nces are also on
record where these larvae have been discharged from the urethra.

Another fly (_Ochromyia anthropophaga_) occurring in the Congo region
has a blood-sucking larvae which is known as the Congo floor-maggot. The
fly which is itself not troublesome deposits its eggs in the cracks and
crevices of the mud floors of the huts. The larvae which hatch from these
crawl out at night and suck the blood of the victim that may be sleeping
on the floor or on a low bed.

BOT-FLIES

Another group of flies known as the bot-flies (Fig. 30) have their
mouth-parts rudimentary or entirely wanting so of course they themselves
cannot bite or pierce an animal. Nevertheless they are the source of an
endless amount of trouble to stockmen and sometimes even attack man.
Although these flies cannot bite, the presence of even a single
individual may be enough to annoy a horse almost to the end of
endurance. Horses seem to have an instinctive fear of them and will do
all in their power to get rid of the annoying pests.

The eggs of the house bot-fly are laid on the hair of the legs or some
other part of the body. The horse licks them off and they hatch and
develop in the alimentary canal of their host. Sometimes the walls of
the stomach may be almost covered with them thus of course seriously
interfering with the functions of this organ. When full grown the larvae
pass from the host and complete their transformation in the ground.

[Illustration: FIG. 27--Blue-bottle fly (_Lucilia sericata_).]

[Illustration: FIG. 28--Flesh-fly (_Sarcophaga sp_).]

[Illustration: FIG. 29--"The little house-fly" (_Homalomyia
canicularis_).]

[Illustration: FIG. 30--Horse bot-fly (_Gastrophilus equi_).]

[Illustration: FIG. 31--Ox warble-fly (_Hypoderma lineata_).]

[Illustration: FIG. 32--Sheep bot-fly (_Gastrophilus nasalis_).]

The bot-flies of cattle or the oxwarbles (Fig. 31) gain an entrance
into the alimentary canal in the same way, that is, by the eggs being
licked from the hairs on the body where they have been laid by the adult
fly. But instead of passing on into the stomach they collect in the
esophagus and later make their way through the walls of this organ and
through the tissues of the body until they at last reach a place along
the back just under the skin. Here as they are completing their
development they make more or less serious sores on the backs of the
infested animals. The hides on such animals are rendered nearly
va