By Hannah Grover
The spread of New World screwworms in Mexico has prompted a halt in the cross-border cattle, horse and bison trade, and now members of the U.S. Congress have introduced legislation they hope will curb the spread before the larval fly can decimate livestock in the United States.
U.S. Sen. Ben Ray Luján, D-New Mexico, is among the members of Congress leading the effort. He introduced legislation Thursday, along with U.S. Sen. John Cornyn, R-Texas, that would provide the U.S. Department of Agriculture with funding to create a new sterile fly production facility.
This effort comes after the United States learned that the screwworm had been found in populations of cattle in November 2024 in the state of Chiapas in southern Mexico. Since then, the screwworm has spread to other parts of Mexico including the states of Campeche and Tabasco.
Sterile flies are unable to reproduce. By releasing sterile male flies in areas with screwworm outbreaks, officials can cause the populations to decline and eventually die out. Luján said this method has been proven to work against screwworms before. It was the method the United States used in the 1960s and 70s to eradicate screwworm. The last time there was a regional outbreak of screwworms — found in Florida deer in 2016 — the sterile flies were also used to eradicate it.
Luján said it is important to get the funding for the production facility in place so that the United States has “this tool at our disposal so that we can stop the spread before we start losing more and more cattle.”
The screwworm is the larval form of a parasitic fly that attacks flesh through either wounds or orifices. The fly larva burrow into the wounds and can result in severe injuries or even death.
Luján said the screwworm could have a devastating impact on the cattle industry if it gains a foothold in the United States again, and New Mexico could be one of the first states impacted given its proximity to Mexico.
“Think about those 10,000 farms and ranches in New Mexico, there’s over 1.4 million head of cattle back in New Mexico,” he told NM Political Report. “Anytime someone’s going to go to that grocery store, or you’re going to run by Laguna Burger, or you might go buy some milk or some ice cream, remember the industry and all those ranchers and farmers that are out there that are raising that and helping give that to you in your refrigerator, on your plate, or whatever it may be.”
He said the screwworm could force small farmers, businesses and ranchers to close up shop. It’s not just the beef industry that could be impacted. Luján said dairy farmers could also lose their stock to the parasitic fly.
New Mexico is the ninth-largest milk producer in the country and the fifth-largest cheese producer.
“The New World Screwworm poses a growing threat to New Mexico livestock, jeopardizing ranchers’ livelihoods, and putting our food supply at risk,” U.S. Sen. Martin Heinrich, D-New Mexico, said in a press release. Heinrich is a co-sponsor of the bill and is a member of the Senate Appropriations Subcommittee on Agriculture, Rural Development, and the Food and Drug Administration.
U.S. Rep. Gabe Vasquez, D-New Mexico, has also been actively working to address the screwworm spread. He sent a letter to the USDA in March urging “ immediate attention to the growing risk posed by the New World screwworm (NWS) and the critical need for expanded eradication and containment efforts.”
Vasquez is also among the sponsors of the legislation in the U.S. House of Representatives to fund a sterile fly production facility.
He said livestock auctions in New Mexico are already “feeling the squeeze” because of the screwworms. Vasquez said ranchers who depend on cross-border trade “are being left in limbo.”
“USDA must be transparent about the timeline for reopening ports of entry, and they need to address the staffing and operational issues that are slowing things down. Our border economies can’t wait,” he said in a press release.
