The US government is ramping up efforts to combat the flesh-eating larvae of the new world screwworm fly, a pest that poses a severe threat to the American beef industry, wildlife, and even pets. The strategy involves breeding billions of sterile male flies, irradiated to prevent reproduction, and releasing them over Mexico and southern Texas. These sterile males mate with wild females, resulting in unfertilized eggs that fail to hatch, gradually eradicating the pest population. This method, proven effective and environmentally friendly, was successfully used from the 1960s to 1970s to eliminate the screwworm fly from the US and parts of Mexico.

The USDA plans to establish new fly breeding and distribution facilities in southern Mexico and Texas by 2026 to respond to the pest’s recent resurgence. The sterile fly program requires large-scale production, with the goal of breeding hundreds of millions of flies weekly. While the flies are relatively easy to raise, ensuring proper conditions for egg-laying and larval nutrition is critical. The approach avoids harmful pesticides and leverages the biological trait that female screwworm flies mate only once, making sterile males highly effective in controlling populations. Officials emphasize maintaining readiness to prevent future outbreaks, as the pest can quickly reemerge and cause devastating losses.