SAN ANTONIO (AP) – The New World screwworm fly is threatening the $113 billion U.S. cattle industry for the first time in more than a half century, with an infestation from its flesh-eating larvae confirmed in south Texas.
The infestation was discovered in a single 3-week-old calf in La Pryor, Texas, about 100 miles (161 kilometers) southwest of San Antonio and 50 miles (80 kilometers) from the U.S.-Mexico border. Federal and state officials had been working to keep the parasite from reaching Texas, home to $17 billion worth of the nation’s cattle, making it the industry’s No. 1 state.
The deadly flies were detected in Mexico in late 2024 after years of being contained in Panama.
The fly was an annual warm-weather scourge of cattle ranchers from at least the 1930s through the 1960s, until the U.S. eradicated the pest by breeding sterile male flies and dropping swarms of them from planes to mate with wild females. The USDA said the most recent case was the first in Texas since 1966.
Here is what to know about the fly, the threat it poses and the response:
Being unusual makes the flies a threat
The New World screwworm fly in the Western Hemisphere and its Old World cousin in Africa and Asia are unusual among flies because their larvae, or maggots, eat live flesh and fluids instead of dead material. Females lay their eggs in open wounds and mucous membranes after mating only once in their monthslong lives.
Any warm-blooded animal, including wildlife, pets and occasionally even humans, can be infested.
Livestock are vulnerable because of how they’re handled, Lee Haines, an associate research professor of biological sciences at the University of Notre Dame, said in an email Thursday. Standard practices with cattle can break the skin, including shearing and de-horning, or even moving them in and out of corrals can cause scrapes and cuts. Birth would also make a mother and calf vulnerable, she said.
Stephen Diebel, a Texas rancher and president of the Texas & Southwestern Cattle Raisers Association, added that even wounds “as small as a tick bite,” can put cattle at risk.
“These flies can lay eggs in very, very small places,” he said.
Scientists and cattle groups say that infested wounds become foul-smelling and cause animals great pain or death if an infestation is not treated. In decades past, ranchers had tens of millions of dollars in losses — potentially billions in today’s dollars.
But agriculture officials were quick to note that the fly does not infest food.
Officials sounded alarms for nearly 2 years
Federal and state officials and cattle industry leaders have been sounding public alarms about the fly’s movement through Mexico and toward the U.S. since a case was confirmed in southern Mexico in November 2024.
The spread has hit Mexico’s beef industry hard, particularly after U.S. Agriculture Secretary Brooke Rollins closed ports of entry along the border to livestock imports in July 2025 to prevent the fly from reaching Texas.
Mexico has confirmed thousands of infestations, and Rollins has argued that the government there has not done enough to control animals moving within the country, a suggestion Mexican authorities have rejected. Rollins also has blamed former Democratic President Joe Biden’s administration, arguing that weak border security has been a factor in the flies’ migration.
But Haines said climate change is a key element in the spread of a tropical species that thrives in warm weather and disappeared after cold snaps in the U.S.
“The cold snaps that once suppressed stray populations in marginal northern regions are becoming rarer and less severe, thus removing a natural biological check on the flies’ migration north,” she said. “ Warmer temperatures are also expanding the geographical band of suitable habitat northward.”
Officials quarantine a swath of Texas
Texas State Veterinarian Bud Dinges imposed a 12-mile (20-kilometer) quarantine zone covering much of Zavala County, home to La Pryor, and a small part of neighboring Uvalde County. Animals cannot leave that zone without being inspected. Dinges has urged people to check their animals — including pets — and to “stay put.”
Rollins said the fly doesn’t travel hundreds or even tens of miles on its own. “The only way this spreads is through animal movement,” she said.
Local ranchers are concerned that the fly will spread among wildlife, particularly deer. The last U.S. outbreak was largely among deer in the the Florida Keys in 2016, though one case was confirmed last year in a Maryland man who had traveled to El Salvador and recovered. In the 2016 Florida instance, the fly was eradicated within six months by releasing sterile male flies to mate with the females.
In Texas, Haines predicted, “Their numbers will continue to expand in wildlife populations.”
In Texas, shots and fly drops
Rollins said that the USDA has been dropping millions of sterile male flies in south Texas since February in hopes of blocking the insects’ spread. The plan is to continue doing so.
The USDA opened a center in south Texas in February to disperse flies bred in Panama, and it invested $21 million in a new fly-breeding facility in southern Mexico that is expect to start operations next month.
Diebel, whose family ranch is about 200 miles (322 kilometers) east of the quarantine zone, said ranchers are proactively giving injections that prevent screwworm infestation. They’re also taking extra care to treat wounds from ear tagging and other practices and keeping a close eye for signs of illness.
“Surveillance is one of the biggest things — just constantly monitoring those cattle,” Diebel said.
He said he wouldn’t be surprised to see other isolated cases confirmed, but added, “I’m very confident we can keep this at bay.”
Officials rely on time-tested science
Government and industry officials are confident that they contain the fly in the U.S. because the best method for eradicating the pest is both time-tested and highly effective: releasing sterile male flies into the wild. While males are “promiscuous,” in the scientific sense, females are not, and if their one mating hookup is with a sterile male, no eggs from that female will hatch.
Once sterile males are prevalent enough — and millions a week can be released — the fly’s population declines and then dies out.
The U.S. shut down its own fly factories after the pest was eradicated decades ago, leaving only an international breeding facility in Panama in the Western Hemisphere until the new one in Mexico opens. However, the USDA also is spending $750 million to build a fly factory in southern Texas that can produce up to 300 million sterile flies a week.
“The sterile insect is not only the most effective tool we have, but it is also considered one of the most environmental friendly insect pest control methods ever developed,” Rollins said.

LINDALE – The cause of death for 8-year-old Adrian Thompson, who had a medical emergency at Velma Penny Elementary School in Lindale in April, has been announced by the Tarrant County Medical Examiner’s Office. Adrian Sue Thompson died in a pediatric intensive care unit on April 16 at around one in the morning. According to a recent report from the Tarrant County Medical Examiner’s Office, her death was determined to be accidental and to have been caused by choking.
TYLER — Bass Pro Way is now officially open as of Thursday morning, improving access in and around South Tyler.


TYLER – Federal charges have been brought against two women who have ties to an East Texas company where an FBI operation was carried out on Tuesday. Magistrate Judge K. Nicole Mitchell announced the federal indictments of Keyla Valdivia and Virginia Ponce Gamez on Wednesday during a court appearance at the federal courthouse in Tyler. They both filed not guilty pleas. Multiple agencies, including the Smith County Sheriff’s Office and the Texas Department of Public Safety, responded to Ximena’s Furniture at 10623 Highway 69 North and 10713 US 69 North. Neither the FBI nor local law enforcement agencies have publicly confirmed the nature of the operation. Gamez is charged with conspiracy to transport undocumented immigrants, trafficking and conspiracy to commit money laundering. Valdivia is charged with conspiracy to harbor undocumented people and conspiracy to commit money laundering.
LONGVIEW — A 27-year-old man from Longview was recently arrested after being accused of having an inappropriate online relationship and sexual assault of a child. According to an arrest affidavit obtained by our news partner KETK, a deputy from the Smith County Sheriff’s Office spoke with the victim’s mother in April 2025, who had recently discovered her 12-year-old daughter was having a sexual relationship with an adult man.
TYLER — A debate over how East Texans should protect their land and water came to a head Tuesday, when the Smith County Commissioners Court split 2–2 on whether to form a subregional commission with Van Zandt County — effectively killing the proposal, according to our news partner KETK. After being tabled multiple times, the measure returned for a vote and resulted in a split 2–2 decision. As the court could not reach a majority, the effort to create the subregional commission failed.
RUSK COUNTY — A routine traffic stop in Rusk County led to the seizure of approximately 11 pounds of suspected cocaine and the arrest of a Missouri man on a felony drug charge, according to the Rusk County Sheriff’s Office. The traffic stop occurred on Tuesday at the intersection of State Highway 315 and Farm-to-Market Road 95. Authorities said deputies stopped a rental vehicle displaying Florida license plates.
TYLER – The North Tyler Planning and Zoning Board voted unanimously on Tuesday to deny a zone change for a proposed metal recycling business. The change would have converted areas designated as light commercial and single-family residential into an industrial district. According to our news partner KETK, the board’s decision came after 90 minutes of public comment at a public hearing, during which the majority of speakers expressed opposition to the proposed development. The site for the planned business was located near the southwest intersection of Loop 323 and West 34th Street.
TYLER — The Texas summer heat doesn’t just take a toll on people; it can be dangerous and even deadly for pets. A 2024 report from the SPCA of Texas shows the state ranks number one in the nation for heat?related pet deaths, a statistic that worries veterinarians across East Texas. Our news partner KETK talked to Dr. Gary Spence of Spence & White Veterinary Hospital in Tyler. Dr. Spence says the extreme temperatures seen across the region each summer put all dogs at risk.
MARSHALL – Students and faculty from the East Texas Baptist University Teague School of Nursing recently returned from a medical mission trip to Costa Rica, where they served local communities through healthcare clinics and patient education.
TYLER – There are some traffic changes to note in downtown Tyler. The intersection of North College Avenue and West Erwin Street is now open. Both College Avenue and West Erwin Street in that area will operate as two-way streets. Drivers heading northbound on North Broadway Avenue are now able to turn left onto West Erwin Street. Drivers are encouraged to exercise caution at the intersection due to the new traffic patterns.
SMITH COUNTY – A man was taken into custody in Smith County on Tuesday on suspicion of sexually abusing a fifteen-year-old girl. Tony Rincker, 60, was placed in the Smith County Jail on a $500,000 bond after being accused of sexual assault of a minor. An arrest affidavit states that a student claimed to have seen a video on the teen’s Snapchat account showing the alleged victim being sexually assaulted. What looked to be a child’s bedroom was shown in the video.
HENDERSON COUNTY – A Scurry man who was found guilty of repeatedly sexually abusing a child in Henderson County, and given a life sentence, was upheld by an appeals court. Manuel Lynn Tijerina, 42, appealed his conviction to the Twelfth Court of Appeals, claiming the trial court had improperly admitted testimony from the victim’s relative, according to the Henderson County District Attorney’s Office. Testimony revealed Tijerina exposed the victim to pornography, touched her inappropriately, and made sexual remarks to her.
TYLER– A public meeting was held in Tyler on Tuesday to discuss the proposed extension of Toll 49, a project designed to relieve congestion and provide shorter travel times. According to our news partner KETK, during the meeting in Tyler community members had the opportunity to review project layouts and data detailing the potential positive impact on drivers.
LONGVIEW — An investigation has been launched after a teenager was shot near a park in Longview on Monday night. According to the Longview Police Department and our news partner KETK, at around 11:26 p.m. officers heard gunshots coming from the 400 block of Fair Street. Once arriving to the area, the officers found a teenager who had sustained gunshot wounds while attending a gathering at a nearby park, the department said.