The U.S. plans to build a US$750M fly factory in Texas to stop a flesh-eating cattle parasite

Cowboys push a cow out of its spot to a veterinarian inspection at a ranch that exports livestock to the U.S., in Zamora, northern Mexico, Monday, July 28, 2025. (AP Photo/Fernando Llano)

The U.S. plans to build a $750 million factory in southern Texas to breed billions of sterile flies, ramping up its efforts to keep flesh-eating maggots in Mexico from crossing the border and damaging the American cattle industry.

Secretary Brooke Rollins announced Friday that the U.S. Department of Agriculture hopes to be producing and releasing sterile male New World screwworm flies into the wild within a year from the new factory on Moore Air Base outside Edinburg, Texas, about 20 miles (32 kilometres) from the border. She also said the USDA plans to deploy US$100 million in technology, such as fly traps and lures, and step up border patrols by “tick riders” mounted on horseback and train dogs to sniff out the parasite.

In addition, Rollins said the U.S. border will remain closed to cattle, horse and bison imports from Mexico until the U.S. sees that the pest is being pushed back south toward Panama, where the fly had been contained through late last year through the breeding of sterile flies there. The U.S. has closed its border to those imports three times in the past eight months, the last in July, following a report of an infestation about 370 miles (595 kilometres) from the Texas border.

American officials worry that if the fly reaches Texas, its flesh-eating maggots could cause billions of dollars in economic losses and cause already record retail beef prices to rise even more, fueling greater inflation. The parasite also can infest wildlife, household pets and, occasionally, humans.

“Farm security is national security,” Rollins said during a news conference at the Texas State Capitol in Austin with Texas Gov. Greg Abbott. “All Americans should be concerned. But it’s certainly Texas and our border and livestock producing states that are on the front lines of this every day.”

The pest was a problem for the American cattle industry for decades until the U.S. largely eradicated it in the 1970s by breeding and releasing sterile male flies to breed with wild females. It shut down fly factories on U.S. soil afterward.

The Mexican cattle industry has been hit hard by infestations and the U.S. closing its border to imports.

Mexico’s Agriculture ministry said in a statement Friday that Mexico Agriculture and Rural Development Secretary Julio Berdegué Sacristán and Rollins signed a screwworm control action plan. It includes monitoring with fly-attracting traps and establishing that livestock can only be moved within Mexico through government-certified corrals, the statement said.

And on the X social media platform, Berdegué said, “We will continue with conversations that lead to actions that will permit the reopening of livestock exports.”

The new fly-breeding factory in Texas would be the first on U.S. soil in decades and represents a ramping up of the USDA’s spending on breeding and releasing sterile New World screwworm flies. The sterile males are released in large enough numbers that wild females can’t help but mate with them, producing sterile eggs that don’t hatch. Eventually, the wild fly population shrinks away because females mate only once in their weekslong lives.

In June, Rollins announced a plan to convert an existing factory for breeding fruit flies into one for breeding sterile New World Screwworm flies, as well as a plan to build a site, also on the air base near Edinburg, for gathering flies imported from Panama and releasing them from small aircraft. Those projects are expected to cost a total of US$29.5 million.

The Panama fly factory can breed up to 117 million flies a week, and the new Mexican fly factory is expected to produce up to 100 million more a week. Rollins said the new Texas factory would produce up to 300 million a week. She said U.S. President Donald Trump’s administration wants to end the U.S. reliance on fly breeding in Mexico and Panama.

“It’s a tactical move that ensures we are prepared and not just reactive, which is today what we have really been working through,” Rollins said.

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Hanna reported from Topeka, Kansas. Associated Press writer Fabiola Sánchez in Mexico City contributed reporting.

John Hanna, The Associated Press