Flesh-eating screwworm returns to U.S., raising food safety concerns
By isabelle // 2026-07-16
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  • The New World screwworm has officially returned to the U.S. with 33 confirmed infections in Texas and New Mexico since early June.
  • The flesh-eating larvae burrow into living tissue, killing infected animals within two weeks if left untreated.
  • Federal officials claim the food supply is safe, but inspections only catch visible problems after animals reach slaughterhouses.
  • Texas's agricultural commissioner rejects relying solely on sterile flies, calling the USDA strategy inadequate and demanding insecticide traps.
  • An unchecked outbreak could cost Texas ranchers $1.8 billion, with Canada already banning livestock that passed through the state.
The New World screwworm, a parasitic flesh-eating fly eradicated from the United States in the 1960s, has officially returned, with 33 confirmed animal infections in Texas and New Mexico since early June. The first detection came June 3 in a three-week-old calf in Zavala County, Texas, and cases have since spread to include cattle, goats and a pet dog. Federal officials insist the food supply remains safe, but the response from state agricultural leaders suggests a deeper problem that could still hit American wallets.

How the parasite spreads

The screwworm is a fly, roughly the size of a common housefly, that lays eggs in open wounds of warm-blooded animals. One female can lay up to 3,000 eggs during her 10-to-30-day lifespan. Unlike maggots, which feed on dead tissue, screwworm larvae burrow into living flesh, and an infected animal left untreated can die within about two weeks from sepsis and internal bleeding. Texas Agriculture Commissioner Sid Miller described it bluntly: "It's something like you'd see in a horror movie. They call them screwworms because they just keep burrowing and burrowing into the flesh."

Food supply assurances rest on after-the-fact inspection

USDA officials and infectious disease experts say screwworm poses no threat to the food supply. Dr. Aaron Glatt of Mount Sinai South Nassau Hospital told Fox News Digital: "The U.S. food supply is not compromised by New World screwworm, which is an animal issue, but not a foodborne pathogen issue." A USDA spokesperson added that "an infestation or animal illness that makes meat unsafe for consumers will prevent the animal from entering the food supply." But that guarantee rests on inspectors catching visibly sick animals once they reach the slaughterhouse — labeling them "U.S. Suspect" for further veterinary review. There's no independent or proactive testing regimen screening meat for screwworm contamination before it reaches store shelves; the system depends entirely on inspectors spotting a problem after the fact.

Texas says sterile flies aren't enough

The USDA's main strategy releases sterilized male flies to mate with wild females, producing no offspring. It worked in the 1960s, but Miller says it's failing now. "It's insanity, doing the same thing over and over and expecting different results," he said on NewsNation's "Morning in America." The USDA releases about 100 million sterile flies weekly along the border, yet the screwworm has still traveled 1,100 miles north into Texas and New Mexico. The agency has spent $21 million renovating a Mexico production facility and plans $750 million on a new Texas facility that won't open until November 2027 — timing Miller calls too slow. Miller wants insecticide-laced traps added alongside sterile flies, citing a 1970s Texas program that cut cases from 29,000 to 35 in a year. Agriculture Secretary Brooke Rollins dismissed his criticism as "a very unserious comment from a perhaps unserious commissioner with just a few months left." Miller, who lost his Republican primary in March, fired back: "We're going to quit waiting on the USDA. We're gonna get this thing under control — we'll just have to do it ourselves."

What it could cost

Texas holds the nation's largest cattle herd, now at its lowest level in 75 years. NewsNation reported, citing Reuters, that an unchecked outbreak could cost Texas ranchers an estimated $1.8 billion. Canada has already banned livestock that passed through Texas in the last 21 days. "You can look for higher beef prices because of the failure of the USDA to control this pest," Miller warned. Human infections remain rare, the CDC says, but symptoms — described by Mayo Clinic's Dr. Bobbi Pritt as "a non-healing wound with pain, redness and swelling that is getting worse, a sensation of movement or crawling in the wound" — warrant immediate medical attention. For now, Americans are being asked to trust a system that only catches problems once they've already happened. Sources for this article include: ChildrensHealthDefense.org FoxNews.com NewsNationNow.com Time.com
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