Texans enjoying the outdoors provide the first line of defense in protecting wildlife, livestock and humans from an infestation that could have devastating effects in the state.
Situational Updates
- Jun 9, 2026
Situational Update: New World Screwworm
Identification
New World screwworms (NWS) are parasitic flies (Cochliomyia hominivorax) that lay eggs in open wounds, genitalia or mucous membranes such as the nostrils, eyes or mouths of live warm-blooded animals.
These eggs hatch into parasitic larvae (maggots) that only feed on living tissue, unlike other fly larvae that prefer dead or necrotic tissue. NWS larvae burrow or “screw” into living tissue with sharp mouth hooks, giving them a screw-like appearance. Infested wounds quickly become infected and, if left untreated, will kill infested animals.
Common Areas of Infestation
- Newborn animals' umbilical stump/navel
- Mucous membranes — genitalia, eyes, nose, mouth
- Damaged skin — cuts, scrapes, stings, tick bites, antler/velvet shedding
- Management-related — dehorning, ear tagging, castration, branding, calving, fawning
What an NWS Infestation Might Look Like
- Open sores or wounds with live maggots
- Animals shaking heads or acting irritated
- Foul, rotted flesh odor
Report Sightings
If you see live animals with live maggots, report immediately. Early detection is key. Do not delay if you suspect an NWS infestation. Reporting is crucial to managing and eradicating an NWS Infestation.
Livestock or Exotic Species
Texas Animal Health Commission
8 a.m. - 5 p.m., contact a local TAHC region office:
- Amarillo (806) 641-7000
- Beeville (361) 358-3234
- Giddings (979) 212-5440
- Laredo (956) 568-5741
- Stephenville (512) 556-6277
- Sulphur Springs (903) 919-3748
5 p.m. - 8 a.m. and on weekends, contact the TAHC headquarters: veterinarian on call (800) 550-8242
Native Wildlife
While all warm-blooded mammals can be infested with NWS, white-tailed deer, jackrabbits, cottontails, small mammals and turkeys are more commonly affected. Report native wildlife sightings to a local TPWD biologist or call (512) 389-4505.
Texas Parks and Wildlife Department
Find a Wildlife Biologist
Humans
Contact your regional zoonosis control veterinarian.
Texas Department of State Health Services
NWS and Humans
Zoonosis Control Contact Information
Domestic Pets
Contact your local veterinarian.
Guidance Documents
- General Wildlife Information for New World Screwworm | PDF
- Gusano Barrenador del Nuevo Mundo Información General | PDF
- Deer Breeding Facilities Best Management Practices for New World Screwworm | PDF
- Wildlife Permit Holders Information Sheet for New World Screwworm | PDF
- Hunter and Landowner Guide for New World Screwworm | PDF
Other Agencies
U.S. Department of Agriculture
- USDA-APHIS New World Screwworm
- History of the New World Screwworm in the U.S.
- Economic Impact Estimates of New World Screwworm in the U.S. | PDF
Texas Animal Health Commission
- Texas Animal Health Commission: New World Screwworm Updates
- New World Screwworm Emergency Management Guide | PDF
- New World Screwworm Fact Sheet | PDF
- Texas Animal Health Commission New World Screwworm Livestock Producer Guidance | PDF