USDA opens sterile fly dispersal facility in Mexico

The USDA has announced the opening of a sterile fly dispersal facility in Tampico, Mexico, for the purpose of mitigating the threat of New World screwworm (NWS) infestation. The facility will allow the USDA to disperse sterile flies aerially across northeastern Mexico, which can help prevent infestation in the US.¹

“The New World screwworm continues its March northward.…Unlike typical maggots that feed on necrotic tissue, this screwworm larva loves living flesh. It will, in fact, disfigure and kill livestock, pets, wildlife, and yes, even you,” Christopher Lee, DVM, MPH, DACVPM, said in a Vet Watch update.²

Two methods are used to disperse sterile insects: aerial dispersal and ground release chambers. “Aerial operations are preferred because they allow for dispersal at a steady rate through a large area and because sterile insects may be dispersed in areas that are unreachable from the ground,” the USDA said in a news release.¹ “Mass production and targeted dispersal of sterile flies remain critical components of our effective response.”

The federal agency is currently dispersing 100 million sterile flies per week in Mexico. However, the majority of reported NWS cases in Mexico have come from the southern regions and aerial operations have been limited to those areas, thus far.¹

Ground release chambers have been used when a need to quickly deploy sterile insects has arisen outside the range of other dispersal facilities.¹ “The [new] facility will ensure flexibility and responsiveness in northern Mexico, giving us a greater ability to drop sterile flies and continue to push the pest south,” US Secretary of Agriculture Brooke L. Rollins said in the USDA release.¹

Earlier this year, NWS was confirmed less than 70 miles south of the US-Mexico border. This confirmation marked the northernmost detection of the parasite during the ongoing outbreak in Mexico and prompted an increase in concern for the US cattle and livestock industry.³

In September 2025, the FDA issued the first conditional approval in the US for a drug indicated to prevent and treat NWS larval infestations in cattle. Doramectin injection solution (Dectomax-CA1 Injectable; Zoetis) is also indicated for the prevention of NWS reinfestation for 21 days in cattle.^4,5

“New World screwworm has the potential to bring unprecedented economic and animal health harm to livestock producers,” Mike Lormore, DVM, MS, MBA, director of cattle and pork technical services at Zoetis, said in a news release.⁴ “Our top priority is to support keeping animals healthy and provide timely, efficacious solutions to our customers and partners.”

FDA Commissioner Marty Makary, MD, MPH, said agency officials understand the urgency for fighting NWS infestation. According to Timothy Schell, PhD, acting director of the FDA’s Center for Veterinary Medicine, the agency will continue to expediate their review of animal drugs that have the potential to protect US livestock and the livelihoods of those that care for them.⁵

Meanwhile, the USDA is working to expand US response to the NWS threat with the construction of a sterile fly dispersal facility at Moore Air Base in Edinburg, Texas. The domestic facility is projected to open and begin sterile fly production in early 2026.¹

References

1. USDA announces opening of sterile fly dispersal facility in Tampico, Mexico. USDA. November 13, 2025. Accessed November 15, 2025. https://content.govdelivery.com/accounts/USDAOC/bulletins/3fb1841
2. Lee C. New World screwworm invasion update; a looming threat to US borders. Vet Watch. July 15, 2025. Accessed September 30, 2025. https://www.dvm360.com/view/new-world-screwworm-invasion-update-a-looming-threat-to-us-borders
3. Bautista-Alejandre A. New World screwworm detected less than 70 miles from the US-Mexico border. dvm360. September 22, 2025. Accessed September 30, 2025. https://www.dvm360.com/view/new-world-screwworm-detected-less-than-70-miles-from-the-us-mexico-border
4. Zoetis receives conditional approval for Dectomax-CA1 injectable for the prevention and treatment of New World screwworm myiasis in cattle. News release. Zoetis. September 30, 2025. Accessed September 30, 2025. https://investor.zoetis.com/news/news-details/2025/Zoetis-Receives-Conditional-Approval-for-Dectomax-CA1-Injectable-for-the-Prevention-and-Treatment-of-New-World-Screwworm-Myiasis-in-Cattle/default.aspx
5. Crossley KC. FDA conditionally approves drug to prevent and treat screwworm in cattle. dvm360. September 30, 2025. Accessed November 14, 2025. https://www.dvm360.com/view/fda-conditionally-approves-drug-to-prevent-and-treat-screwworm-in-cattle