New World screwworm infestation detected in South Texas cattle: USDA
Officials with the Texas Animal Health Commission confirmed that an infestation of the flesh-eating New World screwworm parasite was detected in South Texas cattle, they said Wednesday.
Officials explained on a call earlier Wednesday that the case was a ‘presumptive positive,’ which means preliminary tests were positive but that results needed to be confirmed, according to Reuters. A sample taken from two calves on a ranch in La Pryor, Texas, was tested at a federal government laboratory.
The New World screwworm is a parasitic fly that feeds on the tissue of warm-blooded animals and people, according to the U.S. Centers for Disease Control and Prevention. The feeding can create large wounds on animals that result in “serious, often deadly” damage.
The fly is typically found in South America and the Caribbean, but the species has been tracking northward through Mexico since 2023, according to the USDA.
Texas Agriculture Commissioner Sid Miller on Wednesday criticized the USDA for a “slow, bureaucratic, and incomplete response that allowed the pest to advance unchecked through Mexico and reach American soil,” according to a statement from his office.
Miller urged President Donald Trump to deploy the Screwworm Adult Suppression System (SWASS) to combat the bug in Texas. The system uses bait and EPA-approved pesticides to cut down on the insect population, and was developed by the USDA.
“Mr. President, I am asking you to take direct control of this response,” Miller said. “Cut through the bureaucracy, deploy SWASS immediately, and throw every available federal resource at this threat before it becomes a full-blown agricultural disaster.”
Officials with the U.S. Cattlemen’s Association said Wednesday that they were “closely monitoring” the situation in Texas, and that they commended the Texas Animal Health Commission for a “swift response” to the re-emergence of screwworms.
“Their early activation of personnel in the region, close coordination with state and local partners, and continued focus on prevention, early detection, and rapid response have bought producers and animal health officials critical time to prepare for a situation just like this,” a USCA statement reads.
On a press call Wednesday night, USDA officials stressed that the screwworm was not a threat to the food supply and that the chances of large-scale infestation were tiny. Animal owners can most effectively help combat the spread by monitoring their pets and livestock for symptoms of an infestation.
This story was originally published June 3, 2026 at 8:28 PM.
