Flesh-Eating Screwworm Detected in Texas for First Time Since 1966

The U.S. Department of Agriculture confirmed the detection of a New World screwworm fly in a calf in South Texas on June 4, 2026 ^[3].

The discovery represents a significant threat to the U.S. cattle industry. Because the parasite consumes living tissue, federal officials have launched emergency quarantine measures to prevent a wider outbreak that could devastate livestock populations.

Federal agricultural officials identified the parasite in a calf located approximately 25 miles from the U.S.–Mexico border ^[2]. The New World screwworm is a flesh-eating parasite that targets open wounds in animals. While some reports suggest the parasite was detected in Mexico near the border, the USDA and other federal agencies confirmed the case occurred within the U.S. in South Texas ^[1].

This is the first recorded case of the New World screwworm in the U.S. since 1966 ^[1]. The gap of six decades highlights the severity of the current breach, as the parasite had previously been eradicated from the domestic livestock population through extensive control programs.

USDA officials are now working to contain the spread. The quarantine measures are designed to restrict the movement of livestock from the affected area to ensure the parasite does not migrate further into the interior of the country. Officials said the proximity to the border suggests a possible point of entry for the fly.

Agricultural experts are monitoring the region closely to determine if other animals have been infected. The parasite is known for its ability to spread rapidly across herds if not identified and treated immediately. The USDA said the priority remains the immediate isolation of the affected livestock, and the implementation of strict surveillance protocols in the surrounding border counties.