Screwworm Returns — Infrastructure Collapse, Not Biological Failure

The screwworm didn't return because eradication failed — it returned because we stopped looking. The USDA has identified 74 cases across Arizona, New Mexico. Texas since June, the first sustained reappearance of a parasitic fly that decimated livestock herds for over a century. But the real story isn't biological failure. It's structural amnesia.

From the 1950s through the 1970s, the screwworm was eliminated through one of agriculture's most elegant interventions: the sterile insect technique. Billions of radiation-sterilized male flies were released across the continent, mating with wild females and producing no offspring. This was active suppression requiring constant input. The mechanism itself contained its own measurement — you knew the system was working because you were constantly working it.

Once declared eradicated in 1966, something shifted. The industry pivoted from active suppression to passive border surveillance. The screwworm still existed in Central and South America, so containment relied on monitoring ports, quarantine protocols. Veterinary detection at the border. This was far cheaper than maintaining breeding facilities and release programs. It was also invisible in a way active suppression was not. When nothing goes wrong for decades, the infrastructure that prevents it becomes indistinguishable from nature.

What we're seeing now isn't the screwworm overcoming eradication. It's the screwworm moving through the gap between the system we stopped and the one we never fully built. Climate change has likely expanded suitable habitat northward. The cases cluster in the warmer months and southern states. But climate shifts slowly. Surveillance infrastructure can collapse overnight, especially when success makes it feel expendable. The foot-and-mouth disease resurgence in livestock followed the same arc: decades of assumed regional control, then the quiet dismantling of the infrastructure that had replaced active suppression, then a sudden reappearance that felt like sudden failure.

The screwworm didn't return because eradication failed—it returned because we stopped looking.

This pattern appears everywhere once you see it. A security system works so well you forget about it. Then you cut the budget because the risk seems gone. Code review catches nothing for months, so you reduce the reviewer count, and the next vulnerability ships. The observation that applies here: systems that succeed in making themselves unnecessary are the first ones to be abandoned. The screwworm's return isn't a rebuke of eradication. It's evidence of what happens when your success becomes so complete that you stop being able to see what you're protecting against.