Botfly

A botfly, also written bot fly, bott fly or bot-fly in various combinations, is any fly in the family Oestridae. The life cycles vary greatly according to species, but the larvae of all species are internal parasites of mammals. Largely according to species they also are known variously as warble flies, heel flies, and gadflies. The larvae of some species grow in the flesh of their hosts, while others grow within the hosts' alimentary tracts.

The word "bot" in this sense means a maggot. A warble is a skin lump or callus such as might be caused by an ill-fitting harness, or by the presence of a warble fly maggot under the skin. The human botfly, Dermatobia hominis, is the only species of bot fly whose larvae ordinarily parasitise humans, though flies in some other families episodically cause human myiasis, and sometimes more harmfully.