Texas Ranchers Brace for Restrictions as Sterile Fly Production Remains Biggest Hurdle in Screwworm Fight

Industry estimates suggest approximately 500 million sterile flies per week may be required to fully eradicate the pest.

WASHINGTON, D.C. (RFD NEWS) — Concerns over New World screwworm continue to grow as lawmakers, ranchers, veterinarians, and cattle industry leaders respond to the pest’s spread in Texas.

The issue was front and center this week as agricultural leaders discussed the latest detections and the ongoing effort to prevent further expansion within the United States.

Iowa Senator Chuck Grassley said he wants to see every available tool used to stop the pest from gaining a foothold in the country.

“Get on top of this screwworm issue by the vaccination that’s available to make sure that we can stop the screwworm from expanding in the United States,” Grassley told reporters. “After all, it’s been almost 50 years since we had a screwworm problem in this country, and it’s coming from Mexico, and there’s no reason to go back after 50 years of success.”

According to the USDA, there are currently four confirmed cases of New World screwworm in the United States. Three cases involve cattle, while one case was confirmed in a dog near the Texas-New Mexico border.

Texas Ranchers Brace for Potential Restrictions

As detections continue, livestock producers in South Texas are preparing for possible movement restrictions and quarantines.

Mercedes cattleman Mike England says producers should remain calm while officials work through the response.

“Sensationalism sells, first off,” England said. “I think we need to take a sensible approach to any given problem to work a solution.”

Brooks County veterinarian Dr. Mike Vickers believes the threat deserves serious attention.

“I don’t think it’s been sensationalized enough, actually, because we’re looking at a huge, huge economic disaster,” Vickers said.

Vickers says livestock movement requirements are already changing in some states. He recently had to revise health certificates for cattle traveling to Louisiana after new requirements were implemented.

“We’ve already got states that are coming down on us,” Vickers explained. “I issued a health certificate last week for cattle going to a show in Louisiana. They just changed.”

According to Vickers, the updated requirements include additional documentation and a shorter permit window for animals entering the state.

Could Quarantines Be Next?

Some producers believe additional restrictions are inevitable.

Hidalgo County cattleman Mike Risica says quarantines may soon reach his area if more cases are detected.

“They’ve got one in the Uvalde area up there right now,” Risica said. “I don’t think it’s if it happens, it’s when it happens.”

Vickers agrees that quarantines are likely to become part of the response effort.

“I think there will be some quarantines,” he said. “I’m sure that those properties that the confirmed cases are on are under some kind of quarantine right now.”

He says he is waiting for additional guidance from USDA and the Texas Animal Health Commission so he can provide ranchers with the latest information.

Veterinarians Become Key Information Source

As uncertainty continues, veterinarians are fielding a growing number of calls from concerned livestock owners.

“Most of the calls I get are people reaching out to me,” Vickers said. “We just got one during this interview.”

Vickers says many producers are seeking guidance because of his experience dealing with screwworm outbreaks during the 1970s eradication effort.

Risica says his operation remains in close contact with veterinary experts.

“We have a consultant vet that comes down once a month, and he’s always available to us,” Risica said. “He’s the one kind of keeping us informed on all the new regulations and the new playbook that’s come out by the USDA.”

Industry Says Response Is Going According to Plan

While concern remains high, cattle industry leaders say preparations have been underway for more than a year.

National Cattlemen’s Beef Association (NCBA) CEO Colin Woodall says the industry anticipated the possibility of screwworm reaching the United States after the pest moved north through Mexico in late 2024.

“Ever since New World screwworm made it out of Guatemala into Mexico right before Thanksgiving of 2024, we expected this to be inevitable,” Woodall said. “That gave us over 18 months to get prepared.”

Woodall says cattle organizations, state officials, and USDA have worked together to establish a coordinated response plan.

“What we have seen here since the confirmation by Secretary Rollins is that we’re ready,” he said. “The plan is solid, it’s in place.”

Sterile Fly Production Remains the Biggest Challenge

The primary tool used to combat New World screwworm remains the sterile insect technique, which relies on releasing sterile male flies into affected areas to disrupt reproduction and collapse pest populations.

However, Woodall says current production levels remain well below what will be needed for eradication.

“The thing that we’re dealing with right now is getting enough flies to be able to eradicate them once again,” Woodall said. “Right now, we’re only producing about 100 million flies a week.”

Industry estimates suggest approximately 500 million sterile flies per week may be required to fully eradicate the pest.

To address that challenge, USDA recently broke ground on a new sterile fly production facility in South Texas. The facility is expected to come online sometime next year and significantly increase available fly production capacity.

Until then, producers, veterinarians, and animal health officials say vigilance will remain critical as efforts continue to contain the pest and prevent further spread.

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RFD NEWS Correspondent Frank McCaffrey covers news from Texas, in the US-Mexico border region. He has provided in-depth coverage of immigration, the 2021 Texas freeze, the arrival of the New World screwworm, and Mexico’s water debt owed under a 1944 treaty.

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