Veterinary - New World Screwworm

USDA Confirms Presence of New World Screwworm in the United States

On June 3, 2026 the U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed the detection of a New World screwworm (NWS) in a 3-week-old calf in Zavala County, Texas. Larvae were identified in the umbilical area of the affected animal. 

New World screwworm (NWS, Cochliomyia hominivorax) is a serious pest that affects livestock, pets, wildlife, and, less commonly, people and birds. Adult NWS flies can look very similar to houseflies, and the maggots (larvae) are impossible to tell apart from our native fly maggots. The NWS larvae feed on the living tissue of warm-blooded animals and they cause extensive damage to wounds by feeding on this healthy tissue. If you suspect New World Screwworm maggots in a wound call your local veterinarian or NCDA&CS at (919) 707-3250. New World Screwworm is considered a reportable disease in the United States. 

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USDA Press Release June 3: USDA Confirms New World Screwworm in Texas

Texas Animal Health Commission NWS Webpage: Texas Animal Health Commission