Bōt'-fly, n.

n. (Entom.) An insect of the family Œstridæ, of many different species, some of which are particularly troublesome to domestic animals, as the horse, ox, and sheep, on which they deposit their eggs. The most common species is the bot-fly of the horse, Gasterophilus equi, the larvæ of which are taken into the stomach of the animal, where they live, producing the disease called bots. Baird. “His horse hipped with an old motley saddle, besides begnawn with the bots.” Shak.