The oxen pictured here, from a communal farming area along the Great Kei River in the Eastern Cape, have literally had their ears eaten from their heads by screwworm. According to retired Eastern Cape farmer, Victor Biggs, screwworm flies lay eggs in small skin wounds such as those created by ticks. Eggs hatch rapidly to produce flesh-eating larvae or maggots.
The screwworm maggot differs from other maggots in that it feeds on living tissue rather than on necrotic tissue. Injectable parasiticides are an effective control measure against screwworm. Old World screwworm (Chrysomya bezziana) is endemic to Africa and South Asia while the New World screwworm (Cochliomyia hominivorax) is found in South America.