The New World primary screwworm ("Cochliomyia hominivorax"), once a major pest in southern United States, has been eradicated from the United States, Mexico and Central America through an extensive release program by the USDA of sterilized males. The USDA maintains a sterile screwworm fly production plant and release program in the eastern half of the Republic of Panama to keep fertile screwworms from migrating north. Currently, this species is limited to lowland tropical countries in South America and some Caribbean islands.