LA PRYOR (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 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 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.

Death can result if an infestation is not treated, though a dozen treatments have been approved 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.

But agriculture officials were quick to note that the fly does not infest food, and U.S. Agriculture Secretary Brooke Rollins said it’s unlikely to damage beef production — welcome news given that consumers are already facing record prices.

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.

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 snaps 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.

Local ranchers are concerned that the fly will spread among wildlife, particularly deer, as a small, short-lived outbreak did in the Florida Keys in 2016. That was the last time a U.S. case was confirmed among animals, though the CDC confirmed a case last year in a Maryland man who had traveled to El Salvador and recovered.

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.

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. It is expected to begin operating next fall.

SAVANNAH, Ga. (AP) — A museum in Georgia’s oldest city on Wednesday welcomed a truckload of treasures from the earliest period of U.S. history — 17 cannons that experts believe sank to the bottom of the Savannah River during the American Revolution and remained undiscovered for nearly 240 years.

Workers carefully hoisted the big guns one-by-one from the back of a truck and wheeled them inside their new home at the Savannah History Museum, which will put them on display just in time for the Fourth of July celebration of America’s 250th birthday.

“They look brand new,” said Andrea Farmer, a U.S. Army Corps of Engineers archaeologist who was part of the team that researched and preserved the cannons. “They could pretty much be fired if someone wanted to.”

The artifacts were discovered in 2021 when a dredge scooping sediment from the riverbed as part of an Army Corps project to deepen Savannah’s shipping channel pulled up a cannon in its metal jaws. The crew soon dug up two more.

In the course of just over a year, a total of 19 cannons were hoisted from the location just downstream from Savannah, which is where Georgia was founded in 1733 as the last of Britain’s 13 American colonies.

After being pulled from the river, most of the cannons left Georgia for several years to undergo cleaning and preservation work at a Texas lab.

One of the Revolution’s bloodiest battles was fought in Savannah

Archaeologists initially assumed the cannons likely dated to the Civil War. But further research indicated they’re likely almost a century older and sank during the buildup to the American Revolution’s bloody siege of Savannah.

Savannah was under British occupation in the fall of 1779, when colonists planned an attack to retake the city with help from French allies.

When French ships carrying troops were spotted off the Georgia coast, British forces scuttled at least six ships in the Savannah River downstream from the city to block the French vessels.

The land battle that followed was one of the bloodiest of the war. British forces killed nearly 300 colonial fighters and their allies, and wounded hundreds more.

The Savannah History Museum sits right next to the battlefield. Its staff on Wednesday hoisted the cannons, weighing up to 1500 pounds (680 kilograms) apiece, onto custom display mounts that staffers likened to giant wine racks.

The cannons will be part of a new exhibit on Savannah’s role in the American Revolution, which is scheduled to open Fourth of July weekend, said Samantha Moss, the museum’s curator.

“Our great team has been prepping for months — building mounts and planning how we can safely display these very large, very special artifacts,” she said.

Cleaning the crusty cannons took years

Each of the iron cannons emerged from the river covered by a thick crust of mud and minerals.

Two were left in that raw state and put on display at the museum. The other 17 were sent to Texas A&M University, which has a lab that specializes in preserving underwater artifacts. Its staff spent years painstakingly cleaning the big guns and coating them in paint and wax to prevent rusting and corrosion.

“A lot of them have scour marks on the side from anchors or dredging, so there’s some scarring on the cannons,” said Chris Dostal, a professor of nautical archaeology who leads Texas A&M’s Conservation Research Lab. “But most of them look pretty exceptional.”

Most of the cannons arrived with wooden plugs still sealing their bores, which remained packed with cannonballs and gunpowder charges.

Dostal said radiocarbon dating of the wooden stoppers placed them roughly in the late 1700s. His team shared the cannons’ measurements and other details with experts in London, who concluded three of them were very likely forged by the British military.

The rest appeared to be of French design but bore no telltale markings. Dostal said he suspects those guns may have been cast in America around the time of the war.

Other artifacts found with the cannons included pieces of anchors and a portion of a ship’s bronze bell. Like the cannons, none of them bore engravings indicating which ship they came from.

That means many details of the cannons’ origins remain a mystery.

“You don’t have all of the information,” Farmer said. “You’re trying to piece it together as best as you can.”