The eradication of Florida's primary screwworm population was completed in 1959. The Old World primary screwworm ("Chrysomya bezziana") is an obligate parasite of mammals. Larger flies such as tsetse fly and screwworm cause significant economic harm to cattle. Caretakers should also practice good hygiene themselves to prevent bringing a screwworm with them. New World screwworm flies share many characteristics of the common house fly.