The livestock industry’s worst-case containment scenario gained ground Wednesday, Oct. 21, as officials confirmed the first wildlife case of New World screwworm in an elk. Detected on a private game ranch in Pecos County, Texas, the find raises the pressure on ranchers, hunters and state agencies battling to keep the flesh-eating parasite from gaining a foothold across the Southwest.
The infested elk was harvested by a hunter and reported immediately to wildlife authorities. Because the animal was already dead at the time of reporting, the USDA Animal and Plant Health Inspection Service (APHIS) considers the case inactive, but the Texas Animal Health Commission (TAHC) is modifying existing quarantine zones while USDA and Texas Parks and Wildlife Department (TPWD) ramp up localized surveillance.
Despite the concern of a wildlife detection, USDA Under Secretary for Marketing and Regulatory Programs Dudley Hoskins emphasizes the finding — and a recent bump in detected cases — does not signal an outbreak. Instead, he points to it as evidence that early-warning tripwires established by cattle producers, hunters, and federal and state agencies are holding.
As of Oct. 21, there are seven active NWS cases in the U.S. Since the first case in June, there have been 59 recorded cases in two states. Looking at the monthly totals, there were only three in September compared to six in the last week. Since June 3, USDA has received 1,000 suspect case submissions nationwide, including 531 from Texas. There has also only been one fly trap detection of a wild NWS fly.
“We have seen a few more cases confirmed in the last couple weeks, and not unexpected,” Hoskins says. “Candidly, to us it’s reflective of the system working the way it should. Producers, the outdoor recreation and hunting community — the awareness, the vigilance, the reporting — all of that is so fundamental and critical as we continue our response, our surveillance, and more importantly, the distribution of sterile flies in areas where we find infested animals.”
The Wild Reservoir Risk: Why Containment Matters
For cattle producers, the chief concern since the first case surfaced in a South Texas calf has been the risk of screwworm establishing an unmanaged reservoir in deer, elk or feral hogs. An uncontrolled wild host population could reinfect pastures and complicate herd management.
Hoskins stresses current surveillance data indicates wild fly populations remain low and isolated, rather than widespread.
“When we look at the wildlife component, we have invested an incredible amount of resources with staffing, innovation, technologies and capacity,” Hoskins explains, noting APHIS Wildlife Services has conducted surveillance across more than 39,639 wildlife interactions via trail cameras, aerial drones and targeted feral hog monitoring.
“This is our first detection that we’ve seen so far [in wildlife]. That’s not to say that it’s not in wildlife somewhere else, but the fact that we haven’t seen a flare-up in numbers and detections tells us and our subject matter experts that there’s not a high prevalence of the fly in the wild in the United States,” Hoskins stresses. “Obviously, if we take our foot off the gas and we stop looking for it and stop putting out sterile flies and stop doing the surveillance work, that dynamic could change quickly.”
He also explains the sharp contrast between NWS and infectious livestock epidemics. “At the end of the day, we all have to remember what screwworm is and what it is not,” Hoskins underscores. “Screwworm is a parasite. It’s a pest, but it’s not a pathogen. It’s not a disease that we have to go in and do mass depopulation or stamp out a herd. It is not a food safety risk. We have the tools to treat individual infested animals, and we have the ability to knock down the wild fly population with our sterile insect technique.”
As of Thursday, Oct. 22, USDA has released more than 1.64 billion sterile flies.
Field Vigilance: Mobilizing Hunters for Fall Surveillance
With fall hunting seasons underway across Texas, New Mexico and the broader Southwest, thousands of sportsmen and ranchers are in pastures and brush country daily. USDA and state wildlife agencies are urging anyone handling livestock or wild game to inspect animals carefully.
“The best thing we can all put on our animals, whether it’s cattle, horses, and hogs, cats and dogs, wildlife — you name it — any warm-blooded species, the best thing we can put on those animals is our eyes,” Hoskins explains. “If we’re able to make the effort on the management side, on the vigilance side and when we see something of concern to report it, that gives us our sharpest tool to knock down any kind of infestation that may be in the wild.”
Hunters are encouraged to stay alert for signs of NWS when observing, harvesting or processing wildlife.
What to Look For:
- Visible maggots (larvae) in wounds, navel areas or natural body openings.
- Open, draining, or enlarging wounds.
- Foul-smelling injuries.
- Animals that appear weak, lethargic, isolated or in distress.
- Signs of infestation around the nose, mouth, ears, eyes or genital areas.
If you see anything suspicious, report it immediately to state veterinarians or TAHC (1-800-550-8242 in Texas), while wildlife sightings should go to state wildlife biologists or USDA Wildlife Services. Fast reporting helps animal health officials respond quickly and helps limit the pest’s spread.
For information on identifying and reporting potential cases in wildlife, visit USDA’s wildlife resources at Screwworm.gov/wildlife. The site includes signs to watch for, reporting guidance and additional resources for hunters and outdoor enthusiasts.
The Eradication Arsenal: Building Toward 500 Million Sterile Flies Per Week
While trapping, wound sprays and movement restrictions hold the line locally, total eradication hinges on the Sterile Insect Technique (SIT) — overwhelming wild populations with irradiated, sterile male flies that mate with wild females, producing infertile eggs and collapsing the life cycle.
USDA’s long-term containment offensive centers on three production hubs and genetic innovation:
- Moore Air Base (Edinburg, Texas): Construction on USDA’s domestic, Biosafety Level 2 (BSL-2) sterile fly facility is advancing at an unprecedented pace. “BSL-2 projects are usually three-, four-, five-year projects,” Hoskins notes. “With Moore Air Base, our partners at the U.S. Army Corps of Engineers and our private contractor partner, Mortenson Construction, have really worked miracles... cut down from a four- to five-year shot clock down to one year, effectively. We are tracking construction completion to be wrapped up in April 2027.” Once physical construction is finished, colony rearing will ramp up to an initial 100 million sterile flies per week, followed by Phase 2 expansion adding another 200 million flies per week.
- COPEG (Panama) & Metapa (Chiapas, Mexico): The joint Panama-U.S. commission facility (COPEG) continues producing 100 million sterile flies weekly, while Mexico’s Metapa facility is ramping toward another 100 million weekly.
- The 500-Million Target: “Once Moore Air Base Phase 1 and Phase 2 are online, once Metapa continues to ramp up full production at 100 million sterile flies per week, and as COPEG continues to produce 100 million sterile flies per week, that sum total is about 500 million sterile flies per week,” Hoskins calculates. “That number is significant because that’s the number we needed in the 1960s to effect eradication from the United States and Mexico and Central America through the ’80s and ’90s.”
- NovoFly Technology: In partnership with the EPA and USDA Agricultural Research Service (ARS), field trials are proving out “NovoFly” — an advanced male-only strain currently undergoing biological competitiveness vetting on the ground in Panama. Because female screwworms only mate once, releasing exclusively sterile males prevents sterile-on-sterile matings and effectively doubles operational efficiency in the field.
Quarantine Friction and Producer Fatigue
While containment efforts continue to restrict NWS largely to isolated pockets, Hoskins acknowledges the regulatory friction and operational strain facing livestock producers in quarantine and surveillance zones. For updated zones, visit the Texas Animal Health Commission website or the New Mexico Department of Agriculture website.
“I know there can always be fatigue when it comes to some of the disease response activities, and especially the impact to the producer community when you look at the continuity of business component,” Hoskins says. “We are so grateful to not just our state partners, but also our producer partners, because they have to navigate certain protocols and inconveniences until we can get screwworm out of the United States again.”
He concludes, “Their vigilance and the diligence in the producer community is why we’re able to have a successful response and why we’re able to mitigate the inadvertent movement of infested animals. We still have plenty of work to do, and we just can’t take our foot off the gas.”
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