On June 3, 2026, USDA confirmed the first US case of New World screwworm in decades — a three-week-old calf in La Pryor, Texas, about 90 miles from the border. Two more cases followed by June 8: a calf in La Salle County and a dog in Andrews County. The screwworm is a parasitic fly whose larvae eat the live flesh of warm-blooded animals through open wounds, and it can be fatal to livestock. The US wiped it out in the 1960s using sterile flies, then held a barrier far to the south. As it crept back north through Mexico, USDA closed the southern border to live cattle imports in May 2025.

1. Seal the Border and Breed Billions of Sterile Flies (Agriculture Secretary Brooke Rollins)

The 60-year-old playbook still works. You flood the zone with sterile males until the pest can't reproduce.

The eradication method is the same one that worked last time. You breed male screwworm flies, sterilize them, and release them by the hundreds of millions; females mate once, so enough sterile males collapse the next generation. The US is spending about $750 million on a fly factory near Edinburg, Texas, built to turn out up to 300 million sterile flies a week.

Agriculture Secretary Brooke Rollins is running the containment hard. She announced the first case herself, told Texans to check their pets for infested wounds and larvae, and stressed the bug "do[es] not infest meat, fruits or vegetables," so the food supply is safe. The May 2025 border closure to Mexican livestock was the first wall; the sterile-fly surge is the second.

2. But Can We Really Afford That? (cattle ranchers, consumers)

Closing the border to Mexican cattle strangles the supply.

Shutting out Mexican cattle pushed beef to a record price. The May 2025 import ban cut the cattle supply, especially in Texas, and helped drive retail beef to about $9.64 a pound in April — up roughly 13% in a year. The screwworm hasn't reached most herds, but the policy built to keep it out is already in every grocery bill.

Ranchers are caught between the fly and the fix. A screwworm outbreak in a herd is devastating, so producers want the border sealed — but the same closure that protects them also chokes the feeder-cattle pipeline they rely on. There's no version of this that's cheap.

3. We Beat This Before — But the Factory Isn't Ready (eradication scientists)

The science is proven. The problem is timing: the bug is here now, and the Texas plant isn't.

The barrier already slipped, and the new defenses aren't built yet. Screwworm was supposed to be stopped far south of Texas, and it reached a calf 90 miles from the border anyway. The $750 million Texas fly factory has been reported as opening around fall 2027, and USDA only hopes to be releasing sterile flies within about a year.

For now, the US leans on plants in Panama and Mexico. The existing sterile-fly facilities sit in Panama and Metapa, Mexico, and a joint US-Mexico plant aimed at 100 million flies a week is still being finished. The method is a sure thing; the capacity to run it at the border isn't there yet.

4. Blame Illegal Cattle (Brooke Rollins, InsightCrime)

The fly didn't fly here on its own. It moved north with cattle nobody was checking.

Rollins points straight at the border. She blamed the spread on "open-border policies" and "illicit cattle movement," framing the outbreak as a control failure, not just bad luck. A screwworm barrier only holds if you know which animals are crossing.

Smuggled cattle are part of how it traveled. Reporting ties the first US case to contraband cattle in Mexico, where unregulated smuggling moved animals — and the pest — north past the inspection points meant to catch it.

Where This Lands

USDA says the fix is the one that worked in the 1960s: seal the cattle border and bury the pest under sterile flies until it can't breed. Ranchers and shoppers are already paying for that fix: beef hit a record price while the border stayed shut to Mexican cattle. The scientists say eradication is a sure thing, but the Texas fly factory that's supposed to do it isn't open yet, and the bug is already in Texas. And Rollins says the whole thing rode in on cattle nobody was checking, which makes the next fight about the border as much as the fly.

Sources