By Chester Moore
The New World screwworm is one of the most disturbing parasites in North America. Unlike ordinary maggots that typically consume dead tissue, screwworm larvae infest wounds and feed on the living flesh of warm-blooded animals.
The parasite was eradicated from the United States decades ago, but in 2026 it returned to the U.S. mainland, creating serious concerns for livestock, wildlife and anyone responsible for protecting animals in affected areas.
For generations, one of the primary weapons against screwworm has been the sterile insect technique — producing enormous numbers of sterile male flies and releasing them into affected areas to disrupt reproduction. But could the next major weapon against screwworm come from genetics?
Dark Outdoors Podcast | Episode 80
Listen to Dark Outdoors Episode 80
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Spotify:
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Can Genetics Change the Fight?
In Episode 80 of Dark Outdoors, Chester Moore talks with Matt James of Colossal Biosciences about the potential for advanced genetic technologies to change the fight against New World screwworm.
Colossal has publicly discussed the possibility of using genetic biocontrol and gene-drive technology against the parasite. The concept could represent a major step beyond traditional control methods. Instead of relying solely on releasing sterile flies generation after generation, genetic technologies could potentially introduce traits designed to interfere with reproduction and spread those traits through a screwworm population.
Moore and James discuss what these technologies could mean, how genetics might complement existing eradication methods and the much larger question surrounding modern conservation biotechnology: Can our growing ability to manipulate genetics be used not only to help save threatened species, but also to fight organisms threatening wildlife and livestock?
Investigation Summary
New World screwworm has a gruesome biology. Female flies lay their eggs in wounds or other openings on warm-blooded animals. When the larvae hatch, they burrow into living tissue and feed.
Left untreated, infestations can become severe and potentially fatal.
The United States successfully eradicated screwworm through a massive campaign built around the sterile insect technique. Sterile male flies were produced and released across affected areas. When females mated with sterile males, they produced no viable offspring, gradually suppressing the population.
That strategy remains critically important, but the return of screwworm to the United States in 2026 has brought renewed attention to what additional technologies might someday be available.
Genetic biocontrol could potentially become one of them.
What You’ll Hear
In this episode, Moore and James explore the potential role of advanced genetics in screwworm control and what scientists may eventually be able to accomplish using modern biotechnology.
They discuss the difference between traditional sterile insect releases and emerging genetic approaches, the possibility of targeting reproduction within screwworm populations and how new tools could work alongside established eradication strategies rather than simply replacing them.
The conversation also moves into the broader implications for conservation. Biotechnology is increasingly being discussed as a tool for protecting endangered species, restoring lost genetic diversity and confronting invasive organisms and diseases.
Screwworm presents another side of that equation: What happens when genetics isn’t being used to restore an animal, but to stop one organism from devastating others?
Wildlife on the Front Lines
The screwworm threat extends far beyond cattle operations. Virtually any warm-blooded animal with an exposed wound can potentially become a host.
That makes wildlife an especially difficult part of the equation. Livestock can be inspected, treated and monitored by ranchers and veterinarians. Wild animals often cannot.
An injured deer, wild sheep or other mammal may develop an infestation far from human observation. By the time the animal is discovered — if it is discovered at all — the damage may already be severe.
The threat is particularly concerning in places where wildlife routinely suffer wounds from fighting, predators, fences, vehicle collisions or other causes. Screwworm flies do not distinguish between a cow standing in a pasture and a wild animal living miles from the nearest road.
That is one reason the return of New World screwworm deserves attention throughout the wildlife conservation community.
Biotechnology Meets the Dark Outdoors
There is something almost science-fictional about the possibility of fighting a flesh-eating parasite by altering the genetics of the parasite itself.
But this is no longer purely the territory of science fiction.
The same revolution in genetics that is changing medicine, agriculture and wildlife conservation is opening possibilities that would have been difficult to imagine only a generation ago. Whether genetic biocontrol ultimately becomes an important part of screwworm eradication remains to be seen, but the potential deserves serious attention.
The New World screwworm is back. Could genetics help send it away again?
Related Investigations
New World Screwworm Resource Center
Dark Outdoors has established a New World Screwworm Resource Center to bring our continuing coverage together in one place. Follow the developing threat, wildlife implications, interviews and other screwworm resources as this story continues.
https://darkoutdoors.com/new-world-screwworm-resource-center
Texas Faces Screwworm. The Key Deer Did 10 Years Ago
In 2016, New World screwworm struck the endangered Key deer of the Florida Keys. Chester Moore talks with Dr. Roel Lopez of the Texas A&M Natural Resources Institute, who worked with the U.S. Fish and Wildlife Service during that outbreak. The Key deer experience provides an important example of what screwworm can do to vulnerable wildlife populations and how sterile fly releases helped stop it.
Flesh-Eating Screwworm Is A Huge Threat — And It’s Back In America
Legendary wildlife biologist Larry Weishuhn witnessed the screwworm problem firsthand before the parasite was eradicated from the United States. In this Dark Outdoors feature, Moore and Weishuhn examine the parasite’s biology, its history and why its return presents a serious threat to wildlife and livestock.
Explore More
The screwworm investigation is part of a much larger mission at Dark Outdoors.
The podcast investigates terrifying encounters, unsolved mysteries, true crime and dangerous wildlife, including predator attacks, unexplained events in remote country, wildlife mysteries and emerging threats that can change the way we experience the outdoors.
Explore more investigations and podcast episodes at DarkOutdoors.com.
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About Chester Moore
Chester Moore is an award-winning wildlife journalist, author and host of the Dark Outdoors and Higher Calling Wildlife podcasts. For more than three decades, his work has explored wildlife, conservation, dangerous animal encounters and the mysteries found where people and the wild intersect.
He is also founder of the Gulf Great White Shark Society and co-founder of Higher Calling Wildlife, which provides wildlife encounters and outdoor experiences for children facing special challenges.
Dark Outdoors investigates terrifying encounters, unsolved mysteries, true crime and dangerous wildlife — because the outdoors has a dark side.