Antiparasitic medicine for endangered Key deer and an abundance of sterile New World screwworm flies continue to help fight the screwworm situation in South Florida. More than 101 million sterile screwworm flies have been released by the U.S. Department of Agriculture in Marathon and the Lower Keys since October. In Homestead, where a stray dog was found with a screwworm infestation in December, nearly 2 million have been released. They help to drive down the number of fertile flies by mating with wild flies to produce eggs that never hatch. Screwworms feed inside the open wounds of any warm-blooded living animal, which has resulted in the deaths of 135 endanger Key deer found only in Monroe County. Some have had to be euthanized and others have died from their screwworm-inflicted conditions.