America’s Worst Livestock Nightmare Is Back

Packaged chicken breasts on a factory conveyor belt.

A flesh‑eating livestock pest the United States wiped out in the 1960s is back on American soil, and what happens next will hit ranchers, not city bureaucrats, the hardest.

Story Snapshot

A confirmed New World screwworm case in a Texas calf marks the pest’s return to the U.S.
This parasite eats living flesh and can kill cattle in days if ranchers miss the early signs.
Federal and Texas officials are rolling out quarantines, checkpoints, and mass sterile‑fly releases.
Human risk and food safety remain low, but the economic threat to livestock and wildlife is huge.

What Exactly Came Back, and Why It Matters to Rural America

The U.S. Department of Agriculture (USDA) has confirmed that New World screwworm, a flesh‑eating fly, has reappeared in a calf in Zavala County, Texas, near the border.^[1] This insect is not a normal barn fly. Its larvae burrow into the living flesh of warm‑blooded animals, including cattle, wildlife, and pets, and the wounds often turn deadly if not treated quickly.^[1]^[20] Before its eradication in the 1960s, screwworm caused devastating losses across American cattle country.^[21] Ranchers today face the same basic threat: painful wounds, dead calves, and heavy economic damage if the pest spreads.^[18]

For most readers, especially in cities, this is not a direct health scare. Federal health guidance still says the risk to people is low and that this is not a food‑safety problem.^[3]^[7] Screwworms do not infest meat in the food chain, and inspectors remove any animals with suspicious lesions before slaughter.^[17] But for producers, this is a very different picture. Texas A&M experts warn that if screwworm gained a foothold in Texas, the cattle industry alone could see billions in losses, and the state’s hunting and wildlife economy would also take a massive hit.^[12]

How Screwworm Hurts Cattle, Wildlife, and Family Livelihoods

The New World screwworm fly lays eggs in any fresh wound on a warm‑blooded animal, from a calf’s navel to a branding cut or even a scratch from barbed wire.^[18]^[20] Within days, hundreds of larvae can hatch and eat deeper into the tissue, causing foul‑smelling, enlarging wounds, extreme pain, and deadly infections if ranchers do not step in fast.^[1]^[20] Texas A&M notes that untreated cases often kill animals, so early detection and aggressive treatment with wound cleaning and approved insecticides are essential once larvae appear.^[8]^[20] This is why state animal health officials urge producers to check animals daily, especially newborns and those recently branded, castrated, or dehorned.^[4]

Unlike many pests that only target one species, screwworm infests nearly all warm‑blooded animals.^[18] That includes cattle, sheep, goats, horses, deer, and even pets in the yard.^[18]^[8] In Central America and Mexico, where the current broader outbreak began in 2023, more than 185,000 animal cases and thousands of human cases have been recorded in just a few years.^[1]^[3] A recent scientific review notes that while human cases tend to be rare and treatable, livestock losses can be severe, with rapid spread once the fly settles into a warm region like South Texas.^[3] For rural families already squeezed by high feed costs and tight margins, losing calves or hunting income to a preventable parasite is not a small problem; it is a direct hit to their way of life.

What the Government Is Doing Now — and What Ranchers Must Do Themselves

USDA and Texas officials say they moved quickly after the Texas calf was confirmed positive, following a pre‑planned screwworm response playbook.^[1] Actions include intensive surveillance in affected counties, movement controls and checkpoints for livestock, and rapid deployment of sterile screwworm flies released from the ground and air so they mate with wild flies and stop reproduction.^[1]^[2] Federal leaders describe it as a “One Health” response that links animal health, wildlife, and human health, with local partners helping check animals, set traps, and educate landowners.^[7]^[2] The same sterile‑insect strategy helped eradicate screwworm from the United States and much of Mexico decades ago and is being scaled up again, including a new sterile‑fly production facility in Texas.^[2]^[3]^[21]

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

At the same time, the message from experts is clear: government programs alone cannot patrol every pasture. Texas guidance stresses that landowners are the first line of defense, through regular inspection of cattle, fast reporting of any maggot‑filled wounds, and strict isolation of suspect animals before moving them.^[4]^[8]^[20] If producers or veterinarians find larvae in a live animal, they are required to report it, send samples for official identification, and treat the wounds at once.^[4]^[12] Federal and state sites list direct phone numbers so ranchers can reach animal health officials the same day, and USDA’s national screwworm portal provides status maps and plain‑language updates on where cases are confirmed.^[7]^[10] For conservative readers, this is one area where vigilance and self‑reliance on the ranch pair with a focused, limited government mission: keep this foreign‑born parasite from taking root again in American herds.