A flesh-eating screwworm is back in the U.S. Here’s why officials aren’t panicking
For the first time in decades, inspectors have detected a flesh-eating parasite in American livestock.
Agriculture Secretary Brooke Rollins said experts have found New World screwworm larvae in a South Texas calf, marking the first confirmed U.S. case in decades.
Rollins said the case was discovered in a 3-week-old calf in LaPryor, Texas, about 50 miles from the Mexico border. Since the discovery, state officials established a 12-mile quarantine zone, prohibiting animals within it from leaving without inspection.
While officials stress there is no risk to food safety, they warn that the parasite can cause serious harm to cattle, other livestock and wildlife.
History of flesh-eating parasite
The screwworm was eradicated from the U.S. in the 1970s after causing major losses to ranchers and the livestock industry. Rollins and other agricultural officials have been sounding the alarm about the fly’s movement across Mexico toward the U.S. for more than a year.
“And we all, as you know, have been talking and tracking and working around the clock to contain it, but we have not,” Rollins said. “Mexico, with the illicit movement of cattle and not having enough sterile flies, certainly has led us to today, June 3rd, 2026, the U.S. confirming its first new world screwworm case in the state of Texas since 1966.”
Officials have even taken preventative steps to try to keep the fly out of the U.S., including dropping millions of sterile screwworm flies in the area. They also deployed 8,000 fly traps along the U.S.-Mexico border and tested tens of thousands of flies and wild animals for the parasite.
Because of those preparations, Rollins said the USDA believes “there is no threat of mass infestation.”
“There is no reason to believe this incursion will result in establishment of the pest in our country,” Rollins said.
She said no other cases have been detected in the country, but federal and state officials are now intensifying surveillance in South Texas.
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Ella Rae Greene, Editor In Chief
