Some botflies hitch eggs onto mosquitoes to reach skin
Oestrid flies, known as bots, warbles, heel flies, and gadflies, raise their larvae inside mammal bodies. Only Dermatobia hominis routinely parasitizes people. Some species glue their eggs onto a captured insect, which later delivers the hatchlings to warm skin, and the maggots eventually drop out to pupate in soil.
Botflies are the family Oestridae, whose maggots develop as internal parasites in mammalian flesh or guts. "Bot" here means maggot; a warble is the lump raised by a larva under skin. Dermatobia hominis is the sole species whose larvae ordinarily infest humans, though other bots may do so rarely. Modern classification folds former Cuterebridae, Gasterophilidae, and Hypodermatidae into Oestridae as subfamilies within the larger Oestroidea. The family belongs to the superfamily Oestroidea alongside Calliphoridae, Sarcophagidae, Tachinidae, and six other families.
Among myiasis-causing flies, oestrids hold the highest share of species obliged to grow inside mammals—about 150 species worldwide. Related blow flies and others cause myiasis more opportunistically. Females may lay on a host directly or seize an intermediate carrier—houseflies, mosquitoes, or, for the human bot, a tick—clinging to wings and cementing eggs that hatch when body heat signals a mammal nearby. Horse botflies stick small yellow eggs to the inside of the front legs and knees, and sometimes the throat or nose, making them a seasonal headache for stable keepers.
Some larvae enter after eggs or maggots are licked into the digestive tract. Once under skin or in gut, they feed until ready to drop out and pupate in soil. Because they leave without killing the host, they are true parasites, though in cattle their wounds can be infected by Mannheimia granulomatis, which causes lechiguana, hard fast-growing lumps that kill an untreated animal within 3 to 11 months. People have eaten them as well: caribou warble fly maggots turn up in quantity when reindeer and caribou are butchered in cold regions, European Pleistocene art points to the practice in prehistory, and the Babylonian Talmud debates whether the warble fly is kosher.
Source: Botfly
