CAN’T HOLD ’EM

Flesh-Eating Parasite Outbreak Just Got Worse

A fly whose larvae eat living flesh has now spread to a second Texas county.

A flesh-eating parasite that was wiped out in the U.S. decades ago has turned up in two more locations in Texas, raising fresh alarm about the government’s ability to contain an outbreak that threatens the country’s cattle supply. The U.S. Department of Agriculture confirmed two new cases of the New World screwworm—a fly whose larvae burrow into and devour the living tissue of warm-blooded animals—in a calf and a dog found hundreds of miles apart in separate Texas counties. That brings the total confirmed U.S. cases to four since the pest was first detected last week. “While we address these instances that require immediate attention, and continue to sample suspected cases, we are simultaneously working to eradicate the pest entirely,” said Dudley Hoskins, the USDA’s marketing and regulatory undersecretary. The screwworm was eliminated from the U.S. in the 1960s but resurfaced in Mexico in late 2024 after decades of containment at the southern end of Panama. The government’s primary weapon against it is breeding sterile male flies to mate with wild females, which only mate once. The USDA is also building a fly factory in Texas to ramp up that effort.