July 2025

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New World Screwworm (NWS) is a devastating pest which can infest livestock, pets, wildlife, occasionally birds, and in rare cases, people. When NWS fly larvae burrow into the flesh of a living animal, they cause serious, often deadly damage to the animal. This is a serious concern to the U.S. economy and the U.S. food supply.  NWS was eradicated from the U.S. in the 1960s using sterile insect technology but began spreading northward into Mexico in November 2024.

On May 11, the USDA announced the closure of the southern border to imports of cattle, bison and horses from Mexico.  Recently USDA reported that since that time, there has not been a notable increase in reported NWS cases in Mexico, and the northward movement has also stalled.  To date there have been no cases of NWS in the United States.  To continue combatting NWS movement toward the U.S., USDA announced a 5-pronged plan on June 18, 2025.

1. Stop the Pest from Spreading in Mexico
   • USDA is working to enhance international sterile fly production with a recent $21 million investment in retrofitting a fruit fly facility in Mexico
   • Improve surveillance in Mexico and supply additional traps and lures, with technical assistance deploy and maintain them effectively
   • Limit the movement of animals if needed to quickly halt the spread.
2. Protect the U.S. Border at All Costs
   • Intercept stray and illegally introduced livestock on the border with Mexico
   • Collaborate with state wildlife agencies to identify priority areas for wildlife surveillance and monitoring
   • Continue enhanced inspection of live animals at ports of entry from Mexico.
3. Maximize our Readiness
   • Partner with state animal health officials to update and finalize emergency management plans.
   • Continue training federal and state responders on how to respond to an outbreak, if one occurs in the United States
   • Remove any regulatory hurdles by working with EPA, FDA and others to ensure access to effective wound and treatment products.
4. Take the Fight to Screwworm
   • Immediately begin construction of an $8.5 million sterile insect dispersal facility at Moore Air Base in South Texas, to disperse sterile flies at our border and Northern Mexico
   • Explore all options to eradicate NWS, including possible plans to move forward with the design process of a domestic sterile fly production facility to compliment the new dispersal facility at Moore Air Base
   • Continue to rapidly validate modular rearing facilities and other technologies that may provide quicker construction and surge capacity in the future.
5. Innovate Our Way to Continued Success
   • Pursue innovative research into improving sterile insect technology including exploring the use of additional or modified strains of the pest or genetically engineered organisms
   • Strengthen partnerships with land-grant universities to facilitate local training, trap deployment, surveillance validation, and stakeholder outreach
   • Explore next generation treatments for the screwworm with our partners to help producers deal with the effects should it enter the country.

To view the full policy brief from USDA, please use this link.

For additional information, please contact Geoffrey Patterson.