Mexico and the United States jointly opened a New World screwworm fly production facility in June 2026 to thwart the advance of a pest that threatens livestock and agricultural production in both countries. Mexican President Claudia Sheinbaum, U.S. Agricultural Secretary Brooke Rollins and U.S. Ambassador to Mexico Ron Johnson opened the facility in Metas in Chiapas state in southern Mexico. It will produce sterile flies, a technique that has proved successful in past outbreaks. “The cooperation we are advancing today reflects the commitment of President Trump and President Sheinbaum to deliver tangible solutions and measurable results. By combining expertise, resources, and investment, our countries are addressing a shared challenge in a way that strengthens security, supports producers, and benefits our people,” Johnson stated in an embassy news release.
Sheinbaum also praised the initiative at her daily news conference on June 29. “It is a good example of development cooperation; it is the example of how cooperation should be between the United States and Mexico. In this case, it is in two ways: scientific and technological development, and on the other hand, joint application to eradicate something that can greatly affect cattle,” she said, according to the Courthouse News Service, a U.S. news site.
The New World screwworm is a parasitic insect, slightly larger than a housefly, that lays its eggs in an open wound in animals or humans, leading to myiasis — an infection caused by the larvae feeding on tissue. The screwworm often infects cattle and other livestock, which could potentially lead to billions of losses for the U.S. and Mexican agricultural sectors. Previous outbreaks — in 1966 and 2017 — have been contained by creating sterile male flies in specialized facilities by exposing them to gamma radiation. These sterile flies are reared in labs then released into the wild in numbers large enough to outcompete fertile male flies for females. Female screwworm flies mate just once, and their union with the sterile flies result in no offspring, thus resulting in diminishing population.
Since screwworms were found in southern Mexico in late 2024, Mexican cattle producers have lost about $2.8 billion in exports, according to Farm Progress, a U.S. agricultural news site. In June 2026, the U.S. Department of Agriculture confirmed the first screwworm animal infestation in Texas. Although people can be infected, the largest risk is to livestock. The U.S. Department of State has announced $84 million to support the eradication efforts in Chiapas and strengthening prevention and response measures along the Mexico-U.S. border.
“What we are doing benefits both our countries. A major outbreak could cost our U.S. agricultural sector more than $700 million each year and result in economic losses of almost $2 billion. By combatting this pest here in Mexico, we are also protecting American ranchers, strengthening food security, and helping safeguard the integrated agricultural economy that supports jobs and families on both sides of the border,” Johnson wrote.
The close collaboration between the North American nations is an example of positive outcomes when partners team up to achieve common objectives. “This effort demonstrates a simple reality: we achieve more tangible results for our populations when the United States and Mexico work together. In this case, we are protecting our agricultural industries, strengthening food security, and building a safer and more prosperous future for both nations,” Johnson wrote.