Botfly, a harmful insect that in the larval stage lives as a parasite in animals and sometimes in humans. Its larvae are called bots. The horse botfly looks like a large bee. It secretes a glue-like substance that is used to attach its eggs to the body hairs, lips, nose, and throat of the horse. The eggs develop into larvae in about seven days. The horse licks the larvae off its body and swallows them. The larvae attach themselves to the lining of the horse's stomach. After 8 to 10 months they are passed out in the feces and pupate in the soil. Three to five weeks later, adult flies emerge, ready to repeat the cycle.

The botflyThe botfly has parasitic larvae that live in the cavities or tissues of animals.

The bots of the warble fly, or cattle botfly, hatch on the hair of cattle and burrow into an animal's hide. They make their way through the body to the back where they live just under the hide. Warble flies cause tumorlike lumps, or warbles, on the backs of cattle. Each warble has a small hole in it through which the bot breathes and eventually leaves to pupate in the ground. These holes greatly reduce the value of cattle hides.

The sheep botfly lays its eggs in the nostrils of sheep. The bots live in the sinuses and cause a nervous condition known as blind staggers. The pest can be controlled by drenching sheep's nostrils with disinfectants such as Lysol; smearing the nostrils with pine tar is a preventive. Sheep bots can also infest human beings. They are deposited in the eye by an adult fly, causing a serious irritation.

The bots of robust botflies infest rabbits, deer, squirrels, and reindeer. The human botfly, found in the tropics, infests livestock as well as humans. Its bots are carried to the victim by mosquitoes.

Botflies belong to various families of the order Diptera: horse botflies, family Gasterophilidae; warble flies, family Hypodermatidae; sheep botflies, family Oestridae; robust and human botflies, family Cuterebridae.