New World Screwworm and Feral Hogs: What Landowners Need to Know

July 17, 2026

A pest most of the country forgot about is back. After roughly 60 years without a confirmed domestic case, New World screwworm has returned to the United States, and it has a lot to do with the hogs on your ground.

So far, the confirmed detections are in Texas and New Mexico, and New World screwworm (NWS) is drawing a great deal of attention across the livestock and wildlife world.

To help landowners separate signal from noise, Pig Brig's own Dr. Aaron Sumrall, Director of Outreach, Education and Research, sat down with Dr. John Tomeček, associate professor in the Department of Rangeland, Wildlife, and Fisheries Management at Texas A&M University, whose work centers on wildlife damage management, wildlife diseases, and feral hogs.

What follows is a plain-language look at what NWS is, how feral hogs fit into the picture, and what you can actually do about it on your own ground. One quick note before we start: the experts here are wildlife and outreach professionals, not veterinarians or entomologists. For animal treatment and pesticide questions, always work with your vet and your state animal health officials.

New World screwworm returns to the U.S. after 60 years

New World screwworm was eradicated from the United States generations ago, so for most people it lives in history books, not on the calendar. That changed in 2026.

At the time of the webinar (July 16, 2026), Dr. Tomeček noted the USDA tracker was showing several dozen confirmed cases in Texas, with additional detections in New Mexico. Many of those had already been managed and were listed as inactive. Case counts move constantly, so rather than chase a number here, check the live USDA APHIS dashboard at screwworm.gov for the current snapshot. That is exactly what the experts recommend: go to the source.

Here is the encouraging part. As of the discussion, every treated domestic animal had survived, with no detection in wild populations. Producers spotted the problem, got on it, treated it, and saved the animal. In a country this big and this lightly populated, finding those cases in isolated areas at all is a real accomplishment.

What New World screwworm actually is

It only targets the living

Most flies you know colonize dead things. New World screwworm does the opposite. The females lay their eggs in the open wounds of living, warm-blooded animals, and the larvae feed on living flesh. That single fact drives almost everything about how the pest behaves and how we respond to it.

It also carries a piece of good news for anyone managing wildlife or livestock: screwworms do not infest carcasses. A dead animal is not a breeding site for them.

Where infestations start

Because the fly needs an opening, infestations begin at wounds. That can be a scrape or a gash from animals fighting. It can be an umbilical lesion on a newborn, which is a normal part of being born and a natural point of vulnerability. In wildlife, it can be soft, growing antlers or the cuts bucks give each other while sparring. Key deer in the Florida Keys were hit hard during an outbreak there a little over a decade ago, which is a sobering reminder of what wildlife impacts can look like.

What limits it

Like a lot of insect pests, screwworm is held back by cold. It does well in warm conditions and poorly in cold ones. Historically, when screwworm was widespread in the mid-1900s, the maps stretched surprisingly far north before winter reined it in. Soil temperature also plays a role in the fly's life cycle, which is one reason this new situation still has open questions. We will learn as we go, just as previous generations did.

How New World screwworm is controlled: the sterile fly technique

The primary tool against screwworm is not a chemical fogger. It is biology.

The gold standard is the sterile insect technique. Sterile male flies are released in huge numbers to compete with the fertile males in the wild. The females that mate with them produce no offspring, and after a few fast generations, the population collapses. It is elegant, it is proven, and much of the early work behind it was pioneered in Texas.

This matters for anyone worried about non-target species, pets, or pollinators. There is no blanket pesticide application, no spraying down the countryside the way a town might fog for mosquitoes. Individual infested animals may be treated with veterinarian-approved products so they do not suffer and can heal, but the landscape-level solution is targeted at one fly species. Everything else goes about its life.

Worth repeating, because misinformation spreads fast: the U.S. food supply is not at risk. NWS does not infest meat or produce.

How feral hogs spread New World screwworm

No wild or feral animals had been confirmed infested at the time of the discussion. Every case was in domestic livestock. So why is a feral hog company hosting a webinar on this? Because the question on everyone's mind is what happens if screwworm reaches the feral hog population. And that comes down to scale.

A matter of scale

Texas is home to millions of feral hogs. Estimates vary, but the number is in the range of three to four million or more. To put that in perspective, that is roughly comparable to the state's entire white-tailed deer population, and it eclipses the combined total of sheep, goats, and domestic pigs. That many bodies on the landscape is that many more opportunities.

Feral hogs stack the odds in several ways at once. They are large animals, which means a lot of surface area for a fly to find. They fight and injure themselves often, creating exactly the kind of open wounds screwworm looks for. They breed year-round, so there are newborns with umbilical lesions on the ground in every month of the year. And they live in large groups, so you get a dense cluster of easily infested animals in one place.

They move the problem around

Here is an important distinction. A feral hog will not directly transmit screwworm to another animal. Transmission happens only when a fly lays eggs in a wound. What hogs can do is act as a rolling opportunity. An infested pig that goes unnoticed lets those larvae complete their life cycle and produce more flies out on the landscape, where they can find new hosts. Hogs also cover a lot of ground on their own, and they get moved by people in trailers, which spreads that opportunity farther.

Fewer hogs, fewer opportunities

The takeaway is simple and hopeful. Reducing the number of hogs on your property reduces the number of bodies screwworm can use, and it slows the speed at which the pest could move. Removing feral hogs was already a good idea for your livestock, your native wildlife, your water, and your soil. In this context, it is one more meaningful way to protect your neighbors and your region.

What landowners can do about screwworm

You do not need to be an expert to be part of the solution. A handful of practical habits go a long way.

Keep the pressure on hog numbers

Every hog you remove is one fewer host on the landscape. Consistent, effective removal is the lever landowners control directly, and whole-sounder capture removes the most animals per effort rather than catching a few and educating the rest. Keeping steady pressure on your hog population is good land stewardship in general, and right now it does double duty.

Learn to spot an infestation

Get familiar with what an infested animal looks like before you ever need to. The obvious sign is an open, worsening wound with larvae in it, often with a foul odor. But it can be subtler too. An infested animal may simply look poor, tired, or lethargic, or it may seclude itself. When you dispatch hogs, take the opportunity to look the carcass over. Trained eyes in the field are exactly how these cases get caught. AgriLife Extension, USDA, and your state animal health commission all offer identification resources.

Report what you see

If something looks wrong, pick up the phone. Contact your veterinarian, your state animal health official, or a wildlife biologist with your state agency. In Texas, that means the Texas Animal Health Commission or Texas Parks and Wildlife. Reporting a suspected case brings help, including sterile fly support, to stamp out an infestation before it spreads. See something, say something. We all do better by asking for help than by keeping it to ourselves.

Handle carcasses thoughtfully

Screwworm does not infest dead animals, but a pile of carcasses can still congregate flies and draw in scavengers like coyotes and vultures, sometimes right next to your livestock. Where you can dig a deep pit and bury, that is an excellent disposal method for hogs in general. If you suspect an animal was infested, confirm the identification first, make sure any larvae are dead through veterinarian-approved means, and then dispose of it. When in doubt, call it in before you dump it.

Practice good biosecurity

Feral hogs carry a long list of pathogens that people, pets, and livestock can catch, including pseudorabies, brucellosis, trichinella, salmonella, and E. coli. When you move dead hogs, you are moving that risk into your truck bed, onto your tools, and onto your hands. A little cleanup goes a long way. Wear gloves, and disinfect equipment, knives, and vehicle beds after handling hogs. Yes, it is hard on gear over time, but the peace of mind is worth it, especially before the family dog hops into that same truck bed.

Protect livestock, working dogs, and pets

For livestock, keep up with your veterinarian's recommended regimens, treat and cover open wounds promptly, and check animals often. For hunting dogs, injuries come with the work, so close them up, cover them, monitor them closely, and stay current on the care and vaccines your vet recommends. If you travel with pets, check the current USDA maps for movement restriction or quarantine zones, keep any wounds covered, and be ready for an inspection at an animal health check station. These measures are not something to fear. They are how we keep the problem from hitching a ride home.

The bottom line: informed, not afraid

It is easy to let a phrase like flesh-eating fly do the talking. All of it is technically true, and none of it should send you into a panic. This is a keep calm and carry on moment.

Education really is the power here. Landowners who know what to watch for are the front line that makes rapid response possible.

The best thing you can do is get good information and act on it. Pull your facts from reliable sources like USDA and APHIS at screwworm.gov, AgriLife Extension, and your state animal health commission, not from the loudest voice on social media. Stay observant. Keep pressure on your hogs. Report what looks wrong.

Quick answers: New World screwworm and feral hogs