New World Screwworm Found in US Wildlife for the First Time
24 October 2026, Texas: The US Department of Agriculture has confirmed the first detection of New World screwworm in American wildlife, a development that landed alongside a new livestock case in neighboring New Mexico and a steady rise in weekly infections across the two states.
APHIS, the USDA’s animal health arm, confirmed on October 21 that a hunter-harvested elk from a private game ranch in Pecos County, Texas, tested positive for the flesh-eating larvae. Because the animal was already dead when sampled, the agency classifies the case as inactive, meaning there is no ongoing infestation in that specific animal. On the same day, New Mexico’s state animal health officials confirmed a case in a beef cow in Otero County, one of several New Mexico detections since the pest crossed from Mexico earlier this year.
Taken together with the broader case count, the news has drawn national attention in the United States and renewed scrutiny on the pace of a response that began in June. As of October 21, officials counted seven active US cases and 59 total detections since the first one, a three-week-old calf in Zavala County, Texas, on June 3. The weekly pace has picked up: three cases were recorded in September compared with six in the most recent week alone. Nationwide, roughly 1,000 suspect submissions have come in since June, with 531 from Texas. A single wild screwworm fly was also detected in a trap, separate from the confirmed animal cases.
Dudley Hoskins, the USDA’s Under Secretary for Marketing and Regulatory Programs, told reporters the wildlife finding and the recent uptick do not amount to an outbreak. He credited the detection to the surveillance system working as intended, pointing to producers, hunters, and state agencies flagging suspect cases quickly. He described wild fly populations as low and localized so far, based on more than 39,000 wildlife interactions tracked by APHIS Wildlife Services using trail cameras, drones, and feral hog monitoring. He also stressed that screwworm is a treatable pest, not a food-safety or disease risk to the wider food chain.
A Widening Surveillance Net
In response, the Texas Animal Health Commission is modifying its existing infested zones around the new case, and both USDA and the Texas Parks and Wildlife Department are expanding wildlife surveillance in the affected area. New Mexico has a minimum 20-kilometre infested zone in place around its latest detection, inside which animals must be inspected, and treated if necessary, before they can be moved. Officials in both states are stepping up fly-trapping to establish whether the pest has spread beyond the known zones.
New World screwworm was eradicated from the United States decades ago through one of the most successful pest-control programs in agricultural history: the sterile insect technique, which floods affected areas with lab-reared, radiation-sterilized male flies so that wild females cannot produce viable offspring. That program never fully left the hemisphere, and the pest’s resurgence has moved north through Mexico from Central America over the past two years, with Mexico recording more than 29,000 cases since November 2024.
The current US response leans on the same playbook at a larger scale. USDA says it has released more than 1.64 billion sterile flies as of October 22. A new domestic production facility at Moore Air Base in Edinburg, Texas, is under construction and expected to produce 100 million flies a week once it opens, targeted for April 2027, with a second phase adding 200 million more. Existing facilities in Panama and in Metapa, Mexico, are each working toward 100 million flies a week, with the combined network aiming for roughly 500 million flies weekly once fully operational. Separately, the USDA’s Agricultural Research Service and the US Environmental Protection Agency are field-testing a male-only sterile fly strain, called NovoFly, in Panama.
Why a Texas Pest Matters to Global Cattle Markets
The stakes extend well beyond the two affected counties. The screwworm threat prompted Washington to halt live cattle, horse, and bison imports from Mexico for more than a year, a step that tightened US cattle supplies and has been linked to record domestic beef prices. That ban is being lifted gradually through a phased, port-by-port reopening that began in August, a process regulators are managing carefully precisely because a wildlife reservoir of the pest, even a small one, complicates any full return to open trade.
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