New World Screwworm Spreads in U.S., Threatening Livestock and Wildlife; Hunters Urged for Early Detection
For the first time in over 50 years, the flesh-eating New World screwworm (Cochliomyia hominivorax) is spreading on the U.S. mainland, posing a significant threat to livestock and wildlife. As of November 5, 2026, there have been 116 detections in animals, including two elk shot by hunters in Texas, following the first confirmed case in a calf near La Pryor, Texas, in June 2026. The screwworm larvae feed on living tissue, burrowing into wounds and natural openings, leading to infection and death if untreated. All warm-blooded animals are susceptible, including cattle, deer, elk, small game, and waterfowl. The U.S. government has initiated efforts to ramp up the production of sterile flies, a method successfully used to eradicate the parasite from the mainland in 1966.
