USDA to Release 180 Million Sterile Flies to Fight Outbreak

USDA sterile – The USDA has inaugurated a 22,000-square-foot sterile fly production plant in Metapa, Mexico, as new New World screwworm cases spread in the U.S. after decades without outbreaks. The facility aims to support a sterile insect technique that relies on gamma-ster

On June 27, the USDA opened a 22,000-square-foot sterile fly production plant in Metapa, Mexico—an unusually industrial answer to a problem that is both violent and fast-moving.

The agency is preparing to release sterile flies to combat the New World screwworm, a parasitic fly whose maggots can eat the flesh of warm-blooded animals. The timing matters. Even though the New World screwworm was believed eradicated in the 1960s, cases have returned in the United States.

At the center of the operation is a sterile insect technique, or SIT, designed to break the pest’s ability to reproduce. The USDA says the process uses gamma radiation to sterilize New World screwworm pupae before releasing the sterile insects into environments where the flies are already present.

The USDA says the Metapa facility has been under construction for 11 months, built through collaboration between the current administration and the Mexican government. As the plant opened, the outbreak in the U.S. had already moved from a single report to a growing count.

The USDA says the first animal case was reported on June 3, 2026, then rose to 27 cases by June 29 across two states. The infected animals have been identified as domestic, with no active cases reported in the wild. Texas is currently the only state with active cases, and authorities are quarantining parts of 20 counties.

Lawmakers in Texas estimate an outbreak could cost hundreds of millions of dollars to the state’s constituents. Local officials, though, say they need more than what is currently available. While Texas has sterile flies, the new flow from Mexico is expected to help affected regions.

The USDA estimates the plant will provide an additional 100 million sterile flies once it’s fully operational. In total, the effort is aimed at releasing 180 million sterile flies as part of the broader response.

In a post from the USDA’s New World screwworm Rapid Response official X account, the agency described the approach this way: “Released through ground and aerial operations, these sterile flies disrupt the pest’s life cycle and support our multi‑agency effort to protect livestock.”

That disruption is the goal. With sterile flies in the population, the screwworms can no longer cause harm to animals—because it’s the maggots that feed on flesh. Over time, the fly population is expected to die out as wild screwworms mate with sterile flies.

The method isn’t new. The USDA says the technique is the same one used in the 1960s to eradicate the parasite, and it was also used in a 2017 outbreak in Florida.

“The more sterile flies we produce and deploy, the faster we can suppress and ultimately eradicate this devastating pest,” the Rapid Response account said in the facility’s announcement.

For Texas, and for any livestock operation watching the quarantine lines tighten, the message is simple: speed and scale. “The new facility in Mexico is set to help deliver more flies to the affected regions. ” the USDA said. and its Rapid Response account added. “we’ve beaten New World screwworm before—and together. we’ll do it again.”.

USDA sterile flies New World screwworm sterile insect technique SIT gamma radiation Metapa Mexico Texas quarantine livestock protection USDA New World screwworm Rapid Response