THESIS SOME PARASITES OF DOMESTICATED ANIMALS 7 Arthur J. Cook ~~: . =a _ Zoological Department 1900, THESIS SOME PARASITES'OF DOMESTICATED ANIMALS. The object of this thesis is to give a brief classification and description, with remedial treatments, for some of the most common insect parasites infesting domesticated animals, Parasites are forms of animal life that subsist on the prod. ucts of the bodies, or on the bodies of other forms of animal life. They are degenerate forms of higher types of insects, After many generations of obtaining food so easily, and of be- ing protected by the warmth of the host's body, and continually depending upon it for nourishment ; the parasites have nearly lost the power of free locomotion. This was plainly demonstrat ed with lice collected for this study from cats dnd guinea-pigs As soon as the hosts had been dead for a short time, the lice all crawled from the skin and remained on the ends of the hairs, dying soon afterward, The habits of all the insect parasites should be studied for economic reasons, In very many instances a thorough knowledge of their habits has been necessary in order to free the domes- ticated animals, and even.man,from.them, For example, the com- mon"*Red-louse" was found on cows necks and backs so plentiful- ly, as to be a great source of irritation, causing in some places nearly allthe hair to drop off,and even scabby patches to form on the skin. The following is a brief description and classification of each of several of the more common species. 1034477 CLASS HEXAPODA ORDER DIPTERA Family Oestridae. THe individuals of this far- ily are parasitic only in the larval condition. The fly's egezs are laid.on different parts of the animal's body; -each species on a particular portion and in no other place. Horses with their fore legs, nostrils,or jaws covered with the small, yellowish-colored eggs, are a common sight in summer. A tough chitinous material surroumds the egg and a cap of the same sub- stance covers the top. When the animal moistens the eggs with its tongue , the sap is removed and the larva crawls into the mouth of the animal. If successful in getting to the stomach, it there attaches itsself and develops. In general, it reser bles the larva of many other flies, being when adult, white, cylindrical, and about one-half an inch lons. In the spring when the larva loosens its hooks from the stomach wails, the larva can be seen in fresh horse,near stables, This is a conm- mon sight, for nearly all horses are each year infested with a few vots. If their systematic destruction is desired,-do not allow, in summer, manure to accumilate in large, exposed heaps, The piles of manure are very favorable places for the develop- ment of the larva into an adult fly. The eggs may be ddestéroye by carefully washing and scraping them from the animal's hair If done carefully and soon after being laid, it should entirely 3. prevent infestation . In appeawance, the flies are never hairy. Their heads are large , consisting mainly of large,brilliantly reflective eyes, The bodies are one-half to two-thirds of an inch long. Probably everyone has seen the peculiar manner in which the females suspend their flight in the air. The flies have a great power of vision, and are attracted from a distance vy their particular host; instinct apparently tellang them when and where to lay their ergs. About fifty species of bot- flies are Known, AAl of their larvae are not parasitic on do- mesticated animals, Those most commonly infesting domesticated animais in America are as follows, Gastrophilus equi (Fab), This flv attacks horses, but is seldom seen and is not plentiful. The eggs are attached to the lips and sides of the animal. A cloth attached under the horse's throat will assist in preventing the eggs being laid. Hypoderma lineata. This is the warble, or bot-fly of cattle. The larva enters the stomach, as does @astrophilus; but from the stomach, it burrows through its walls to the skin, falis to the ground, and subsequently develons there into an adult fly. Yorty to sixty percent of American cattle are af- fected by it. The only sure remedy is the comlete extinctidan of the larvae for one season. The fly never attacks cattle when they stani in the water, mud, or shady,protected places, in sheds ,and elsewhere , 4. Oestrus ovis(Linn). The sheep bot, The eggs of the insect are deposited in the nostrils of the sheep. ‘They soon hatch there,and the larvae crawl farther into the head, causing much irritation,- often the death of the sheep. The eggs are laid at midday during hot surmer weather. The adult larvae crawl from the sheep's head , and the transformationito the fiy takes place in the ground as with other bot-flies. Other spe- cies of this genus infest rabbits, squirrels, and reindeer, The principal remedies are;to rub the sheep's nose with tar du- ring the egg-laying season , and to provide fresh earth for the sheep to rub its nose in, when the fly is troublesore, ORDER SIPHONAPTEA The fleas, The members of this order of insects are small, have sucking mouth-parts and are wingless, Their most notable character, is their long posterior legs,which enables them to jump, making capture very difficult. The few species troublesome to dogs and to the human body can be eradicated by Cleanliness and the use of pyrethrun. CLASS ARACHNIDA ORDER ACARINA The mites, This order consists of individuals with unsegmented bodies, having a sack-like appearance and four pairs of legs, All families except one produce eggs instead of living young. The mites are very small and variable, T+ch 5e mites belong to this order. Others are small mites causirg scab and mange diseases of horses, ‘The effect of one species ig seen in the scaly legs of chickens, The latter affliction eof fowls has been seen commonly, ard like itch, spreads from one individual to another. ‘The use of grease together with ex treme cleanliness will usually remove mites in any form in which they may affect animals, CLASS HEXAPODA- ORDER HIMITTERA FAMILV PEDICULIDAE This is a class of insects in which the sucking lice are degenerate.forms of what had once more nearly the appear- ance of true bugs. The metamorphosis is incomplete, The lice suck blood from the animal host, and are analogous to seale insects which obtain nourishment from plants in the same man- ner, Wings are absent. The young are similar to the old ex- cept in size. The lice infest animals only, ard are not ca- pable of adapting themselves to hosts of another class from — those to which they are accustomed. Eggs are laid and glued upon the hairs of the host, and open as do those of the bot- fly by means of a cap; though surplus moisture is unnecessary for this purpose, Pediculus capitis (De G.). Plate 4, Ne, 1. This is the cemmen head-leuse of man, and all races ar@ affected by it. It is the best known of any louse, It has a very simi- lar appearance to the cow louse but is smaller, Cleanliness is usually a satisfactory remedy. Haemat opinus durypternus-Plate 3, No. 1. This is the conmmon"blue louse*of cattle, Specimens were collected in great numbers at the college barns during the winter of 1900- 1901. The large size and sucking capacity of this species, together with the great mumbers in which it usually thrives; irritate stock very mich, It is not unusual to see cattle with nearly all the hair from their necks, shoulders, backs, or hips, rubbed off. The females are larger than the males, usually being from one-fifth to one-eighth of an inch long. The males are characterized by two brushes at the posterior portions of their abdemens, one being on each side of the cer- ter. The males are provided with black stripes; one along the center of the body, reaching to their abdomens, This is plainly seen from the dorsal surface, Both sexes have,~on the erds of their beaks,-two rows of curved hooks, not read- ily seen upon a hasty examination of the specimens, Rows of very prominent tubercles are found on each side of the abdo- mens. Spiraciles can be seen in the tubréles,-one in eachs in the form of cylindrical tubes extending forward and inward toward the center of the body. ‘They are found in the tuber- Cles of the six posterior segments, not including the last one. The anternae are as long as the head. The eggs are oval in form, and have a cap at the uprer end of each, which is removed upor the eggs' hatching, 7. Haematopinus urius (N) Plate 8, No. 8, This is the common heg-louse. It is very large, often approaching in size the above species, Iteften occurs in great numbers, fhe killing of a large percentage of hogs at an early age, destroys many lice and tends to keep them in check. The color ef the individuals is grey. The head is long. Males are characterized by having large, often irregular, black spots on their abdomens. On each,a pad-like organ on the outer portion of the tibia , is arranged for firmly grasping the hair of the host. The eggs are large and of a yellowish color, ORDER MALLOPHAGA, This order is nearly related to the hemiptera. The general appearance of the insects is similar to that of the previous true lice, and they afte with equal accuracy termed lice. The members of this order have biting mouth-parts; met- amorphesis is incomplete. The adults are similar to the young. The antennae are five jointed, except in the genus Trichodec- tes.The abdemens are eval, nine to ten segmented, Suctorial organs are often present, but are inconspicnous and undevelop- ed. The eyes,when visible, are located back of the antennae, The eggs are glued to the hairs, and open by means of & cap, Several days afe needed for incubation to take place, Trichodectes latis (N) Plate 2, NO. 1-2. This is a very common species infesting dogs, having an especial pref- erence for puppies. Its head is large in proportion to its 8. body. The color is dark yellow, ‘The legs have strong, curved Claws. The joints of the thorax are as long as erg as the abdomen, which is ten jeinted, The length of its body is equal to that of the cat-louse (Trichodectes subrostratus N), but the body of the former is broader. . This species repro- duces very rapidly. Trichodectes scalaris (N) Plate 1, No. 1, This is. the scormmon *"red-louse"of cattle. It is very common in Mich- igan, and was found quite abundantly on College cattle during the winter of 1900-1901, Its effects on the hosts are appa rently the same as those of Ha@matopinus, judged by the irri- tation which the pest causes, Its name "red-louse"is applied because of the red, chitinous material, conspicuously located as rib-like, parallel blotches on the abdomen, This together with the same material of the head and other parts of the body, gives the insect the appearance of being nearly entirely red. Other prominent characteristics are;- the heart-shaped head; sides of head being covered with bristles; smalland in- conspicuous eyes; and the small first segment of the thorax, Trichodectes subrostratus (N) Plate 2, No, 3-4, This leuse found on the cat, is somewhat emailer than the pre- ceding species, It is incenspicuous, of a whitish color, and usually eccura in great numbers. It is very Slender, easily killed; and is in direct direct contrast to both species of Haematopinus in size and tenacity ef life, The head and thorax 9. tegether are as long as the net ey ee which has nine segments, Beth sexes ate characterized by one and sometimes two or three very long, coarse hairs on the last four sepments of the abdemen. A groeve is provided on the under surface of the head for olasping the hest's hair, The specimens held to the hair very tenaciously, even after death. In those col- lected in February, 1900-all‘ crawled away from the dead cat's body. They firmly clasped the hairs about one-eighth of an inch from the skin, dying there very soon after the death of the host. Gyropus ovalis (N) Plate 1, No, 3, This is one of the two mest cemmen lice of the guinea-pig. Both this and the succeeding species were found on the same animal. The pest is smaller than any of the species described, is of a whitish color, is very fragile,and is easily Killed. The body is rat- her broad, appears stout,and has a moderate amount of chitin- ous material throughout. The celor is pale yellow or white; fead and thorax have a bright,reddish tinge,- making the abde- men seem celorless and inconspicuous. In the specimens of this and the succeeding species from the same animal, both were mingled,and in great numbers. As with Trichodectes sub— rostratus, the lice crawled from the hest as soon as it was killed, remaining on the hairs, The tenacity of life in this species is not great, Gyropus gracilis Plate 1, No. 4. This species is lo, also found on the guinea-pig. It is very mich more slender and inconspicuous in appearance than the preceding species, being smaller, due more to diameter than length. The body is elongate and lacks firmness, due to the absence of mich chi- tinous material. The color is pale vellow, rather translucent with a darker, more conspicuous head and therax, The entire body is densely and very finely pubescent. The tarsi are very smalland slender. This species can usually be disting- uished from Gyropus ovalis, from the latter's cemparitively short, firm appearance; contrasted with the very slender, in- conspicuous body of Gyropus gracilis. Both species usually are intimately associated with one another, and have very similar habits, Menoporn. - Two species of this genus are very nearly alike, and infest the same fowl in the same colony. They are often described as one géneral species. They are the great pests of demestic fowls, and where found, usually are in great numbers, Unlike any of the ether described species, they are found in colonies containig twenty-five, fifty, or one-hundred individuals, and they appear to prefer the abdomen, and the portion of the body under the wings; probably because the warmth and protection is greatest at these two places,They are very active on the host, and are extremely irritating, espeo- lally to young fowls. At least a few can be found during every month of the year, even in the best rerulated poultry ll. houses, The members of the species have a very long abdomen, occunying at least three-fourths of the length of the entire body. The body is conspicuous in another manner, as it is en- tirely covered with long, coarse hairs; two rows being on each of the ten segments of the abdomer., except the last one, Equ- ally conspicuous ones are along the sides of the body, and on the head and legs, with a dense fringe of them underneath. The digestive tract can be seen through the ahdominal walls as an irregular mass of dark material, the conspicuousness and shape varying with the individual louse. Four good reme- a@ies are known,- the use of pyrethrum; grease; free access of fowls to a dust bath; and the spraying of the hen-house with keresere pr whitewash. The remedies for all the lice mentioned can be sun- marized, in general, by sgying that any strong solutions like scotch snuff, tobacco water, and keresere emulsion; will kill allthe lice, Care must be taken to vary the strength and num ber of applications to the species, and to the condition of the affected animal. The lice which are here referred to have been colle ected by the writer. The method of preserving them is to fir first place the lot collected in a solution consisting of one hundred parts of ninety-six percent alcohol; one hundred parts of distilled water; and ter. parts of forty percent conmercial formalin. From this solution they are transferred, after a 12. few hours to a solution of pure alcohol, From there they are placed in a turpentine clearing solution; then are removed to glass microscopic slides, and are inmersed in damar under cover glasses, The specimens will keep for years in this con- ditior. A complete list accurately labeled is very valuable for reference to any worker on insect parasites, Plate 1. Plate 4: Plates, Tle i. ‘Teichodectes Scalaris (TL) 2. Ylenopon 3. yroprs ovale) 4, + gracilis Plate 4. Tle f, Tiichodecrtes latie (If) Teale i, " ” ” female ; Subroctratusil[) male, ° . jemale P) abe : Tot, :(eametopsnns eurysternus (I[) male a " « 4 pemale 3. Ha matopinus unine uy P late 4f, Ke i. Raveuwlus caprics (De G) Plate 4. iii TATE UNI ! TA 3 1 3046 6936 293 0