Mexico Builds Sterile Fly Plant to Fight Screwworm

Mexico has begun construction on a $51 million facility aimed at tackling the New World Screwworm, a flesh-eating pest that has disrupted Mexican cattle exports to the United States in recent months.

According to Mexico’s agriculture ministry, the new plant — a joint project with the U.S. — will produce up to 100 million sterile screwworm flies per week when it opens in the first half of next year. Releasing sterile flies into the wild is a proven way to control the pest’s spread by disrupting its reproduction cycle.

Mexico is covering $30 million of the cost, while the U.S. is contributing $21 million. The U.S. Department of Agriculture (USDA) also plans to open a sterile fly dispersal facility in Texas to bolster the effort.

“Our partnership with Mexico is crucial in making this effort a success,” said U.S. Secretary of Agriculture Brooke L. Rollins. “We are continuing to work closely with Mexico to push NWS away from the United States and out of Mexico. The investment I am announcing today is one of many efforts my team is making around the clock to protect our animals, our farm economy, and the security of our nation’s food supply.”

The screwworm carries maggots that burrow into the skin of living animals, causing severe and often fatal wounds. It was officially eradicated from the U.S. in 1966, but the pest reappeared in southern Mexico last year, prompting a halt in live cattle imports. Imports resumed only after Mexican officials ramped up inspections, quarantine controls, and pest treatments at key border crossings.

In addition to the new facility, USDA is investing in the renovation of an existing fruit fly production plant in Metapa, Mexico, which will produce an extra 60–100 million sterile screwworm flies weekly.

“This additional production capacity will be critical to our response,” Rollins said during an update call with Mexico’s Secretary Berdegue in late May.

Long-Term Battle to Protect Herds

The New World Screwworm has long been a concern across Central and South America. The U.S. and Mexico have worked together for decades to suppress the pest using the Sterile Insect Technique (SIT). The Panama – United States Commission for the Eradication and Prevention of Screwworm (COPEG) currently produces all sterile flies used in aerial and ground dispersal missions throughout Central America.

In recent years, however, the pest has advanced northward, spreading from Panama into Costa Rica, Nicaragua, Honduras, Guatemala, Belize, and now deep into Mexico, raising the stakes for both nations’ livestock industries.

Trade and Economic Stakes

The U.S. imports over a million Mexican cattle each year, helping offset domestic herd declines and stabilizing beef prices. Any disruption to this trade — like the import ban from November 2024 to February 2025 — can strain the U.S. beef supply chain and push up prices for ranchers and consumers alike.

Broader Biosecurity Push

The USDA’s Animal and Plant Health Inspection Service (APHIS) continues to meet with Mexican counterparts to tighten surveillance, strengthen pre-export inspections, and approve more border crossings for cattle trade. “We are making strong progress toward enhancing surveillance in Mexico, addressing administrative or regulatory roadblocks that could impair an effective response, and ensuring appropriate animal movement controls are in place,” Rollins said.

Efforts are also underway to rebuild the biological barrier in Panama — a crucial line of defense since 2006 — to prevent further northward spread.

Originally reported by Jody Heemstra in DRG News.