06/07/2026
Before everyone ones started pointing fingers, here the story of the
Screwworm,
Ranchers in the 1930s knew the sound of a suffering animal. They knew it the way you know a bad storm before it arrives — in your gut, before your eyes can confirm it. And what was causing that suffering was one of the most gruesome parasites ever to plague the American West: the New World Screwworm.
The screwworm fly — Cochliomyia hominivorax, Latin for "man-eater of livestock" — didn't just feed on animals. It fed on living animals. A female fly would find the smallest wound, even a tick bite, and deposit her eggs. Within hours, the larvae would hatch and begin to burrow inward, spinning in a corkscrew motion that gave them their name. Left unchecked, a single infestation could kill a full-grown cow within two weeks. Calves, deer, even humans were not safe. Losses to the American cattle industry reached into the hundreds of millions of dollars every year. Ranchers were in a constant, exhausting battle they could not win.
Nobody had a solution. Until two men decided there had to be one.
Edward F. Knipling was a USDA entomologist who grew up in Texas, the son of a farmer who had watched screwworms devastate livestock firsthand. That personal history made the problem feel urgent in a way that mere science never could. By the late 1930s, Knipling had developed a theory so counterintuitive that his colleagues thought it bordered on lunacy. Instead of trying to kill the flies with pesticides — a battle that could never be fully won — what if you made them unable to reproduce?
His idea was elegant in its brutality. The New World Screwworm female mates only once in her lifetime. If you could sterilize enough males and release them into the wild population, females would mate with sterile males, lay eggs that would never hatch, and produce no offspring. Over successive generations, the population would not just decline — it would collapse. He called it the Sterile Insect Technique.
There was just one problem. Nobody knew how to do it.
That's where Raymond C. Bushland came in.
Bushland was a researcher at the USDA's Kerrville, Texas laboratory — a methodical, patient scientist who had spent years studying screwworm biology. Where Knipling was the visionary, Bushland was the engineer. He took the idea and got to work on the impossible part: how do you raise millions of screwworm flies in captivity? How do you sterilize them with radiation without killing them? How do you keep them viable long enough to release them into the field?
The work was painstaking, often disgusting, and frequently discouraging. They were, after all, intentionally breeding one of the most destructive parasites in the Western Hemisphere — by the millions. Bushland spent years perfecting rearing techniques, calibrating radiation doses, testing release methods. The margin for error was razor thin. Too much radiation and the flies died. Too little and they weren't sterile. The flies had to be healthy enough to compete with wild males for the attention of females.
In 1954, they got their first real test. The island of Curaçao, a Dutch territory off the coast of Venezuela, had a small, geographically isolated screwworm population — a perfect contained laboratory. They released sterile males. They watched. They waited.
Within months, the screwworm was gone from Curaçao.
It had never been done before. A pest species — eliminated not with poison, not with fire, not with years of futile chemical warfare — but with science, patience, and a radical idea from a Texas farm kid who refused to accept that the problem couldn't be solved.
The USDA scaled the program up. By 1966, the screwworm had been eradicated from the United States. The eradication line was pushed south through Mexico, then through Central America, until a biological barrier was established at the Darién Gap in Panama — a wall not of stone, but of sterile flies, maintained to this day.
In 1992, Knipling and Bushland were awarded the World Food Prize, the highest honor in food and agriculture. The committee estimated their work had saved the American cattle industry alone more than $20 billion over the decades since eradication.
Two men. One idea that sounded crazy. And a parasite that hadn't counted on being outsmarted.
Now, in 2026, the screwworm has been confirmed in Texas again — crossing up from Mexico, threatening livestock and wildlife across the South. The barrier held for decades. The question now is whether we have the will, the resources, and the memory of what it took to hold it again.
Knipling and Bushland gave us the playbook. They proved it could be done.
The rest is up to us.
