Wool maggots, the larvae of blow flies, live in wet, matted, and soiled wool around the rear of the animal and in wool surrounding wounds. The eggs are deposited in dirty wool or on wounds. After hatching, the maggots spread over the animal and feed on dead tissue under the fleece. Maggot-infested sheep become restless, stamp their feet, try to bite the irritated areas, and may leave the flock to hide in secluded places. The main species are metallic flies such as Phormia regina , Phormis cuprina, and Cochliomyia macellaria . Fatal secondary infections often follow wool maggot attacks.
Control includes care and medication of wounds and early shearing, or clipping and cleaning dirty areas on the sheep before the spring blowfly season. After maggot infestation has occurred, spraying or dipping with recommended insecticides will control the maggots.