Screwworm Hits Texas Soil: A Nightmare a Year in the Making for Ranchers and Rodeo

A flesh-eating parasite confirmed in a South Texas calf Wednesday marks the first U.S. screwworm detection in nearly a decade. For the rodeo world, the damage started a year ago.

Santa Teresa Cattle Union and Union Ganadera Ciudad Juárez show cattle enclosures empty on May 13, 2025. | Omar Ornelas / El Paso Times / USA TODAY NETWORK via Imagn Images

This has been a discussion in the cattle and western industry for over a year now, and on June 3, 2026, the nightmare scenario for ranchers and rodeo producers is no longer a ‘what if, but a ‘what now’.

On Wednesday, the U.S. Department of Agriculture confirmed the first case of the New World screwworm in the United States in nearly a decade. The unfortunate victim was a three-week-old calf in Zavala County, Texas, which is approximately 60 miles from the Mexican border.

The larvae (maggots) were found burrowed into the calf’s umbilical area, and after being suspected, tests confirmed the dreaded concern.

The USDA and Texas officials are taking immediate action in order to stop the spread. Quarantine zones are in effect and movement of livestock in the region is being restricted.

For the rodeo industry, a 14-month border closure has already taken its toll and now, we have to sit back and see what comes next.

"There's no doubt that this is a very, very serious threat to our livestock," Agriculture Secretary Brooke Rollins said Wednesday in a press briefing.

What is New World Screwworm?

Cattle | DENNY SIMMONS / THE TENNESSEAN / USA TODAY NETWORK via Imagn Images

Despite the name, this is not a worm; it is actually a parasitic fly whose larvae feed exclusively on the living flesh of warm-blooded animals. The New World screwworm’s scientific name is Cochliomyia hominivorax. The pesky flies host include cattle, horses, dogs, deer, and sometimes even the occasional human.

The maggots burrow in a corkscrew fashion through open wounds, which enlarges them and kills their host in as little as 10 days if left untreated. Thus, the name ‘screwworm.’

This is also not a new thing. The United States dealt with this in the 1960s when it eradicated the pest using sterile fly releases, which is exactly what they intend to do once again. It stayed gone, until now.

A Border Closed and Rodeo World Already Hurting

Long before the confirmation of the finding in Texas, the screwworm was already causing havoc in the rodeo world. The USDA closed the US-Mexico border to cattle, horses and bison in May 2025 which essentially cut off the primary supply of Mexican Corriente cattle - the backbone of the team roping and steer wrestling industry.

The results of that have been brutal so far.

Roping steers that once sold for under $1,000 apiece are now selling for closer to upwards of $2,400 apiece. This is unprecedented in the industry, making producing a very hard thing to do. It is very hard to turn a profit right now with cattle costing so much to acquire.

Not only is it hard to produce, but it is very expensive for competitors to have practice stock as well. The quality of steers is going to be very hard to keep at a top level because new stock can’t be imported due to the main source being Mexico.

What Happens Now

Horned cattle | Andrew West/The News-Press & Naples Daily News/USA Today Network-Florida / USA TODAY NETWORK via

With the NWS confirmed inside the borders of the United States, Texas, federal and state agencies are moving as fast as possible.

According to the Texas Animal Health Commission, an infestation zone has been established around Zavala County. Aerial dispersal of sterile flies, currently at 100 million per week, is being increased dramatically.

Since female screwworms only mate once, if one mates with a sterile male fly, she will produce no offspring, and gradually they will be eliminated once again.

The USDA says it will now need 400 million sterile flies per week to fully take control of the wild population.

People should not panic about the food supply. That, officials have stressed over and over, is not at risk. The cattle supply and market though could take a devastating hit.

The US herd is already at its lowest level in 75 years. Beef prices hit record highs in 2025, and prices have only continued to rise. An NWS outbreak in Texas would be devastating and could carry enormous economic effects.

For rodeo, the stakes are high as well. The culture is built around livestock, specifically horses and cattle and this one little tiny fly is threatening to cause havoc.

USDA officials urged, “All animal owners need to put your eyes on your animals. Monitor all wounds and contact a veterinarian immediately if you suspect New World screwworm.”

For the rodeo world, this is not just good advice, it serves as a warning.

For the latest updates, visit screwworm.gov and the Texas Animal Health Commission at tahc.texas.gov/emergency/nws.html