Mexico, U.S. Launch Sterile Fly Facility to Combat New World Screwworm Outbreak

Mexico and the United States have officially launched a new sterile fly production facility in southern Chiapas as both countries intensify efforts to contain the growing New World screwworm outbreak, which has disrupted livestock production and cross-border cattle trade.

Mexican President Claudia Sheinbaum and U.S. Agriculture Secretary Brooke Rollins inaugurated the $50 million joint facility in Metapa de Dominguez, near the Guatemala border. Once fully operational, the plant will produce up to 100 million sterile flies each week, a key component of the biological control strategy used to reduce the wild screwworm population.

The New World screwworm is a destructive parasite that burrows into the flesh of warm-blooded animals, causing severe wounds that can become fatal if left untreated. While the new plant significantly boosts production capacity, experts caution that the number of sterile flies available will still be below the level required to completely eradicate the pest.

The facility opens more than 18 months after Mexico confirmed its first screwworm case in November 2024. Since then, the parasite has spread steadily northward, eventually reaching the United States. In early June 2026, Texas confirmed its first screwworm cases in decades, raising alarm across the U.S. cattle industry.

"Our countries have beaten this before, 40, 50 years ago. We will beat the New World screwworm again sooner than anyone would have thought because of the extraordinary work that is going to happen at this facility," Rollins said during the inauguration.

Warnings about the parasite's northward movement had been issued as early as 2023 by the Panama-United States Commission for the Eradication and Prevention of Screwworm (COPEG). Despite those alerts, containment efforts struggled to keep pace, and the parasite has since infected more than 30,000 animals across Mexico.

Neither Mexico nor the United States announced plans to build new sterile fly production facilities until 2025. Alongside the Chiapas project, the U.S. is constructing its own sterile fly production plant in Texas to strengthen long-term eradication efforts.

The outbreak has had a major impact on livestock trade. Since May 2025, the United States has kept most of its border closed to Mexican live cattle to prevent further spread of the parasite. Before the restrictions, Mexico exported more than one million live cattle annually to U.S. feedlots.

The border closure has tightened cattle supplies in Texas, leaving some feedlots operating below capacity and contributing to historically low cattle inventories in the United States.

The disruption has also reshaped Mexico's beef industry. Ranchers who previously relied on exporting live cattle have increasingly invested in domestic feedlots and meat processing facilities, allowing them to fatten cattle locally before slaughter. As a result, Mexican beef exports to the United States have risen sharply throughout 2026.

President Sheinbaum emphasized that agricultural pests and animal diseases require international cooperation rather than isolated responses.

"Animal diseases, pests and the challenges of food safety aren't limited by borders," Sheinbaum said. "In the face of those challenges, the best response is to team up, share our experiences and build solutions together."

The new Chiapas facility is expected to double the supply of sterile flies currently available beyond the output of COPEG's long-running production plant in Panama, which has been operating at full capacity with approximately 100 million sterile flies produced each week. Those insects have recently been released primarily along the U.S.-Mexico border near Texas as part of ongoing efforts to suppress the screwworm population and protect North America's livestock industry.