The sheep bot fly reaches body lengths of 10-12 mm. The thorax is covered with thick golden fur. The abdomen is whitish-grey with black markings. The sheep bot fly has a broad head with large, reddish to brown compound eyes. The mouth tools are degenerate and allow only a small quantity of food to be ingested. The large, strong wings are brownish in colour. The legs are dark, hairy, and strong. The sheep bot fly is active in summer.
The females lay their eggs in the nostrils or eyes of sheep. The larvae hatch from their eggs inside the females and are shot into the host animals in drops of liquid. The host animals resist this. The laying of the maggots must be done quickly, otherwise the mother will be attacked by her own brood. The larvae, approximately 500 in number, nest in the nasal cavities and sinuses of the sheep, remaining there for months. In the spring of the following year, the host animalsalready show symptoms such as sneezing and inflammatory discharge.
The larvae are up to 30 mm in length. After the last larval stage, the larvae are sneezed or coughed out by the host animals and fall down to the soil in which they pupate. The sheep bot fly occasionally lays its larvae in humans, especially in the eyes.