New World screwworm Texas detections now total six confirmed cases in less than two weeks, sending shockwaves through the U.S. livestock industry. USDA confirmed the first case on June 3, 2026, in Zavala County — the pest’s first appearance on American soil in 60 years. Federal and state agencies immediately activated emergency response protocols. Ranchers across South Texas now face serious biosecurity threats to their herds.
Background on New World Screwworm Texas
Furthermore, this parasite carries a dark history in American agriculture. New World screwworm eradication workers cleared the pest from the United States in 1966 using the sterile insect technique. Since 2023, the fly has marched northward through Central America and Mexico, infesting livestock, pets, and wildlife. By November 2024, USDA confirmed the pest in southern Mexico, just miles from the U.S. border. Models consistently predicted an American arrival — and now that moment has arrived.
Key Details
However, the outbreak escalated with alarming speed after that first detection. USDA’s National Veterinary Services Laboratories confirmed a sixth case — a calf in La Salle County, Texas — on June 9, 2026. Cases span Edwards, Gillespie, La Salle, and Zavala counties in Texas, plus a dog linked to recent travel in Mexico. Texas Governor Greg Abbott issued a disaster proclamation and the Texas Animal Health Commission established quarantine zones. Ten Texas counties now fall inside the infested zone, with strict movement controls on all warm-blooded animals.
Industry Impact of New World Screwworm Texas Outbreak
In addition, cattle markets felt the shock immediately. Feeder cattle futures surged the daily trading limit after traders processed the confirmed detection. The larvae burrow into living animal tissue, causing severe wounds, suffering, and significant economic losses. Left untreated, an infested animal can die within one week. Cattle feeders, ranchers, and companion animal owners across South Texas scrambled to inspect their animals and secure treatment supplies from state health officials.
What Comes Next
As a result, USDA launched its most aggressive domestic eradication campaign in decades. Sterile fly dispersal began June 4, releasing 2 million sterile screwworms twice weekly by aircraft. USDA activated its sterile fly facility at Moore Air Base in Edinburg, Texas, adding aerial flights directly from the base. Ground release chambers numbering 24 deploy an additional 4 million sterile flies per week inside the detection zone. USDA Secretary Brooke Rollins told the House Agriculture Committee the agency treats this situation “with the utmost seriousness.”
Meanwhile, treatment supplies moved quickly to affected producers. The National Veterinary Stockpile relocated New World screwworm treatment supplies to Texas. The Texas Animal Health Commission now distributes these supplies directly to producers in infested zones. FDA emergency use authorizations cover several treatment options for livestock and companion animals. Producers must contact their state animal health official or local veterinarian immediately upon suspecting any infestation.
Conclusion
Consequently, every livestock producer in the southern United States must heighten biosecurity vigilance right now. USDA officials stress the food supply remains fully safe — screwworms do not infest meat, fruits, or vegetables. Therefore, producers should inspect animals daily for draining wounds, unusual discomfort, or larvae near body openings. Early reporting and fast treatment remain the two most critical tools available. Ranchers should visit Screwworm.gov for the latest confirmed case locations, movement control guidance, and eradication updates as this outbreak continues to evolve.
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Originally reported by USDA APHIS. Analysis by the GardenScoop Editorial Team.
