Dark Outdoors’ Complete Guide to the Flesh-Eating Parasite Threatening Wildlife, Livestock, Pets and More

Welcome to the Dark Outdoors® New World Screwworm Resource Center.

This page serves as a continually updated resource covering New World Screwworm news, wildlife impacts, deer concerns, livestock issues, expert interviews, podcasts, maps, preparedness information and ongoing developments across Texas and the United States.

The New World Screwworm (Cochliomyia hominivorax) is one of the most destructive parasites ever to threaten North American wildlife and livestock. Unlike ordinary maggots that feed on dead tissue, screwworm larvae feed on living flesh.

After decades of successful eradication efforts, the parasite has returned to the United States and is now the focus of a major response effort involving USDA, Texas Parks and Wildlife Department, the Texas Animal Health Commission and other state and federal agencies.

Latest Screwworm News

July 2026 Situational Update

Update (July 10, 2026): New World Screwworm has now been detected in far West Texas. On July 10, USDA officials confirmed the parasite’s presence in a surveillance fly trap in Brewster County, marking the westernmost detection in the current Texas outbreak. The finding did not involve an infected animal, but instead came through the state’s intensive monitoring network, demonstrating that the pest has expanded beyond South Texas and reinforcing concerns about its continued spread into livestock and wildlife habitats.

The westward detection follows the first confirmed U.S. case of New World Screwworm in decades. On June 5, 2026, the Texas Parks and Wildlife Department released its first statewide situational update after the USDA National Veterinary Services Laboratory confirmed the parasite in a three-week-old calf with an umbilical wound in Zavala County, Texas.

Since that initial detection, confirmed cases have expanded into 12 Texas counties, along with additional cases in neighboring New Mexico. The response has grown to include livestock movement restrictions, quarantines, sterile fly releases, intensive trapping and surveillance, and coordinated containment efforts by state and federal agencies.

Governor Greg Abbott has issued and continued disaster declarations related to the outbreak, while the Texas Animal Health Commission, USDA APHIS, Texas Parks and Wildlife Department, Texas A&M AgriLife, and numerous local partners continue working to slow the parasite’s spread and protect both livestock and wildlife populations.

The expansion into West Texas raises concerns not only for cattle producers but also for native wildlife, including mule deer, elk, desert bighorn sheep, and the iconic desert bighorn sheep herds of the Trans-Pecos, all of which could be vulnerable if New World Screwworm becomes established in the region.

Because the situation continues to evolve, USDA APHIS regularly updates its confirmed-case dashboard as new detections are verified, making it the primary source for the latest county-by-county information on the outbreak.

Featured Interview

Larry Weishuhn Discusses the New World Screwworm Threat

Renowned wildlife biologist, author and outdoor communicator Larry Weishuhn joins Dark Outdoors to discuss the implications for deer, wildlife, livestock, hunters, ranchers and landowners.

Topics include:

• Potential impacts on whitetail deer
• Risks to wildlife populations
• Concerns for livestock producers
• What hunters should know
• How the parasite could affect Texas wildlife management

Video:
https://youtu.be/_d5X-ASDJ-o?si=VEtgzkZZZ-XZWGpd

The Forgotten Key Deer Screwworm Outbreak of 2016

In this exclusive interview, I sit down with Dr. Roel Lopez, Director of the Texas A&M Natural Resources Institute, who worked with the U.S. Fish and Wildlife Service during the 2016 Florida Keys outbreak. He shares firsthand insight into what happened, how the endangered Key deer were affected, and how one of the greatest wildlife disease eradication efforts in history—using millions of sterile flies—helped stop the outbreak before it spread.

Dark Outdoors Podcast Deep Dive

For a more detailed examination of the screwworm situation, listen to our Dark Outdoors podcast special.

Topics include:

• How screwworm spread northward
• Wildlife implications
• Questions surrounding preparedness
• What Texans need to know moving forward

Podcast:
https://www.podbean.com/ew/pb-232ss-1aeb995

What Is New World Screwworm?

New World Screwworm is the larval stage of a fly known as Cochliomyia hominivorax.

Female flies deposit eggs in wounds, cuts or body openings of warm-blooded animals. Once the eggs hatch, the larvae feed on living tissue.

Animals can suffer severe infections, extensive tissue damage and death if infestations are not treated. The parasite can affect livestock, wildlife, pets and, in rare cases, humans.

Screwworm and Deer

One of the most important questions for hunters and wildlife managers is how screwworm may affect deer populations.

Whitetail deer routinely experience wounds from:

• Antler fights
• Fencing
• Vehicle collisions
• Predators
• Environmental injuries

These wounds may provide opportunities for screwworm infestation.

Wildlife experts continue monitoring the situation because free-ranging deer are significantly harder to inspect and treat than livestock.

Dark Outdoors will continue providing updates on potential impacts to deer populations across Texas and beyond.

Screwworm and Wildlife

While livestock receive much of the attention, wildlife may play a critical role in the future spread and management of New World Screwworm.

Species potentially affected include:

• White-tailed deer
• Mule deer
• Elk
• Exotic hoofstock
• Wild hogs
• Predators
• Small mammals

Some wildlife rehabilitation operations in Texas have already adjusted intake procedures because of concerns surrounding screwworm movement restrictions and animal transfers.

Screwworm and Livestock

Livestock remain at greatest economic risk.

Animals affected may include:

• Cattle
• Horses
• Sheep
• Goats
• Swine

Agricultural leaders have warned that a widespread outbreak could create major economic consequences for Texas producers and the broader agricultural industry. Multiple quarantines and movement restrictions have already been implemented in response to confirmed cases.

How Did Screwworm Return to America?

This is one of the most frequently asked questions.

The parasite was successfully pushed south through decades of sterile-fly eradication efforts.

However, officials report that the containment line in Panama was breached and the parasite began moving north through Central America and Mexico beginning in 2023. By late May 2026, cases had been reported near the Texas border. On June 3, USDA confirmed the first Texas case.

Questions continue to be asked regarding:

• Animal movement
• Border security
• Government preparedness
• Surveillance efforts
• Sterile-fly production capacity
• Wildlife movement

Dark Outdoors will continue examining these questions while separating documented facts from speculation.

What To Do If You Suspect Screwworm

Signs may include:

• Maggots in wounds
• Foul-smelling wounds
• Animals repeatedly licking or biting a wound
• Enlarging wounds
• Visible tissue damage

Suspected cases should be reported immediately.

Texas Animal Health Commission:
1-800-550-8242

Texas Parks and Wildlife Department:
Contact your local wildlife biologist.

Early reporting is considered critical to containment efforts.

Frequently Asked Questions

Can deer get screwworm?

Yes. Deer are susceptible if flies gain access to wounds or injuries.

Can humans get screwworm?

Yes, although human infestations are uncommon. No locally acquired human infestations have been reported in the current U.S. outbreak.

Is screwworm in Texas?

Yes. Multiple confirmed cases have been identified in Texas.

Is screwworm in New Mexico?

Yes. A confirmed case has been reported in New Mexico.

Can dogs get screwworm?

Yes. Dogs are susceptible to infestation.

How do screwworms spread?

Adult flies lay eggs in wounds or body openings of warm-blooded animals. Larvae hatch and feed on living tissue.

Does screwworm affect hunters?

Potentially. Hunters are often among the first people to observe abnormal conditions in wild deer and other game animals.

Dark Outdoors Screwworm Coverage

This resource center will be updated regularly with:

• Breaking news
• Expert interviews
• Wildlife updates
• Deer-specific coverage
• Livestock developments
• Podcasts
• Videos
• Maps
• Preparedness resources

Bookmark this page and check back frequently for the latest information on New World Screwworm and its impact on wildlife, hunting, conservation and agriculture.