New World Screwworm Confirmed in South Texas
First domestic detection in decades puts cattle country on high alert
USDA’s Animal and Plant Health Inspection Service confirmed today what livestock producers across South Texas have feared: New World screwworm (NWS) has crossed the border. The detection — in a three-week-old calf in Zavala County, Texas — marks the first confirmed domestic case in more than 60 years.
NWS is a serious pest that affects livestock, pets, wildlife, and less commonly, people and birds. NWS larvae (maggots) burrow into the flesh of living animals, causing serious damage to livestock and economic losses.
The affected animal is a 3-week-old calf and larvae were identified in its umbilical area. To date, there have been no further detections.
The confirmation follows a turbulent 24 hours. The announcement came just one day after USDA Secretary Brooke Rollins publicly disputed claims by a state lawmaker that the pest had already been spotted less than a mile from the U.S./Mexico border.
Quote of note: “All models showed New World Screwworm entering the country in 2025; however, thanks to the hard work across the entire Trump administration and our industry, state, and local partners, we were able to buy time for this moment. Protecting our livestock industry is a national security issue of the utmost importance, and USDA is wasting no time in taking action,” said Dudley Hoskins, Undersecretary for Marketing and Regulatory Programs. “USDA invested heavily in the tools needed to eliminate NWS ever since cases started increasing in Central America and Mexico. The United States has defeated this pest before, and we will do it again.”
The stakes are significant. New World screwworm is a parasitic fly poised to cause serious harm to Texas’s $15 billion cattle industry. The pest, whose larvae burrow into the living flesh of warm-blooded animals, had been marching steadily northward for years. The NWS fly has migrated across Central America from Panama through Mexico before reaching the U.S. Feeder cattle futures markets reacted immediately to the news, falling more than $5 per hundred across contracts.
USDA and Texas officials are taking immediate action to contain and eradicate NWS from the United States, following the strategies and actions outlined in the NWS Response Playbook. This includes:
• Forming a unified Incident Command Team with the Texas Animal Health Commission and deploying response personnel to the area;
• Establishing a 20 km infested zone around the detection and implementing quarantines, movement controls, and surveillance in this area;
• Expediting targeted release of sterile NWS flies by immediately deploying ground release chambers in the area, in addition to the 4 million sterile flies per week already being released aerially in the area;
• Increasing trapping for NWS flies along the border and just outside of the dispersal area;
• Implementing NWS surveillance and management strategies in wildlife; and
• Conducting targeted outreach in the local area.
Additionally, USDA’s National Veterinary Stockpile stands ready to assist, and will provide resources including treatments, equipment, and logistics support the response as needed.
USDA will continue to work with state departments of agriculture, animal health officials, industry, and producers to mitigate economic impacts of restrictions as much as possible, including negotiating with our trading partners to regionalize any trade restrictions on live animals, limiting them to defined geographic areas.
The agency has been investing heavily in preparedness infrastructure. USDA recently opened the Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, Texas — a 52,000-square-foot facility with cattle housing and genomic research capabilities — to accelerate work on surveillance, trapping, pesticide delivery, and novel pest control tools.
Officials are also working to limit the trade fallout. USDA says it will negotiate with trading partners to regionalize any restrictions on live animal exports, confining them to defined geographic areas rather than applying them nationally.
USDA and state officials urge producers to inspect livestock for signs of infestation — including draining or enlarging wounds, signs of distress, and larvae in or around body openings. Suspected cases should be reported immediately to the Texas Animal Health Commission or a USDA area veterinarian.
The U.S. food supply is not at risk. Screwworms do not infest meat or food products, and USDA’s Food Safety and Inspection Service inspection protocols ensure any affected animals would be identified before entering the commercial supply chain.
The U.S. Meat Export Federation said that it doesn’t expect any disruptions to US beef exports, but will “monitor the situation carefully for any trading partner actions that could interrupt beef trade.”
Ag panel leaders Boozman, Thompson statement on domestic detection of NWS:
“For well over a year, Secretary Brooke Rollins and her team at USDA have been working around the clock alongside federal agencies, state partners and animal health experts to prevent New World Screwworm from entering the United States—longer than many thought possible—and to ensure we are prepared to respond to a potential domestic case. Their proactive efforts have strengthened our defenses against this serious threat to animal health and the livestock industry, and we appreciate their continued commitment to protecting American agriculture.
“The detection of New World Screwworm within our borders should not be cause for panic, but rather time for the full deployment of the next phase of the whole-of-government response USDA has been planning for months. We have the tools, resources and an action plan to aggressively respond, enhance surveillance and prevent further spread. By working closely with producers, animal health officials, and our federal and state partners, we will take the necessary steps to protect and safeguard America’s livestock industry. We have successfully eradicated this threat to livestock, wildlife and animal health before, and we’re confident we will do so again.”
American Farm Bureau Federation President Zippy Duvall said:
“The re-emergence of New World screwworm in the United States after 60 years will have an immediate impact on farmers and ranchers in the affected areas. We are confident that the longstanding coordination between the states and USDA will enable a quick response and hopefully limit the negative impacts and resulting market volatility.
“We encourage farmers, ranchers and pet owners to familiarize themselves with the signs of NWS and notify a veterinarian if infection is suspected. It is important to be clear about the fact that this re-emergence does not threaten the safety of our food supply. We are fortunate to have one of the safest food supplies in the world, which includes multiple layers of protection.
“We knew the screwworm could one day migrate north, and we appreciate USDA and Secretary Rollins for the coordination and mitigation efforts that have already occurred. Farm Bureau is committed to working with USDA and the affected areas in any way to eliminate this pest once again from the U.S.”
