New World screwworm has breached the United States border for the first time in six decades, triggering a sweeping federal emergency response. USDA’s Animal and Plant Health Inspection Service confirmed the devastating livestock pest in Zavala County, Texas, on June 3, 2026. The detection sent shockwaves across the American cattle industry, already stretched by record-high beef prices and a historically thin national herd.
Background on New World Screwworm
Furthermore, this pest carries a brutal history. New World screwworm larvae burrow into the living flesh of warm-blooded animals, entering through wounds as small as a tick bite. One female fly lays up to 3,000 eggs during her short lifespan. USDA researchers eradicated the pest from the United States in 1966 using the sterile insect technique. However, cases in Central America surged after 2023, spreading rapidly to Costa Rica, Nicaragua, Honduras, Guatemala, Belize, and El Salvador. In November 2024, Mexican officials confirmed a detection in Chiapas. The pest then marched more than 1,100 miles northward through Mexico to reach South Texas.
Key Details of the New World Screwworm Outbreak
Notably, the first confirmed case involved a three-week-old beef calf near La Pryor, Texas, roughly 50 miles from the Mexico border. A rancher spotted signs of distress and called a veterinarian immediately. Laboratory confirmation arrived on June 3, 2026, and the calf received treatment and survived. Since that initial detection, USDA confirmed additional cases across multiple Texas counties. Cases appeared in Zavala, La Salle, Gillespie, and Edwards counties in Texas, plus an isolated case in Lea County, New Mexico. The Texas Animal Health Commission now places a quarantine across 16 Texas counties, restricting all warm-blooded animal movement out of the infested zone.
Industry Impact of New World Screwworm
Consequently, the cattle industry faces serious economic danger. Texas leads US cattle production, generating $15 billion annually for the state. A full outbreak could inflict $1.8 billion in damage to Texas’ economy alone, according to a USDA estimate. Ground beef already hit a record $6.89 per pound in May 2026. The US beef herd currently sits at its smallest point in 75 years. Moreover, few American producers today carry firsthand experience identifying a screwworm infestation. Nearly 60 years have passed since USDA eradicated the pest, leaving a dangerous knowledge gap at the farm level. Added treatment costs and biosecurity burdens further pressure ranchers already squeezed by drought and high feed prices.
What Comes Next for New World Screwworm Response
Meanwhile, USDA moves aggressively on multiple fronts. The agency deploys sterile fly releases by air and ground across the infested zone. USDA and the Texas Animal Health Commission established a unified incident command to coordinate surveillance and quarantine enforcement. On June 16, USDA announced $105 million in funding across 40 research and response projects through its NWS Grand Challenge. USDA received 226 applications requesting $664 million before selecting 40 awards through competitive review. A new sterile fly production facility at Moore Air Base near Edinburg, Texas, will produce approximately 300 million sterile flies per week once operational in 2027. The Grand Challenge targets improved sterile fly production, novel traps and lures, new therapeutics, and ecological modeling tools to fight New World screwworm nationwide.
Conclusion
Importantly, officials stress the US food supply remains fully safe. Screwworms do not infest meat, fruits, vegetables, or other food sources. USDA urges all producers and veterinarians in affected regions to inspect animals daily. Ranchers must treat wounds immediately with approved insecticides and report any suspicious infestations within 24 hours. Therefore, early detection now determines how fast and how far this outbreak spreads. The United States defeated New World screwworm once before, and federal and state agencies say they will do it again — but time, resources, and producer vigilance will decide the outcome.
Related: New World Screwworm Threatens US Livestock 2026
Originally reported by USDA APHIS / AgWeb / DTN Progressive Farmer. Analysis by the GardenScoop Editorial Team.
