USDA Criticizes Mexico’s Handling of Screwworm Outbreak

Web Editor

September 25, 2025

a cow and a calf are standing next to each other in a field of grass and trees, with a green marker

Background on the Issue

The screwworm, a devastating livestock pest from the Old World, has been spreading in Mexico and is now a threat to cross into the United States. The US Department of Agriculture (USDA) Secretary, Brooke Rollins, has expressed concerns over Mexico’s efforts to control the screwworm outbreak.

USDA’s Concerns and Mexico’s Response

On Thursday, Brooke Rollins criticized Mexico for not implementing proper protocols to curb the screwworm’s spread. The recent detection of screwworms less than 113 kilometers from the US border is attributed to Mexico’s failure to restrict cattle movements and set up fly traps to reduce the wild screwworm population, which can infest and kill cattle.

The screwworm has not yet crossed into the US, but it poses a significant risk to the American meat industry. Since May, the US has virtually closed its border to Mexican cattle imports.

This outbreak has heightened tensions between the two countries, especially as they prepare for a review of the US-Mexico-Canada Agreement (T-MEC) and as their agricultural sectors face uncertainty.

On September 21, the USDA learned of a case in Nuevo León, which borders Texas. In response, the USDA quickly dispatched personnel to the region, according to Rollins during the Ag Outlook Forum in Kansas City, Missouri.

“Unfortunately, what we found is that Mexico has not applied appropriate cattle movement controls in infected regions and has not been setting up daily flying traps as promised, which hinders our real-time detection capabilities. This is unacceptable,” Rollins stated.

She added that reopening the border for cattle trade depends on full compliance with agreed-upon surveillance protocols.

Mexico’s Agriculture Secretary’s spokesperson and Mexico City Mayor Claudia Sheinbaum did not immediately respond to requests for comment.

Sheinbaum mentioned on Wednesday that Mexico had not been notified by the USDA of any changes regarding the border reopening before November and that controlling cattle movement within Mexico is complex.

The US has invested $21 million in a facility in southern Mexico to produce sterile flies for release, aiming to reduce wild screwworm populations.

Key Questions and Answers

  • What is the screwworm? The screwworm is a livestock pest from the Old World that can devastate cattle populations by infesting and killing them.
  • Why is the screwworm outbreak a concern? The outbreak poses a significant risk to the US meat industry and has led to the virtual closure of the US-Mexico border for cattle imports.
  • What are the USDA’s concerns regarding Mexico’s handling of the outbreak? The USDA criticizes Mexico for not implementing proper cattle movement controls and setting up fly traps as promised, which hinders real-time detection capabilities.
  • What is Mexico’s response to the USDA’s criticism? Mexico’s Agriculture Secretary and Mayor Claudia Sheinbaum have not directly addressed the USDA’s concerns, stating that controlling cattle movement within Mexico is complex and they were not notified of any changes regarding the border reopening.
  • What measures is the US taking to combat the screwworm? The US has invested $21 million in a facility in southern Mexico to produce sterile flies for release, aiming to reduce wild screwworm populations.