USDA invests $21M to expand Mexico’s fly rearing facility and boost the screwworm eradication effort, securing livestock health and paving the way for resumed exports.
On May 27, 2025, in Washington, D.C., U.S. Secretary of Agriculture Brooke L. Rollins announced a $21 million investment to renovate the Metapa fly production facility in southern Mexico and accelerate efforts to eradicate screwworms from the region. The project will upgrade insect-rearing labs, sterilization chambers and packing areas ahead of the next release season. Rollins said the enhancements will boost weekly output of sterile flies from 60 million to 100 million, pushing remaining wild populations farther south. The move builds on decades of partnership between the USDA and Mexican authorities to shield livestock herds from this destructive pest.
The New World screwworm (Cochliomyia hominivorax) poses a severe threat to livestock across tropical and subtropical regions. Screwworm larvae burrow into open wounds on cattle, sheep, goats and other animals. Left unchecked, infestations can trigger sepsis and death. The United States eradicated the pest from its mainland over half a century ago through the sterile insect technique, or SIT, but Mexico and Central America remain vulnerable. Maintaining a buffer zone south of the border has formed a critical line of defense ever since.
Current restrictions on live animal imports from Mexico remain in place as part of U.S. measures to prevent screwworm reintroduction. The USDA reviews the suspension on a 30-day cycle, assessing surveillance data and pest status before deciding whether to extend or lift the ban. Rollins emphasized that federal officials will continue these regular reviews until the threat subsides. Meanwhile, U.S. livestock producers await clear indicators that officials can safely resume cross-border trade without risking their herds.
In a press release, Rollins reported that she spoke by phone with Mexican Agriculture Secretary Julio Berdegué to align strategies on containing the pest. The two officials discussed ongoing surveillance efforts, field releases of sterile flies and technical support from USDA laboratories. Rollins said each country would deploy joint teams to track worm hotspots and coordinate releases along the border. “We have to work hand in glove to keep screwworm out of both our countries,” she noted after the call.
The sterile insect technique lies at the heart of the eradication campaign. SIT relies on mass-rearing male screwworm flies, sterilizing them with radiation, then releasing them into the wild. When sterile males mate with wild females, the eggs fail to hatch, driving population decline. USDA-supported operations in Mexico and Central America run at full tilt, with aircraft making up to 44 weekly flights over designated areas. Each flight disperses millions of sterile flies, forming an invisible barrier that moves steadily south.
Under the new funding, the Metapa production facility will ramp up to yield between 60 million and 100 million sterile flies per week. USDA officials project that doubling production will reinforce the buffer zone along Mexico’s southern frontier and shorten the time needed to suppress residual pockets of wild worms. Renovation plans include upgrading rearing infrastructure, modernizing sterilization equipment and adding new quality-control labs. USDA technical teams will embed in Metapa for the duration of construction to ensure a smooth transition.
So far, the U.S. Commission for the Eradication and Prevention of Common Flyworms (COPEG) facility in Panama has bred all sterile flies used in the program. COPEG teams rear tens of thousands of flies daily, sterilize them and ship them north for release. Once Metapa reaches full capacity, the two governments plan to share production duties more evenly. USDA officials say the dual-facility model will cut transportation time and costs, improve genetic diversity among reared flies and allow a more flexible response to outbreak hotspots.
“Our partnership with Mexico is crucial to the success of this effort,” Rollins said. “We continue to work closely with our neighbors to keep the worm out of the United States and Mexico. The investment I’m announcing today is one of many efforts my team is making around the clock to protect our animals, our agricultural economy and the security of our nation’s food supply.” She added that USDA teams stand ready to adjust tactics as field data dictate, ensuring no gaps appear in the buffer.
Mexican authorities expressed confidence that the enhanced facility will pave the way for resuming livestock exports soon. In a joint statement, Mexico’s agriculture ministry said results on the ground and technical pacts reached during Rollins’s discussions give “solid grounds” to lift export restrictions. Producers in Mexico’s key beef and dairy regions hope to restart shipments once USDA field assessments confirm sustained suppression of worm populations. Both governments plan a joint review after the first quarter of operations to chart the next phase.
