On June 3, a flesh-eating screwworm larva was found in a three-week-old calf near La Pryor, Texas—the first New World screwworm case in the United States since the 1980s. Dozens have followed across Texas and New Mexico, with more than 32 cases by early July.
The return is not bad luck. It is a mastery deliberately let lapse. Screwworm—whose maggots eat living flesh and, untreated, kill the animal—once made ranching in the Southwest nearly unprofitable, killing 1.3 million animals in a single year during the 1930s. It was defeated not by poison but by human reason applied to biology: USDA scientists Edward Knipling and Raymond Bushland realized the females mate only once, and that male flies sterilized by cobalt-60 gamma rays—supported by the Atomic Energy Commission, the peaceful atom at work—could be dropped by the millions to breed the species out of existence. By 1966 the U.S. was free of it; by 2006 the permanent “fly barrier” had been pushed all the way to the Darién Gap. The two men later shared the World Food Prize.
Then the barrier was allowed to rot. Production was cut to the bare minimum, cattle inspections lapsed, the rainforest chokepoint was cleared for grazing, and COVID knocked out inspectors and killed sterile flies in power outages. Around 2023 the screwworm broke through and has marched north ever since, as Brian Potter details at Construction Physics.
Here is the lesson in miniature: a civilization that stops maintaining its infrastructure does not hold its ground—it loses it, and relearns old horrors the hard way. The arrow of progress is not self-sustaining. It must be willfully recreated with every year and every generation.
