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 deadly flies were detected in Mexico late in 2024, after years of being contained at the southern end of 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 scres 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.

Death can result if an infestation is not treated, though a dozen treatments have been proved for use in a variety of species. In decades past, ranchers had tens of millions of dollars in losses — potentially billions in today’s dollars.

Officials sounded alarms for nearly 2 years

Officials had considered the pest eradicated from Central and North America nearly two decades before an outbreak in Panana prompted a state of emergency there early in 2023, according to the joint U.S.-Panama program established in 1994 to stop the parasite. Cases jumped to Costa Rica and Nicaragua later that year.

Edward Burgess, a University of Florida entomologist who studies the fly, said it reproduces quickly and is carried across wide areas by its hosts, namely wild animals such as deer. Outside of Panama, he said, programs that produced and released sterile flies have largely shut down.

“It’s hard to stay ahead of it because of how fast that fly is able to move and regenerate,” Burgess said.

Outside the US, thousands of animals and hundreds of humans sickened

As of June 2, the parasite had sickened more than 171,700 animals and 2,000 people across Central America and Mexico, according to the U.S. Centers for Disease Control and Prevention. There have been 10 human deaths, the CDC says.

Starting in May 2025, Rollins closed border entries to livestock and on Thursday she credited that move with delaying the fly’s arrival in Texas by a year.

Rollins has argued that the Mexican government has not done enough to control animals moving within the country, a suggestion Mexican authorities have rejected.

But Haines said climate change is a key element in the spread of a tropical species that thrives in warm weather. Warmer temperatures are expanding the fly’s habitat and cold sns that killed them off each year in marginal habitats are becoming less frequent and less severe, she said.

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.

Zavalas County Sheriff Eusevio Salinas said Thursday that state officials were setting up several road checkpoints in the county to enforce the quarantine.

“They said they were going to do that for three to four days, and hopefully after that it’s already under control,” Salinas said.

In Texas, shots and fly drops

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.

The USDA has been dropping sterile flies in south Texas since February, when it opened a center for dispersing them in south Texas. It is now dropping them twice a week, for a total of 4 million flies, and it’s also putting 4 million more a week in the ground as pupae, flies in the stage between larvae and adult, said Rear Admiral Michael Schmoyer, a member of the USDA’s response team.

Releasing sterile files is both time-tested and highly effective. 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, the fly’s population declines and then dies out.

But with sites outside Panama shut down for years, the USDA didn’t think sterile flies were being bred fast enough. It invested $21 million in a new fly-breeding facility in southern Mexico that is expected to start operations next month.

Spencer’s attorneys do not deny that he shot and killed Michael Fosler in 2024, saying he did so to protect his child. Special Circuit Court Judge Ralph Wilson Jr. granted a motion by Spencer’s attorney to dismiss the charge over a dash camera memory card that may have ctured the shooting and was lost by law enforcement.

“The court finds that conduct by law enforcement was so egregious that dismissal of this case is warranted,” Wilson wrote.

At the time of the shooting, Fosler, 67, was out on bond after being charged with dozens of sexual offenses against Spencer’s then-13-year-old daughter.

Court documents show on the night of the shooting, Spencer had woken up to find his daughter missing, and later found the girl in the passenger seat of a vehicle Fosler was driving. Spencer forced Fosler’s truck off the road and, after an altercation, called 911 to report he had shot the man.

Prosecutors said Spencer planned the killing and that he could have called police while pursuing Fosler. But Spencer pleaded not guilty and maintained he acted to protect his child from a predator.

Spencer’s attorney, Erin Cassinelli, said she is thankful for the court’s decision.

“No member of this family should ever again be forced to walk into a courtroom and relive this horror,” she said in a statement. “This father should have never been charged for protecting his child.”

Spencer said he is grateful this chter is over and that his focus is now on his family and returning to normal life.

“There’s still work to do in Lonoke County, and I’m more committed to it than ever,” he said in a statement. “Together we can build a safer and stronger Lonoke County.”

Lonoke County Prosecuting Attorney Chuck Graham did not return messages Thursday seeking comment on the decision.

The Associated Press typically does not identify sex abuse victims, but Spencer has made his daughter’s experience with the criminal justice system a central part of his campaign for sheriff, pledging to establish a dedicated team to combat sex crimes against children.

Spencer’s attorneys filed the motion seeking to have the case dismissed, contending that video and audio of the dash camera from Fosler’s truck may have contained evidence that would have cleared Spencer of any wrongdoing. According to court records, a detective with the Lonoke County Sheriff’s Office removed the dash camera from the truck when responding to the scene of the shooting.

But the camera’s internal settings were not preserved and the battery of the camera was allowed to drain, and as a result the camera went back to its default settings. When the camera was sent to the attorney general’s office for a forensic exam, the memory card that was in it when it was collected from the truck was missing. The detective who collected the camera later admitted that it was not logged into evidence right away, but was instead stored in his personal office rather than the evidence room, according to court records.

Wilson replaced the original judge handling the murder case in January after the Arkansas Supreme Court removed Judge Barbara Elmore from the case, finding she had issued an overly broad gag order that violated Spencer’s First Amendment rights.

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Boone reported from Boise, Idaho. Associated Press reporter Hallie Golden in Seattle contributed.

“It’s a different part of the world,” Trump told reporters in the Oval Office. “You know, I’d say in that part of the world, a ceasefire is when you’re shooting in a more moderate manner.”

There’s anxiety Trump is getting boxed in

There’s growing concern inside the administration and among key advisers and allies that Trump now finds himself in a bind, according to a U.S. official and another person familiar with the administration’s internal deliberations, both of whom spoke to The Associated Press on the condition of anonymity to discuss private conversations.

Trump is privately hearing from other Republican lawmakers as well as Pentagon officials and Gulf allies that a return to the bombing campaign is a bad idea.

Meanwhile, Gulf allies are worried Iran will retaliate against them and their critical infrastructure and energy interests and further set back their economies.

Now, Trump, according to those familiar with internal deliberations, has made clear he feels strongly he can’t make “a bad deal” and is acutely aware he’s at risk of tarnishing his legacy if he missteps.

White House spokeswoman Anna Kelly dismissed the notion Trump has been boxed in or there’s any concern within the administration about the pace of talks.

Trump resisted Israel push for Lebanon bombings

Israeli and hawkish allies in Washington have made the case to Trump that a deal at this point would amount to unconditional surrender, urging him to ratchet up economic pressure on Iran and back Israel’s assault on the Hezbollah militant group in Lebanon.

Remaining in the current status quo with Tehran — neither a full resumption of hostilities nor sealing an interim agreement to restart nuclear talks — is a situation Iran pears better poised to exploit, argued Behnam Ben Taleblu, a senior fellow at the hawkish Washington think tank Foundation for Defense of Democracies.

Despite being the weaker party, Iran pears to be calculating that the longer the holding pattern lasts, the better the chances are it can “box in” Trump, he added.

“Either way, Tehran pears more resolute than ever to not provide Trump with a victory image, hence why it isn’t budging on the battlefield or negotiating table,” Taleblu said.

Holding pattern isn’t helpful for Republicans on the ballot

“The Democrats are fueled by Trump Derangement Syndrome,” Trump fumed in a social media post. “The four Republicans, that’s a whole other story – They’re GRANDSTANDERS! They should be ashamed of themselves.”

In one tense exchange, New Jersey Democratic Sen. Cory Booker pointed to the unsteady ceasefire as a sign Iran has the upper hand.

“We are the strongest nation on the planet Earth, and we’re in a stalemate with Iran,” Booker said. “And now we’re begging to get back into a deal that you all trashed in the first place.”

Rubio dismissed the criticism, underscoring that Iran has been placed on its heels with the strikes, which have taken out multiple layers of senior leadership and left Iran’s economy in shambles.

“There’s no one begging,” Rubio responded. “I don’t know where you’re getting this perception that Iran is stronger.”

Another Democrat, Sen. Chris Van Hollen of Maryland, homed in on Trump’s comments last month that voter anxiety about the cost of living was “not even a little bit” of a motivating factor for him to reach a deal to end the war.

The president continues to downplay the rising costs for Americans at the pump and predict that gas prices would fall sharply after the conflict ends.

Christopher Borick, the director of the Muhlenberg College Institute of Public Opinion in Pennsylvania, said that Democrats running in swing districts around the country are already zeroing in on Trump’s rhetoric on the war’s impact on Americans’ pocketbooks.

“There’s significant risk in having this thing drag on for Republicans,” Borick said. “But for Republicans in some of these tough swing districts, there’s a case to be made to rip the bandage off now, get some easing in the oil markets and hope there’s enough time for voters to turn the page.”

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Associated Press writers Farnoush Amiri in New York and Lisa Mascaro contributed to this report.