New World Screwworm (NWS) continues to creep towards the United States border from Mexico. On September 21, 2025, Mexico’s National Service of Agro-Alimientary Health, Safety, and Quality (SENASICA) confirmed the detection of New World Screwworm less than 70 miles from the U.S.-Mexico border. New World Screwworms are parasitic fly larvae that burrow into the flesh of animals and humans, causing painful, often deadly infestations. It's important for horse owners to be aware of this pest, and to know the plan set by the United States Department of Agriculture if it reaches the United States.