Flesh-eating screwworm found in Texas calf as ranchers brace for possible spread

The New World Screwworm (NWS) – a parasitic fly that eats the flesh of livestock and other warm-blooded animals – has arrived in South Texas.

The United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed on June 3 that NWS larvae had been identified in a three-week-old calf’s umbilical area in Zavala County, Texas. As of June 11, federal officials had confirmed six total cases, Fox7 Austin reported.

According to the USDA, "NWS is a serious pest that affects livestock, pets, wildlife, and less commonly, people and birds. NWS larvae (maggots) burrow into the flesh of living animals, causing serious damage to livestock and economic losses."

CLICK HERE FOR MORE LIFESTYLE STORIES

Screwworms don’t make meat unsafe to eat, but they do threaten to raise beef prices that are already at a record high.

The USDA is led by U.S. Secretary of Agriculture Brooke Rollins. On May 11, 2025, she announced "the suspension of live cattle, horse and bison imports through U.S. ports of entry along the southern border due to the continued and rapid northward spread of NWS in Mexico."

Models projected the NWS would enter the U.S. in 2025, "but thanks to the hard work across the entire Trump administration and our industry, state and local partners, we were able to buy time for this moment," said Dudley Hoskins, USDA Under Secretary for Marketing and Regulatory Programs.

"USDA invested heavily in the tools needed to eliminate NWS ever since cases started increasing in Central America and Mexico," Hoskins said. "The United States has defeated this pest before, and we will do it again."

The USDA announced that "an APHIS strike team is already on-site in Texas." The agency said it has mounted a "rapid, efficient response" that involves releasing sterile male flies and establishing a movement control zone to quarantine livestock.

TEST YOURSELF WITH OUR LATEST LIFESTYLE QUIZ

Beginning in the 1920s and 1930s, USDA scientists began NWS eradication efforts. Part of the solution was the Screwworm Adult Suppression System (SWASS), which lures flies to a bait mixture that contains insecticides that kill them before they can reproduce. Since female flies only reproduce once, they also released sterile male flies so the females would mate and produce no offspring.

In 1966, Agricultural Research Magazine declared, "The screwworm has been eradicated from the United States."

Texas Agriculture Commissioner Sid Miller has been critical of the USDA’s response to the new NWS outbreak.

"For months, the screwworm has advanced rapidly through Mexico in spite of the USDA’s existing gameplan," Miller said in a statement. "Even though billions of sterile flies have been dispersed by USDA, the screwworm has still advanced over 1,100 miles from southern Mexico to Texas, and USDA has missed an important component. Now that it appears the first screwworm has arrived in Texas, the consequences of that decision are now staring us in the face."

Miller said he "personally provided research and the SWASS bait formula to Rollins and her team on three separate occasions while the screwworm continued its northward trek to Texas."

He added, "Instead of using every available tool, USDA moved too slowly and relied solely on a partial solution that takes years to fully implement."

CLICK HERE TO SIGN UP FOR OUR LIFESTYLE NEWSLETTER

Miller asked President Trump to take control of the NWS response.

"Cut through the bureaucracy, deploy SWASS immediately and throw every available federal resource at this threat before it becomes a full-blown agricultural disaster," he urged the president.

As Texas Land Commissioner, Dawn Buckingham, M.D., oversees more than 13 million acres of state land, including roughly three-quarters of a million acres of grazing and hunting leases managed by the Texas General Land Office. Her office sent a letter to Rollins and Texas governor Greg Abbott offering full access to the lands to support the government’s response to "the active, escalating threat of the New World Screwworm."

"This is a big deal," Buckingham told Fox News Digital. "It's going to be a real problem, and it doesn't just impact our cattle, but it impacts all of the wild animals as well as our dogs and our cats. We want to be sure that we get these insects out of our state."

The Land Commission has offered access to property to house workers, grow sterile flies, set up traps, whatever is needed, Buckingham said.

According to Buckingham, the Land Commission met with South Texas ranchers "many months ago" when they observed screwworm flies marching up through Central America and Mexico. She said the pests have been slowly working their way back after they were pushed down to South America several decades ago.

"[Screwworms] come and go with the world population being so mobile," Buckingham said. "It's very easy for insects to travel, whether they jump on a fruit truck or they come on animals or whether they've infected a person. Diseases move much more quickly these days than they used to."

Buckingham added that, "The good news is we've got medication to treat [screwworms], and we know how to stop the propagation of the insect, so we should be able to get it under pretty good control. It's not reinventing the wheel. We fought them before. We'll fight them successfully again."