A Dallas Biotech Says It Can Wipe Out the Flesh-Eating Screwworm in the U.S. for Good — In a Year, Not Decades

For sixty years, the United States has fought the New World screwworm essentially the same way: by drowning it in its own kind. Billions of sterilized flies, released season after season, generation after generation, holding the line so the flesh-eating parasite can’t breed its way back.

It works. It also never ends. And this week, when the screwworm turned up in a three-week-old calf in Zavala County, Texas — the first detection on the U.S. mainland in decades — one Dallas company argued the country shouldn’t have to keep fighting this fight forever.   

Colossal Biosciences, best known for its headline-grabbing mission to resurrect the woolly mammoth, is now pointing its gene-editing toolkit in the opposite direction — not bringing a species back, but engineering one out of existence.

The screwworm earns its name honestly: females lay eggs in open wounds, and the hatched larvae screw into living tissue with hooked mouths, feeding on their host until, untreated, it often dies. The current defense — the sterile insect technique — demands a permanent barrier of flies and a continuous supply of billions, an effort researchers have long called expensive and, on its own, not powerful enough to finish the job.

But here’s what makes Colossal’s bet bigger than a better bug spray.

The company isn’t proposing to manage the screwworm. It’s proposing to end it. The tool is a gene drive — a single edit to the parasitic fly’s genome that, unlike a normal trait, passes to virtually every offspring instead of half. 

Colossal’s approach engineers that change so it produces infertile females. Once released, the trait spreads through the population on its own, moving from generation to generation like a built-in genetic off switch, until no fertile females remain and the population collapses.

Colossal calls the approach “genetic biocontrol,” and says that where the old method takes decades, gene-drive flies could clear an infested zone in a matter of months.

The pitch is as much economic as scientific.

CEO Ben Lamm has framed invasive species as a massive global problem: “The New World screwworm is advancing faster than existing control efforts can keep pace, and relying indefinitely on decades-old methods like mass sterile insect releases is an increasingly costly and unsustainable strategy. It will just slow the war, not win it. Through Colossal’s next-generation genetic biocontrol technologies, we now have the ability to safely, precisely, and efficiently eliminate screwworm populations in the US. To prevent a widespread outbreak that threatens livestock, wildlife, food security, and the economy, we must act now before the screwworm decimates the U.S. cattle industry.”

None of this is settled. Gene drives remain new, somewhat controversial, and subject to regulators who have never cleared one for open release in the U.S. — and the question of what happens ecologically when you erase even a parasite is a real one.

But the contrast on the table is stark: a sixty-year holding action that costs billions and never finishes, against a one-time genetic intervention that, if it works, finishes for good.

Sixty years ago, America became the first country to push the screwworm off its soil. Colossal is betting the next chapter isn’t about pushing it back again — it’s about making sure there’s nothing left at all.