Livestock Nightmare Spreads — Quarantine Expands

A flesh-eating parasite is spreading through Texas livestock, and the key tool to stop it — sterile fly production — may not be ready in time.

Story Snapshot

The U.S. Department of Agriculture confirmed six New World screwworm cases in Texas by June 11, 2026, with a quarantine covering ten counties.
The parasite re-emerged in Mexico in November 2024 and has been moving north toward the Texas border ever since.
Sterile fly releases are the main weapon against screwworm, but production capacity is limited and eradication depends on how many flies are available.
Texas Governor Greg Abbott activated an emergency response, and ranchers near the border face real economic risk if the outbreak spreads.

Flesh-Eating Parasite Confirmed in Texas Cattle

The Centers for Disease Control and Prevention confirmed that the first U.S. animal case in the current outbreak was detected on June 3, 2026. ^[11] The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) identified the infected animal as a three-week-old calf in Zavala County, Texas. ^[9] Within days, cases spread to other counties. By June 11, federal officials confirmed six total cases across Texas, including cattle, a goat, and a dog. ^[1] Governor Abbott declared a disaster and placed a quarantine on ten counties.

New World screwworm is not a minor nuisance. The larvae — maggots — burrow into the living flesh of animals and cause severe tissue damage. ^[9] Left untreated, infested animals can die. The pest was eradicated from the United States decades ago through a massive sterile fly program. Its return is a serious threat to Texas ranchers and the broader U.S. cattle industry, which experts say could face billions of dollars in losses if the parasite takes hold again. ^[3]

The Parasite Has Been Moving North Since Late 2024

New World screwworm re-emerged in Mexico in November 2024. ^[2] Since then, it has moved steadily northward through the border region. Federal officials say that as long as the parasite remains active in Mexico, Texas and the rest of the United States face increased risk. ^[7] Confirmed Texas cases were found dozens of miles from the southern border — meaning the pest is already well inside the state, not just a border-zone problem. That gap is alarming for ranchers across South and Central Texas.

USDA and APHIS responded quickly. They launched aerial sterile fly releases in Mexico and along the Texas border, set up quarantine zones, and restricted animal movement in affected counties. ^[2] Texas A&M AgriLife Extension is urging livestock owners to report any suspected cases immediately and to avoid moving animals that may be infected, to prevent the parasite from spreading further. ^[5] The official message is that the U.S. food supply remains safe — but the threat to livestock is real and growing.

Sterile Flies Are the Key — and Supply Is the Problem

The proven way to eradicate New World screwworm is to flood an area with sterile male flies. When they mate with wild females, no offspring are produced. Over time, the population collapses. This strategy worked before, and it is the centerpiece of the current response. But experts warn that the number of sterile flies available directly determines whether eradication succeeds or fails. ^[3] If supply falls short, the parasite survives and spreads.

Scaling up sterile fly production takes time. Facilities must be built, permitted, and staffed. The U.S. has been relying on production capacity in Mexico while domestic options are developed. That dependency creates a real vulnerability — especially when the outbreak is already inside U.S. borders. Texas ranchers and agriculture officials are right to push hard for answers on when full production capacity will be ready. The faster sterile flies reach infested areas in large numbers, the better the odds of stopping this outbreak before it becomes a catastrophe for the Texas cattle industry.