How did this flesh eating parasite make its way back into the United States after 60 years? The New World screwworm was once one of the most devastating livestock pests in America. Throughout the early 1900s, it cost farmers and ranchers millions of dollars every year. Unlike most maggots, screwworm larvae feed on living tissue, infesting wounds on cattle, sheep, goats, wildlife, pets, and even people. In one of the most interesting agriculture stories in history, the USDA launched a massive eradication campaign using sterile flies. Millions of sterile male flies were released across the southern United States, then Mexico, and eventually Central America. Because female screwworm flies only mate once, mating with a sterile male meant no offspring. Over time, the population collapsed. The program was so successful that screwworm was eradicated from the United States in 1966 and eventually pushed all the way to a biological barrier in Panama. For decades, the U.S. and Panama maintained ...