The New World Screwworm (NWS), Cochliomyia hominivorax, is a devastating parasite primarily affecting warm-blooded animals, including livestock, wildlife, pets, and, in rare cases, humans.Unlike most maggots that feed on decaying tissue, NWS larvae consume living flesh, burrowing deep into wounds and causing severe damage, secondary infections, and often death if left untreated.Historically, this pest caused significant economic losses to the U.S. livestock industry.
New World Screwworm- Updates and NCDA&CS State Vet's Office Webinar
(Updated: July 10, 2025, 6:42 a.m.)
The United States successfully eradicated the New World Screwworm in 1966 through a cooperative effort led by the U.S. Department of Agriculture (USDA), primarily utilizing the Sterile Insect Technique (SIT).This method involves releasing radiation-sterilized male flies that mate with wild female flies, leading to unfertilized eggs and a subsequent decline in the screwworm population.For decades, a biological barrier maintained by the USDA in Panama prevented the pest's northward migration.However, recent detections of NWS in Mexico, close to the U.S. border, have heightened concerns, prompting renewed vigilance and strategic actions from U.S. agricultural agencies.
Both the USDA and the North Carolina Department of Agriculture & Consumer Services (NCDA&CS) emphasize the critical importance of early detection and reporting to prevent the re-establishment of NWS in the United States. They urge veterinarians, livestock producers, and the public to be vigilant for any signs of screwworm infestation, such as maggots in wounds, irritated animal behavior, head shaking, or a foul odor from wounds.Prompt reporting to state animal health officials or USDA veterinarians is crucial for immediate response and containment efforts, safeguarding animal health and the agricultural economy.If you were not able to join us for the webinar on June 27, you can find a recording of that webinar here. (go.ncsu.edu/nwswebinar)
Here are some reference pages from the USDA and NCDA&CS:
- New World Screwworm - USDA APHIS:
- New World Screwworm - NC Department of Agriculture:
