There’s news breaking as we prepare to send this issue to press: Mexico confirms case of New World screwworm (NWS) in Nuevo León — which is less than 70 miles from the U.S.-Mexico border.

I don’t think I’ve ever wished so hard for an early cold spell.

USDA made the announcement the last day of summer. Mexico’s National Service of Agro-Alimentary Health, Safety and Quality (SENASICA) confirmed a new case of NWS in Sabinas Hidalgo, located in the state of Nuevo León.

Sabinas Hidalgo is located near the major highway from Monterrey, Nuevo León, to Laredo, Texas. According to the USDA announcement, that highway is one of the most heavily trafficked commercial thoroughfares in the world.

We’ve done it once

USDA declared screwworms to be eradicated in the United States in 1966; however, I remember as a kid years later catching newborn calves to apply fly spray to navels and rear ends and combing out any maggots that might be eating on tissue, dead or alive. It may have been residual management persistence, but I remember it being imperative to make sure newborns were not fly-blown.

It is somewhat reassuring to know we have eradicated screwworm here in the United States before. It was tough, but not defeating. And, if we’ve eradicated it once, we can surely do it again — especially with 60 years of technology advancement.

The worrisome news is knowing how harmful they can be and reading the tone to the USDA announcement.

“Protecting the United States from NWS is non-negotiable and a top priority of the Trump administration,” said Ag Secretary Brooke Rollins. “This is a national security priority.”

That’s expected.

“We have given Mexico every opportunity and every resource necessary to counter NWS since announcing the NWS Bold Plan in June 2025,” she continues. “Nevertheless, American ranchers and families should know that we will not rely on Mexico to defend our industry, our food supply, or our way of life. We are firmly executing our five-pronged plan and will take decisive action to protect our borders, even in the absence of cooperation. Furthermore, we will pursue aggressive measures against anyone who harms American livestock.”

That’s not.

Specific to the case

Though reports are preliminary, it appears the affected animal was an 8-month-old stocker that had been moved to a certified feedlot in Nuevo León from a region in southern Mexico with known active NWS cases. According to USDA, the potential link to animal movement emphasizes the “non-negotiable” need for Mexico to fully implement and comply with the U.S.-Mexico Joint Action Plan for NWS in Mexico.

Since July, USDA alongside Mexico has been monitoring nearly 8,000 traps across the states of Texas, Arizona and New Mexico. More than 13,000 screening samples have been submitted with no NWS flies detected. USDA is analyzing all new information related to the recent case in Nuevo León and assures it will pursue all options to release sterile flies in the region as necessary.