Recent detection (on June 3, 2026) of New World screwworm in Texas (Zavala County) have renewed attention to a livestock pest that was eradicated from the United States more than 50 years ago. While the current detections are far from New Jersey, they serve as a reminder of the importance of animal health surveillance and routine livestock inspections.

• What is New World Screwworm: New World screwworm (Cochliomyia hominivorax) is a parasitic fly whose larvae (maggots) feed on the living tissue of warm-blooded animals. Unlike common fly maggots that typically feed on dead or decaying tissue, screwworm larvae invade healthy tissue, causing painful and rapidly expanding wounds that can lead to severe animal health problems if left untreated.
• Why Is It in the News: The pest was eradicated from the United States in the 1960s and 1970s through a successful sterile insect release program. However, outbreaks in Central America and Mexico have moved northward in recent years, resulting in recent detections in Texas. Federal and state animal health officials are actively responding to these detections to prevent establishment and further spread.
• Should New Jersey Producers Be Concerned: At this time, there is no reason for alarm in New Jersey. However, livestock owners should be aware of the pest and its symptoms because early detection is critical to successful control efforts.
• Animals at Risk: New World Screwworm can affect cattle, sheep, goats, horses, swine, pets (dogs and cats), and wildlife. Any warm-blooded animal with an open wound can potentially be infested.
• What to Watch For: Producers should monitor animals for wounds that enlarge rapidly, foul-smelling lesions, bloody or pink-tinged discharge, visible maggots in wounds, excessive irritation or rubbing, reduced feed intake, and lethargy or weakness. Pay particular attention to newborn navels, castration sites, dehorning wounds, ear-tagging sites, branding wounds, cuts and abrasions.
• Good Management Practices: The best defense remains good animal husbandry. Inspect livestock regularly, treat wounds promptly, maintain fly-control programs, monitor newborn and recently processed animals closely, and consult a veterinarian if unusual wound development is observed.
• Food Safety: New World screwworm is primarily an animal health concern and does not pose a food safety risk to consumers. Its impact is related to animal welfare, livestock productivity, and economic losses rather than meat safety.
• Stay Informed: Rutgers Cooperative Extension encourages livestock owners to stay informed through USDA Animal and Plant Health Inspection Service (APHIS), the New Jersey Department of Agriculture, and their local veterinarian. While the current risk to New Jersey remains low, awareness and early recognition are important components of protecting animal health.

References

• Texas Animal Health Commission. (2026, June 3). New World screwworm confirmed in Zavala County calf: First case of NWS in Texas [News release]. (https://www.tahc.texas.gov/news/2026/2026-06-03_NWS_InitialCase.pdf?utm_source=chatgpt.com)
• Kaufman, P., Swiger, S. L., & Herring, A. (2026). New World screwworm fact sheet. (https://agrilifeextension.tamu.edu/new-world-screwworm-fact-sheet/)
• Kansas State University Agricultural Experiment Station and Cooperative Extension Service. (2025, June). New World screwworms: Fact sheet for producers. Kansas State University. (https://entomology.k-state.edu/extension/human-and-animal-health/New%20World%20Screwworms_June2025.pdf)
• California Department of Food and Agriculture. (2025, June). New World screwworm fact sheet. California Department of Food and Agriculture. (https://www.cdfa.ca.gov/ahfss/animal_health/pdfs/screwworm_fact_sheet.pdf)