79. Human Bot Worm.
We now come to the Bot flies, which are among the most extraordinary, in their habits, of all insects. The history of the Bot flies is in brief thus. The adult two-winged fly lays its eggs on the exterior of the animal to be infested. They are conveyed into the interior of the host, where they hatch, and the worm or maggot lives by sucking in the purulent matter, caused by the irritation set up by its presence in its host; or else the worm itself, after hatching, bores under the skin. When fully grown, it quits the body and finishes its transformations to the fly-state under ground. Many quadrupeds, from mice, squirrels, and rabbits, up to the ox, horse, and even the rhinoceros, suffer from their attacks, while man himself is not exempt. The body of the adult fly is stout and hairy, and it is easily recognized by having the opening of the mouth very small, the mouth-parts being very rudimentary. The larvæ are, in general, thick, fleshy, footless grubs, consisting of eleven segments, exclusive of the head, which are covered with rows of spines and tubercles, by which they move about within the body, thus irritating the animals in which they take up their abode. The breathing pores (stigmata) open in a scaly plate at the posterior end of the body. The mouth-parts (mandibles, etc.) of the subcutaneous larvæ consist of fleshy tubercles, while in those species which live in the stomachs and frontal sinuses of their host, they are armed with horny hooks.
80. Horse Bot Fly.
The larvæ attain their full size after moulting twice. Just before assuming the pupa state, the maggot leaves its peculiar dwelling place, descends into the ground and there becomes a pupa, though retaining its larval skin, which serves as a protection to it, whence it is called a "puparium."
Several well-authenticated instances are on record of a species of bot fly inhabiting the body of man, in Central and South America, producing painful tumors under the skin of the arm, legs and abdomen. It is still under dispute whether this human bot fly is a true or accidental parasite, the more probable opinion being that its proper host is the monkey or dog. In Cayenne, this revolting grub is called the Ver macaque (Fig. 79); in Para, Ura; in Costa Rica, Torcel; and in New Granada, Gusano peludo, or Nuche. The Dermatobia noxialis, supposed to be the Ver moyocuil of the inhabitants of Mexico and New Granada, lives beneath the skin of the dog.
81. Bot Fly of Ox, and Larva.
