Border Fly Invades — Flesh-Eating Threat

Rabbit and various birds on the farm grass

A flesh‑eating livestock pest just crossed our southern border again, and Texas ranchers know this is exactly what they’ve been warning Washington about for years.

Story Snapshot

Federal officials confirmed New World screwworm in a Texas calf, a parasite that eats living flesh and can kill livestock fast.
USDA and Texas authorities launched checkpoints, surveillance, and mass releases of sterile flies to stop the spread.
Health agencies say the risk to people and the food supply is low, but the economic threat to cattle and wildlife is huge.
Ranchers are being told to step up barn‑lot vigilance while the multi‑agency eradication effort plays out over many months.

What exactly is the New World screwworm and why it matters to ranch families

The New World screwworm is a parasitic fly whose larvae do something most of us would rather not picture: they burrow into the living flesh of warm‑blooded animals and eat from the inside out.^[20] Female flies lay eggs in fresh wounds, like branding marks or the navel of a newborn calf.^[18] Within days, hundreds of maggots can hatch in one spot, causing deep, foul‑smelling wounds, severe pain, infection, and often death if the animal is not treated quickly.^[18]

This pest is not new, and that is part of the story. It once caused devastating losses in American cattle and wildlife until a World War II–era program using sterile fly releases finally wiped it out here by the late 1960s.^[21] That effort is still remembered inside agriculture as one of the greatest success stories in the history of farming.^[21] Because of that hard‑won victory, any confirmed case on U.S. soil now triggers an emergency response. Ranchers understand why: they know how fast this bug can turn a healthy calf into a carcass.

How the screwworm got back in and what the government is doing now

On June 3, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service confirmed New World screwworm in a three‑week‑old calf in Zavala County, Texas, near the border.^[1] Larvae were found in the umbilical area, a high‑risk target on a newborn.^[1] USDA immediately labeled screwworm a “serious pest” that threatens livestock, pets, wildlife, and, less often, people.^[1] Texas declared an emergency as additional animal cases were later reported across South Texas.^[11]

Federal and state teams responded with the same tools that won the fight decades ago. USDA, the Texas Animal Health Commission, and Texas Parks and Wildlife set up animal checkpoints, expanded trapping, and began aggressive ground and aerial releases of sterile flies in infested zones.^[2] These sterile males mate with wild females and prevent them from producing viable offspring, driving the population down over time.^[2]^[21] The department also moved to build a new sterile‑fly production facility in the Rio Grande Valley to support months, and likely more than a year, of intense eradication work.^[2]^[3]

How big is the threat and what are agencies telling regular Americans?

While headlines about “flesh‑eating worms” sound like a horror movie, health officials are stressing two things at once: the bug is deadly for animals, but current risk to people and the food supply is low. The Centers for Disease Control and Prevention reports no locally acquired human screwworm cases in the United States in this outbreak and says overall human risk “remains low” and is limited to areas where the flies are active.^[3] The worst human cases so far are in Central America and Mexico, not here.^[13]

USDA’s unified screwworm response site makes a similar point. It calls screwworm “a serious pest of livestock and wildlife,” but clearly states that this is not a food‑safety issue and that the U.S. food supply remains safe.^[7] State health officials in Texas echo that message, reminding people that every slaughter animal is inspected for signs of disease before it enters the food chain.^[17] For now, federal science agencies are telling Americans to stay alert, especially along the border and in ranch country, but not to panic or stop buying beef.

What this means for border security, ranchers, and everyday families

For many conservative Texans, the screwworm’s return looks like one more cost of a long‑neglected border. This parasite did not come from Iowa or Kansas; it rode north as outbreaks spread through Central America and Mexico starting in 2023, with thousands of animal cases and more than a thousand human cases reported there.^[3]^[13] Scientists had already warned that Texas, with its huge cattle herd and warm climate, is one of the most favorable places for this fly to take hold if it ever crosses the line.^[2]

After being previously eradicated in the U.S. in the 1960s, the destructive livestock pest known as New World screwworm was discovered in a calf in Zavala County in the first week of June. Since then, 14 more domestic cases have been confirmed. https://t.co/bmWtfgqPZ0

— The Texan (@TheTexanNews) June 22, 2026

That is why the Trump administration’s agriculture and border teams are leaning hard on early detection and tight movement controls. USDA had already halted cattle imports from parts of Mexico in earlier years to slow the pest’s advance.^[12] Now, ranchers are being asked to check cattle often for draining wounds, bad odors, or visible maggots, to isolate any suspect animal, and to call their veterinarian or state animal health officials right away.^[1]^[8] The message is simple: Washington can fly sterile insects, but local producers are the true front line.

What you can do now to protect your herd, pets, and family

For livestock owners, the practical steps matter more than any political speech. Experts say to keep all wounds on cattle, horses, and pets clean and covered when possible, and to work with a trusted veterinarian on preventive treatments in high‑risk areas.^[4]^[20] Delay non‑essential surgeries or branding that create open wounds if you are in or near an infested zone.^[6] Do not move any animal you suspect might be infested until a vet or state official gives the all‑clear.^[8]

Families in South Texas and other warm regions can also take basic steps. Health guidance from federal and state agencies recommends keeping your own cuts clean and covered and using screens or nets to keep flies off at night.^[3]^[7] If anyone ever sees maggots in a wound on themselves or a loved one, they should seek medical care immediately and not try to pick or throw the larvae away, since that can help the pest spread.^[3]^[13] These are simple, common‑sense habits that fit well with a culture of personal responsibility.