US Might Restrict Livestock Imports From Mexico Over Screwworm Concerns: USDA

“We are now at a critical inflection point in this shared campaign against pests. I am very concerned about our collaboration,” the secretary said.

The USDA said on April 27 that it would restrict livestock imports from Mexico if it does not intensify its fight against the threatening pest known as the New World screwworm.

Agriculture Secretary Brooke Rollins wrote to Mexican Secretary of Agriculture, Giulio Antonio Verdeglistan on April 26, warning that the US will “restrict the import of animal goods” if the issue is not resolved by April 30.

“We are currently at a critical inflection point in this shared campaign against pests. I am very concerned about our collaboration,” Rollins wrote.

“The outbreak in southern Mexico continues to expand, and passing daily without the full deployment of sterile insect technology surgery represents a lack of opportunity to contain this pest and prevent it from spreading beyond the isthmus of Tehantepec.”

Screwworms are known to infect livestock, wildlife and, in some rare cases, humans. Screwworms can dig holes into the skin of living animals, causing serious or fatal damage.

According to the USDA, signs and symptoms of invasion include irritating behavior, head shaking and the smell of rot.

In the letter, Rollins said that only one of the companies hired to do air sprays to kill pests and fly six days a week has allowed Mexico to impose “a burdensome tariff” on the parts needed to keep the plane in the air.

Rollins’ letter was sent during a burgeoning trade tension between the US and Mexico after the Trump administration imposed a 25% tariff on its southern neighbours earlier this year for not staving deadly opioid trafficking to the US.

Products covered by the US-Mexico-Canada agreement are exempt from customs duties.

Screwworms are endemic in countries in Cuba, Haiti, the Dominican Republic and South America. In recent years, cases have spread to Costa Rica, Nicaragua, Honduras, Guatemala and today’s Mexico.

Before the discovery of screwworms, Mexico was the largest supplier of cows in the United States. According to the USDA, 24,000 cattle were imported from Mexico in March, and imported from around 114,000 in March 2024.

The agency temporarily blocked shipments of Mexican livestock in November 2024 after the pests were discovered. At the time, the USDA said it was working with Mexico to implement measures to continue the normal flow of exports in the country.

The restrictions were lifted in February after the implementation of “broad discussions between national representatives” and “implementation of comprehensive pre-release testing and treatment protocols to ensure safe movement and mitigate the threat of (screw bugs).

On April 26, Rep. Tony Gonzalez (R-Texas) thanked Rollins in a post on Social Platform X, saying he “continue to fight for the farmers and the ranchers.”

He linked the March 11 announcement, which prompted Congressmen to write bipartisan letters with 43 Congressional colleagues, urging the USDA to “expand eradication and containment efforts related to the New World Screwworm (NWS).”

“Unchecked, outbreaks can cost livestock producers millions of dollars a year, causing harmful economic losses to the national economy,” Gonzalez wrote in a statement.

“We urge USDA to work with stakeholders in state, local and related industry stakeholders to actively address this emerging threat, given the possibility of establishing sterile fly production facilities in Texas or the southwest to address this emerging threat.”

Catabella Roberts contributed to this report.