The New World Screwworm outbreak has arrived on American soil, threatening the U.S. cattle industry for the first time in more than six decades. On June 3, 2026, USDA’s Animal and Plant Health Inspection Service confirmed a detection in a three-week-old calf in Zavala County, Texas. The confirmation sent shockwaves through livestock markets and triggered an immediate federal emergency response.
Background on the New World Screwworm Outbreak
Furthermore, this pest carries a dark history on American farms. USDA successfully eradicated New World Screwworm from the United States in the 1960s using the sterile insect technique. The current outbreak advanced north through Central America in 2023, reached Mexico in November 2024, and crossed the U.S. border in June 2026. The fly threatens the $113 billion U.S. cattle industry for the first time in more than a half century. Texas alone holds $17 billion worth of the nation’s cattle, making it the industry’s top state.
However, the pest did not arrive without warning. The deadly flies appeared in Mexico’s southern Chiapas state in late 2024, triggering urgent cross-border response efforts. Central American countries and Mexico reported more than 185,000 NWS animal cases and 2,175 cases in people before the pest reached U.S. borders. USDA deployed surveillance systems and sterile fly releases along the Texas border for months ahead of this confirmed detection.
Key Details of the New World Screwworm Outbreak
In addition, the case count has climbed rapidly since the first detection. USDA data now show 16 domestically acquired animal cases of New World Screwworm across the United States. Cases spread across multiple Texas counties — including Zavala, La Salle, Gillespie, and Edwards — and reached Lea County, New Mexico. The affected species include cattle, goats, and at least one pet dog, demonstrating the pest’s wide host range.
As a result, livestock markets reacted sharply to the news. Live cattle contracts closed $1 to $2 lower immediately following the first confirmation. Feeder cattle contracts fell even harder, dropping $4 to $5 lower on the same session. Canada temporarily restricted livestock imports originating from Texas following the confirmed detections. These market disruptions compounded an already strained cattle sector facing record prices and historically tight supplies.
Industry Impact of the New World Screwworm Outbreak
Meanwhile, industry experts warn of serious economic consequences if the pest spreads unchecked. NWS larvae burrow into the flesh of living animals, causing severe damage to livestock and significant economic losses. Standard cattle practices — including branding, castration, dehorning, and calving — create exactly the kind of wounds that attract egg-laying females. Even wounds as small as a tick bite can put cattle at risk of infestation.
Therefore, the financial stakes extend well beyond individual operations. Lower cattle supplies paired with strong consumer demand have already produced record cattle and beef prices in 2026. Added NWS costs arrive precisely when producers need capital most. If a mass livestock selloff materializes, experts warn it would prolong tight cattle supplies and become a massive barrier to rebuilding the national herd over the next several years.
Consequently, the beef supply chain faces longer-term uncertainty. A leading veterinary parasitologist cautioned that the first Texas detection almost certainly understates the full threat. Ramping sterile-fly production facilities to full capacity could take 18 months to two years. Americans should expect this fight to stretch across multiple years, requiring sustained investment and vigilance from producers and federal agencies alike.
What Comes Next for the New World Screwworm Outbreak
Notably, USDA launched an aggressive, multi-agency response immediately after confirmation. USDA’s strike team deploys sterile fly dispersal by air, vehicle, and ground release chambers across South Texas. Since February 2026, more than 129 million sterile NWS flies have been released in the sterile fly release zone. Production targets aim to approach approximately 500 million sterile flies per week — matching the scale used to eradicate the pest decades ago.
Importantly, USDA also committed major funding to win the long-term battle. The agency announced up to $100 million through the NWS Grand Challenge to support innovative sterile fly production and response strategies. An additional $750 million supports construction of a new sterile fly facility in South Texas. USDA established a dedicated New World Screwworm Directorate within APHIS to coordinate the full federal response.
Moreover, FDA authorized emergency-use drugs to treat infested animals. The FDA issued an Emergency Use Authorization for generic Nitenpyram Tablets, making it the first generic drug authorized to treat New World Screwworm myiasis in dogs and cats. Three animal drug products now hold conditional approval or emergency authorization for treatment and prevention in cattle. Producers should contact their veterinarians immediately if they spot suspicious wounds, drainage, or larvae on any animal.
Conclusion
Furthermore, the path forward demands vigilance at every level of the supply chain. Ranchers must inspect animals daily, treat all wounds promptly with approved insecticides, and report any suspected case immediately to state animal health officials. The U.S. food supply remains safe — screwworms do not infest meat, fruits, or vegetables, and USDA inspection systems protect the commercial food chain.
Ultimately, the New World Screwworm outbreak tests the resilience of American agriculture at a critical moment. USDA defeated this pest once before, and federal officials express strong confidence in doing so again. However, producers, veterinarians, state agencies, and federal partners must work in tight coordination to stop its spread before it gains a permanent foothold across the southern United States.
Related: Senate Farm Bill 2026 Advances With New Draft
Originally reported by USDA Animal and Plant Health Inspection Service (APHIS). Analysis by the GardenScoop Editorial Team.
