US and Mexico Expand Sterile Fly Program to Fight New World Screwworm

State and federal officials in Iowa say the historic sterile‑fly technique that eradicated the New World screwworm from the United States in the mid‑20th century will again be key to stopping the pest. Secretary of Agriculture Mike Naig noted that while the fly is still confined to parts of Texas, New Mexico and Mexico, the strategy of releasing sterilized male flies—so that females, which mate only once, produce no offspring—remains the foundation of the response. He highlighted the need to boost production capacity and to keep infested animals under strict movement controls.

The U.S. Department of Agriculture has opened a renovated facility in Metapa, Mexico, investing about $21 million to produce millions of sterile flies. USDA Agriculture Secretary Brooke Rollins said the site is expected to begin outputting 30 million sterile flies by mid‑July, adding, “The more sterile flies we produce and deploy, the faster we can suppress and ultimately eradicate this devastating pest.” Since the first U.S. case was confirmed in a calf on June 3, the count has risen to 16, prompting concerns that a full‑scale outbreak could cost Texas livestock producers up to $1.8 billion annually.