The New World Screwworm (NWS) fly, Cochliomyia homnivorax, was eradicated from the United States in 1966. Prior to eradication, it cost the U.S. livestock industry more than $100 million annually.

In 2023, increased cases of Screwworm infestation were noted in Central America and began advancing north. In February 2025, the first cases were identified in southern Mexico and more cases have been identified further north, creating a concern to the U.S., especially with border states such as Texas and New Mexico. Unfortunately, with the increase in international travel, this pest can hitch a ride and travel into the U.S. and become established before it can be stopped.

On May 13, 2025, Secretary of Agriculture Brooke Rollins announced that the border was closed for cattle, bison and horses coming out of Mexico due to the NWS threat. Sheep and goat imports into the U.S. were already restricted due to Scrapie disease.

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