Each body segment is ringed with strong spines. They can be identified, in part, by the shape of the eggs. Larvae develop in the digestive tracts of host animals during the winter. In the late winter and early spring months, full grown larvae are found in host s feces. They transform into adult flies inside the puparium and emerge in 3 to 10 weeks.
Adults are active from mid-summer through fall.
Adult females glue eggs on the hairs of horses, particularly to hair on the front legs but also on the belly, shoulders and hind legs. There is one generation per year. Horses, mules, donkeys are primary hosts. Larvae live in the digestive tract, injuring the tongue, lips, stomach lining and intestine. They apparently feed on the inflammatory products produced by the host in response to their presence.