Chapter Xii. Four Blood-Sucking Species Belonging to Three Genera Have

been reported. Of these Symphoromyia pachyceras is a western species. Dr. J. C. Bradley, from personal experience, reports it as a vicious biter.

Oestridae or Bot-flies

To the family OESTRIDAE belong the bot and warble-flies so frequently injurious to animals. The adults are large, or of medium size, heavy bodied, rather hairy, and usually resemble bees in appearance.

The larvae live parasitically in various parts of the body of mammals, such as the stomach (horse bot-fly), the subcutaneous connective tissue (warble-fly of cattle), or the nasal passage (sheep bot-fly or head maggot).

There are on record many cases of the occurrence of the larvae of Oestridae as occasional parasites of man. A number of these have been collected and reviewed in a thesis by Mme. Petrovskaia (1910). The majority of them relate to the following species.

Gastrophilus haemorrhoidalis, the red tailed bot-fly, is one of the species whose larvae are most commonly found in the stomach of the horse. Schoch (1877) cites the case of a woman who suffered from a severe case of chronic catarrh of the stomach, and who vomited, and also passed from the anus, larvae which apparently belonged to this species. Such cases are exceedingly rare but instances of subcutaneous infestation are fairly numerous. In the latter type these larvae are sometimes the cause of the peculiar "creeping myasis." This is characterized at its beginning by a very painful swelling which gradually migrates, producing a narrow raised line four to twenty-five millimeters broad. When the larva is mature, sometimes after several months, it becomes stationary and a tumor is formed which opens and discharges the larva along with pus and serum.

Gastrophilus equi is the most widespread and common of the horse bot-flies. Portschinsky reports it as commonly causing subcutaneous myasis of man in Russia.

Hypoderma bovis (= Oestrus bovis), and Hypoderma lineata are the so-called warble-flies of cattle. The latter species is the more common in North America but Dr. C. G. Hewitt has recently shown that H. bovis also occurs. Though warbles are very common in cattle in this country, the adult flies are very rarely seen. They are about half an inch in length, very hairy, dark, and closely resemble common honey-bees.

They deposit their eggs on the hairs of cattle and the animals in licking themselves take in the young larvae. These pass out through the walls of the oesophagus and migrate through the tissues of the animal, to finally settle down in the subcutaneous tissue of the back. The possibility of their entering directly through the skin, especially in case of infestation of man, is not absolutely precluded, although it is doubtful.

For both species of Hypoderma there are numerous cases on record of their occurrence in man. Hamilton (1893) saw a boy, six years of age, who had been suffering for some months from the glands on one side of his neck being swollen and from a fetid ulceration around the back teeth of the lower jaw of the same side. Three months' treatment was of no avail and the end seemed near; one day a white object, which was seen to move, was observed in the ulcer at the root of the tongue, and on being extracted was recognized as a full grown larva of Hypoderma. It was of usual tawny color, about half an inch long when contracted, about one third that thickness, and quite lively. The case resulted fatally. The boy had been on a dairy farm the previous fall, where probably the egg (or larva) was in some way taken into his mouth, and the larva found between the base of the tongue and the jaw suitable tissue in which to develop.

Topsent (1901) reports a case of "creeping myasis" caused by H. lineata in the skin of the neck and shoulders of a girl eight years of age. The larva travelled a distance of nearly six and a half inches. The little patient suffered excruciating pain in the place occupied by the larva.

Hypoderma diana infests deer, and has been known to occur in man.

Oestris ovis, the sheep bot-fly, or head maggot, is widely distributed in all parts of the world. In mid-summer the flies deposit living maggots in the nostrils of sheep. These larvae promptly pass up the nasal passages into the frontal and maxillary sinuses, where they feed on the mucous to be found there. In their migrations they cause great irritation to their host, and when present in numbers may cause vertigo, paroxysms, and even death. Portschinsky in an important monograph on this species, has discussed in detail its relation to man. He shows that it is not uncommon for the fly to attack man and that the minute living larvae are deposited in the eyes, nostrils, lips, or mouth. A typical case in which the larvae were deposited in the eye was described by a German oculist Kayser, in 1905. A woman brought her six year old daughter to him and said that the day before, about noontime, a flying insect struck the eye of the child and that since then she had felt a pain which increased towards evening. In the morning the pain ceased but the eye was very red. She was examined at about noon, at which time she was quiet and felt no pain. She was not sensitive to light, and the only thing noticed was a slight congestion and accumulation of secretion in the corner of the right eye. A careful examination of the eye disclosed small, active, white larvae that crawled out from the folds of the conjunctiva and then back and disappeared. Five of these larvae were removed and although an uncomfortable feeling persisted for a while, the eye became normal in about three weeks.

Some of the other recorded cases have not resulted so favorably, for the eyesight has been seriously affected or even lost.

According to Edmund and Etienne Sergent (1907), myasis caused by the larvae of Oestris ovis is very common among the shepherds in Algeria. The natives say that the fly deposits its larvae quickly, while on the wing, without pause. The greatest pain is caused when these larvae establish themselves in the nasal cavities. They then produce severe frontal headaches, making sleep impossible. This is accompanied by continuous secretion from the nasal cavities and itching pains in the sinuses. If the larvae happen to get into the mouth, the throat becomes inflamed, swallowing is painful, and sometimes vomiting results. The diseased condition may last for from three to ten days or in the case of nasal infection, longer, but recovery always follows. The natives remove the larvae from the eye mechanically by means of a small rag. When the nose is infested, tobacco fumigations are applied, and in case of throat infestation gargles of pepper, onion, or garlic extracts are used.

Rhinoestrus nasalis, the Russian gad-fly, parasitizes the nasopharyngeal region of the horse. According to Portschinsky, it not infrequently attacks man and then, in all the known cases deposits its larvae in the eye, only. This is generally done while the person is quiet, but not during sleep. The fly strikes without stopping and deposits its larva instantaneously. Immediately after, the victim experiences lancinating pains which without intermission increase in violence. There is an intense conjunctivitis and if the larvae are not removed promptly the envelopes of the eye are gradually destroyed and the organ lost.

Dermatobia cyaniventris--This fly (fig. 83) is widely distributed throughout tropical America, and in its larval stage is well known as a parasite of man. The larvae (figs. 81 and 82) which are known as the "ver macaque," "torcel," "ver moyocuil" or by several other local names, enter the skin and give rise to a boil-like swelling, open at the top, and comparable with the swelling produced by the warble fly larvae, in cattle. They cause itching and occasional excruciating pain. When mature, nearly an inch in length, they voluntarily leave their host, drop to the ground and complete their development. The adult female is about 12 mm. in length. The face is yellow, the frons black with a grayish bloom; antennae yellow, the third segment four times as long as the second, the arista pectinate. The thorax is bluish black with grayish bloom; the abdomen depressed, brilliant metallescent blue with violet tinge. The legs are yellowish, the squamae and wings brownish.

The different types of larvae represented in figure 81 were formerly supposed to belong to different species but Blanchard regards them as merely various stages of the same species. It is only very recently that the early stage and the method by which man becomes infested were made known.

About 1900, Blanchard observed the presence of packets of large-sized eggs under the abdomen of certain mosquitoes from Central America; and in 1910, Dr. Morales, of Costa Rica, declared that the Dermatobia deposited its eggs directly under the abdomen of the mosquito and that they were thus carried to vertebrates. Dr. Nunez Tovar observed the mosquito carriers of the eggs and placing larvae from this source on animals, produced typical tumors and reared the adult flies. It remained for Surcouf (1913) to work out the full details. He found that the Dermatobia deposits its eggs in packets covered by a very viscid substance, on leaves. These become attached to mosquitoes of the species Janthinosoma lutzi (fig. 84) which walk over the leaves. The eggs which adhere to the abdomen, remain attached and are thus transported. The embryo develops, but the young larva (fig. 82) remains in the egg until it has opportunity to drop upon a vertebrate fed upon by the mosquito.

Muscidae

The following MUSCIDAE, characterized elsewhere, deserve special mention under our present grouping of parasitic species. Other important species will be considered as facultative parasites.

Stomoxys calcitrans, the stable-fly, or the biting house-fly, is often confused with Musca domestica and therefore is discussed especially in our consideration of the latter species as an accidental carrier of disease. Its possible relation to the spread of infantile paralysis is also considered later.

The tsetse flies, belonging to the genus Glossina, are African species of blood-sucking Muscidae which have attracted much attention because of their role in transmitting various trypanosome diseases of man and animals. They are characterized in Chapter XII and are also discussed in connection with the diseases which they convey.

Chrysomyia macellaria, (= Compsomyia), the "screw worm"-fly is one of the most important species of flies directly affecting man, in North America. It is not normally parasitic, however, and hence will be considered with other facultative parasites in Chapter IV.

Auchmeromyia luteola, the Congo floor maggot. This is a muscid of grewsome habits, which has a wide distribution throughout Africa. The fly (fig. 86) deposits its eggs on the ground of the huts of the natives. The whitish larvae (fig. 85) on hatching are slightly flattened ventrally, and each segment bears posteriorly three foot-pads transversely arranged. At night the larvae find their way into the low beds or couches of the natives and suck their blood. The adult flies do not bite man and, as far as known, the larvae do not play any role in the transmission of sleeping sickness or other diseases.

This habit of blood-sucking by muscid larvae is usually referred to as peculiar to Auchmeromyia luteola but it should be noted that the larvae of Protocalliphora frequent the nests of birds and feed upon the young. Mr. A. F. Coutant has studied especially the life-history and habits of P. azurea, whose larvae he found attacking young crows at Ithaca, N.Y. He was unable to induce the larvae to feed on man.

Cordylobia anthropophaga, (Ochromyia anthropophaga), or Tumbu-fly (fig. 87) is an African species whose larvae affect man much as do those of Dermatobia cyniventris, of Central and South America. The larva (fig. 88), which is known as "ver du Cayor" because it was first observed in Cayor, in Senegambia, develops in the skin of man and of various animals, such as dogs, cats, and monkeys. It is about 12 mm. in length, and of the form of the larvae of other muscids. Upon the intermediate segments are minute, brownish recurved spines which give to the larva its characteristic appearance. The life-history is not satisfactorily worked out, but Fuller (1914), after reviewing the evidence believes that, as a rule, it deposits its young in the sleeping places of man and animals, whether such be a bed, a board, the floor, or the bare ground. In the case of babies, the maggots may be deposited on the scalp. The minute maggots bore their way painlessly into the skin. As many as forty parasites have been found in one individual and one author has reported finding more than three hundred in a spaniel puppy. Though their attacks are at times extremely painful, it is seldom that any serious results follow.

THE SIPHONAPTERA OR FLEAS

The SIPHONAPTERA, or fleas (fig. 89) are wingless insects, with highly chitinized and laterally compressed bodies. The mouth-parts are formed for piercing and sucking. Compound eyes are lacking but some species possess ocelli. The metamorphosis is complete.

This group of parasites, concerning which little was known until recently, has assumed a very great importance since it was learned that fleas are the carriers of bubonic plague. Now over four hundred species are known. Of these, several species commonly attack man. The most common hominoxious species are Pulex irritans, Xenopsylla cheopis, Ctenocephalus canis, Ctenocephalus felis, Ceratophyllus fasciatus and Dermatophilus penetrans, but many others will feed readily on human blood if occasion arises.

We shall treat in this place of the general biology and habits of the hominoxious forms and reserve for the systematic section the discussion of the characteristics of the different genera.

The most common fleas infesting houses in the Eastern United States are the cosmopolitan dog and cat fleas, Ctenocephalus canis (fig. 90) and C. felis. Their life cycles will serve as typical. These two species have until recently been considered as one, under the name Pulex serraticeps. See figure 92.

The eggs are oval, slightly translucent or pearly white, and measure about .5 mm. in their long diameter. They are deposited loosely in the hairs of the host and readily drop off as the animal moves around. Howard found that these eggs hatch in one to two days. The larvae are elongate, legless, white, worm-like creatures. They are exceedingly active, and avoid the light in every way possible. They cast their first skin in from three to seven days and their second in from three to four days. They commenced spinning in from seven to fourteen days after hatching and the imago appeared five days later. Thus in summer, at Washington, the entire life cycle may be completed in about two weeks. (cf. fig. 91, 92).

Strickland's (1914) studies on the biology of the rat flea, Ceratophyllus fasciatus, have so important a general bearing that we shall cite them in considerable detail.

He found, to begin with, that there is a marked inherent range in the rate of development. Thus, of a batch of seventy-three eggs, all laid in the same day and kept together under the same conditions, one hatched in ten days; four in eleven days; twenty-five in twelve days; thirty-one in thirteen days; ten in fourteen days; one in fifteen days; and one in sixteen days. Within these limits the duration of the egg period seems to depend mainly on the degree of humidity. The incubation period is never abnormally prolonged as in the case of lice, (Warburton) and varying conditions of temperature and humidity have practically no effect on the percentage of eggs which ultimately hatch.

The same investigator found that the most favorable condition for the larva is a low temperature, combined with a high degree of humidity; and that the presence of rubbish in which the larva may bury itself is essential to its successful development. When larvae are placed in a bottle containing either wood-wool soiled by excrement, or with feathers or filter paper covered with dried blood they will thrive readily and pupate. They seem to have no choice between dried blood and powdered rat feces for food, and also feed readily on flea excrement. They possess the curious habit of always devouring their molted skins.

An important part of Strickland's experiments dealt with the question of duration of the pupal stage under the influence of temperature and with the longevity and habits of the adult. In October, he placed a batch of freshly formed cocoons in a small dish that was kept near a white rat in a deep glass jar in the laboratory. Two months later one small and feeble flea had emerged, but no more until February, four months after the beginning of the experiment. Eight cocoons were then dissected and seven more found to contain the imago fully formed but in a resting state. The remainder of the batch was then placed at 70^o F. for one night, near a white rat. The next day all the cocoons were empty and the fleas were found on the white rat.

Thus, temperature greatly influences the duration of the pupal period, which in Ceratophyllus fasciatus averages seventeen days. Moreover, when metamorphosis is complete a low temperature will cause the imago to remain within the cocoon.

Sexually mature and ovipositing fleas, he fed at intervals and kept alive for two months, when the experiment was discontinued. In the presence of rubbish in which they could bury themselves, unfed rat fleas were kept alive for many months, whereas in the absence of any such substratum they rarely lived a month. In the former case, it was found that the length of life is influenced to some degree by the temperature and humidity. In an experiment carried out at 70^o F. and 45 per cent humidity, the fleas did not live for more than four months, while in an experiment at 60^o F. and 70 per cent humidity they lived for at least seventeen months. There was no indication that fleas kept under these conditions sucked moisture from surrounding objects, and those kept in bell jars, with an extract of flea-rubbish on filter paper, did not live any longer than those which were not so supplied.

Curiously enough, although the rat is the normal host of Ceratophyllus fasciatus, it was found that when given the choice these fleas would feed upon man in preference to rats. However, none of the fleas laid eggs unless they fed on rat blood.

The experiments of Strickland on copulation and oviposition in the rat flea showed that fleas do not copulate until they are sexually mature and that, at least in the case of Ceratophyllus fasciatus, the reproductive organs are imperfectly developed for some time (more than a week) after emerging from the pupa. When mature, copulation takes place soon after the fleas have fed on their true host--the rat--but not if they have fed on a facultative host only, such as man. Copulation is always followed by oviposition within a very short time.

The effect of the rat's blood on the female with regard to egg-laying, Strickland concludes, is stimulating rather than nutritive, as fleas that were without food for many months were observed to lay eggs immediately after one feed. Similarly, the male requires the stimulus of a meal of rat's blood before it displays any copulatory activity.

Mitzmain (1910) has described in detail the act of biting on man, as observed in the squirrel flea, Ceratophyllus acutus. "The flea when permitted to walk freely on the arm selects a suitable hairy space where it ceases abruptly in its locomotion, takes a firm hold with the tarsi, projects its proboscis, and prepares to puncture the skin. A puncture is drilled by the pricking epipharynx, the saw-tooth mandibles supplementing the movement by lacerating the cavity formed. The two organs of the rostrum work alternately, the middle piece boring, while the two lateral elements execute a sawing movement. The mandibles, owing to their basal attachments, are, as is expressed by the advisory committee on plague investigations in India (Journal of Hygiene, vol. 6, No. 4, p. 499), 'capable of independent action, sliding up and down but maintaining their relative positions and preserving the lumen of the aspiratory channel.' The labium doubles back, the V-shaped groove of this organ guiding the mandibles on either side."

"The action of the proboscis is executed with a forward movement of the head and a lateral and downward thrust of the entire body. As the mouth-parts are sharply inserted, the abdomen rises simultaneously. The hind and middle legs are elevated, resembling oars. The forelegs are doubled under the thorax, the tibia and tarsi resting firmly on the epidermis serve as a support for the body during the feeding. The maxillary palpi are retracted beneath the head and thorax. The labium continues to bend, at first acting as a sheath for the sawing mandibles, and as these are more deeply inserted, it bends beneath the head with the elasticity of a bow, forcing the mandibles into the wound until the maxillae are embedded in the skin of the victim. When the proboscis is fully inserted, the abdomen ceases for a time its lateral swinging."

"The acute pain of biting is first felt when the mandibles have not quite penetrated and subsequently during each distinct movement of the abdomen. The swinging of the abdomen gradually ceases as it becomes filled with blood. The sting of the biting gradually becomes duller and less sensitive as feeding progresses. The movements of the elevated abdomen grow noticeably feebler as the downward thrusts of the springy bow-like labium becomes less frequent."

"As the feeding process advances one can discern through the translucent walls of the abdomen a constant flow of blood, caudally from the pharynx, accompanied by a peristaltic movement. The end of the meal is signified in an abrupt manner. The flea shakes its entire body, and gradually withdraws its proboscis by lowering the abdomen and legs and violently twisting the head."

"When starved for several days the feeding of the rat fleas is conducted in a rather vigorous manner. As soon as the proboscis is buried to the full length the abdomen is raised and there ensues a gradual lateral swaying motion, increasing the altitude of the raised end of the abdomen until it assumes the perpendicular. The flea is observed at this point to gain a better foothold by advancing the fore tarsi, and then, gradually doubling back the abdomen, it turns with extreme agility, nearly touching with its dorsal side the skin of the hand upon which it is feeding. Meanwhile, the hungry parasite feeds ravenously."

"It is interesting to note the peculiar nervous action which the rodent fleas exhibit immediately when the feeding process is completed or when disturbed during the biting. Even while the rostrum is inserted to the fullest the parasite shakes its head spasmodically; in a twinkling the mouth is withdrawn and then the flea hops away."

A habit of fleas which we shall see is of significance in considering their agency in the spread of bubonic plague, is that of ejecting blood from the anus as they feed.

Fleas are famous for their jumping powers, and in control measures it is of importance to determine their ability along this line. It is often stated that they can jump about four inches, or, according to the Indian Plague Commission Xenopsylla cheopis cannot hop farther than five inches. Mitzmain (1910) conducted some careful experiments in which he found that the human flea, Pulex irritans, was able to jump as far as thirteen inches on a horizontal plane. The mean average of five specimens permitted to jump at will was seven and three-tenths inches. The same species was observed to jump perpendicularly to a height of at least seven and three-fourths inches. Other species were not able to equal this record.

The effect of the bite of fleas on man varies considerably according to the individual susceptibility. According to Patton and Cragg, this was borne out in a curious manner by the experiments of Chick and Martin. "In these, eight human hosts were tried; in seven, little or no irritation was produced, while in one quite severe inflammation was set up around each bite." Of two individuals, equally accustomed to the insects, going into an infested room, one may be literally tormented by them while the other will not notice them. Indeed it is not altogether a question of susceptibility, for fleas seem to have a special predilection for certain individuals. The typical itching wheals produced by the bites are sometimes followed, especially after scratching, by inflammatory papules.

The itching can be relieved by the use of lotions of carbolic acid (2-3 per cent), camphor, menthol lotion, or carbolated vaseline. If forced to sleep in an infested room, protection from attacks can be in a large measure gained by sprinkling pyrethrum, bubach, or California insect powder between the sheets. The use of camphor, menthol, or oil of eucalyptus, or oil of pennyroyal is also said to afford protection to a certain extent.

In the Eastern United States the occurrence of fleas as household pests is usually due to infested cats and dogs which have the run of the house. We have seen that the eggs are not attached to the host but drop to the floor when they are laid. Verrill, cited by Osborn, states that on one occasion he was able to collect fully a teaspoonful of eggs from the dress of a lady in whose lap a half-grown kitten had been held for a short time. Patton and Cragg record seeing the inside of a hat in which a kitten had spent the night, so covered with flea eggs that it looked "as if it had been sprinkled with sugar from a sifter." It is no wonder that houses in which pets live become overrun with the fleas.

One of the first control measures, then, consists in keeping such animals out of the house or in rigorously keeping them free from fleas. The latter can best be accomplished by the use of strong tar soap or Armour's "Flesope," which may be obtained from most druggists. The use of a three per cent solution of creolin, approximately four teaspoonfuls to a quart of warm water, has also been recommended. While this is satisfactory in the case of dogs, it is liable to sicken cats, who will lick their fur in an effort to dry themselves. Howard recommends thoroughly rubbing into the fur a quantity of pyrethrum powder. This partially stupifies the fleas which should be promptly swept up and burned.

He also recommends providing a rug for the dog or cat to sleep on and giving this rug a frequent shaking and brushing, afterwards sweeping up and burning the dust thus removed.

Since the larvae of fleas are very susceptible to exposure, the use of bare floors, with few rugs, instead of carpets or matting, is to be recommended. Thorough sweeping, so as to allow no accumulation of dust in cracks and crevices will prove efficient. If a house is once infested it may be necessary to thoroughly scrub the floors with hot soapsuds, or to spray them with gasoline. If the latter method is adopted, care must be taken to avoid the possibility of fire.

To clear a house of fleas Skinner recommends the use of flake naphthalene. In a badly infested house he took one room at a time, scattering on the floor five pounds of flake naphthalene, and closed it for twenty-four hours. It proved to be a perfect and effectual remedy and very inexpensive, as the naphthalene could be swept up and transferred to other rooms. Dr. Skinner adds, "so far as I am concerned, the flea question is solved and if I have further trouble I know the remedy. I intend to keep the dog and cat."

The late Professor Slingerland very effectively used hydrocyanic acid gas fumigation in exterminating fleas in houses. In one case, where failure was reported, he found on investigation that the house had become thoroughly reinfested from pet cats, which had been left untreated. Fumigation with sulphur is likewise efficient.

The fact that adult fleas are usually to be found on the floor, when not on their hosts, was ingeniously taken advantage of by Professor S. H. Gage in ridding an animal room at Cornell University of the pests. He swathed the legs of a janitor with sticky fly-paper and had him walk back and forth in the room. Large numbers of the fleas were collected in this manner.

In some parts of the southern United States hogs are commonly infested and in turn infest sheds, barns and even houses. Mr. H. E. Vick informs us that it is a common practice to turn sheep into barn-lots and sheds in the spring of the year to collect in their wool, the fleas which abound in these places after the hogs have been turned out.

It is a common belief that adult fleas are attracted to fresh meat and that advantage of this can be taken in trapping them. Various workers, notably Mitzman (1910), have shown that there is no basis for such a belief.

THE TRUE CHIGGERS--The chigoes, or true chiggers, are the most completely parasitic of any of the fleas. Of the dozen or more known species, one commonly attacks man. This is Dermatophilus penetrans, more commonly known as Sarcopsylla penetrans or Pulex penetrans.

This species occurs in Mexico, the West Indies, Central and South America. There are no authentic records of its occurrence in the United States although, as Baker has pointed out, there is no reason why it should not become established in Florida and Texas. It is usually believed that Brazil was its original home. Sometime about the middle of the nineteenth century it was introduced into West Africa and has spread across that continent.

The males and the immature females of Dermatophilus penetrans (fig. 93) closely resemble those of other fleas. They are very active little brown insects about 1-1.2 mm. in size, which live in the dust of native huts and stables, and in dry, sandy soil. In such places they often occur in enormous numbers and become a veritable plague.

They attack not only man but various animals. According to Castellani and Chalmers, "Perhaps the most noted feature is the way in which it attacks pigs. On the Gold Coast it appeared to be largely kept in existence by these animals. It is very easily captured in the free state by taking a little pig with a pale abdomen, and placing it on its back on the ground on which infected pigs are living. After watching a few moments, a black speck will appear on the pig's abdomen, and quickly another and another. These black specks are jiggers which can easily be transferred to a test tube. On examination they will be found to be males and females in about equal numbers."

Both the males and females suck blood. That which characterizes this species as distinguished from other fleas attacking man is that when the impregnated female attacks she burrows into the skin and there swells until in a few days she has the size and appearance of a small pea (fig. 94). Where they are abundant, hundreds of the pests may attack a single individual (fig. 95). Here they lie with the apex of the abdomen blocking the opening. According to Fulleborn (1908) they do not penetrate beneath the epidermis. The eggs are not laid in the flesh of the victim, as is sometimes stated, but are expelled through this opening. The female then dies, withers and falls away or is expelled by ulceration. According to Brumpt, she first quits the skin and then, falling to the ground, deposits her eggs. The subsequent development in so far as known, is like that of other fleas.

The chigoe usually enters between the toes, the skin about the roots of the nails, or the soles of the feet, although it may attack other parts of the body. Mense records the occurrence in folds of the epidermis, as in the neighborhood of the anus. They give rise to irritation and unless promptly and aseptically removed there often occurs pus formation and the development of a more or less serious abscess. Gangrene and even tetanus may ensue.

Treatment consists in the careful removal of the insect, an operation more easily accomplished a day or two after its entrance, than at first, when it is unswollen. The ulcerated point should then be treated with weak carbolic acid, or tincture of iodine, or dusted thoroughly with an antiseptic powder.

Castellani and Chalmers recommend as prophylactic measures, keeping the house clean and keeping pigs, poultry, and cattle away therefrom. "High boots should be used, and especial care should be taken not to go to a ground floor bathroom with bare feet. The feet, especially the toes, and under the nails, should be carefully examined every morning to see if any black dots can be discovered, when the jigger should be at once removed, and in this way suppuration will be prevented. It is advisable, also, to sprinkle the floors with carbolic lotion, Jeyes' fluid, or with pyrethrum powder, or with a strong infusion of native tobacco, as recommended by Law and Castellani."

Echidnophaga gallinacea (fig. 96) is a widely distributed Hectopsyllid attacking poultry (fig. 97). It occurs in the Southern and Southwestern United States and has been occasionally reported as attacking man, especially children. It is less highly specialized than Dermatophilus penetrans, and does not ordinarily cause serious trouble in man.