Sheep bot (head bot, nasal bot), Oestrus ovis

Sheep bot (head bot, nasal bot)

Oestrus ovis

Description: Adult flies are _ to 5/8 inch long, wide-bodied, mottled yellowish to gray-brown, and quite hairy; mouthparts are rudimentary. Larvae are grublike maggots that reach one to one and one-fourth inch in length.

Domestic animals affected: sheep, goats.

Damaged caused: extreme annoyance during larviposition; later, during larval development, a snotty and sometimes bloody nasal discharge, loss of appetite, vigorous head shaking, secondary infection of the sinuses; sometimes death.

Development: complete metamorphosis: egg (hatches within female), larval stages, pupa, adult fly.

Generational time: typically one year, but spring larviposition may result in a complete developmental cycle that produces adults within 10 to 12 weeks.

Larviposition site: Sheep bot flies do not oviposit; larvae hatch within the female fly; she deposits them in or near the host’s nostrils.

Larval habitat, feeding: Larvae feed on mucosal tissue of nasal passages and frontal sinuses of the host. Fully grown larvae exit the nostrils and pupate in debris on the soil for 3 to 6 weeks or more, depending on temperature.

Adult habitat, feeding: Like other bot flies, adult sheep bot flies have incompletely formed mouthparts and do not feed. They live for up to 4 weeks, long enough to mate and develop eggs ready to hatch for larviposition.

Method of dispersal or infestation: by host-seeking flight of adult females and, as larvae, by host mobility and transportation.

Seasonality: Larviposition may occur early summer to late autumn. Parasitism by larvae may be ongoing any month of the year.


		For additional information contact:
		Ludek Zurek Ph.D. Medical and Veterinary Entomology Department of Entomology Kansas State University Manhattan KS 66506 (785) 532-4731 lzurek@ksu.edu