New World screwworm in Texas went from a border concern to a real issue for landowners in 2026. After the first U.S. case was confirmed in a calf in Zavala County on June 3, 2026, cases have been found in livestock and other animals across 17 Texas counties. If you are buying or selling a ranch, especially one with cattle, goats, or a managed deer herd, here is what you need to know and how to plan around it.
What Is New World Screwworm?
New World screwworm (NWS) is a fly whose larvae infest open wounds on warm-blooded animals and feed on living tissue. It affects livestock, wildlife like white-tailed deer, pets, and, less commonly, people. Left untreated, an infested animal can die within about a week. The United States eradicated screwworm decades ago using sterile fly releases, and USDA is using the same approach now, releasing millions of sterile flies each week along the border.
Where Screwworm Has Been Found in Texas
Since June 2026, cases have been confirmed on 39 premises in 17 Texas counties, mostly along the Rio Grande, in West Texas, and on the western edge of the Hill Country. The Texas Animal Health Commission (TAHC) has set infested zones with movement restrictions in parts of those counties.
The situation changes week to week, so always check the current infested zone map on the Texas Animal Health Commission’s screwworm page before you buy, sell, or move animals.
What Screwworm in Texas Means for Ranch Buyers
Screwworm does not make a ranch a bad purchase, but it adds a few questions to your due diligence:
Is the property in or near an infested zone? Check the TAHC map for the ranch and the surrounding counties.
Does livestock convey with the sale? Inside an infested zone, warm-blooded animals cannot leave the zone without prior TAHC authorization, an inspection, and a movement certificate. Factor that into your timeline if you plan to bring cattle in or move them out.
Who manages the herd today? Ask the seller or ranch manager how often animals are checked, how wounds are treated, and whether any cases have been reported on the property.
Are there grazing or hunting leases? Find out who is responsible for monitoring animals under each lease, and make sure that carries over after closing.
What Screwworm Means for Ranch Sellers
Most ranch sales are not affected at all, but if your property has livestock or is in an infested zone, plan ahead. If cattle or goats are part of the sale or need to be moved before closing, contact TAHC early, since inspections and movement certificates take time. Keep records showing how animals have been checked and treated, because organized records help buyers feel confident. Your broker can help you decide how to address screwworm in your listing and disclosures.
Hunting Season and Screwworm
With hunting season underway, hunters and landowners are some of the best eyes in the field. Texas Parks and Wildlife asks hunters to inspect every harvested deer for wounds that may contain larvae and to report wildlife with suspicious wounds. Watch for open sores with live maggots, animals shaking their heads or acting irritated, and a strong rotting odor. Game cameras can help you spot problems early. If you enroll your property in the Managed Lands Deer Program, your more active harvest and herd monitoring can also help with early detection.
How to Protect Your Ranch
- Check livestock regularly, especially around navels on newborns, ear tags, and any cuts or sores.
- Treat wounds right away and work with your veterinarian on approved treatment and prevention products.
- Talk with your vet about timing procedures like branding and castration to limit open wounds during fly season.
- Watch your deer and other wildlife through game cameras and while hunting.
- Report suspected cases within 24 hours.
Who to Contact
Livestock and exotics: Texas Animal Health Commission, 1-800-550-8242
Native wildlife: Texas Parks and Wildlife, 512-389-4505
Pets: your local veterinarian
Buying or Selling a Ranch During the Screwworm Outbreak
Ranches are still being bought and sold across Texas, and with the right planning, screwworm in Texas is one more item on the checklist, not a deal breaker. Our team knows the counties we work in and can help you understand what applies to a specific property. Browse our South Texas ranches for sale or call us at (833) 697-2624 to talk through your plans.
