SB llfl b?2 
 
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EXCHANGE 
 
 BIOLOGY 
 
 LIBRARY 
 
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Ar 
 
 BRITISH MUSEUM (NATURAL HISTORY) 
 
 SPECIAL GUIDE N6; ?: 
 
 GUIDE TO THE SPECIMENS 
 AND ENLARGED MODELS OF 
 
 INSECTS 
 
 AND TICKS EXHIBITED IN THE 
 
 CENTRAL HALL 
 
 ILLUSTRATING THEIR IMPORTANCE 
 IN THE SPREAD OF 
 
 DISEASE 
 
 LONDON 
 
 PRINTED BY ORDER OF THE TRUSTEES 
 OF THE BRITISH MUSEUM 
 
 1916 
 
 ("PRICE SIXPENCE] 
 

 l)c 
 
 
 THE BRITISH MUSEUM. 
 
RITISH MUSEUM (NATURAL HISTORY) 
 
 SPECIAL GUIDE No. 7 
 
 (iLJIDE TO THE SPEC ij;?^ 
 AM) EXLARGED MODELS OF 
 
 INSECTS 
 
 VXD TICKS EXHIBITED IN THE 
 
 CENTRAL HALL 
 
 ILLUSTRATING THEIR IMPORTANCE 
 IX THE SPREAD OF 
 
 DISEASE 
 
 LONDON 
 
 PRINTED BY ORDER OF THE TRUSTEES 
 
 OF THE BRITISH MUSEUM 
 
 1916 
 
 (A/I rights reserved) 
 
I'l 
 
 BIOLOGY 
 
 LIBRARY 
 
 G 
 
 rill.NTKD liV \VIL1.IAM CI,ii\\KS AM' SONS, I.IMITKI>, 
 iKEET, STAMFUKD STKEET, S.E., AND GREAT WINDMILL 
 
 EXCHANGE 
 

 PREFACE. 
 
 THE method of explaining to visitors the general appearance and 
 the details of the external features of insects by means of models 
 on a large scale, rather than by the more customary drawings, 
 was first adopted by Sir E. Kay Lankester, Director of the 
 Museum, in the year 1900. The earliest models were those of two 
 mosquitoes and a tsetse-fly. After Sir Ray Lankester's retirement 
 in December 1907, the method was followed up by the preparation 
 of a model of a flea (presented by the Entomological Eesearch 
 Committee) ; more recently, models of a house-fly and a tick 
 have been added. During the present year the series of disease- 
 spreading insects and ticks has been further increased by placing 
 on view a collection of specimens and models of tsetse-flies, 
 tabanid flies, mosquitoes and ticks ; this collection was prepared, 
 on behalf of the Exhibitions Branch of the Board of Trade, in 
 1913, under the direction of Mr. E. E. Austen, Assistant in the 
 Department of Entomology, and was shown in the " Tropical 
 Diseases " Section of the International Exhibition at Ghent in 
 the summer of that year. The models have been kindly lent to 
 the Museum by the Board. 
 
 Only those insects and ticks that are of importance in the 
 spread of disease have been selected for exhibition in the middle 
 of the Central Hall ; the general series of insects and ticks is 
 to be found in the Arthropod Gallery; in the West Wing of the 
 Museum ; the collection of insects injurious to crops is exhibited 
 in the North Hall. 
 
 The large models shown in the Hall were constructed 
 under the supervision of expert entomologists by Mrs. E. D. 
 Blackman and Miss Grace Edwards, and so far as is possible 
 they are correct in the smallest details. 
 
 The present guide-book is to a large extent a compilation, made 
 by Dr. W. G. Eidewood, of the exhibited labels that accompany 
 the insects and the models. 
 
 The acknowledgments of the Trustees are due to Drs. Castellani 
 and Chalmers for permission to use the figures of the house-fly, 
 bed-bug and tick given in their Manual of Tropical Medicine. 
 
 L. FLETCHER, 
 
 Director. 
 
 BRITISH MUSEUM (NATURAL HISTOBY), 
 December, 1915. 
 
 941397 
 
TABLE OF CONTENTS. 
 
 FAGK 
 
 INTRODUCTION ........ 7 
 
 MOSQUITOES AND MALARIA ...... 8 
 
 MOSQUITOES AND YELLOW FEVER ..... 18 
 
 MOSQUITOES AND FILARIASIS ...... 20 
 
 FISHES THAT FEED UPON THE LARVAE OF MOSQUITOES . 21 
 
 TSETSE-FLIES AND TRYPANOSOMIASIS .... 22 
 
 TABANID FLIES AND " CALABAR SWELLINGS " . . .26 
 
 HOUSE-FLIES AND INTESTINAL DISEASES .... 27 
 
 SHEEP BOT-FLY 31 
 
 FLEAS AND PLAGUE ....... 32 
 
 BED-BUGS AND DISEASE ...... 37 
 
 LICE AND DISEASE ....... 38 
 
 TICKS AND DISEASE 40 
 
LIST OF ILLUSTRATIONS. 
 
 FIG. PAGE 
 
 1. Organisms of Malaria . . . . . .11 
 
 2. Resting Attitudes of Anopheline and Culicine Mosquitoes 13 
 
 3. A Mosquito, Anopheles maculipennis ; Carrier of Malaria 15 
 
 4. A Mosquito, Stcyomyia fasciata ; Carrier of Yellow Fever 19 
 
 5. Organisms of Sleeping Sickness .... 23 
 
 6. A Tsetse-Fly, Glossina palpalis ; Carrier of Sleeping 
 
 Sickness ........ 25 
 
 7. Organisms of Typhoid Fever ..... 28 
 
 8.- House-Fly, Mitsca domcstica ; Carrier of Various 
 
 Intestinal Diseases ...... 29 
 
 9. A Eat-Flea, Xenopsylla clicopis ; Carrier of Plague . 33 
 
 10. Organisms of Plague ...... 34 
 
 11. Bed-Butf, Clinocariv Icctuluruix .... 37 
 
 12. Clothes-Louse, Pcdicidna humanus ; Carrier of Typhus 
 
 Fever .39 
 
 13. Organisms of Relapsing Fever . . . . .41 
 
 14. A Tick, Orniihodoros mnnlmtii ; Gamer of African 
 
 Relapsing Fever ...... 42 
 
INSECTS AND : r 
 AND THEIE IMPORTANCE 'ifr 
 SPEEAD OF DISEASE. 
 
 INTRODUCTION. 
 
 THE entrance to the museum is at the South end of the Central 
 Hall, and the main staircase at the North end ; the side of the 
 Hall to the right of the visitor as he enters is the East. The 
 Bays or Recesses around the Hall are designated by numerals, 
 painted below the end windows. On the East side the most 
 southern bay, that near the statue of Prof. Huxley, is No. X ; on 
 the West side the southern bay, with the bust of Sir William 
 Flower against the arch, is No. I. 
 
 The grouping of the objects in the following pages is one based 
 upon the systematic, position of the insects themselves, and not 
 according to the sequence of the show-cases in which they are 
 exhibited. This arrangement has the effect of causing a visitor 
 who reads the pages consecutively to walk away from a case before 
 exhausting it, and to return to the case later in order to see other 
 insects contained in it ; but the method has the advantage of 
 preventing any mental confusion that might possibly arise from a 
 study of both mosquitoes and tsetse-flies in one show-case, followed 
 by an examination of mosquitoes and tsetse-flies in other cases. 
 It is preferable to complete the examination of all the mosquitoes 
 exhibited, and then to commence the study of the tsetse-flies, and 
 to pass on subsequently to other groups of insects in their turn. 
 
 While most of the specimens are displayed in ordinary 
 museum show-cases, a few, mainly fleas, are shown under two 
 microscopes of special construction which permits of the 
 examination of several specimens in succession. The slides are 
 
8 , Guide to Insects and Ticks 
 
 attached to a drum, whieh rotates upon its axis by menus of a 
 milled wheel operated 1>\ the visitor. Another milled \vheelat the 
 <>[' tin.' ii^i; un.ent enables the visitor to adjust the focus to 
 .soil his cwr, eyesight. The microscope on the West side of the 
 Hall parries twelve slides, that on the East live slides. 
 
 MOSQUITOES AND MALAWI A. 
 
 MVLAKIA is a disease of man caused by minute parasites that 
 invade the red corpuscles of the blood. The parasites belong to a 
 very low grade of animals, and are included in the division of the 
 Protozoa known as Haemosporidia. 
 
 Formerly malaria, commonly known in this country as ague, 
 was thought to be contracted by breathing the air of marshy 
 districts, but it is now proved that it is due to these parasites, 
 transmitted from man to man by the bite of certain kinds of 
 mosquitoes or gnats. Although there are many hundreds of 
 species of mosquitoes, it is only those belonging to the genus 
 Annjilirles, and only certain species of that genus, that are capable 
 of conveying malarial parasites to man. The parasite multiplies 
 not only in the human blood, but also in the walls of the stomach 
 of the mosquito. 
 
 Various forms of malaria are distinguished by medical men 
 according to the frequency of the recurrence of fever and other 
 symptoms, as tertian, quartan, etc. Each is due to a distinct 
 species of parasite, though the visible differences between the 
 species are very slight. The parasite of pernicious or aestivo- 
 autumnal fever is known under the name of Pl<ixmaflinw f<ild- 
 m Welch (= Laverania malariac Grassi and Feletti) ; that 
 of tertian fever is Plaxmatlhim vivax Grassi and Feletti, and 
 that of quartan fever, Plammxlitnn nmlminc. Laveran. Parasites 1 
 similar to these frequently occur in the blood of other mammals, 
 more especially in that of apes and monkeys, and also in the 
 blood of birds of many species. 
 
 Malaria almost extinct in Northern Europe, but in 
 
 v parts of the tropics it is still one of the commonest of 
 
 At tho be^innin.u of the present century, however, 
 
 practical measures for the extermination of mosquitoes were 
 
 introduced in many parts of the tropics, and the ri^id enforcement 
 
that spread Disease. 9 
 
 of these precautions has frequently been followed by marked 
 diminution in the prevalence of malaria, or even its total or almost 
 complete disappearance. 
 
 In a table-case that stands at the entrance to Bay X, near the 
 statue of Prof. Huxley, are shown two greatly enlarged models 
 (X 28) of one of the malaria-carrying species of mosquito, 
 Anopheles maculipennis Mg., together with an actual specimen, for 
 the purpose of giving a correct impression of the real size of the 
 insect. The model on the left hand panel shows the attitude of 
 the mosquito when flying (fig. 3, p. 15) ; that on the right hand 
 panel shows its attitude when at rest (fig. 2, A). Both of the 
 models represent the female insect, for in the species of mosquito 
 that suck blood the blood-sucking habit is confined to the female. 
 In the case of an infected mosquito capable of communicating the 
 disease, the young forms of the malarial parasite escape into the 
 blood with the secretion of the salivary glands, which is introduced 
 into the wound at the time of the bite. 
 
 In the middle part of this case is shown a series of greatly 
 enlarged models (x 6,000) illustrating the complete life-cycle of 
 the parasite of pernicious or aestivo-autumnal malarial fever, 
 Plasmodium falciparum, some stages of which are passed through 
 in the blood of man, others in the body of the mosquito. The 
 models are numbered consecutively, and are explained in the 
 following terms : 
 
 1. A malarial germ or sporozoite (fig. 1, a), as introduced 
 into the blood of man by the proboscis of a female anopheline 
 mosquito. 
 
 2. The sporozoite penetrates into a red blood-corpuscle, and 
 becomes rounded off into a compact mass (fig. 1, b). 
 
 3. The parasite enlarges and a vacuole appears within it. 
 Signet ring stage. 
 
 4. The vacuole disappears, and the parasite enlarges and 
 emits blunt processes. Amoebula stage. 
 
 5. The nucleus multiplies, and the pigment granules increase 
 in number (fig. 1, c). 
 
 6. The nuclei arrange themselves at the periphery. Rosette 
 stage. 
 
 7. The daughter-individuals (merozoites) separate from the 
 central non -nucleate protoplasm (fig. 1, <7). 
 
io (niidc to Insects and Ticks 
 
 8. The merozoites become free in the blood-plasma by the 
 disintegration of the red corpuscle (fig. 1, c). Each merozoite 
 invades a red blood-corpuscle, and develops into amoebula, rosette, 
 and further merozoites, as explained in the preceding models. 
 
 9, 10. After several cycles of amoebula, rosette, and 
 merozoites, a merozoite on entering a red corpuscle grows into a 
 sexual form which may be crescentic (fig. I,/). 
 
 11. The crescent increases at the expense of the corpuscle, 
 and male crescents become distinguishable from female crescents, 
 as explained in models 12 and 15. The crescents undergo no 
 further change in human blood, but when blood containing 
 crescents is sucked by a female anopheline mosquito, the crescents 
 undergo development. 
 
 12. The male crescent (fig. 1, g) is shorter and more rounded 
 than the female crescent. It has clearer protoplasm and a larger 
 nucleus, and the pigment granules are more scattered. 
 
 13, 14. The male crescent becomes spherical and the nucleus 
 multiplies. 
 
 15. The female crescent (fig. 1, li) has denser protoplasm and 
 aller nucleus than the male, and the pigment granules are in 
 the middle part of the crescent. 
 
 16, 17, 18. The female crescent becomes spherical, and, after 
 extruding two small cells (? polar bodies) in succession, becomes 
 the niacrogamete or ovum, and is ready for fertilisation. 
 
 19. The male sphere shoots out four, five or six slender pro- 
 cesses (microgametes or sperms) consisting mainly of nuclear 
 material (fig. 1, i). The remainder of the sphere plays no further 
 part in the life-history. 
 
 20. A microgamete is attracted by, and enters into an ovum 
 
 (% U). 
 
 I I-;. 1. LIFE HISTORY OF THE ORGANISM OF PERNICIOUS MALAUIA. 
 
 ". malarial jjerin or spoi o/<,itc. a> introduced into the blood of man by :i female 
 anopheline mos.jnito at the time \\hen it is sin-kin-.: Mood; b, gporo/oite after cut ry into a 
 blood-corpuscle of man; r, growth of the spoi-o/oite into an amocbiila ; </, division of the 
 ila to form inei-o/oiu-s; e , liberated inen./oite- : /. growth of a mero/oite into a 
 crenceiit ; .-;. free malt- cri-scen( ; A, five female crescent; t, male cell with projections. 
 which lengthen and are set free as Bpei ins ; /', fcrtili.-ation of an ovum by a sperm ; A;, ferti- 
 lised egg an an a. ti\e motile veimicule ; /. sj)here formed from the enlar-.-d \. rmicnle. after 
 this has borod thron-h tin- .-tomach-vvall of (he nioM|iiito: //(. portion of the sphere or c\ >l 
 ftt a late Hta ; ment . containing eoiintle- ne.-dle-ha].ed IpOTM, \\lii--h. s\lien ( he 
 
 urstB, escape a8I>]-. l /-.ite. int., the oi-an- of the mo-,|uit..- body, and pass through 
 the salivary glauds into the pr..bo,ei^. and IO infect a man bitten (i.e. pricked) by the 
 -I 1,600 -li :- ih-a\\n to a smaller .--ale of ma-_'iiilieation. 
 
A 
 
 i 
 
 c. 
 
 V. 
 
 
 
 
 FIG. l. 
 
i 2 Guide to Insects and Ticks 
 
 21. On entry into the ovum the microgamcte becomes a 
 nucleus. The two nuclei unite, and the fertilised ovum or ^ygote 
 becomes motile. 
 
 22. The zygote elongates and bores its way through the 
 wall of the stomach of the mosquito. Ookinete or vermicule 
 stage (fig. 1, A-). 
 
 23. On the outer surface of the stomach of the mosquito the 
 ookinete becomes spherical, and increases greatly in size, the 
 nucleus multiplying at a rapid rate. A protective covering or cyst 
 forms around the sphere. (Only one half of the sphere is shown.) 
 
 24. The sphere divides up into sporoblasts, each being a small 
 cell with a single nucleus (fig. 1, /). (Only one half of the sphere 
 is shown.) 
 
 25. In each sporoblast the nucleus divides into a great number 
 of small nuclei, and the surface of the sporoblast grows out into a 
 great number of pointed processes, into each of which a nucleus 
 enters. These nucleated processes elongate further, and separate 
 from the central part of the sporoblast, and become motile spores 
 or sporozoites (fig. 1, m). (The model shows only one half of the 
 cyst.) On the bursting of the cyst the sporozoites escape into the 
 various organs of the body of the mosquito. 
 
 26. Free motile sporozoites. Such of these as reach the 
 salivary glands pass through the ducts of the glands into the 
 proboscis, and when next the mosquito pricks the skin of a man 
 for the purpose of sucking blood, some of them are left in his 
 body, and develop in the red corpuscles in the manner explained 
 by the models in the upper part of the series. 
 
 In the large table-case that stands in Bay VI, on the East 
 side of the main staircase, are shown models of the malarial 
 ^ite somewhat similar to those just referred to, but of earlier 
 construction. They illustrate the phases in the life-history of the 
 organism so far as they were known at the time when the models 
 were made (1901) ; the more recent series, in the case near Bay X, 
 embodies the results of investigations up to May 1913. 
 
 On the sloping panels in this table- case in Bay VI are 
 mounted enlarged models (x 28) of one of the malaria-ram in- 
 mceqmtoes, Anophele* maculipennit M^., similar to tho two models 
 alre;i ID the other case(l';i\ X). Side by side with these 
 
 are shown, lor p til-poses of comparison, enl.-i r-.'d models of another 
 
thai spread Disease. 
 
 gnat or mosquito, Culc.r pqiiens Linn., an insect which, although 
 it can make itself unpleasant, does not transmit malaria. 
 
 The models on the South side of the case represent the insects 
 in the resting attitude, and illustrate a characteristic difference 
 between anopheline and culicine mosquitoes. The former have 
 the proboscis, thorax and abdomen set in a straight line, whereas 
 culicine mosquitoes, when viewed from the side, have a hump- 
 backed appearance, owing to an arching of the thorax, so that the 
 line of the proboscis is set at an angle to the axis of the hinder 
 part of the body. When resting on a wall or other flat surface, a 
 
 FIG. 2. ANOPHELINE ANDTCULICINE MOSQUITOES IN BESTING ATTITUDE. 
 
 A. AiiupJiele*: maculipeiinix, female, X 4. 
 
 B. Culex p'qnen-f, female, X 4. 
 
 culiciue keeps the abdomen more or less parallel to the surface, 
 whereas an anopheline slopes the abdomen away (fig. 2). 
 Anophelines nearly always have spots on the wing. In both 
 sexes of anopheline mosquitoes the maxillary palps are as long 
 as the proboscis, and those of the male are clubbed at the tip. 
 In culicines the palps of the female are much shorter than the 
 proboscis, and those of the male are a little longer than the 
 proboscis, and usually not clubbed at the tip in mosquitoes the male 
 can be reudily distinguished from the female by the more plumose 
 or fluffy antennae. In culicines the abdomen is completely clothed 
 with scales like those on a moth's w r ing, some of the scales forming 
 
14 Guide to Insects and Ticks 
 
 in many species conspicuous white transverse bands at the base 
 of each segment ; in anophelines the abdomen is without distinct 
 scales, and hence without well-defined markings. 
 
 In the lower part of the South side of the case are displayed a 
 series of models, enlarged 28 diameters, like those of the adult 
 insects, showing the appearance of the eggs, the larvae and the 
 pupae of O//rr and AnopJu-les. The black threads stretched 
 horizontally represent the surface of the water. The eggs of 
 mosquitoes float upon the surface, and the larvae and pupae move 
 about in the water, breathing by means of their air-tubes, which 
 now and again are caused to project very slightly above the 
 surface. The eggs of Culex are massed into a raft composed 
 of two or three hundred eggs with their more pointed ends 
 directed upwards. The eggs of Anopheles float singly or in 
 small groups easily scattered by the wind, and are disposed on 
 their sides instead of standing erect upon the water. Each egg 
 has a pair of small air spaces, as shown in the upper model ( x 65) 
 at the right hand end of the series, above the group of eggs 
 (X38). 
 
 The characteristic attitude of the larva of the culicine mosquito 
 is one in which the head is downmost, the body slightly inclined 
 to the vertical, and the extremity of the air tube at the hind end 
 of the body just touching the surface of the water. The larva of 
 the anopheline mosquito rests horizontally just below the surface 
 of the water ; the air-tube at the hind end of the body is very short, 
 and just level with the surface. When feeding, the larva twists 
 its head half-way round, and laps the surface of the water for 
 minute vegetable organisms. Both culicine and anopheline larvae 
 when alarmed strike down into the water with a rapid jerking 
 movement. 
 
 The pupae of the culicine and anopheline mosquitoes do not 
 differ greatly. In each case the pupa rests with the two horn-like 
 air-tubes on the thorax at the surface of the water, but it can swim 
 rapidly by a jerking movement of the abdomen, which is provided 
 at its extremity with two transparent paddle-like organs. 
 
 In the lower part of the North side of the case are enlarged 
 drawings of the mouth-parts of the two species of gnat or mosquito 
 illustialrd, the culicine, r//A-.r jiij>icns, and llio iiiiophelinc, 
 .\nnjilirli-fi maculipennis. TIM- proboscis of mosquitoes consists of 
 si long, channelled lahium and six piercing instruments contained 
 
that spread Disease. 15 
 
 within it a labrum, a hypopharynx, a pair of maxillae, and a 
 pair of mandibles. The labrum of mosquitoes is generally 
 long, slender, and pointed, and grooved beneath for the re- 
 ception of the hypopharynx, which lies immediately below, 
 and has its apex more or less wrapped round by the inflected 
 margins of the labrum. The two maxillae are long, and each 
 tapers gradually to the apex, which is provided with fine teeth. 
 The two mandibles are of the same length as the maxillae, and 
 their tips partially embrace the apices of the maxillae. All these 
 
 FIG. 3. A MOSQUITO THAT SPREADS MALARIA, 
 Anopheles maculipcnnis, female, X 4. 
 
 parts when at rest lie concealed in the labium, which is deeply 
 channelled for their reception, and is furnished at its extremity 
 with two fleshy lobes, the labella. The labium does not enter 
 the skin of the animal attacked, but bends back beneath the 
 body of the insect, the labella acting as guides to support the 
 piercing organs. 
 
 In male gnats the mandibles are absent, and the maxillae are 
 very short, and cannot be used as piercing instruments. The 
 maxillary palps of the male Culex are as long as the proboscis, 
 
1 6 Guide to Insects and Ticks 
 
 and are somewhat brush-like, but in the female they are very 
 short and simple. 
 
 In Anopheles the maxillary palps are long in both sexes. In 
 the male the apical joint is thickened and hairy, and diverges from 
 the proboscis, while in the female the palps are straight and lie 
 close to the sides of the proboscis for their whole length. 
 
 The first three drawings exhibited show the head, as seen from 
 above, of the female Anopheles maculipennis, and the female and 
 male Culex pipiens. In order that the six piercing instruments 
 may be clearly seen, they are represented as dislodged from the 
 gutter-like labium, within which they are concealed in the living 
 insect. The next two drawings show the forms of the extremities 
 of the labrum, hypopharynx, maxillae and mandibles of female 
 specimens of Anopheles maculipennis and Culex pipicns. The 
 lubrum is viewed from beneath, the other parts from above. The 
 sixth drawing is that of a cross-section through the proboscis of a 
 female Culex pipiens, showing the relative positions of the piercing 
 organs when at rest; and the last is a diagram of the terminal 
 portion of the labium of the same insect showing the form of the 
 labella as viewed from above and from below. 
 
 On the sloping panel above the drawings are two diagrammatic 
 models of the head of a female culicine mosquito or gnat, viewed 
 from the side. The upper model shows the proboscis as it appears 
 when beginning to pierce, the lower one shows the disposition of 
 the parts when the lancets have penetrated a short distance into 
 the skin. The labium does not enter the skin, but loops down- 
 ward and backward beneath the body of the gnat, so that the six 
 lancets are no longer enclosed in its gutter-like groove ; the 
 apposed labella continue to surround the lancets, and slide along 
 them from point to base as the skin is penetrated. 
 
 For comparison with the culicine and anopheline mosquitoes 
 there is shown, at the East end of the case, a model, enlarged 
 28 diameters like those of the mosquitoes, of a common midge, 
 OhironOTMU jilnumxux Linn., a harmless insect, not to be mistaken 
 for a mosquito or gnat. The model represents the female midge ; 
 the differences between tin: heads of the two sexes are illustrated 
 in the two drawings above the model. An arlnal specimen of u 
 niid^'- is also exhibited, ('hiromnmifi JI/HIHVXIIX is one of 
 the large- ami occurs in swarms in the air from 
 
 April to August. The larger midges may be distinguished from 
 
tJial spread Disease. i 7 
 
 mosquitoes or gnats by the absence of the long proboscis, by the 
 length of the front legs, and by their habit of resting with the front 
 legs raised in mosquitoes it is the hind legs that are raised when 
 the insect is resting (see the models on the South side of the case). 
 
 In the lower part of this (East) end of the case is a model of 
 the larva of Ch-ironomus plumosus, a red, caterpillar-like, aquatic 
 form sometimes termed a blood-worm. The larva lives in a 
 tunnel which it makes at the bottom of some ditch, pool or rain- 
 water butt. It breathes by means of four filaments, or blood-gills, 
 at the hind end of the body, on the last segment but one, and 
 four thicker processes on the last segment. Crawling movements 
 are effected by a pair of foot-like organs beneath the head, and a 
 pair at the hind end of the body. At night, and sometimes by 
 day, the larva sw T ims freely, jerking the body suddenly to the right 
 and to the left in such a manner as to present the appearance of a 
 figure of eight. When in its tunnel the larva imparts to its body 
 an undulating movement, thus creating a flow of fresh water 
 through the tunnel. 
 
 The series is completed by a model, enlarged 28 times linear 
 like that of the larva and adult, of the pupa of the midge 
 Chironomus plumosus. While still within its tunnel the larva 
 turns into a pupa, and remains there, lying on its side and 
 imparting an undulating movement to the body. The pupa 
 breathes by means of a pair of tufted tracheal gills on the thorax. 
 When approaching the stage of the imago or perfect insect, it 
 leaves the tunnel and swims to the surface of the water ; the skin 
 splits along the back, and the winged midge emerges, and flies 
 away almost immediately. 
 
 In the table-case that stands at the entrance to Bay I, near 
 the bust of Sir William Flower, are shown dipterous insects of 
 various kinds, tsetse-flies, tabanids and mosquitoes, selected 
 because of their capacity for spreading diseases, and mounted 
 together with examples of their near relatives, which, so far as our 
 present knowledge goes, are harmless. Since almost all insects 
 associated with maladies are of small size, the specimens are 
 mounted close to the glass of the case, in order to enable visitors 
 to see as much as possible of their general appearance and 
 external characters. The mosquitoes of this series are on the 
 West side of the case, away from the middle of the Hall. 
 Examples are show r n of both males and females, and the 
 
 c 
 
i S Guide to Insects and Ticks 
 
 geographical distribution of each of the species of which examples 
 are shown is explained by means of a small map, with the regions 
 in which the insect is found marked in red. 
 
 The following species of mosquitoes are exhibited, all known 
 to convey the parasites of malaria from man to man, and thus to 
 disseminate the disease: Anopheles maculipennis Mg. (fig. 3, 
 p. 15), A. bifurcatns Linn., Europe and North America A. 
 (M'l/zomyia) listoni Liston, A. (M.) culicifacies Giles, A. (Mi/z<>- 
 rhi/nchus) barbirostris v.d. Wulp, A. (M.) sincnsis Wied., A. Nco- 
 cellia steplicnsi Liston, A. (N.) willmori James, A. (Nyssorhyncluts) 
 tlicobaldi Giles, A. (N.)fuliginosus Giles, Asia A. (N.) maculipalpis 
 Giles, Asia and Africa A. (Myzamyia) funcstus Giles, A. (P//rctt>- 
 phorus) costalis Loew, A. (Myzorhynchus) mauritianus Grandpre, 
 A. (AT.) paludis Theob., A. (Cellia) pharoensis Theob., Africa 
 A. (Nyssorhynchus) aunitlipcs Walker, Australia A. (Myzomyia) 
 lutzi Theob., A. (C cilia] albimanus Wied., A. (C.) argyrotarsis 
 Rob.-Desv., South America. 
 
 Disregarding for the present the mosquitoes that spread yellow 
 fever and filariasis, these being dealt with in this guide-book 
 under subsequent headings, the visitor arrives at a selection of 
 " apparently harmless " mosquitoes those which do not, or at all 
 events are not known to, disseminate disease, namely : -Anopliclt's 
 (Christya) iinplrxus Theob., Mcgnrhimtn xcpunttn* Arrib., To.ro- 
 rlupicliitcs speciosus Skuse, Janthinosoma sayi Dyar and Knab, 
 Stnjomyia scutfUttris Walk., S. apicoar</cnte<i Theob., Dcsvoidt/a 
 oliturbans Walk., Ochlerotatus cnnuninni Theob., 0. vit tiger Skuse, 
 Taeniorhiinrhnfi nitrites Theob., Aedcomyia catasticta Knab., 
 ! >(ililia spathipalpis Eond., Culcx concolor Eob.-Desv., C. 
 (innidirostris Skuse, C. tigripcs Grandpr6> var. fusciis Theob., 
 MimiHiiifiii jiliunosa Theob., Harpagomyia (jnmruxlris Leic., 
 in IJH id iim chrysogaster Graham, Wyeomyia communis Leic., 
 . 1'abr. 
 
 MOSQUITOES AND YELLOW FEVER. 
 
 So far as is at present known, yellow fever is disseminaicd 
 solely by the mosquito ,S/<v/f/////m fnxriata Fabr., sometimes called 
 the tiger-mosquito (fig. 4). As in all other mosquitoes that suck 
 blood, tho blood -sucking huhit is confined to the female. The 
 vims of the disease is introduced into the blood by the proboscis 
 
that spread Disease. 19 
 
 of the infected insect at the time of the bite. Yellow fever is 
 primarily a disease of the West Indies and the East Coast of 
 Mexico, but it has been spread by shipping to many other parts of 
 the world. 
 
 The causal agent of yellow fever is not known with certainty, 
 although the disease has been attributed to an extremely minute 
 protozoon found in the blood. That it is a living organism and 
 not a chemical substance is evident from the fact that some time 
 (about three days) elapses between the bite of the mosquito and 
 the onset of the febrile symptoms, and a mosquito is not capable 
 
 FIG. 4. A MOSQUITO THAT SPREADS YELLOW FEVER, 
 Stegomyia fasciata, female, X 4. 
 
 of infecting until about twelve days after it has sucked the blood 
 of a yellow-fever patient. These intervals of time are clearly 
 periods during which an organism is undergoing some parts of its 
 developmental process. 
 
 Specimens of Stegomyia fasciata Fabr. are shown in the series 
 of mosquitoes on the West side of the table-case that stands 
 at the entrance of Bay I. The species occurs in tropical and 
 subtropical regions throughout the world, and is also found in 
 Southern Europe and other countries bordering the Mediterranean 
 Sea, and in the southern parts of the United States of America. 
 
 c 2 
 
2O Guide to Insects and Ticks 
 
 In a small case standing between the statue of Sir Kichard 
 Owen and the bust of Sir William Flower in Bay I is shown a 
 model of the yellow-fever mosquito, Stegomyia fuscuitu, enlarged 
 28 diameters so as to be comparable w r ith the enlarged models of 
 Culexpipiens and Annphelcx maculipennis shown elsewhere. On the 
 back of the panel is a map showing the distribution of the species. 
 
 In general attitude a Stegomyia resembles a Culcx rather than 
 an Anopheles (fig. 2, p. 13) ; the thorax is arched, giving a hump- 
 backed appearance to the body. The thorax of Stegomyia fasciata 
 is black, with a conspicuous lyre-shaped wihte mark 011 the back ; 
 the tarsi are black, ringed with white at the base of each joint. 
 In Cnh'jL- pi^icns the thorax is brown, without distinct markings, 
 and the tarsi are black. 
 
 Essentially a domestic species, Stegomyia fasciata is always 
 found in the vicinity of human habitations. Its wide distribution 
 is believed to be largely due to the insect, in the egg, larval and 
 adult stages, having been carried about the world in ships. It 
 breeds not only in water-barrels and cisterns, wells, and the bilges 
 of ships, but also frequently in puddles and pools of clean, foul, 
 or brackish water, and even in a small quantity of rain-water 
 standing in an old sardine-tin or broken bottle. The eggs are 
 remarkably resistant, and are not necessarily rendered incapable 
 of development if the water on which they are laid happens to 
 dry up. In one instance some eggs of Stegomyia that had been 
 kept in a dry state for six months gave rise to living larvae after 
 being placed in water. 
 
 MOSQUITOES AND FILAHTASIS. 
 
 Filariasis is a general term applied to diseases caused by thin 
 thread-worms of the genus Filaria. Elephantiasis, one of these 
 diseases, is due to J-'ilnriii bancrofti Cobbold, the embryos or larv:ie 
 of which are carried from man to man by certain mosquitoes, particu- 
 larly Culcx fatiyans Wied. Mosquitoes are also responsible for the 
 spread of some other forms of filariasis, and it is interest in^ to note 
 that some species of mosquito spread both malaria and filariasis. 
 
 In the table-case that stands at the entrance of Bay I are 
 shown the following mosquitoes known to be instrumental in the 
 spread of various forms of lilariasis : Am-jilu'lrx maculipennis M,u'. 
 (fig. 3, p. loj, .1. (Mt/:i'lii/nclii(s) ///r//.s/.s Wied, var. 
 
that spread Disease. 21 
 
 Giles, and var. minutus Theob., A. (Myzomyia) rossi Giles, A. 
 (M.) funfstus Giles, A. (Pyretophorus) costalis Loew, A. (C cilia) 
 argyrotarsis Eob.-Desv., Culcx fatigans Wied., Stegomyia pseu- 
 doscutellaris Theob., Mansonioidcs uniformis Tbeob., Tacnio- 
 rhynchus titillans Walk., T. pscudotitillans Theob. 
 
 FISHES THAT FEED UPON THE LARVAE 
 OF MOSQUITOES. 
 
 By reducing the numbers of the larvae, and consequently the 
 number of mosquitoes, certain fishes are beneficial in their effect, 
 and lessen the chance of transmission to man of mosquito-borne 
 diseases. 
 
 The five fishes exhibited in the glass vessel of alcohol are 
 denoted by letters. A is the male, and B the female of a little fish 
 known as " millions " (Lebistes reticulatus Peters). C is a female 
 specimen of a " top-minnow " (Gambusia affinis Girard). D is a 
 male, and E a female of Haplochilus pumilus Blgr., a fish without 
 a popular name. 
 
 " Millions " (A and B) occur in fresh and brackish waters of 
 Venezuela, Guiana, Trinidad, and the Windward Islands. The 
 correct scientific name is Lebistes reticulatus, but the species has 
 also been described as Girardinus poeciloides (from Barbados), as 
 Gimrdinus guppyi (from Trinidad), and as Poecilia reticulata 
 (from Venezuela). The females are viviparous ; the males are 
 smaller than the females, and have ornamental markings, whereas 
 the females are plain in coloration. " Millions " are very prolific, 
 producing a brood every few weeks. They have been exported 
 into various tropical countries for the purpose of reducing the 
 numbers of mosquitoes, but those recently introduced into Africa 
 are said to have been devoured by the frogs. 
 
 " Top-minnows " (C) like " Millions," are viviparous, and 
 belong to the Poeciliine group of the Cyprinodont fishes ; they 
 inhabit the Mississippi and fresh and brackish waters from Florida 
 to Texas. 
 
 Ifiiplochiliis pumilm occurs in Lake Tanganyika and Lake 
 Victoria in Central Africa ; it is oviparous, and although it is known 
 to devour mosquito-larvae but little has been recorded as to its 
 natural history. 
 
22 Guide to Insects and Ticks 
 
 TSETSE-FLIES AND TRYPANOSOMIASIS. 
 
 Trypanosorniasis is a general term applied to diseases caused 
 by species of TrypaDosomes, small blood-parasites of an animal 
 nature, belonging to the division of the Protozoa known as the 
 Haemoflagellata. 
 
 Tsetse-flies are African, blood-sucking, dipterous insects, with 
 peculiarly modified, piercing mouth-parts. The blood-sucking 
 habit in tsetse-flies is common to both sexes, whereas in 
 mosquitoes the females alone suck blood. The virus of the 
 disease is introduced into the blood by the proboscis of the 
 infected insect at the time of the bite. 
 
 In one of the cases in the middle part of the Hall, near the 
 statue of Sir Eichard Owen, is shown a large model ( x 28) of one 
 of the tsetse-flies, Glossina morsitans Westw., which is mainly 
 responsible for the spread of a deadly disease nagana among 
 domesticated animals. In the blood of African animals, such as 
 antelopes and buffaloes, there is frequently found a parasite, 
 Tri/panosoma brucci Plimmer and Bradford, which apparently 
 causes little inconvenience to the host, but this, if transferred to 
 a horse, ox or dog by the piercing proboscis of a tsetse-fly that has 
 previously fed upon the blood of an infected antelope, gives rise to 
 the nagana or tsetse-fly disease. The fatal disease of man known 
 as sleeping sickness is spread by the tsetse-flies Glowum jxi/jxil/s 
 Rob.-Desv. (fig. 6, p. 25) and G. morsitans Westw. The organisms 
 causing sleeping sickness are Trypanosoma i/tuithicnse Button (fig. 5) 
 and T. rh<>(lexi<'inse Stephens and Fantham, in West and Central 
 Africa and North-east Rhodesia respectively. 
 
 In the same case are shown actual specimens of the tsetse- 
 flies (iltwinu mom'tnns and G. palpalis, and enlarged coloured 
 drawings (x 2) of the under and side views of a specimen of 
 the former species, showing the collapsed and the gorged condition 
 of the abdomen before and after a meal of blood. Another drawing, 
 of the natural size, shows how the wings of a tsetse-fly overlap 
 one another above the abdomen when the insect is at rest. In the 
 s vessel are four larvae at different stages of growl h, and a 
 pupa, of (rluxxiiiii /HiljHilifi. The end of the pupa-case that be.-n-s 
 the two projections is the hind end, as is explained in Hie enlarged 
 drawing ( x 12) placed alongside. 
 
 Sketches are exhibited of a horse and a dog suffering from 
 
tJiat spread Disease. 23 
 
 nagana or tsetse-fly disease. In the horse the onset of an attack 
 may be detected by the coat staring, and by a watery discharge 
 from the eyes and nose. Shortly afterwards there appears a 
 general swelling of the belly and hind extremities, which fluctuates 
 from day to day. The animal hangs its head, and there is a 
 general emaciation, sometimes accompanied by blindness. Death 
 results from exhaustion ; there are no symptoms of pain, and the 
 appetite continues good till the last. In the dog the disease runs 
 a rapid course, and is invariably fatal. The chief symptoms are 
 extreme emaciation, swelling of the extremities, eruption over the 
 body with the formation of blebs and pustules containing more or 
 less purulent matter, and finally milky opacity of the cornea 
 giving rise to blindness. 
 
 FIG. 5. ORGANISMS OF SLEEPING SICKNESS, 
 Trypanosoma gambiense, and red blood -corpusc les ; X 1,500. 
 
 A map of Central and Southern Africa is exhibited, showing 
 our knowledge of the distribution of the tsetse-flies (Glossina) in 
 1911, at the time of the issue of Mr. E. E. Austen's " Handbook 
 of the Tsetse-Flies," published by the Trustees of the Museum. 
 
 Around the lower part of the case are shown enlarged coloured 
 illustrations ( X 6) of the ten species of tsetse-flies that were 
 known at the time of the publication of the book in 1911. 
 
 Displayed upon the glass shelf in the case are greatly enlarged 
 transparent models ( x 6,000) of red blood-corpuscles and a form 
 of trypanosome (T. Icwisi Kent) found commonly in the blood 
 of rats. Trypanosomes are small, elongated, parasitic animals 
 occurring in the fluid part (plasma) of the blood; they have an 
 undulating membrane or longitudinal fin which runs along the 
 
24 Guide to Insects and Ticks 
 
 body, and is continued forwards into a filament or flagellum. In 
 an allied genus, Trypanoplasma, there is a flagellum at each end of 
 the body. 
 
 Although many forms of trypanosomes are spread from one 
 vertebrate host to another by tsetse-flies, some are spread by other 
 blood-sucking invertebrates, such as gnats, fleas, leeches, etc. ; the 
 trypanosomes that are found in skates and similar fishes, for 
 instance, are known to be conveyed by marine leeches. In the 
 case is shown a specimen of an African fly, Hippobo&ca r//jij>es von 
 Olfers, allied to the forest-fly of Britain, Hippobosca cquimi Linn, 
 (see enlarged photograph ( x 6) below the glass plate), and respon- 
 sible for the spread of the blood-parasite Trypano&oma the Her/ 
 Bruce, causing gall-sickness among cattle in the Transvaal. 
 
 Other trypanosomes of interest in connection with disease are 
 T. cquinum Vosges, causing " mal de caderas " of horses in South 
 America, T. evansi Steel, causing surra of horses and cattle in 
 India, and T. equipcrdum Doflein, causing dourine in horses in the 
 countries around the Mediterranean Sea, and T. cruzi Chagas, the 
 cause of the fatal disease barbeiro in man, particularly children, 
 in South America, and conveyed by a hemipterous insect or bug, 
 Li units megistus Burmeister, more than an inch in length. 
 
 In the large case that stands at the entrance to Bay I, near 
 the bust of Sir William Flower, is shown a selection of tsetse- 
 flies, together with enlarged coloured drawings ( x 6), and maps 
 showing the distribution of the several species. Tsetse-flies may 
 l>e said to be African insects, although one species is met with in 
 south-western Arabia, and in former times tsetse-flies existed in 
 North America. 
 
 The first examples shown are those of Glossina pal pa Us 
 Rob.-Desv. (fig. 6) of West and Central Africa, the principal 
 disseminator of Trypanosoma </(iil>i<'tiM Dutton, causing sleeping 
 sickness in man. These tsetse-flies exist only in shady places, 
 and haunt the margins of lakes and water-courses where the 
 banks are covered with vegetation. Specimens are shown of 
 young and full-grown larvae (in the small glass vessel of alcohol), 
 and of pupae, together with some of the soil in which they \\vn> 
 found (in the glass-topped box). (Uoxxiiin /xi/jxilis, like other 
 -flii'S but unlike; the vast majority of flies in general, docs 
 not lay eggs; the Irmalc produces ill intervals ;i single larva, or 
 got, Which 18 retained within the body of ihe mother until I'nll 
 
tliat spread Disease. 25 
 
 grown. The maggot of G. palpalis is dropped by the mother in a 
 shady place near water, where the soil is loose or sandy, moderately 
 dry, and often consisting of crumbling vegetation. On being 
 deposited, the maggot buries itself in the loose earth ; its skin 
 then becomes dark in colour, contracts, and hardens into a barrel- 
 shaped puparium or case, within which the change to the pupa or 
 chrysalis takes place. A female fly of this species may produce 
 from eight to ten larvae altogether, one at a time at intervals of 
 nine or ten days. 
 
 FIG. 6. A TSETSE-FLY THAT SPREADS SLEEPING SICKNESS, 
 Glossina palpalix, female, X 5. 
 
 Specimens of Glossina palpalis are shown in the attitude in 
 which they rest. A resting tsetse-fly can be distinguished from 
 any other blood-sucking fly with which it could possibly be 
 confused by the fact that the wings, instead of diverging at the 
 tips, lie closed flat over one another down the back like the blades 
 of a pair of scissors, while the proboscis with which the bite is 
 inflicted projects horizontally in front of the head. 
 
 Glossina morsitans Westw. is a widely distributed tsetse-fly 
 (see map), spreading nagan.i jmioiitf domestic animals, and i 
 Ny.isuhuid and Northern Rhodesia conveying to man th 
 
26 Guide to Insects and Ticks 
 
 form of sleeping sickness caused by Tnjpanosoma rhodcsiensc 
 Stephens and Fantham. This species of tsetse-fly is usually 
 confined to definite tracts of country, known as " fly-belts," often 
 of very limited extent. Unlike G. palpalis, G. morsitans is not 
 confined to the immediate vicinity of water. The female deposits 
 its maggot or larva in hollows about the roots of trees, and not in 
 the soil under bushes, where it might be found by the scratching 
 of guinea-fowl and other birds in search of food. Some empty 
 pupa-cases are shown. 
 
 In the larger of the two glass vessels are specimens of tsetse- 
 flies (Glossina palpalis, G. morsitans and G. tachinoides) before 
 and after a full meal, showing the extent to which the abdomen 
 can be distended with blood. Tsetse-flies are dependent for their 
 continued existence upon the blood of vertebrate animals, including 
 man, wild and domesticated mammals, birds and reptiles. Contrary 
 to what is the case in the majority of blood-sucking flies, such as 
 mosquitoes and horse-flies, in which the females alone suck blood, 
 in tsetse-flies the habit is common to both sexes. The amount of 
 blood imbibed at one meal is relatively considerable, the fly's 
 abdomen originally empty and flat becoming swollen out like a 
 bead in consequence. 
 
 The tsetse-flies on the second panel are examples of species 
 which have not been proved to convey sleeping sickness to man, 
 though many, if not all, are concerned in the dissemination of 
 trypanosomiasis among domestic animals. The species exhibited 
 are: Glossina caiiijincti Austen, G. palliccra Bigot, G. tachinoidcs 
 Westw., G. imllitUjH's Austen, G. longipalpis Wied., G. austcni 
 Newst., G. fusca Walk., G. niyrofusca Newst., G. brevipalpis 
 Newst., G. mcdicorum Austen, and (/. It m<ii Dennis Corti. 
 
 TABANID FLIES AND "GALA HAH 
 SWELLINGS." 
 
 The disease known as " Calabar swellings," a form of filariasis 
 
 prevalent in West Africa, is caused by thin thread- worms of the 
 
 species /''//////</ (/,"<>) ha Stiles, the larva of which undergoes its 
 
 morphoeifl in the salivary glands of female tabanid flies of 
 
 the # MIUS 
 
tliat spread Disease. 27 
 
 Tabanid flies are large flies, sometimes termed horse-flies or 
 mangrove-flies, widely represented in tropical, subtropical and 
 temperate parts of the world. Only the females suck blood. The 
 larvae of the flies are carnivorous, and live in water, wet sand or 
 mud, earth or decaying vegetable matter. 
 
 In the table-case that stands at the entrance to Bay I are 
 shown examples of Chrysops diniidiata v. d. Wulp and Chrysops 
 silacca Austen, both of which are known to be instrumental in 
 the spread of the disease. Both species occur in West Africa, the 
 former ranging from Portuguese West Africa to Ashanti, the latter 
 through Southern and Northern Nigeria and the Belgian Congo. 
 
 For comparison with the two foregoing species are shown 
 some tabanid flies that do not, or, at all events, are not definitely 
 known to disseminate disease, although certain of them are 
 suspected of spreading forms of trypanosomiasis among domestic 
 animals. In many parts of tropical Africa tabanid flies are 
 abundant at certain seasons, when owing to the bloodthirstiness 
 and pertinacity of the females, the insects become an intolerable 
 pest, both to man and to stock. The exhibited specimens belong 
 mainly to the genera Chrysops, Silvias, Panyonia, Tabanus, 
 ILtonatopota and Hippoccntrum, and in each case the range of 
 the species and any features of interest in their natural history 
 are mentioned. 
 
 HOUSE-FLIES AND INTESTINAL 
 DISEASES. 
 
 Many of the diseases broadly termed filth diseases are spread 
 by house-flies; some of them are skin-diseases, others are 
 diseases of the alimentary canal, such as enteric or typhoid 
 fever, cholera, dysentery and infantile summer diarrhoea. 
 House-flies are something more than disagreeable com- 
 panions and pertinacious nuisances of the hot weather; they 
 are dangerous by reason of their habit of settling upon food 
 and contaminating it with such disease germs as they may 
 happen to be carrying. In America the common house-fly has 
 been termed the typhoid-fly, an unfortunate expression implying 
 that typhoid fever is the principal, if not the only, disease that 
 
28 Guide to Insects and Ticks 
 
 is spread by the insect ; in large towns, where the arrange- 
 ments for the disposal of sewage are good, the greatest harm 
 done by the house-fly is in the dissemination of infantile summer 
 diarrhoea, with a large death rate. In camps and other places 
 away from towns, where it is difficult to secure adequate disposal 
 of human excreta, the danger of the spread of gastro-intestinal 
 diseases by flies becomes very considerable. The organisms 
 causing these diseases are mostly of a bacterial nature ; enteric or 
 typhoid fever is due to a motile bacillus (Bacilliix iiiphosus Eberth- 
 Gaffky), which in certain conditions exhibits from eight to twelve 
 delicate threads or cilia projecting from the body (fig. 7). 
 
 In a table-case that stands on the East side of the Hall, 
 between the statue of Sir Richard Owen and that of Prof. Huxley, 
 are models of the common house-fly, Musca domestica Linn., 
 adult female (fig. 8), and a group of eggs, a larva and a pupa, all 
 
 FIG. 7. ORGANISMS OF TYPHOID FEVKK, 
 Bacillus typhosus ; X 1,500. 
 
 enlarged 28 diameters. Actual specimens are also shown of the 
 common house-fly and of three other species of house-fly, the 
 most abundant of which in houses is the lesser house-fly, Fann'nt 
 run irul aris Linn. 
 
 The lesser house-fly is smaller than Musca domes lira, and is 
 often taken by the ignorant to be a common house-fly that has 
 not yet grown up. As a matter of fact, a fly that has once 
 emerged from its pupa-case does not increase in size. Occasionally 
 small specimens of Musca dmm'xlit'a are met with, but these are 
 undersized flies whose small dimensions are due to insufficiency 
 or excessive dryness of food during the larval or maggot stage, 
 lesser house-fly differs in its hahits Irom the common house- 
 fly, and rarely n wiih the latter. While Ihr common 
 house-fly is found largely in ihe kitchen and dining-room, and 
 settles indiscriminately on the wall, the tahle, exposed lo:,d, and 
 
that spread Disease. 
 
 29 
 
 one's hands and face, the lesser house-fly remains mostly on the 
 wing, flying about with a curious darting movement beneath the 
 gas-bracket or electrolier in the middle of the bedroom. The 
 lesser house-fly appears earlier in the year than the common 
 house-fly, and persists later, being still found in dwelling rooms 
 as late as November. The lesser house-fly is closely related to 
 the latrine-fly or privy-fly, Fannia scalaris Fabr., but the latter, 
 although a dangerous disseminator of intestinal disease in villages 
 and camps, is scarcely a house-fly ; it rarely enters houses. 
 
 FIG. 8. COMMON HOUSE-FLY, 
 
 M iisca domestica, female, x 6 ; largely responsible for the spread of typhoid fever 
 and summer diarrhoea. 
 
 Shown in the same case are specimens of two other house-flies, 
 Muscina stabulans Fin., a large fly, not frequent in its occurrence, 
 and Stomoxys calcitrans Linn., commonly termed the stable-fly. 
 This last is a biting, blood-sucking fly, common in the country and 
 in suburbs, and met with sometimes in the middle of large towns. 
 People who do not discriminate between the different kinds of 
 house-fly imagine, when bitten by a Stomoxys , that it is an ordinary 
 house-fly that has become particularly vicious. Critical examination 
 
30 Guide to Insects and Ticks 
 
 of the insect shows that it 1ms a straight piercing proboscis 
 projecting forwards from the lu-ad. 
 
 The common house-fly is incapable of biting ; its proboscis is 
 large and soft, and is situated on the under side of the head, and 
 contains numerous minute tubes through which fluid nutriment is 
 sucked. A fly cannot take in solid food ; if the food is dry, as for 
 instance a piece of sugar, the fly moistens it by ejecting salivary 
 fluid or by regurgitating the fluid contents of its storage-stomach 
 or crop. It is in this way, among others, that the fly infects food 
 with disease organisms, for flies are indiscriminate in their habits, 
 and the previous meal of the fly in question may have been made 
 upon the excrement of a person suffering from typhoid, or of an 
 infant ill with summer diarrhoea. The mere walking of a fly upon 
 food may infect it with microbes, for the feet are hairy, and readily 
 carry minute droplets of substance that the fly has recently been 
 visiting. 
 
 At one end of the case is shown a representation of a tray of 
 food such as might serve for a light lunch a plate of ham, a roll, 
 a few plums and a jug of milk looking repellent by reason of the 
 house-flies that swarm upon it. At the other end of the case is a 
 representation of a heap of kitchen refuse which, by being allowed 
 to accumulate for some time in the dustbin, forms a suitable 
 breeding-ground for house-flies ; for flies, although an indoor 
 pest, do not breed indoors. In this exhibit are shown the 
 four chief phases in the life-history eggs, larvae or maggots, 
 resting pupae in their brown coats, and adult flies. In the heap 
 of rubbish can be recognised cinders, feathers, egg-shells, fish- 
 bones, mouldy bread, vegetable refuse and tea leaves, the last two 
 being particularly harmful because, by keeping the whole mass 
 damp and in a state of fermentation, flies are attracted to lay their 
 eggs in it, their instinct prompting them to deposit the eggs where 
 the maggots, on hatching out, will find themselves in surroundings 
 most suitable for their development. Flies breed also largely in 
 heaps of stable manure, and any decaying and fermenting vege- 
 table refuse in the fields. 
 
 lust us the mosquitoes that carry malaria and yellow fever can 
 le. kept in check by attacking their breeding haunts, by preventing 
 accumulations of rain-water, by draining marshes and by spraying 
 with paraffin oil tracts of stagnant water, so as to prevent the 
 development of eggs and larvae that would grow into mosquitoes, 
 
that spread Disease. 3 1 
 
 so in the case of house-flies, it is more practicable to attack the 
 next generation than the present generation, that is to say, to 
 prevent the development of the larvae rather than to attempt to 
 destroy the winged flies, and this can be done by taking measures 
 such that moist rubbish and stable manure are not allowed to 
 accumulate and serve as breeding places for the flies. 
 
 A single female of the common house-fly lays from 120 to 150 
 eggs at a time, and may deposit five or six batches during its life ; 
 and since in very hot weather the entire life-cycle may be com- 
 pleted in about three weeks, it is easy to account for the enormous 
 swarms of flies sometimes seen. 
 
 The attention of visitors is drawn to a pamphlet entitled " The 
 House-Fly as a Danger to Health," which can be purchased in the 
 Museum for a penny. 
 
 Blow-flies are not included in the series exhibited, for although 
 they are flies that enter houses and settle on food, particularly 
 cold meat and fish, they are not dangerous in the same sense as 
 the common house-fly. They are not attracted to dung-heaps and 
 other exposed faecal matter, and they breed in flesh, such as the 
 carcase of a recently dead animal. Blow-flies are a nuisance 
 principally from their habit of laying their eggs in any cold joint 
 of meat to which they have access. The eggs soon develop into 
 maggots or gentles, and owing to the power which these larvae 
 have of liquifying the meat around them, the joint becomes putrid 
 much more rapidly than if it had not become " fly-blown." 
 
 SHEEP BOT-FLY. 
 
 In one of the two sloping-faced table-cases in the middle of 
 the floor of the Hall are shown a specimen of the bot-fly of the 
 sheep, Oestrus avis Linn., three larvae, and enlarged coloured 
 drawings ( x 6) of the larva, pupa and adult female. The larvae 
 or maggots of this fly live parasitically in the cavities in the front 
 part of the head of the sheep, and when about to become pupae, 
 escape from the nostrils and fall to the ground. After a time the 
 winged flies escape, and lay their eggs in the nostrils of sheep. 
 
 In Algeria, especially in districts in which sheep are few and 
 the human population fairly dense, the sheep bot-fly attacks the 
 
32 Guide to Insects and Ticks 
 
 Kabyl shepherds, laying its eggs, while flying, in the eyes, nostrils 
 iiiul lips; the larvae, when hatched, cause intense irritation of the 
 conjunctiva, and of the cavities and sinuses of the nose and 
 throat. The disease lasts about twelve days, and is known 
 locally as thim'ni. 
 
 FLEAS AND PLAGUE. 
 
 Plague or bubonic pest is a disease of tbe rat, communicated 
 from infected to healthy rats by fleas, of which Xcnopsylla clirojiix 
 Rothsch. is the most important in tropical and subtropical 
 countries. On the death of an infected rat the fleas leave the 
 body, and if other rats are not available, will fasten upon man, 
 and may communicate the disease. In man bubonic plague 
 proves fatal in a large percentage of cases, and a marked feature 
 of the disease is the enlargement of the superficial glands, such as 
 those of the groin and armpit, into painful swellings or buboes. 
 
 Another type of plague, known as pneumonic plague, affects 
 the lungs. The Manchurian epidemic of 1911 was of this type. 
 The infection in this case appears to have originated from plague 
 among the Mongolian marmots or tarbagans, Marniota bobac 
 Pallas, that are trapped by the Manchurian hunters for the sake 
 of their fur. The flea found upon the tarbagan is Ceratophyllus 
 fiildntirn-i Wagn. 
 
 In one of the table-cases in the middle of the floor of the Hall 
 there are shown selected specimens and enlarged models of the 
 tropical rat-flea, Xcnopsylla cheopis Eothsch. (fig. 9), which, as 
 stated above, is most responsible for the spread of plague in 
 hot countries. The tropical rat-flea is found on several other 
 mammals besides the rat ; the hosts are mostly rodents, but 
 include a few shrews. This species of flea has been spread by 
 rats to such an extent that it is now found all over the world ; it 
 does not flourish, however, in cold climates. 
 
 The model on the pedestal is that of a male, enlarged 200 
 diameters. The names of the parts of the insect, so far as external 
 features are concerned, are given in the coloured drawing below. 
 At the ends of the case are shown enlarged models of the head ami 
 tin- hind end of a female tropical rat-flea (x 250), so in-ranged 
 
that spread Disease. 
 
 33 
 
 that they may be readily compared with the corresponding parts 
 of the male. 
 
 Models are also shown of the egg and larva of the tropical rat- 
 flea, enlarged 150 diameters. The eggs of fleas are ellipsoidal in 
 shape, similar at the two ends, and of a translucent appearance, 
 suggesting thin china. The eggs laid by the rat-flea fall out of the 
 fur of the host, and remain on the ground, usually within the 
 
 FIG. 9. TROPICAL BAT-FLEA, 
 Xenopsylla cheopi*; male, X 36 ; largely responsible for the spread of plague. 
 
 nest, run or burrow of the rat, until in about a week they hatch 
 out into active, maggot-like larvae. 
 
 The larvae of fleas are not parasitic ; they live on the ground 
 either in the nest or the run of the host, and feed on all kinds of 
 refuse that may occur there, their mouth-parts being adapted for 
 chewing, and unlike those of the adult. They have no eyes, and 
 no legs, but move about by means of the hairs or bristles projecting 
 from the body, and the pair of processes or " struts " at the hind 
 end. After spinning cocoons and passing through a pupal or 
 
 D 
 
34 Guide to Insects and Ticks 
 
 resting phase, they become slowly transformed into fleas, which 
 finally emerge from their cocoons, and invade the fur of new 
 hosts. 
 
 On the small glass table in the case are shown transparent 
 models of human red blood-corpuscles and plague bacilli, enlarged 
 6,000 diameters (fig. 10). Bubonic plague, the disease that is 
 transmitted by the bite of various kinds of flea, of which 
 Xenopsylla chcopis is the most important in tropical regions, so 
 that it is sometimes termed the plague-flea, is due to the presence 
 of minute bacterial organisms, known as Bacillus pestis Kit., 
 occurring in the blood. These organisms were first discovered 
 during the epidemic of plague in Hong Kong in 1894. The bacilli 
 occur in the fluid part (plasma) of the blood, and not in the 
 
 FIG. 10. ORGANISMS OF PLAGUE, 
 BaciUu* pestis, and red blood-corpuscles; X !,."< ID. 
 
 corpuscles ; they may have the form of small rods with rounded 
 ends, and sometimes show a constriction across the middle. 
 Occasionally they are found in chains or series set end to end ; 
 each bacillus repeatedly elongates and divides across, thus 
 increasing the total number at a rapid rate. 
 
 On the floor of the case are shown actual specimens of the 
 tropical rat-flea and its larva, mounted on slips of glass. The 
 specimens are so small that no details can be seen ; they an; 
 introduced into the series merely to give a correct impression of 
 the real size. 
 
 I nder the microscope that is set upon the fable at tho 
 entrance to Bay X on the East side of the Hall, near the statue of 
 Prof. Huxley, :iro shown specimens of tho tn>]>i<-;il rat-flea, 
 AV///////// flu-tipix, in fivo shines of its life-history. Slido A show* 
 
that spread Disease. 35 
 
 the eggs ; the thinness of the translucent shell is seen in the two 
 broken eggs. Slide B shows the larva, stained red with carmine 
 solution ; the head end is to the left. The body of the larva is seen 
 to be sparsely covered with stiff hairs or bristles, and there are no 
 eyes nor legs. Slide C shows an early pupa, shrinking in length 
 while still within the hairy larval skin. The first traces of the legs 
 can be seen. Slide D shows a later pupa, very transparent and 
 delicate in texture, owing to a reconstruction of all the internal 
 parts of the body which takes place at this period of development. 
 The legs are of considerable length, and the body is assuming the 
 size and shape of the flea. Slide E shows an adult male ; the 
 body is now yellow, with an external hard casing of chitin, 
 produced into numerous hairs and spines. 
 
 Returning to the middle of the Hall, the visitor will see in one 
 of the two sloping-faced table-cases an enlarged, coloured drawing 
 ( x 40) of a female specimen of the human flea, Pulex irritans 
 Linn. The flea of man is larger and darker in colour than the 
 tropical rat-flea (Xenopsylla cheopis), and has larger stigmata or 
 breathing pores, larger claws on the feet, and much larger eyes ; 
 the piercing mouth-parts, also, are stronger and broader. The 
 long bristle which in the rat-flea passes backwards across or near 
 the eye is much lower down in the flea of man ; and in the latter 
 there is no internal bar extending from the mid-coxa into the 
 thorax this last feature can only be seen in specimens that have 
 been made transparent so as to render the internal structures 
 visible. Other differences between the species occur in the sexual 
 organs. 
 
 Under the microscope placed on the West side of the Hall 
 near the entrance to Bay I. are shown twelve slides, of which nine 
 are preparations of adult fleas of general interest. 
 
 A is a male tropical rat-flea, Xenopsylla cheopi-s Rothsch. 
 (fig. 9). As already explained, this flea is common on rats (and 
 other rodents) in warm countries, having become almost cosmo- 
 politan in distribution. It is known to transmit the bacillus of 
 bubonic plague from infected rats to man, and is frequently termed 
 the plague-flea. 
 
 B is a male flea of the species Ctenophthalmus <i</t/rtes Heller. 
 This species of flea is common on rats, and also on field-mice, 
 stoats and weasels, in Europe. It is not known to transmit any 
 disease. It is distinguished from "A" by having no eyes, and by 
 
 D 2 
 
36 Guide to Insects and Ticks 
 
 having three spines on the lower edge (gena) of the head. There 
 is also a comb of spines projecting back from the pronotum or lirst 
 division of the thorax. 
 
 C is a male Ijeptopsylla mtou'itU Duges, the common flea of the 
 mouse, but also found on the rat. Though primarily European, 
 it is now almost cosmopolitan. It has a comb of spines on the 
 pronotum, but no eyes, and is distinguishable from " B" by having 
 four genal spines instead of three. 
 
 D is a male Ceratophyllus fascialus Bosc., a common rat-flea, 
 almost cosmopolitan in distribution. It has eyes, and a comb of 
 spines on the pronotum, but no genal spines. 
 
 E is a male Ceratophyllus x/ltintictri Wagn., the flea found on 
 the Mongolian marmot, Maniiota bobac Pallas, and responsible for 
 the spread of pneumonic plague. It is with difficulty distinguish- 
 able from the common rat-flea (D). 
 
 F is a female cat-flea, Ctrnoccjiluilux /<//* Bouche, found not 
 only on cats, but also on wild species of felidae, and on dogs. It 
 is widely distributed, and is distinguished by having eyes, a comb 
 of spines on the pronotum, and a row of eight spines (genal spines) 
 at the lower edge of the head. 
 
 G is a female dog-flea, Ctenocephalus can is Curtis, found on 
 cats as well as dogs. The flea resembles Ctenocephalus frlix, but 
 has the head more rounded. 
 
 H is a male human flea, I'nlc.r irrihnix Linn. This flea is 
 short and thick-set, with eyes, but no comb of spines on the 
 pronotum. It is almost cosmopolitan in distribution. 
 
 J is a young female jigger flea, "Dermatophilus jH-ni'lranx Linn. 
 The female jigger flea burrows into the human skin, and its 
 abdomen becomes so enormously distended with eggs as to attain 
 the size of a small pea. The part of the skin affected may become 
 ulcerated and infected with various pathogenic bacteria, and so 
 lead to serious consequences. Although a native of Mexico, Bra/il 
 and Argentina, the jij^or flea is now spread also over most parts 
 of tropical Africa, and lias even reached India. It attacks other 
 mammals brsidi-s man. 
 
 The slides K, L and M are preparations of a louse and two 
 bugs and will bo referred to under their respective headings. 
 
that spread Disease. 37 
 
 BED-BUGS AND DISEASE. 
 
 In one of the two sloping-faced table-cases in the middle of 
 the floor of the Hall is a specimen and an enlarged, coloured 
 drawing (x 20) of a female bed-bug, Cimex or Clinocoris lectu- 
 I tu- ins Linn. ; and under the microscope at the entrance to Bay I 
 are shown specimens (slides L and M) of this species and the 
 bed-bug of tropical* Africa and the Oriental Region, Clinocoris 
 rotundatus Sign. 
 
 Clinocoris lectularius (fig. 11), although commonly termed the 
 European bed-bug, is a parasite which by the facilities for travel 
 
 FIG. 11. COMMON BED-BUG, 
 
 lei-tiilarim, male, X H. 
 
 now possible has been spread all over the temperate and tropical 
 parts of the world. It differs from C. rotundatus by its relatively 
 broader abdomen ; the prothorax also is broader, and the lateral 
 lobes project more forward, and almost reach the eyes. The form of 
 the mouth-parts of a bed-bug are seen in slide L. The labium 
 has the form of a segmented proboscis ; the four bristles seen 
 projecting from the front of the head are the two maxillae and 
 two mandibles, which in the living insect lie within a groove in 
 the labium. 
 
 The common bed-bug has been suspected of carrying the virus 
 of various diseases, such as leprosy, typhus and relapsing fever, 
 
38 Guide to Insects and Ticks 
 
 from infected to healthy persons, and Clinocoris rotiindutH* \+ 
 known to be the carrier of a piroplasma parasite, Leisliman'm 
 (lonorani Laveran and Mesnil, the cause of the tropical disease 
 kala-azar, common in India. 
 
 LICE AXD DISEASE. 
 
 Apart from the irritation which they cause, in some cases so 
 great as to lead to loss of sleep and nervous prostration, lice are 
 noxious insects because of their capacity for spreading typhus fever 
 and some forms of relapsing fever (those of Europe and North 
 Africa) ; lice have also been suspected as the infective agent in 
 certain cases of leprosy, tuberculosis and plague. The organism 
 of typhus fever has so far not been identified. That the causal 
 organism undergoes some part of its development in the louse is 
 evident from the fact that lice are especially infective from the 
 fifth to the seventh day after feeding upon a person suffering from 
 typhus fever. The organisms of the relapsing fevers are spiro- 
 chaetes, blood parasites of spirally twisted, thread-like form. 
 
 Lice feed entirely upon blood, which they suck through 
 punctures made in the skin ; they soon die when removed from 
 the body, and differ in this respect from fleas and bugs. Three 
 species of louse occur on man the clothes-louse or body-louse, 
 Pediculus humanus Linn. (fig. 12), the head-louse, Pcdicnlim cujntis 
 de Geer, and the crab-louse, Ph-thirti* jmbis Linn. These are 
 also found occasionally upon cats, dogs and monkeys living in 
 association with man. Various kinds of mammals, from elephants 
 to shrew-mice, have their own particular species of lice. 
 
 In one of the two sloping-faced cases in the middle of the Hall 
 are shown some specimens and enlarged coloured drawings ( x 50) 
 of the clothes-louse and head-louse. In the same case a series of 
 lenses is arranged over mounted specimens of a head-louse, 
 some pieces of human hair with nits or eggs of the louse, a 
 clothes-louse, a crab-louse, and a louse (7W/V/////.S- xchajji Fahr.) 
 from a chimpanzee. . Under the microscope near the bust of 
 Sir William Flower, on the West side of the Hall, is shown a 
 mounted specimen (slide K) of the clothes-loiter. 
 
that spread Disease. 39 
 
 The clothes-louse is larger than the head-louse, and the sides 
 of the abdomen are less deeply cleft between the segments. The 
 antennae are slightly thinner in the clothes-louse than in the 
 head-louse, and the front border of the thorax is less rounded. 
 Other differences occur in the female sexual organs. In the crab- 
 louse the body is shorter than in the two former species, and the 
 thorax is broader than the abdomen ; along each side of the 
 abdomen are projections which at their tips carry pencils of 
 
 FIG. 12. CLOTHES-LOUSE OB BODY-LOUSE, 
 Pedievlufs humanus, female, X 18 ; largely responsible for the spread of typhus fever. 
 
 hairs. In the louse of the chimpanzee the lateral margins of 
 the abdomen are straight in front, but behind they present the 
 appearance of a saw. 
 
 A female louse lays four or five eggs a day for about a month, 
 and then dies. There is no caterpillar or maggot stage ; the 
 young, on hatching out, differ from the adults only in their smaller 
 size and in certain trifling differences'- of structure. As they grow 
 they moult the skin three times before arriving at the adult 
 
4O Guide to Insects and Ticks 
 
 condition, which is reached in about twelve days from the time of 
 the hatching of the egg. 
 
 Lice are commonest in the poorer districts of a town, and 
 spread rapidly among the children in a school. In times of war 
 lice are apt to becoms particularly troublesome owing to their 
 rapid increase in numbers, and the ease with which they can 
 spread in the crowded life of a camp ; the men have usually but 
 few opportunities for effecting a complete change of garments and 
 otherwise cleansing themselves, and so the conditions are favour- 
 able for a continuance of the infestation. 
 
 The attention of visitors is directed to a pamphlet entitled 
 " The Louse and its Eelation to Disease," which can be purchased 
 in the Museum for a penny. 
 
 TICKS AND DISEASE. 
 
 The transmission of several diseases caused by blood-parasites, 
 known as spirochaetes, may be traced to the bite of ticks, c.<j., 
 human tick-fever or relapsing fever of tropical Africa, due to 
 Sjiinn-lnirtii /i/iUoni Novy and Knapp (fig. 13), conveyed from one 
 person to another by the tick Omithodoros moubata Murray 
 (fig. 14) ; and spirochaetosis in fowls and cattle, the fowl-tick 
 being . 1 />/</* persicus Oken. A typhus-like disease in man, known 
 as Rocky Mountain spotted fever, is spread by the tick Dermacentor 
 r I- nti* hi* Banks, and a recently observed obscure affection known 
 as tick-paralysis in man, sheep and dogs, has also been shown to 
 be due to the effects of tick-bites. Concerning the blood-parasite 
 of heartwater of sheep, etc., conveyed by the bont tick, Amblijoinma 
 hebraeum Koch, in South and Central Africa, but little is known. 
 A somewhat similar disease, the East Coast fever of cattle, is due 
 to Tln'ilt'rid, a blood-parasite which occurs within the red blood- 
 corpuscles of the host, like the forms of Pi/roplasma (l>uln'x'm and 
 Xntfiillid), which cause redwater or Texas fever of cattle in man\ 
 of the warmer parts of the world, malignant jaundice of dogs in 
 India and South Africa, biliary fever of horses in Africa and India, 
 and canjeag of sheep in Southern Europe, all transmitted by ticks 
 of the genera y/////mvy>//(////.s, Mtu-ijtn-ujHi*, and their allies. 
 
 In one of the two sloping-faced cases in the middle of the Hall, 
 
that spread Disease. 41 
 
 between the main staircase and the statue of Sir Richard Owen, 
 there is shown, on the North side, a series of ticks arranged in 
 three groups. The first group consists of ticks that convey disease 
 to human beings, and includes Omithodoros moubata Murray, 
 Omithodoros savignyi Aud. and Dermacentor remistus Banks. 
 
 Omithodoros moubata (fig. 14) is very widely distributed in 
 Africa, and the regions where it is known to occur are marked in 
 red in the map that is placed by the side of the specimens. This 
 tick, which sometimes attacks domestic animals as well as human 
 beings, transmits the blood-parasite Spirochaeta duttoni Novy and 
 Knapp, the cause of the human relapsing fever of tropical Africa. 
 
 FIG. 13. ORGANISMS OF AFRICAN RELAPSING FEVER, 
 Spirochaeta duttoni, and red blood-corpuscles ; X 1,500. 
 
 The larval stage of the tick is not well developed in this species, 
 and is inert, the tick emerging from the eggshell as a nymph. 
 After freeing itself from the larval skin, the nymph is ready to 
 feed. It casts its skin several times before becoming adult, a 
 moult taking place after each meal of blood. The female tick does 
 not lay eggs until it has fed on blood. The spirochaetes are taken 
 up by the tick whilst sucking blood from an infected person. They 
 make their way into the ovaries of the tick, penetrating into the 
 undeveloped eggs and multiplying within them. The first nymphal 
 stage that develops from these eggs is capable of conveying the 
 disease. The spirochaetes can be transmitted to the third genera- 
 tion of ticks, even if the second generation was fed on blood free 
 from spirochaetes. 
 
Guide to Insects and Ticks 
 
 Omithodoros .sv/ r/f////// is very widely distributed in Africa, from 
 Egypt to Cape Colony, and is also recorded from Southern India. 
 It occurs on both man and domestic animals, and experiments 
 have shown that the species is capable of transmitting the human 
 relapsing fever of tropical Africa. 
 
 Dermacentor retnixtux is a North American form, ranging from 
 British Columbia southwards to Northern New Mexico, and from 
 the foothills of the Eocky Mountains in Colorado to the base of the 
 Cascade Eange, in Oregon and California (see map). Almost all 
 the small mammals found in the localities in which this tick occurs 
 serve as hosts for the larvae and nymphs. The adult tick is 
 
 +JP 
 
 FIG. 14. AN AFRICAN TICK, 
 
 Oniithodoros moubata, female, under surface, X 4; largely n-sponsible for tin spiv.-nl t 
 the relapsing fever of Africa. 
 
 nearly always met with on the larger domestic animals, especially 
 on horses and oxen. The species also attacks man, and transmits 
 the spotted fever of the Kocky Mountains, a disease with a high 
 rate of mortality. According to some authorities, more than 
 one species has been included under the name D. rr;///.s///.s, and 
 the species conveying Kocky Mountain fever should be called 
 ]). umliTsoni Stiles. 
 
 The second group exhibited comprises examples of ticks that, 
 convey disease to domestic animals, but not to human beings; it 
 includes the following species : 
 
 Hit ijiicr/ilniltix rrrrlsi Nn. is a tick found in most parts of 
 Africa (see map), and transmits East Coast fever of cattle and the 
 
that spread Disease. 43 
 
 South African biliary fever of horses. It is known to attack oxen, 
 sheep, horses and dogs, and has also been met with upon antelopes, 
 giraffes and elephants. 
 
 Ixodes ricinus Linn, is apparently the chief carrier of red water 
 fever, a form of piroplasmosis, in cattle in Northern Europe. It 
 ranges through Europe, North Africa, Transcaucasia, Arabia, 
 China, Japan and North America. It is met with upon sheep, 
 cattle, goats, horses, dogs, deer, hedgehogs, and many other 
 mammals, also lizards, and occasionally on man. 
 
 Amblyomma hebraeum Koch is known as the bont tick ; it is a 
 common species in South Africa, and is distributed as far as 
 Central Africa. Owing to the fact that it transmits heartwater in 
 sheep, goats, and sometimes in cattle, this tick is of considerable 
 importance to agriculturists. Further remarks upon the bont tick 
 are given below. 
 
 The third group includes examples of ticks that are not known 
 to convey disease to man or other vertebrates ; three species are 
 shown, as follows : 
 
 Amblyoinma cohaerens Donitz is found in Uganda upon 
 buffaloes. 
 
 Dcrmaccntor rliinocerotis de Geer ranges from South Africa to 
 Uganda and British East Africa, and is found usually upon the 
 rhinoceros, but sometimes on antelopes. 
 
 Dermacentor circumguttatus Nn. is met with upon elephants in 
 Uganda and West Africa. 
 
 In one of the table-cases in the middle of the floor of the Hall 
 is a series of specimens and enlarged models of the bont tick, 
 Amblyomma hebraeum Koch, an African tick parasitic upon sheep, 
 goats and oxen. The exhibited series includes a drawing of a 
 small group of eggs, a model of a larva enlarged to the same size 
 as the models of the adult, namely 20 diameters, and another 
 model of the same larva still further enlarged ( x 120) to show the 
 details of structure. Models are shown of an adult male and 
 female (x 20), and actual specimens are mounted on the tablet 
 between them. The great model in the middle of the case repre- 
 sents the female when fully gorged and distended with blood and 
 eggs, magnified to the same extent ( x 20). Two actual specimens 
 of gorged females, of the size of cherries, are shown in the small 
 glass vessel of alcohol. 
 
 The bont tick is capable of transmitting to sheep, goats and 
 
44 Guide to Insects and Ticks. 
 
 oxen the deadly disease known as heartwater, when it bites a 
 healthy animal after having fed upon one that is suffering from 1 1 it- 
 disease. The organism that causes the disease has not been seen 
 in the blood of the vertebrate host, but experimental investigation 
 shows that it is not transmitted through the egg of the tick as aro 
 some other tick-borne blood-parasites of the genera Piroplasma 
 and Sj)inn-]i(ti'tn. 
 
 The larva, nymph and adult of the bont tick feed on three 
 different individual hosts, dropping to the ground after each meal ; 
 the organisms imbibed with the blood of an infected host by tlu- 
 larva are transmitted to the second host by the nymph ; and 
 similarly, if a nymph' feeds on an infected host it may, when adult, 
 transmit the organisms to the third host. Mating of the ticks 
 occurs on the skin of the third host, and the female then feeds 
 until fully gorged; afterwards it drops to the ground, and in 
 course of time produces a vast number of eggs. 
 
INDEX. 
 
 Amblyomma, 40, 43-44 
 Anopheles, 8-18, 20 
 
 Babesia, 40 
 Bacillus pestis, 34 
 Bacillus typhosus, 28 
 Bed-bugs, 37 
 Blood-worm, 17 
 Blow-flies, 31 
 Bont tick, 40, 43-44 
 Bot-fly, 31 
 
 Calabar swellings, 26 
 Ceratophyllus, 32, 36 
 Chironomus, 16-17 
 Chrysops, 26-27 
 Cimex, 37 
 Clinocoris, 37-38 
 Crab-louse, 38-39 
 Ctenocephalus, 36 
 Ctenophthalmus, 35 
 Culex, 13-16, 18, 20-21 
 
 Dermacentor, 40-43 
 Dermatophilus, 36 
 Diarrhoea, 27-30 
 Dourine, 24 
 
 Elephantiasis, 20 
 Enteric fever, 27-30 
 
 Fannia, 28-29 
 Filaria. 20, 26 
 Fishes that devour the 
 
 larvae of mosquitoes, 
 
 21 
 
 Fleas, 32-36 
 Forest-fly, 24 
 
 Gall-sickness, 24 
 Gambusia, 21 
 Glossina, 22-26 
 Gnats, 8-20 
 
 Haplochilus, 21 
 Head-louse, 38 
 Heart-water, 40, 43-44 
 Hippobosca, 24 
 Horse-fly, 27 
 House-flies, 27-31 
 
 Ixodes, 43 
 Jigger flea, 36 
 Kala-azar, 38 
 
 Laverania, 8 
 Lebistes, 21 
 Leishmania, 38 
 Leptopsylla, 36 
 Lice, 38-40 
 
 Malaria, 8-12 
 Mangrove-fly, 27 
 Margaropus, 40 
 Microscopes, 7, 34-38 
 Midge, 16-17 
 Millions, 21 
 Mosquitoes, 8-20 
 Musca, 28-31 
 Muscina, 29 
 
 Nagana, 22-23, 25 
 Nuttallia, 40 
 
 Oestrus, 31 
 Ornithodoros, 40-42 
 
 Pediculus, 38-40 
 Phthirus, 38-39 
 Piroplasma, 40 
 Plague, 32, 34, 41 
 Plasmodium, 8-12 
 Pulex, 35-36 
 
 Rat-flea, 32-36 
 edwater, 43 
 Kelapsing fever, 38,40-42 
 Rhipicephalus, 40, 42 
 
 Sheep bot-fly, 31 
 Sleeping sickness, 22-26 
 Spirochaeta, 40-41 
 Stable-fly, 29 
 Stegomyia, 18-20 
 Stomoxys, 29 
 Summer diarrhoea, 27- 
 
 30 
 Surra, 24 
 
 Tabanid flies, 26-27 
 Theileria, 40 
 Ticks, 40-44 
 Tiger-mosquito, 18 
 Top-minnows, 21 
 Trypanosoma, 22-24 
 Tsetse-flies, 22-26 
 Typhoid fever, 27-30 
 Typhus fever, 37-39 
 
 Xenopsylla, 32-35 
 Yellow fever, 18-20 
 
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