Adult Cuterebra flies are large and bee-like and do not feed or bite. Females deposit eggs around the openings of animal nests, burrows, along runways of the normal hosts, or on stones or vegetation in these areas. A female fly may deposit 5-15 eggs/site and >2,000 eggs in her lifetime. Animals become infested as they pass through contaminated areas; the eggs hatch in response to heat from a nearby host. In the target host, the larvae enter the body through the mouth or nares during grooming or, less commonly, through open wounds. After penetration, the larvae migrate to various species-specific subcutaneous locations on the body, where they develop and communicate with the air through a breathing pore. After ~30 days, the larvae exit the skin, fall to the soil, and pupate.
Cuterebra lesions are most common in the summer and fall when the larvae enlarge and produce a fistulous swelling ~1 cm in diameter.
