The United States eradicated the New World screwworm decades ago. This summer it came back.

USDA confirmed the first U.S. animal case on June 3, 2026, in cattle in Zavala County, Texas. Detections have since been confirmed in other Texas counties and in Lea County, New Mexico, and several of the cases have been dogs, not just livestock. USDA keeps a live count on its current status page and detection dashboard.

What it is

The New World screwworm (Cochliomyia hominivorax) is a fly. The female lays eggs in open wounds, and the larvae feed on living tissue, not dead tissue like most fly maggots. Untreated, an infestation can seriously injure or kill an animal. In the 1950s it cost Southwest ranchers an estimated $50 to $100 million a year before the sterile-fly program pushed it all the way south to Panama, according to researchers at UC San Diego.

Who is at risk

  • Livestock and wildlife carry most of the risk.
  • Pets can be infested through any open wound, including small scrapes, bites, and surgical sites.
  • People: the CDC says the risk "remains very low." There have been no locally acquired human cases in the U.S. The one U.S. human case on record was travel-related, in August 2025.

What homeowners and pet owners should do

The CDC's guidance for people in affected areas:

  • Keep open wounds clean and covered, no matter how small, on people and pets.
  • Use an EPA-registered insect repellent and wear long sleeves, pants, and socks outdoors.
  • Check pets daily for unexplained sores, a foul smell, or visible maggots, especially around wounds, ears, and the nose.
  • If you see maggots in a wound, get medical or veterinary care right away. Don't try to remove them yourself.

USDA asks anyone who sees suspicious wounds or maggots in animals or people to report it immediately through its screwworm response resources.

What it means for pest control companies

Screwworm response is a USDA and state animal health job. The main tool is releasing millions of sterile male flies so wild females can't reproduce. But local pest pros are often the first call when a homeowner finds maggots or a sudden fly problem, so it helps to:

  • Know the look-alikes. Most maggots homeowners find come from blow flies and house flies breeding in garbage or dead animals. Those don't attack living tissue. Screwworm larvae are found in wounds on living animals.
  • Know where to send people. Infested animals go to a veterinarian, people to a doctor, and suspected cases to the state animal health office or USDA. Treating a wound infestation is not a pest control service.
  • Keep sanitation and fly control tight on accounts with animals: kennels, boarding facilities, ranches, and properties with livestock.

Pest control companies in Texas and New Mexico that want to be a trusted local voice on this can share the CDC and USDA links above with customers who have pets or animals.

This article is general information, not veterinary or medical advice. Case counts change quickly; check USDA's dashboard for the latest.