The American beef industry and the landowners who support it are facing the alarming return of a pest that hasn’t seriously threatened the U.S. in more than 50 years. The New World Screwworm, Cochliomyia hominivorax, has been spotted throughout Mexico and appears to be advancing north toward the U.S. Many experts today warn it’s no longer a question of if it reaches American soil, but when.

This destructive parasite doesn’t just threaten cattle; it endangers wildlife, pets, and livestock of all kinds. Its reemergence is forcing producers and landowners alike to prepare for one of the most serious animal health threats the country has seen in decades.

During a recent episode of the National Land Podcast, Colin Woodall, CEO for the National Cattlemen’s Beef Association, shared their concerns about the reemergence of New World Screwworm and what ranchers can do to protect their herds.

What is the New World Screwworm?

Despite its name, the New World Screwworm is actually a highly invasive parasitic fly. It looks like a larger version of the common housefly, with a blue-green body and prominent red eyes. What makes it dangerous is its life cycle. Female flies lay their eggs in wounds or moist body openings of warm-blooded animals. Once hatched, the larvae burrow into the host’s flesh and begin feeding on living tissue.

As CEO for the National Cattlemen’s Beef Association, Colin Woodall explains, “It does exactly what the name says. It screws or burrows into the flesh of any warm-blooded animal… and eats that animal alive.” Without treatment, animals can die within four to seven days of infestation.

Why Is It a Big Deal Now?

The U.S. successfully eradicated the screwworm in the 1960s using an aggressive sterilization program. Millions of sterile male flies were air-dropped over large areas, fooling wild females into mating without producing offspring. The campaign pushed the pest as far south as Panama.

But now, that containment line has been breached.

“When the fly was finally pushed into South America, it was determined that one facility in Panama could hold the line,” Woodall notes. “That line has been breached… and away they came.” Government oversight lapses, illegal cattle movement, and slow containment response allowed the pest to spread rapidly north.

Even more concerning is that the U.S. no longer has the infrastructure to mass-produce sterile flies. The Panama facility currently produces about 100 million sterile flies per week, but Woodall emphasizes, “It was utilizing about 400 to 500 million sterile flies a week back in the 60s to eradicate it.”

What’s at Stake for Landowners?

The return of the screwworm will place a massive burden on cattle producers and landowners. Ranchers will face rising labor demands, as livestock must be monitored daily for open wounds and signs of infestation. Any delay in detection can result in animal death, an expensive and preventable loss in today’s high-value cattle market.

As Woodall points out, “If you miss one and you don’t come back for a week, it’s very easy to foresee that animal would be dead… And when you look at the price of cattle these days, that is a significant loss.”

The economic risks extend beyond cattle. Screwworms can also infect deer, hogs, and other wildlife, which poses a serious threat to landowners with hunting leases or conservation efforts. “It could be devastating to the wildlife,” says Woodall, “and devastating to landowners and cattle producers who have diversified their operations for hunting.”

What’s Being Done?

The NCBA is pushing hard for federal action. A top priority is establishing a domestic sterile fly production facility. “Everybody now knows we need one,” Woodall stresses. “It could take a year or more to construct… and every day we lose is an opportunity for further incursion.”

NCBA is also exploring new technologies, including genetic engineering, to accelerate the creation of sterile flies. At the same time, they’re working with animal health companies to find more effective treatments for infected livestock.

Perhaps most importantly, NCBA is spearheading producer education. Landowners and ranchers are being trained on what to look for, everything from spotting the adult fly to recognizing eggs, larvae, and lesions. “What do you need to pay attention to? What portions of the cattle do you look at? Who do you need to call?” These are the questions NCBA is helping landowners answer.

The fight against the New World Screwworm is not a short-term crisis, and landowners would be wise to start making a plan today. If you’ve got questions about protecting your land investment or ranchland values in your area, get in touch with your local Land Professional today!