Note:  Do not rely on this information. It is very old.

Bot Flies

Bot Flies, a family of flies known as the OEstridae, of which the larvae are parasitic on various mammals; thus Gastrophilus lives in the stomach of the horse, and OEstrus, the type-genus, in the nasal cavities of sheep. The common name is derived from the fact that the swellings known as bots on the skin of cattle are caused by the larva of Hypoderma, a, genus of this family.