Bot Fly, common name for any member of a family of large, stout-bodied, parasitic flies, also called warble flies. Bot flies are believed to be the fastest-flying of all insects and attain speeds of 64 to 80 km/h (40 to 50 mph). Although harmless in the adult stage, the larvae, called bots, are parasites that live in the body-cavity tissues of mammals, usually causing severe pain and sometimes death. The adult horse bot fly resembles a bee. It lays its eggs on the shoulders or flanks of the animal; the eggs are licked off by the horse and enter the digestive tract, where the larvae quickly hatch and attach themselves to the walls of the stomach and intestines. The sheep bot fly lays eggs in the nostrils of sheep. When hatched, the larvae can block the respiratory tract, thereby causing the animal's death. The human bot fly affects humans and members of the deer family in the Tropics. The female lays her eggs on mosquitoes and other biting insects, which carry them to the actual host. When the eggs come into contact with the warm host, the larvae hatch, burrow beneath the skin, and lodge in the muscles.
Scientific classification: Bot flies constitute the family Oestridae, order Diptera. The horse bot fly is classified as Gasterophilus intestinalis, the sheep bot fly as Oestrus ovis, and the human bot fly as Dermatobia hominis.