USDA Mobilizes 180 Million Sterile Flies to Counter New World Screwworm Outbreak

Why the USDA Is Deploying Sterile Flies

The U.S. Department of Agriculture has green‑lit the mass release of sterile flies to halt a resurgence of the New World screwworm, a parasitic blowfly whose larvae devour the flesh of livestock. On June 27 the agency inaugurated a 22,000‑sq‑ft production hub in Metapa, Mexico, poised to churn out ↑ 180 million sterile insects over the coming months.

Rising Threat Across Texas

Since the first case surfaced on June 3, 27 confirmed infestations have been logged in two states, with Texas accounting for all active sites. Officials have sealed portions of 20 counties to curb spread, warning that unchecked growth could cost the state hundreds of millions in livestock losses.

“We’ve beaten New World screwworm before—and together, we’ll do it again,” the USDA’s Rapid Response account posted on X.

The sterile‑insect technique (SIT) relies on gamma‑radiated pupae that emerge unable to reproduce. When released by ground and aerial drops, these flies mate with wild counterparts, diluting the gene pool and ultimately collapsing the pest population—a strategy that eradicated the parasite in the 1960s and contained a 2017 Florida flare‑up.

Mexico’s new facility, a joint venture between the current U.S. administration and the Mexican government, is expected to add ↑ 100 million sterile flies to the supply chain once fully operational, bolstering the fight ahead of the peak breeding season. For more on the science behind SIT, see Reuters.