New World Screwworm Threatens Texas Wildlife & Livestock

By Chester Moore

For decades, the New World screwworm was considered one of America’s greatest wildlife and livestock success stories. Through an unprecedented eradication campaign, this flesh-eating parasite was eliminated from the United States, saving countless wild animals, pets, and livestock from one of nature’s most horrifying infestations. Many assumed it was a problem permanently confined to history.

That assumption has changed. The New World screwworm has returned to Texas, prompting an aggressive response from wildlife agencies, livestock producers, veterinarians, and state and federal officials. The parasite poses serious risks to wildlife ranging from white-tailed deer to desert bighorn sheep, as well as cattle, horses, pets, and other warm-blooded animals. In this episode of Dark Outdoors, Chester Moore examines how America defeated the screwworm once before, why it has returned, and what its resurgence could mean for wildlife conservation and agriculture across the Southwest.

Dark Outdoors Podcast | Episode 68

Listen to the episode:

Apple Podcasts: https://podcasts.apple.com/us/podcast/screwworm-america-defeated-this-wildlife-nightmare/id1630809603?i=1000772707689

Spotify: https://open.spotify.com/episode/6hY8FHwXvf8rucGcDvHqYw?si=xc7OD4RDQa2iF0jothQTDw

Investigation Summary

Episode 68 takes a comprehensive look at the New World screwworm (Cochliomyia hominivorax), one of the most destructive parasites ever to threaten North American wildlife and livestock. Unlike ordinary maggots that feed on dead tissue, screwworm larvae invade living flesh, creating wounds that become progressively larger as the larvae consume healthy tissue.

Chester Moore explains the remarkable eradication campaign that removed screwworms from the United States during the twentieth century through the innovative Sterile Insect Technique. That victory protected millions of livestock and countless wild animals for decades, making the parasite largely forgotten outside veterinary and wildlife circles.

Today, however, confirmed cases in Texas have reignited concern among wildlife professionals. The episode explores how the parasite spreads, the coordinated response by state and federal agencies, and why rapid detection is essential to protecting both domestic animals and free-ranging wildlife populations.

What You’ll Hear

You’ll hear the fascinating history of America’s successful campaign against the New World screwworm and why it remains one of the greatest achievements in wildlife disease management.

The episode explains how screwworm infestations occur, why even small wounds can become life-threatening, and which species are most vulnerable. White-tailed deer, mule deer, desert bighorn sheep, elk, livestock, and numerous other mammals can all be affected if infestations are left untreated.

Chester Moore also discusses the current situation in Texas, including why wildlife agencies, ranchers, hunters, veterinarians, and conservation organizations are working together to slow the parasite’s spread. Early detection, public awareness, and coordinated management will play critical roles in determining whether the United States can once again contain this devastating pest.

Throughout the investigation, the emphasis remains on facts rather than fear. While the return of the New World screwworm is a serious conservation issue, history demonstrates that science, surveillance, and coordinated action can provide powerful tools for protecting wildlife and livestock.

Readers interested in wildlife conservation challenges should also explore America’s Teen Poaching Crisis: Deer Massacres, Dolphin Shootings & Wildlife Crime, which examines another major threat facing wildlife populations, as well as Border Dangers: Hidden Threats Facing Hunters, Hikers & Ranchers in South Texas, which discusses issues affecting wildlife and landowners in Texas border regions.

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About Chester Moore

Chester Moore is an award-winning wildlife journalist, investigative outdoor writer, and host of Dark Outdoors. For more than three decades, he has covered wildlife conservation, endangered species, emerging threats to native wildlife, and the intersection of science and the outdoors. His reporting has included extensive coverage of Texas wildlife, conservation policy, and the people working to protect North America’s natural heritage.