New World Screwworm

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 Resources

New World Screwworm | PDF

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

TAHC Region Offices

Wildlife

Texas Parks and Wildlife Department

Find a Wildlife Biologist

Humans

Texas Department of State Health Services

Public Health Regions

Domestic Pets

Contact your local veterinarian.

FAQ's

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.

Additional Resources