Botflies are flies of the genus Cuterebra that proliferate by laying eggs on grass or nests. When these eggs hatch, they release maggots that crawl onto the skin of the passing host. These small maggots can enter a body orifice and make their way to the skin, where they establish themselves within a warble (a small lump in the skin). Once matured, these maggots then drop out of the host and pupate in the soil.
The disease is seasonal, mostly occurring in late summer and early fall when the adult flies are active, although in areas with warmer temperatures where flies are active through longer periods of the year, the seasonality may vary.
Besides the warble, other symptoms may include cough, fever, shortness of breath, dizziness, circling, paralysis, blindness, and ophthalmic lesions.