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.
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.
If you see LIVE animals with LIVE maggots, report the sighting to your local TPWD wildlife biologist. Early detection is key. Do not delay if you suspect an NWS infestation. Reporting is crucial to managing and eradicating an NWS Infestation.
An NWS infestation might look like:
- Open sores or wounds with live maggots
- Animals shaking heads or acting irritated
- Foul, rotted flesh odor
TPWD News
- Sep 23, 2025
Wildlife Health Alert: Texans Encouraged to Stay Vigilant for New World Screwworms - Sep 16, 2025
White-tailed Deer Archery Hunters Should Have Plenty of Opportunities to Harvest Quality Bucks Before the General Season - Jun 25, 2025
Texas New World Screwworm Response Team Formed to Amplify Preparedness - Dec 30, 2024
TPWD Fomenta el Monitoreo y la Notificación de los Animales Afectados por el Gusano Barrenador del Nuevo Mundo - Dec 30, 2024
TPWD Encourages Monitoring, Reporting of Animals Affected by New World Screwworm
Resources
New World Screwworm General Wildlife Information | PDF
Gusano Barrenador del Nuevo Mundo Información General | PDF
Best Management Practices for Deer Breeding Facilities | PDF
Information Sheet for Texas Wildlife Permit Holders | PDF
Texas A&M Wildlife Monitoring and Management for New World Screwworm Document.
Who to Contact
Livestock
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
Wildlife
Texas Parks and Wildlife Department
Humans
Texas Department of State Health Services
Domestic Pets
Contact your local veterinarian.
FAQs
What areas of an animal are commonly infested?
- 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 kinds of wildlife are more commonly affected?
While all warm-blooded mammals can be infested with NWS, white-tailed deer, rabbits (jackrabbits, cottontails), small mammals and turkeys are wildlife species that are more commonly affected.
What should a landowner do if they suspect wildlife might be infested with NWS?
Landowners who suspect an NWS infestation should contact their local TPWD wildlife biologist.