Bot flies

Definition

Flies of the family Oestridae whose larvae are obligate internal parasites of mammals. First-instar larvae actively penetrate host skin or are ingested, then develop in subcutaneous tissue (producing warbles) or within the gastrointestinal tract. Adults are non-feeding, short-lived, and often mimic bees or wasps.

Etymology

From Middle English 'bot,' a parasitic worm or maggot; 'bot' likely derived from Gaelic 'boiteag' (maggot)

Example

Dermatobia hominis, the human bot fly, attaches eggs to mosquitoes which then transfer larvae to human skin; Gasterophilus species infect horses, developing in the stomach lining.

Synonyms

• warble flies
• heel flies
• Gadflies

Related Terms

• Myiasis
• Oestridae
• Cuterebra
• Gasterophilus
• Dermatobia hominis
• parasitoid
• endoparasite

Usage Notes

The common name applies to the family Oestridae, not a single species. 'Warble fly' emphasizes subcutaneous species (Hypodermatinae in cattle); 'heel fly' refers to adult harassment of cattle. 'Gadfly' is broader and sometimes includes non-oestrid pests. Larvae cause myiasis—distinguish between obligatory (Oestridae) and facultative myiasis agents (e.g., blow flies).