing Fever....... 233
Euproctis chrysorrhoea.......... 48
BusimuUliwmM oagars ae Pana dene ee 286
Facultative parasites........... 131
Fannia............ 136, 138, 145, 300
Federal Health Service.......... 169
Fever, lenticular ............... 237
African Relapsing......... 230, 234
Carrion Sicc2ineceemr eased oes 253
tim Gu4 ae snes coe cpanacsacnawe 154
European Relapsing.......... 233
PAPPAliCl ee gerass eon doing 96
fed, Wateties sey nieiawddue eset 220
Rocky Mt. Spotted........... 226
three day 0 eee siisentccwiges acted 96
Tey PHUS oe ascaicuntina eter ngns 237
Bilaria®. eco vie aes em eta 178, 221
MWMMIS oo ned Reade Sa eeee tow 182
PUAMASIS: valiccadsaciainaia uae eens 178
343
Flannel-moth larve............. 44
TRL CA Sis os iectatyes dish davies us eutin 11g, 166, 213
| a er ee ee are ee ee 172
OP ice niacartinaenatden etme gee a 172
AumMan-sevanes dees ves ees 172, 176
TOGENE 6.5 diuse Yeieca Sakae ogs 123, 172
TAU cdc Aisha & pA eaeebaee Toil 171
HIGSOPC haa ny camiencucmgadeccn 125
Formaldehyde ................. 91
FOmitess« 2a saccrudenes axes 199, 204
Fulgoride ........-...00 0c cues 28
Fumigation ................... 320
Gaiiiasid: sew penance ananimnancninn 68
Gangrene vornvexnnayrsankes gens 129
Gastrophilus ............... 113, 297
Giant crab spiders.............. 13
Giant water bugs............... 30
Gigantorhynchus............... 185
Glossitiais sit cag-atintose atte 117, 297, 303
Glossina morsitans.......... 214, 217
Palpaliss .sne seis dia sie 215, 217, 218
Glyciphagus ...............00. 267
GPAID TIO seo seccs sea awe a wma 69
Grocer’sitch............0..00-5 72
Guinea-worm ................. 182
Habronema musce.......... 156, 183
Hematobia ................ 166, 304.
JTTANS acne aciwaaeeer ne 146
Hematobosca ..............44.. 304.
Hematomyidium .............. 288
Hematopinus spinulosus........ 213
Hematopota ...............0.. 2904
Hematosiphon ................ 279
Hemoglobinuria ............... 220
FA BMOZOM! soci aha bese earners Were 189
Harpactorescccss ha veseamrseoey 284
Harvest mites................. 60
ELC CHNON sci seseccetdatagt dudisnersenecnne’ 59
Head-louse ................... 173
Helminthiasis,..2ccscccseawerax ge 138
Helophilus..; 5:10 cence ws anres ees 205
Hemiptera........... 27, 86, 273-275
Heteropodide ................. 13
Heuchis sanguinea.............. 55
Hexapod larve...............4. 58
344
Hippelates: 2 cde th ieee dees 297
HippobOsean. io eaas cen eeares 285
FNStiOgaSter sac ccinge dere neee s 269
spermaticus ...secc.seaeeey or 132
Homalomyia........... 136, 138, 300
HIGH ey: DEC i ise igceratieivn cain Pca wun ee 36
POSOM OF a 3.03 css eee ee ee Sones By
Hornets puns gic cine donee acing 43
Hornty vac csas eae hes 137, 304, 308
FROPseehly ys cc aah hed eve ae hie 110, 165
House-fly.......... 137-139, 144, 183
control of................ 156, 160
Human flea: eciong Aecawe'een Uhre 124
Host, definitive................ 175
intermediate................. 175
PRIMAL a 445 Sates apa panels 175
Hyalomma ................... 264
Sey pticuM < 24.448 vee shee 224-225
Hydrocyanic Acid Gas.......... 318
FAVA Ota cic Ses dis Galag Gk vende 300
Hymenolepis diminuta.......... 176
Hymenoptera................ 36, 275
Fy podérma. opus senna ences 113, 298
Giana: wseadin se sak ys wee ees 113
lineata. ey.c eases goeoue say ees 113
Hypopharynx ................. 80
Immunity from stings........... 39
Incomplete metamorphosis...... 80
Infantile paralysis........... 162,241
SPIGNIC. dagen nonetaaneuahea neved 220
Direct inoculation............ 164
THSCCUS! «ci: ocene ew gurpceaeien te 258
blood-sucking................ 170
Intermediate host........... 192, 203
Intestinal infestation........ 112, 133
AN ASS! C555, s0hoi Sakeeazoe Gull a79 cial Be 137
TSOSOIMa: Ga deys aes yee td tees 69
Tt@hin 22 bv Secebe cee tate coeds 73-74
MAGEE eens van ete ees eee 73
Norwegian <: 2445 vsceopacnsas 77
EROUES:. Stsel wut boc huh pankiea artes ae 260
HICHMUS es ada adewenerniren 66, 225
SCAPUUATIS os. 5. ccacccces wean eeues 66
Ixodidae s.. j.tuvenwivesa vax wes ey 64-65
TFxodoidea' s.cs see vey paw ve coed 62
Janthinosoma lutzi............. 116
Index
Jigeer «sane hxteui ie sess eee ae 60
Johannseniella ............. 110, 288
Journal of Tropical Medicine and
TAY S1ENG. oe creas eye 36
Julus terrestris ................ 25
June DUP so s62 os dese garer ene eA 185
Kalacazat ics anccacsienncianuns 220
Kara, kurtes..¢0.66c¢0u: epee: 14
Katipo’ sacpcesgece we eyed ewes: 14
Kong AVES Asda c ae vedun se eee 3
Kircher, Athanasius ........... 1, 8
Kissin g-bug ccc carcn Gace Somes 31
Labia 20.4 can Ge Scan vege Be 29, 80
Ta DROI 2 2 titan cts higdg ole Pees 28, 80
Lachnosterna ................. 185
LBLADS a sas. sicd days pict is Des ees Re 266
Loemopsylla, 2. se:2: e404 68 eats 172
Lagoa crispata................. 45
Lamblia intestinalis............ 154
Langer, Josef..-............... 37
Larder beetles... .2..c ces en oes 135
Latrodectus.............-. 12, 14, 17
MACTANS sesso saad die bacg dno 15
Leishmanioses ................. 220
Lenticular fever................ 237
Lepidoptera ................... 274
Lepidopterous larve............ 134
LeprOSyi2y eye dace ee hed Ree Se 252
Weep tides cc2 nt cnn sake seusieed punts 112
Opus a Noten or aetewiekonss ead ae 295
LEptSs. cr engcdnte aaaraeees 60, 273
DICE. lishiey Aces oe Bese Obs ews 80
Linguatulina .................. 258
LApOnySSts. ici ccs paced nen ada es 265
Lone star tick.................. 228
Louse, body...............005. 84
CLAD is Sincere nade bog Bs 4 ee 85
OR stem hse ay ves Ne area eces Bie 176
TGA 3 oor cee aieuse tetas whine 82
PUBIC pity seseu es keen gedhonsa 85
Loemopsylla................ 172, 317
Wuctliais «ostev as a dare Pe eed 136, 312
Lycosa tarantula............... 10
LY COSIVE oc ikea eaalageanes's 10
IL YCtOCOHS 106 29 ac Ged Beas ee e 279
Lygus pratensis................ 33
Index
Lymphangitis........... ...... 67
Lymph scrotum................ 178
LAV PETOSIA sis 4c deasesi ace tease aosateer ar 304
Lyperosiops ................05. 305
Macloskie: jigccrgadeaislasonses 34
Maggots, rat-tail............... 137
Magnes sive de Arte Magnetica.. 8
INV ANA TTS «aca adotsascie deus tend grb iha connate’ 186
Malmigniatté: 2. c0sc0 cence wines I4
Man GIblES! . wnsotiarnrtiisa wat tacue a 28, 80
Mange nucss sxcccteeene sedans 73-75
Margaropus ................. 237, 264
ANNUAUS 5 advances paar eaaaees 223
Masked bed-bug hunter......... 32
Mastigoproctus giganteus...... 19, 80
Miaxillae:. inn rs eee aeins wierd Seas: 28
Meal infesting species........... 135
Melanin granules............... 189
Melanolestes .................. 280
PICIPES” wis cusigin cde gees eee 32
Meénazvodies win aurae tenn sayin 14
Mercurialis: 20... cece cae I
Merozoites ............. 00.000 190
Metamorphosis ................ 80
MEARE DUe ies oncartbiannn cenonae 63
Microgametoblast ............. 192
Mad g6S ser cgchewencdea aks okee es 107
Migratory ookinete............. 192
MAlliped esi. ouicacninndeaardenae 25, 257
IMGCES ere pee are ganas hens 23, 58
Monteziellan cic cena, eeadeee ates 269
Mosquitoes....... 33,97, 178, 196, 250
treatment for bites of... .34, 36, 102
INGISCA 2.25 aia Ha dtuudandrane d msies 137, 307
domestica... .139, 145, 146, 157, 162
MS C1GES isch Si erciites Qurtee, tae same ears 117
Muscina wes canst waceiy nies 137, 146, 307
stabulans: x05. .qsaveerereawey « 140
Miuttralismy, ... gcd ak don na cea tiene 57
INIVASISS Jeicce sia cae AS eee 112, 135
intestinal ................ 135-140
Nasal oss ve wlainp rine media clindines 141
Mycterotypus ................. 287
Myospilay oo cais ancient 146, 307
Myriapoda ............. 25, 132, 257
INagand, socvuinrceernenene 165, 214
345
Nasal infestation............ 114, 133
IN GGHODIA: orci ekerdiahe semras Reyna eam 135
Nematode parasite............. 182
NCB Ee cstdwanecind ponies wieehee vi cceotacente 28
Nephrophages sanguinarius...... 132
Nettling insects................ 43
larve, poison of.............. 53
Neurasthenia: #2...cc00 ocj¢caved 89
INESS asacdisscaet: fein uae audhakaiue Seancarsen inane ns 86
North African Relapsing Fever.. 234
Norwegian itch................ 77
INO-S€e-UMS: xs Grek ewuleemnanes 109
Noteedres . 255 os. ccaasesenesees 269
CBU, satis capilde Bavavucbestitareiduebenlee Beee 78
Notonecta.. ccsinccaraccenes 28,277
NGtOneCtide v0 ccsdacai cedar ws 30
Nott; Dr. Josiah wiicnessve neuen 2
Nuttall. suaceyeraseestrewvawes 34
Occipital headaches............. 138
ORCACE: ccatynenaricamauagen ee 288
QeCiA CUS gnciy-seue rena ceokstie-aele 279
(Esophageal diverticula......... 35
Oestride .c.5 csc oeer tues 112, 136
OESCHIS! OVAS oso eece-avemtnsceos lod erded tobe 113
OESCROS 5c qcragertiernd sue aeulgneias 298
OOCYS bi je ari cicseeatie. cs ce eat ed vn pictns hein 192
OOKINEEE: ge aucaeetig sneer 192
Opsicoetes personatus........... 32
Opthalitia: os .ccseien a eke soos 155
TOM OSA as soil aescn sass dc doles Grareeh Ga ernetr’ 52
Orental ste .acarescnmeawiaaada 221
Ornithodoros .............06. 65, 260
MOUDAtAy acinus be uliekrome 220, 230
Orthotylus flavosparsus......... 33
OPEN ONIV IE. 5 secs} eies ue gow bose 286
OTOV Ey ccc gun hae demdunmicteatal ind 253
OSCIMUS!” 2¢d.i8-Gin dhe aeeietn hee aes 207
OuUodIUS: sory eedns ginee medians 259
MEPCNIN: si sewaneaee aeeee ders 65
Otodectes ...........02.00-0008 271
PATRON carci astrmie manner aabiaen ae 294
Pappatic fevers: camscianesiaawe 96
Parasimulium: sy2g,0ndareeed ews 286
Parasite .......... 3, 57, 131, 134, 182
ACCP EH BAL. cde cen mee 3, 131, 134
facultative.............. 3, 57, 131
346
Parasite, nematode............. 182
StalONALy cocina sander ness 57
temporary ..... ee cee eee eee 57
THUG s ind ak Qe Rad Reps Mesa BEE BA 3
Parasitism, accidental........... 134
Pathogenic bacteria............ 152
OTQANISMS 6 eee sae eres 144, 164
Pawlowsky .............ee eee 81
Pediculoides .............2000- 267
ventricosuS .2.........00005 69, 72
POdICUIOSIS! 05 4c sy piearece ees ed a are 81
Pediculus:». cine. der oresarn owes s 275
COPPOMS 2s aos ven irene se 84, 233, 238
humans: 4 vases seme wee eed 82,173
Pellaera: vay spor i saeds cat ea ea 162, 246
Pernicious fever................ 186
PGSE i Sc.adcnns wicca Paredes 2 166
Phidippus audax............... 19
Philematomyia ............... 306
PhisahixX! iiss diets agra sees 13, 43
Phlebotomus .................- 289
PAapatasi ascccccnoy hes seer. 94
verrucarum ..............004 254
VEXBtOL is ccs cide sue St Kenai eC 95
Phorat sss sevins vexog sa haee sey 295
Phormiar. ia. eue deca ah Sins Sita 136
Phormictopus carcerides........ 13
Phthirus pubis............... 85, 275
PROPtHCA sed costes ao oe Ae a eae 296
Pieris brassice................. 56
Piophila. vei sndeveaeeeee anes es 207
Piophila casei.............. 136, 137
Piroplasmosis ...............-. 222
PIAGUE: . acnic cine tmagegios ee woe 166
bubonic.......... ... 166, 169, 170
PNEWMONIC .chexeueesdas cannes 167
Plasmodium 5 oa: socades ann ih ses 186
Platymetopius acutus........... 33
Plica palonica...............04% 83
PHEUMONIG saan gewsaytenis aan 166
PlACUESs as anesidmie sn vende 167, 173
Poisoning by nettling larve...... 53
Poison of spiders............... 7
Pollehiacis\2. sah asaea re ae reese 308
TUCISs wide tea ae wae 146, 147
primary gland................. 28
Prionurus citrinus.............. 20
Prosimulium .................. 286
Index
Protocalliphora ............ 136, 312
Protozoan blood parasite........ 165
Pseudo-tubercular ............. 52
PSOFOPHOTA paces e cede arene: waceos = 293.
PSOrOpteS: siisiee ws cae awrres eae 270
Psychodidae. on aii siess 22 erie eee 94.
Pulexs vocca sakes 120, 124, 126, 172, 317
CHEGPIS! Mac sd Medohes od Re en 172
TITANS 2a Shae onede wed baal 124.
penetrans .............02 eee 126
SerraticepS ..i0cavaresedeseas 120
Pialvalls oo iaiiisrater gc.g ce a nae wee 150
PUK 6S 3g cceot. sh 4k SRS pede BEBE 109
PYCNOSOMA: cs wavid asain eaves 308
Rasahus cc eacd-nocee esse ese ae 280
THOPACICUS 26a eee ee es 32
Rat Meassis wcasae aeons 120, 124, 171
Rat. 1OUSC sai s2 gsc ia ony ee erece oe ge 213
Red bugs sicicsteeasereravas e 70-72
Reéduvitde: oc ance cu egasiames as 31
Reduviolus ..............0000. 280
RedUViUS << node ceeceeuneae ae 282
PETSONATUS 24.0 dds wren gwrnee es 32
Redwater fever................ 220
Relapsing fever............. 230, 233
Rhineestrus nasalis............. 115
Rhipicentor ..............000.. 264.
Rhipicephalus ................. 264.
Rhizoglyphus a. ossces se 2 oe eh e945 269
Rhodnius 244s cdaseaw ee ss « 280
Rocky Mountain Spotted Fever.. 226.
spotted fever tick............ 67
Russian gad-fly................ 115,
St. Vitus’s or St. John’s dance.... 8
Salivary syringe................ 28.
Sand-flies «00.02 s06 94 ace x 109, 250:
Sanguinetti........ Gry wales Seas) EE
Sarcophaga............ 136, 142, 143.
Sarcophila ...........0...00005 302
Sarcopsylla ................04, 317
PENETANS 622 esas civ oma deca 126
Sarcoptes ......... 0.0 cee eae 270:
TIMOR srr wen oe een cody 33x oe eh 78
SCAbIE! e-nes Sh gauvien tsavaglon wah 73.
Sarcoptide ............000000e 72
NCADIES ie. ¢ getcet aaah dots 72, 73: 74) 75
Index
Scaurus striatus................ 177
Schatidinn 5s ciagee saat Saweawarund, Ud
SCHIZONG oem scsercariw wna werent 189, 190
SCHOKCIASIS! i wcsiwis eure a waish's susenlis ¢ 134
Scolopendra morsitans.......... 26
Scorpions ...........00 02 ee eee 20
POISOHMOL 6 nc eannaiw nuke gore 21
Screw worm fly................ 140
DEPSIdAs oie years sale aautiee Bente 296
SOPSIS ne siaaeyeyeereeeeewk 136, 297
OHI EY cicada ssn eaten erated onus 34
DIDINE a annkag ca renad aeaese mes 46
Silvius: 2oecowanseksnhdw ce thaeed 294
Simple carriers............... 4, 144
Simuludees cuss sex es caaiseews 33, 104
Simulium.......... 247, 249, 286, 321
PICEIPES: aiinve auacsarssuveele a poree wumtlont 104
Siphonaptera........... 119, 274, 316
Siphunculata................ 80, 275
Sitotroga cerealella............... 69
SKIPPOES sere 5 ahaesd caase Seite ever 137
Sleeping sickness............ 166, 215
Snipe-flies ...............0000. 112
SOlpugida a: sieaes garage oesey gna’ 22
Spanish fly, c..0.sese22 Has yesios 54
SPETMAatozod was e..cavagweeesias 192
Spinose ear-tick................ 65
DSPIPOCh Eta: sus sieswaiay se ukae tildes 35
berbert: as axaae rus vane ve ese ® 234
UCEONE i scsste ew din cdiaiee tise: Swine 234
Spirochetosis ................. 235
Sporozoite ............. eee 189
Spotted fever................ 67, 226
Squirrel flea................... 123
Stable-fly.......... 137, 160, 163, 165
Stegomyia................. 182, 293
CAlOPUS win isossununalncvananascnels 206
fasciatay ons: as wkomieeaens “22. 206
StOMOKYV Suis is cides sinned se dined 137, 305
calcitrans 117, 146, 160, 161, 165, 242
Straw WORM) sym wanes Vea eesuas 69
SEY RETOMYIA. asin ce eed eee ewan © 305
Sucking stomach............... 35
Sulphur ointment.......... ewe, “FF
Sutra: z..d.54 oseeeaeeepnie ees ed 2 165
SVIMDIOSIS® yicecnan may dew vcames 57
Symphoromyia............. 112, 295
347
Tabanide: v2eccewsavarsiwes ses 110
TRADARUS) op.cce ecscandsoe gains II0, 166, 294
STRAUS csc cna swiaetavinid os 165
ARGON iis serclan's evalu entiiers argh Sard 175
Tapeworm. :scciancaveuevcxues 4, 176
TAT ANCE A: yds sions given cilendy as Bs 8
PPATATUISID aciacra caida arden eaniie indus 8
Tarantula. saccades + naienwne sas 10
Tarsonemide ..............005 69
TarsOneMUS yeu cewrscren genes se 267
Tenebrionid beetles............. 127
Tersesthes .............-4--- 110, 288
REAUS! « oieaga an scaner names en 129
NetranyChus eeu. enue sass yee oe 273
Texas fevers: css¢aecaeas vax 220-223
Three-day fever............-... 96
TEACH ss cost exgieduest dgusstlavbusnaien aonb t 23, 226
bites, Treatment of........... 68
LEVER a cichicsount enon ate ape merece ah 230
Paralysis: vd ecwmomie sevilaee 67
Treatment,
BG Sti gS aces aici s sie ns RAMS 36, 41
Bites of,
Bed-bugs ................ 90, 93
Blackflies | 5 csaiineccis vematan 107
Buitalo: fies..s22¢% guseees we 107
Bugs: caecaceriactadrerdss S133
Centipedes............... 26, 27
CHIGB ETS, oo pies eodicien « mimaed aes 127
CHIGGES! ss incaeedaad ome ate 127
PICA viratsitis maecn ig quan gre venta 127
Harvest mites............. 61
JISBELS nse ae cena oe ea 129
TEGO. case tutcoses tance sto secure 83, 85
Mosquitoes........... 34, 36, 102
Phlebotomus flies...... Sane OF
Sand flies........... 96, 107, 109
Scorpions .s6+6e0e¢sawees 22, 23
Spiders ig cia ios de eotaw eas 19
ATT GIES — pat ca icthrndBusrirdas ose 61, 68, 72
TICKS CAPs sedi cuaeta cain a suet 65
Blister beetle poison.......... 55
Brown-tail moth rash......... 45
Cantharidin poison........... 55
Caterpillar rash.............. 45
Har ticks sg. csnasa aed eden duaneudattaans 65
House fly control.......... 156, 160
Dt Che 2 wis sere veos ea pinaahs sya es 77
348
Itchy ‘grocer'si ws sa2% urs aurea 72
TICES 4 dss Gis ae barn ee cee 85
Nasal myasis................ 143
Rocky Mt. spotted fever. ..228, 229
Rash, caterpillar............. 45
SCABIES oda cee cd tea eeeeed aes 77:
Sleeping sickness control...... 218
Spotted fever............. 228, 229
Stn GS; DEE) seine.) Slerigee en 36, 41
Typhus fever, prophylaxis. .... 239
Trichodectes canis.............. 176
MPIC Oma ics 4le fea dene 4 a Aor Gland 82
"EMMGUPa, \x.0.5 x9 aaa eaew ae Ee 295
Trochosa singoriensis............. II
Trombidium), : 2544.50 iedes os 60, 273
True insects. 6.6. c.c cece bs ves 80
TIYPANOSOMA. 1. iocenedi na eesaens 35
Trypanosoma, brucei........... 165
Trypanosoma cruzi............. 219
Trypanosoma lewisi............ 213
Trypanosomiases............... 212
Trypanosomiasis ........... 165, 219
Testse flies......... 117, 166, 214, 219
Tsetse flies disease.............. 165
Tuberculosis... 0.000 60023 40.0 0es 155
EOMID URRY yc psser'e we ies dee kee aa 118
TYMSUS) os eee ge eadec gigs wba ac new ale 271
Index
Typhoid fever................. 154
Typhus: 2 ccgez ive eos Sa eee oe 237
Typhus fever.................-- 237
Tyroglyphus............ 72, 131, 268
Drs TY 22ers acniy nook aeaieet ana 49
Uranotenia 2 ices asus sss sone 292
VanGoho + iad nci acer drgae eee ee 14
Varicose groin glands........... 178
Verruga peruviana............. 253
Vescicating insects............. 54
Wanzenspritze ................ 29
Warblé-fies:. cincguige-newee ered: 112
IWASDS) States ects Cickcsaneat Skene 43
Whip-scorpions ..............4. 19
Wohlfahrtia................ 143, 302
Wolf-spiders:. » 54 42+s4% 28 wees ees 10
Wyeomyia smithii......... IOI, 293
Xenopsylla ................ 172, 317
Xenopsylla cheopis......... 171, 124
Xestopsylla ............. 0000 ee 317
NAWS" 2 Sista euobhGt Gs cima tinanhnn an 2
Yellow fever .......... 196, 203, 205
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