New World Screwworm Confirmed in Texas

New World screwworm is back in the United States. On June 3, 2026, USDA’s Animal and Plant Health Inspection Service confirmed the pest in a three-week-old calf in Zavala County, Texas. The larvae were found in the calf’s navel area.

Screwworm is a fly whose larvae feed on the living flesh of warm-blooded animals. It mostly hits livestock, but it can also infest pets, wildlife and, less often, people and birds. The female lays eggs in open wounds or around body openings, and the maggots burrow in.

The first case did not stay alone for long. By June 12, USDA data listed nine confirmed U.S. cases: eight in Texas and one in a dog in Lea County, New Mexico. Texas cases at that point involved cattle and goats in Zavala, La Salle, Gillespie and Edwards counties. A July 2026 update from a University of Tennessee vector-borne disease working group reported 41 total Texas cases, with activity in six counties.

APHIS said its response includes a unified incident command with the Texas Animal Health Commission, a 20-kilometer infested zone with quarantines and movement controls, extra trapping along the border, and wildlife surveillance. The agency also added ground release of sterile flies on top of the roughly 4 million sterile flies per week already being dropped from the air. More than 130 million sterile male flies had been released in Texas since January, according to reporting on USDA data.

Under Secretary Dudley Hoskins said, “The United States has defeated this pest before, and we will do it again.” USDA stressed that the food supply is safe, since screwworm does not infect meat or produce.

USDA’s advice to animal owners is to check animals for wounds that drain or grow, signs of discomfort, and maggots near the nose, ears, genitals or navel. Suspected cases should go to a state animal health official or USDA area veterinarian right away. People with suspicious sores should see a doctor.

Pest control crews working rural properties, ranch homes, kennels and wildlife exclusion jobs in South Texas are among the people most likely to see an animal up close. A dog with a draining wound full of maggots or a dead animal under a deck is not just a fly job anymore in an affected area. It is a possible report to animal health officials.