Page:The American Cyclopædia (1879) Volume VI.djvu/709

 EPIZOA 697 glands that contain a red and granular matter. This pest inhabits the crevices of beds, walls, and furniture, or wherever it can find a con- venient place to conceal itself by day. It will lodge in garments also, but always emerges at night to prey upon the blood of man. Its predatory excursions are not wholly confined to the night, for when present in the clothing it bites as well by day. The skin of some in- dividuals seems quite insensible to their bite, while upon others it causes great local irrita- tion. The black point seen in the centre of the spot is caused by the coagulation of the blood left in the wound. Sometimes a person is literally almost devoured by these creatures, and the whole body may be covered with the eruption they produce. They are found gen- erally wherever man exists. The flea (pulex irritans) belongs to the holometabolous apJia- niptera, or hopping diptera, which undergo a complete metamorphosis. Its head is short and rounded. The eye is simple. The mouth is provided with two four-jointed palpi, with a long tongue protected above by a short double upper jaw, and a sort of upper double lip or taster, and below by a projecting under jaw. The thorax is provided with two pairs of stig- mata, and with three pairs of legs, the first of which are seemingly on the head. The two hindermost are com- posed of many tarsal joints, which are very long, and furnish the means by which its enormous leaps are ta- n ea (Pulex irritans). ken. They are provi- ded also with long double claws. The pos- terior segment is covered with ten plates or rings lapping over each other, like shingles on a roof. The color of this parasite is a reddish brown. The male is smaller than the female, and its abdomen is flatter and broader. The eggs are oval, white, and covered, with a glu- tinous matter. In six days after their depo- sition, either in dust or beneath the nails, small, worm-like, jointed larvae without feet creep forth from them. In 11 days more they en- velope themselves in a thin cocoon, from which at the expiration of 11 days they emerge per- fect animals. It is a disputed point whether the males are parasitic ; Kiichenmeister argues from the structure of their head that they are not. Little need be said here about the hab- its of this insect, which in some countries, as Italy, Turkey, and Germany, is such an intol- erable nuisance. It bites all the time, day and night, and is never satisfied. Its bite, though productive of more itching, does not cause the great irritation the acanthia produces. Their horny covering or mail protects them from being crushed except by a wonderful degree of pressure, and their alert senses enable them to avoid the hunter's hand, unless it be skilful and experienced. The pulex penetrans, or chigo, jigger, or sand flea, as it is variously called, is smaller than its relative, and has a proboscis longer than its body. (See CHIGO.) The larvae of several forms of insects are oc- casionally found either in or on some part of man ; but as they are an accidental occurrence, they need only be alluded to here. The larvae of some unknown ceutrus are sometimes met with beneath the skin. They form pimples from which flows a moisture, while around them the skin is red and painful. Humboldt in his South American travels met Indians with large parts of their exposed bodies thus affected. In the intestinal canal the larvae of anthomyia scalaris and canicularis are some- times found. The musca vomitoria, or blue- bottle, sometimes deposits its larvae in open cavities of the body, as the ear, eye, or wher- ever else moisture and heat are found. The common flesh fly, M. carnaria, and the M. domestic^ also deposit their eggs at times in hot weather either on open wounds or moist places of the body, and cause the appearance known as "live sores." The larvae are some- times deposited in a highly developed condi- tion, so that they become maggots even in a few hours. Quadrupeds also are infested by lice, almost without exception each by one peculiar to itself, though sometimes one species is known to live upon several animals of the same genus. They increase with great rapid- ity upon such beasts as are kept in dirty sta- bles, seldom cleaned, and poorly cared for, and most frequently are seen upon old horses. They cause irritation, roughness of skin, and loss of hair, in consequence of the disposition of their hosts to bite and rub the affected parts. Fleas abound upon several animals, and are nearly always distinct species. The most fre- quent and troublesome pests of the herbivora are various cestri (gasterophili) or breeze flies. The oestrus peculiar to the horse, for instance, produces the well known disease called bots. (See BOTS.) Another species, (E. ovis, deposits its eggs in the nostrils of sheep, usually about half a dozen in each individual. The larvae are soon hatched, and creep by means of their two anterior hooks upward into the frontal and maxillary sinuses. There they remain until ready to undergo metamorphosis, when they fall out, gain their wings, and repeat the process. The larvae are composed of 12 seg- ments besides the head. Sheep fear these flies greatly, and often huddle together with their heads 'close to the ground to avoid them. The symptoms of their presence are sneezing and a discharge of glairy mucus from the nostrils, but they seldom do serious injury. The (E. ~boms lays its eggs on the backs and sides of oxen and cows. The larvae, hatched by the heat, penetrate the skin, and by increase of size form tumors as large as pigeon's eggs. They live upon the pus their presence produces. After a time they make a larger aperture, and, creeping out, seek a proper place in which to become chrysalids. The fly when discovered creates a great panic among cattle, and often