Last Friday, Governor Greg Abbott expanded a statewide disaster declaration in response to the New World screwworm’s arrival in Texas.
This expansion authorizes the use of “all available resources of state government to respond to this disaster,” said Abbott shortly before signing the declaration during a news conference.
The New World screwworm is one of “the most destructive livestock and wildlife pests in history,” according to a press release from the Texas Department of Agriculture Commissioner Sid Miller’s office.
“Unlike common flies, screwworm larvae feed on the living flesh of warmblooded animals, causing severe injury, infection, and death if left untreated. A widespread outbreak could devastate Texas ranchers, wildlife populations, companion animals, and the broader agricultural economy.”
The disaster declaration order reassigns all resources from across the state as necessary and makes available all state personnel to speed the shipment of sterile flies into Texas and the construction of a sterile fly facility in South Texas. Sterile flies are used as a means of breaking the reproduction cycle of the screwworm fly.
The first case of screwworm was confirmed in Texas last week in Zavala County, located about two hours southwest of San Antonio. A sample from a threeweek- old calf tested positive for the country’s first case of New World screwworm, according to United States Department of Agriculture (USDA) Secretary Brooke Rollins.
The calf’s herd was subsequently inspected, but no other cases were found, and there have been no other signs of screwworm in the country so far.
An “infested zone” surrounds the Zavala County and Nueces River site as of Friday, June 5, and wider surveillance surrounds the infested area.
“Texas livestock producers and all Texans must now be vigilant in their efforts to manage and combat the invasive pest,” said Farm Bureau President Russell Boening.
Miller and other South Texas officials have expressed frustration with the USDA for alleged lack of communication.
Miller specifically called out the USDA for what he called “a slow, bureaucratic, and incomplete response that allowed the pest to advance unchecked through Mexico and reach American soil.”
“For months, the screwworm has advanced rapidly through Mexico in spite of the USDA’s existing gameplan,” claimed Miller, adding that “even though billions of sterile flies had been dispersed by USDA, the screwworm has still advanced over 1,100 miles from southern Mexico to Texas, and USDA has missed an important component. Now that it appears the first screwworm has arrived in Texas, the consequences of that decision are now staring us in the face.”
Lewis Owens, the Val Verde County Judge, said border counties were being kept in the dark over the locations of cases, leaving them unable to provide answers to their communities.
“It’s a complete lack of information,” he said. “If we know what the hell’s going on, then I can tell my constituents. If we don’t, then the anger goes up. A little bit of communication goes a long way.”
Others have turned to blaming President Joe Biden’s “open border” policies for the proliferation of screwworm, as he allowed the illicit movement of cattle throughout Mexico.
Rollins claims that “these flies do not fly to new areas on their own. If they move, it’s because they are moving with the animal.”
Owen took issue with this statement, citing that ports of entry had been closed to cattle imports from Mexico since 2024, under the Biden administration. The Trump administration temporarily reopened them in February 2025, before shutting them down again that May.
“Let’s not keep blaming individuals or blaming other parties,” Owens says.
Federal officials are currently working with Mexican partners to launch a sterile flyproducing facility in Metapa, Mexico, that is expected to be operational by the end of the month. The only active facility as of now is in Panama, which is shipping flies to dispersal facilities in Texas and Mexico.
Nowell Borders, an Edinburg rancher, said popup facilities on his property could be up and running within a month, but that the federal government had not taken him up on his offer. He says that he’d like the USDA to start dispersing sterile flies near San Antonio as soon as possible.
“I think that’s the most important thing you could get going. They need a facility to start, like, last week,” said Borders.
Commissioner Miller is currently attempting to persuade the Trump administration to direct USDA to immediately deploy the Screwworm Suppression System (SWASS), which is a proven technology developed by USDA scientists and successfully used during previous eradication campaigns. SWASS uses attractants, bait, and targeted, EPA-approved insecticides to “dramatically reduce adult screwworm populations, allowing sterile fly releases to finish the job.”
“SWASS was developed by USDA, tested by USDA, and successfully deployed by USDA to eradicate screwworm in Mexico and Texas when it last appeared,” said Miller. “USDA already owns the playbook; the only question is whether USDA will use it before the situation gets worse.”
Texas producers and pet owners are encouraged by the Texas Department of Agriculture to report suspicious wounds or signs of screwworm infestation to their veterinarian, the Texas Animal Health Commission, USDA officials, or the Texas Department of Agriculture at 800-TELL-TDA.