On Wednesday evening, June 3, 2026, the USDA confirmed the thing that Texas ranchers and agriculture officials had been dreading for months. A three-week-old calf on a cattle ranch near La Pryor in Zavala County, South Texas, tested positive for New World screwworm. The parasitic fly, whose larvae literally eat through living flesh, hadn’t been found in U.S. livestock in decades. Now it’s here, and the scramble to contain it is already underway.
If you’ve never heard of a screwworm before, consider yourself lucky. This isn’t your average pest problem. This is the kind of thing that cost American ranchers hundreds of millions of dollars a year before the government managed to wipe it out in the 1960s. The fact that it’s back on U.S. soil is a very big deal, and not just for people who own cattle.
What Exactly Is a Screwworm?
The New World screwworm (scientific name: Cochliomyia hominivorax, which roughly translates to “man eater”) is a parasitic fly. The adult flies look somewhat ordinary, but what they do is anything but. Female screwworm flies seek out open wounds on warm-blooded animals and lay their eggs directly in them. We’re talking cattle, dogs, cats, wild mammals, and yes, occasionally people.
Once those eggs hatch, hundreds of larvae use their sharp mouthparts to burrow into the living tissue of their host. They don’t feed on dead flesh like regular maggots. They eat living flesh. Left untreated, the larvae can damage organs, cause severe bacterial infections, and kill the animal. A small scratch or insect bite is enough of an entry point. Even the navel of a newborn calf can attract these flies.
How It Got to Texas
This didn’t happen overnight. The screwworm has been moving northward through Mexico for more than a year. Over the past 18 months, more than 26,000 cases were identified across Mexico. In the Mexican state of Coahuila, which shares a border with Texas, officials were tracking 32 cases at the time the Texas detection was made, with 19 of those still active.
Earlier in the same week as the Texas confirmation, the USDA had reported a confirmed screwworm case in Coahuila, roughly 25 miles south of the border. Texas officials had been preparing for months, knowing full well that a 25-mile buffer wasn’t exactly comforting when the flies can travel up to 12.5 miles on their own, and much farther when hitching a ride on an infested animal being transported.
The U.S. had already banned livestock imports from Mexico back in July 2025 as a precaution. Governor Greg Abbott declared a disaster in January 2026. Texas officials even launched plans for a new $750 million facility in South Texas aimed specifically at preventing the parasite’s spread. Despite all of that, screwworm crossed the border anyway.
The USDA’s Emergency Response
The moment the La Pryor case was confirmed, the federal government kicked into high gear. USDA personnel are now on the ground in South Texas, and they’ve set up a 12-mile “infested zone” around the detection site. Inside that zone, quarantines and movement controls are in effect. No livestock goes in or out without clearance.
One of the more interesting weapons in the USDA’s arsenal is something called the sterile insect technique. The agency is fast-tracking the release of sterile male screwworm flies into the area. The idea is simple: flood the zone with sterile males so that when female flies mate, the resulting eggs don’t develop. If enough sterile matings occur, the population collapses. This is the same strategy the USDA used to wipe out screwworm from the U.S. back in 1966, and it worked again during a smaller outbreak in the Florida Keys in 2017.
The USDA and Panama’s agriculture ministry jointly run the only sterile fly production facility currently operating in North America. That facility is now a critical piece of the containment effort.
USDA Secretary Brooke Rollins held a press conference and urged calm, stating there is “no reason to believe that this incursion will result in an establishment of the pest in our country.” She also made clear that screwworms do not infest meat, fruits, vegetables, or any food products. The food supply is safe. This is a livestock and animal issue, not a grocery store issue.
Why Beef Prices Could Get Even Worse
Here’s where this story hits your wallet. The American beef industry is already in rough shape. Beef prices have gone up 57 percent since 2020. Just in the first four months of 2026, they climbed another 3 percent. The U.S. cattle herd is sitting at a 75-year low, with an estimated 86.2 million head of cattle in 2025. That’s the fewest since 1951.
According to economic analysis from the Dallas Federal Reserve, steak prices have already jumped by more than $2 per pound to an average of $13.02. Ground beef has gone up $1.35 per pound since the start of 2025. Consumers are still buying, but the numbers are getting painful.
Texas is far and away the biggest cattle state in the country, holding 14 percent of the total U.S. supply. A widespread screwworm outbreak there could cause an estimated $1.8 billion in damage to the state’s economy alone and would almost certainly push beef prices higher nationwide. The beef industry moves slowly because it takes years to breed and raise cattle. Any disruption now ripples forward for a long time.
Cattle futures markets reacted immediately. Traders had long been sensitive to the screwworm threat, and widespread market chatter about the suspected case rattled prices even before the lab results were in. Market players believe a U.S. screwworm outbreak could initially reduce consumer demand for beef (people get squeamish about flesh-eating parasites, understandably), but the long-term effect of a smaller cattle supply would push prices up even further.
It’s Not Just Cattle
If you don’t own a ranch, you might think this doesn’t affect you. But screwworm flies don’t check paperwork. They’ll go after any warm-blooded animal with an open wound. That includes your dog, your cat, and the deer in your backyard.
Dogs and cats are particularly vulnerable because even minor injuries can attract the flies. A tick bite, a scratch from a fence, a small cut from rough terrain. The Texas Farm Bureau is urging pet owners to check their animals daily for wounds, especially around areas where ticks have been. They also recommend looking out for wounds that don’t seem to heal, foul odors, or visible larvae.
Wildlife is also a major concern. The Texas hunting industry is a multi-billion dollar business, and screwworm doesn’t discriminate between a prize buck and a barnyard cow. Increased wildlife mortality could have a serious economic ripple effect beyond just ranching.
Can Humans Get Screwworm?
It’s rare, but yes. Any open wound on a person, even something as small as a scratch or a bug bite, can theoretically attract a female screwworm fly looking for a place to lay eggs. Secretary Rollins said the current risk to people in the U.S. is extremely low, but she noted that those who work with livestock or spend extended time outdoors in affected areas should be more vigilant.
People who sleep outside and those with conditions that cause slow-healing wounds or open sores are considered more at risk. The USDA recommends keeping wounds clean and covered, wearing long sleeves and pants in areas where flies may be present, and using EPA-registered insect repellents.
What Vets and Officials Are Telling People Right Now
Veterinarians across Texas, Arizona, and New Mexico have been told to watch for new infections. The USDA has established an Incident Command Team working with the Texas Animal Health Commission, and surveillance is being ramped up along the border. The agency has also been providing twice-weekly updates on new cases found within 400 miles of the U.S. border in Mexico.
For livestock owners, the guidance is straightforward: treat all wounds immediately with approved insecticide, avoid procedures that create wounds (like branding, dehorning, or castration) if you’re in or near the infested zone, and protect animals from ticks and other wound-causing parasites. If you suspect screwworm, contact your state animal health official or USDA area veterinarian immediately. You can also visit screwworm.gov for updates.
For pet owners, check your animals daily. Look for wounds that seem to be getting worse instead of better, especially around body openings like the nose, ears, and genitalia. Look for visible larvae or eggs. And pay attention to your pet’s environment. Metal collars, wire fencing, and sharp brush can all cause the small cuts that attract these flies.
The Stakes Are Enormous
Right now, this is one confirmed case on one ranch in one county. The containment measures are aggressive, and the USDA has dealt with this before successfully. But nobody in the agriculture world is taking this lightly. The parasite was tracked moving north through Mexico. Officials had months to prepare. They knew this was coming. And it still got through.
The next few weeks will tell us whether this was an isolated incident or the beginning of something much more expensive and disruptive. With beef already at record prices, the cattle herd at its smallest in 75 years, and $1.8 billion in potential economic damage on the line for Texas alone, the pressure to contain this fast is about as high as it gets.
If you live in South Texas or anywhere near the border, pay attention to the USDA’s guidance. Check your animals. Report anything suspicious. And if you’re just a regular consumer wondering what this means for your grocery bill, keep watching. The answer depends entirely on what happens next.