Parasite Marches North — Ranchers Panic

A flesh-eating parasite has crossed into Texas and New Mexico, and a fierce fight is now underway between federal officials and state leaders over whether Washington is doing enough — fast enough — to stop it.

Story Snapshot

The U.S. Department of Agriculture opened a new sterile fly facility in Edinburg, Texas, capable of producing 100 million flies per week to fight the New World screwworm outbreak.
The pest has spread 1,100 miles northward from southern Mexico and at least five confirmed cases have been found in Texas and New Mexico.
Texas Agriculture Commissioner Sid Miller says the federal program is flawed and demands use of a proven fly-bait system the USDA refuses to deploy.
USDA Secretary Brooke Rollins unveiled a five-part eradication plan and says the agency has grown its response team from 10 to 110 employees since January 2024.

A Parasite That Kills Livestock — and Threatens People

The New World screwworm is not just a farm problem. This parasite lays eggs in open wounds of warm-blooded animals. The larvae then burrow into living flesh. Left untreated, the infestation is deadly. Texas Agriculture Commissioner Sid Miller has warned that 275 people were infected in Mexico, with two deaths. Cattle, pets, and wildlife are all at risk. The pest was wiped out in the U.S. back in 1966, but it has now returned — and it is moving fast.

The screwworm crossed the Panama barrier around 2023 and has marched more than 1,100 miles north through Mexico into the United States. At least five confirmed cases have been found — three calves and one goat in Texas, plus one dog in New Mexico. Critics argue the true number is higher because some ranchers fear government quarantines and are not reporting cases.^[1]

USDA Opens New Facility, Launches Five-Point Plan

The U.S. Department of Agriculture (USDA) opened a sterile fly production facility at Moore Air Base in Edinburg, Texas, with a capacity of 100 million sterile flies per week.^[2] The agency is also investing $21 million to renovate a facility in Metapa, Mexico, which will add another 60 to 100 million sterile flies weekly.^[2] The strategy relies on a proven method: releasing sterile male flies so wild females mate with them, producing no offspring, eventually collapsing the population. This same approach eradicated the pest in the U.S. in 1966.

USDA Secretary Brooke Rollins announced a five-part plan at the Moore Air Base ceremony covering animal movement controls, surveillance, public outreach, sterile insect releases, and new technology.^[3] The agency says it has grown its screwworm response team from 10 full-time employees in January 2024 to 110 by June 2025 — a tenfold increase.^[6] The USDA is also using artificial intelligence-assisted drone surveillance and predictive analytics to track the pest’s movement.^[6]

Texas Commissioner Says the Plan Is Failing

Commissioner Miller is not satisfied. He points out that more than 7 billion sterile flies were released over 20 months, yet the pest kept spreading.^[1] His core complaint is biological: the current fly strain releases both males and females. Female sterile flies end up mating with sterile males instead of targeting fertile wild females, which cuts the program’s effectiveness roughly in half. Miller calls this a serious flaw the USDA has not fixed.

🤝 Defeating New World screwworm requires strong partnerships.

Today, @SecRollins joined President @Claudiashein, @USAmbMex, and our partners in Mexico to celebrate the opening of the new sterile fly production facility. They also discussed rapidly integrating the NOVO fly into… pic.twitter.com/wJTJIZQ8Q6

— New World Screwworm Rapid Response (@Screwworm_RR) June 27, 2026

Miller also wants the USDA to deploy a fly-bait system called the Screwworm Adult Suppression System, which the agency itself developed and used historically to kill up to 95% of adult flies.^[13] The USDA has declined to use it, citing environmental concerns about harming other fly species. Miller dismisses those concerns as misplaced given the scale of the threat. Secretary Rollins called Miller’s criticism “unserious” and “dangerous” — a response that has fueled accusations of federal arrogance and stonewalling of a legitimate state concern.

What Is Actually at Stake for Ranchers

A full-blown screwworm outbreak could cost the U.S. livestock industry billions of dollars. The USDA estimates the prior eradication program saved the industry more than $900 million per year.^[19] Texas ranchers are already on high alert, checking animals daily for wounds. The USDA is monitoring 8,000 fly traps along the Texas border and has submitted nearly 60,000 flies for testing.^[6] A new male-only sterile fly strain called NovoFly is being developed at North Carolina State University and could double production efficiency, but it is not yet approved for deployment.^[8]

The federal-state friction here is real and worth watching. Miller raises valid technical questions that deserve straight answers — not dismissal. Ranchers need the fastest, most effective tools available, not a bureaucratic standoff. The USDA’s sterile fly method has a strong track record, but if a proven alternative like the Screwworm Adult Suppression System could stop this outbreak faster, American farmers deserve to know exactly why it is sitting on the shelf.