For first time in decades, US opens Texas facility to disperse sterile screwworm flies

The first facility in decades to disperse sterile New World screwworm (NWS) flies from the United States opened Monday in Edinburg, Texas,¹ as part of efforts to protect US livestock and other animals from the flesh-eating parasite.

The parasite has been moving northward toward the US-Mexico border, with officials detecting cases in the northern border state of Nuevo León, Mexico, including in a calf, in fall 2025.² NWS larvae feed on living tissue, causing serious wounds and, if untreated, death in livestock and other mammals. The parasite can also, rarely, infest humans. The insect was eradicated from the US decades ago, but reintroduction via natural spread or animal movement remains a concern for producers, veterinarians, and public health officials.

In a statement released earlier this week, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) said the new fly dispersal facility will expand the USDA’s ability to diffuse sterile flies along the border and even into the US if necessary.¹

The sterile fly technique works by flooding an area with sterile male flies that mate with wild females. Because female NWS flies mate only once in their lifetime, mating with a sterile male results in unfertilized eggs that will not hatch, reducing the wild population. This technique was key to eliminating the parasite from the US in the 1960s.³

At a celebration last week at the new facility, developed on the former Moore Air Base, US Secretary of Agriculture Brooke L. Rollins and Texas Governor Greg Abbott highlighted the facility’s role in strengthening defenses along the US‑Mexico border. “This new facility is a monumental achievement for our domestic preparedness efforts, but we are also diligently working to stop the spread of screwworm in Mexico, conduct extensive trapping and surveillance along the border, increase US response capacity, and encourage innovative solutions,” Rollins said in the announcement.¹

The Edinburg facility expands the USDA’s ability to disperse sterile flies into areas where NWS might appear, complementing an existing sterile fly facility at the Commission for the Eradication and Prevention of Screwworm in Panama.³

The USDA is also allocating $21 million to convert a fruit fly breeding facility in southern Mexico into a screwworm breeding site, with the project expected to begin this summer.⁴ In addition, the agency is working on another nearby sterile fly production facility, estimated to cost $750 million, with a completion projected for the end of 2027.⁴

Still, surveillance and early detection remain important to veterinary and animal health efforts. Veterinary professionals are encouraged to remain alert for signs of NWS infestation, including draining wounds, larvae or eggs in or around body openings, and signs of animal discomfort. According to USDA information, if infestation is suspected, veterinarians should guide diagnostic and treatment steps and immediately report the case to state animal health officials and APHIS Area Veterinarians in Charge according to their state reporting regulations.³

References

1. USDA announces completion of sterile fly dispersal facility in Texas. News release. News release. USDA. February 9, 2026. Accessed February 11, 2026. https://www.usda.gov/about-usda/news/press-releases/2026/02/09/usda-announces-completion-sterile-fly-dispersal-facility-texas
2. Garrison C. Mexico confirms new screwworm case in northern border state Nuevo Leon. News release. Reuters. October 6, 2025. Accessed February 11, 2026. https://www.reuters.com/business/healthcare-pharmaceuticals/mexico-intercepts-new-screwworm-case-northern-border-state-2025-10-06/
3. New World screwworm. USDA. December 22, 2025. Accessed February 11, 2026. https://www.aphis.usda.gov/livestock-poultry-disease/cattle/ticks/screwworm
4. Hanna J, Gay E. The US has a new center in Texas to disperse sterile screwworm flies to block a parasite it spawns. AP News. February 9, 2026. Accessed February 11, 2026. https://apnews.com/article/flesheating-screwworm-fly-factory-cattle-texas-dca5a51ae8ba30559ccfa8991c2e9a97