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New World screwworm (NWS, Cochliomyia hominivorax) is a devastating pest. When NWS fly larvae (maggots) burrow into the flesh of a living animal, they cause serious, often deadly damage. NWS can infest livestock, pets, wildlife, occasionally birds, and in rare cases, people.
While NWS has been eradicated from the United States for decades, recent detections in Mexico as far north as Oaxaca and Veracruz, about 700 miles away from the U.S. border, led to the immediate suspension of live cattle, horse, and bison imports through U.S. ports of entry along the southern border on May 11, 2025. As of October 17, NWS has not been detected in any animals or traps in the United States.
The U.S. Department of Agriculture (USDA) continues to make substantial progress on its sweeping, five-pronged plan to protect the nation’s livestock, wildlife, and agricultural communities from the threat of NWS.
USDA is deploying intensive surveillance and monitoring systems; investing in NWS innovation; and supporting robust response activities in Mexico and Central America. Teams are in place along the U.S. border, deploying over 113 NWS-specific traps and lures across high-risk areas of border states, and leveraging thousands of fruit fly/insect traps aligned all along the Southern border.
USDA has conducted extensive U.S. training efforts and over 50 stakeholder meetings, increasing regional awareness of NWS and enabling more comprehensive suspect case reporting and response. USDA has also shared the NWS Response Playbook, an operational plan with detailed strategies of how USDA will work with States and other partners if we had an NWS detection within the U.S.
In addition, USDA examines all wildlife captured in high-risk counties in Texas for signs of NWS infestation.
Although Mexico continues to confirm new cases of NWS, the overwhelming majority of these remain in the far southern part of the country, with no significant northward expansion over the past several months.
On August 19, USDA and Mexico’s agriculture authority, SENASICA, signed a collaborative NWS Action Plan with detailed actions about trapping, surveillance, and movement protocols that will help stop the spread of the parasite. Southern U.S. ports of entry remain closed to livestock imports as part of ongoing efforts to maintain robust safeguards.
October 17, 2025/ USDA/ United States.
https://www.aphis.usda.gov
