Flesh-Eating Screwworm Detected In Texas, Threatening Already-Strained U.S. Cattle Herd

Concerns over the New World screwworm (NWS) have been building for the last 12 months as the deadly cattle parasite spread through Mexico and the Trump administration attempted to prevent its spread into the U.S. Those concerns have now turned into red alerts after the USDA confirmed a single case in Texas, marking the first U.S. detection in years.

"A case of NWS may have been detected in South Texas. The sample is now at USDA's National Veterinary Services Laboratories (NVSL) in Ames, lowa for confirmatory testing. We will provide updates the moment results are available," USDA wrote on X.

A case of NWS may have been detected in South Texas. The sample is now at USDA's National Veterinary Services Laboratories (NVSL) in Ames, lowa for confirmatory testing. We will provide updates the moment results are available.

We have already activated personnel on the ground…

— Dept. of Agriculture (@USDA) June 3, 2026

USDA Secretary Brooke Rollins wrote on X that the "confirmed the detection of a New World Screwworm (NWS) fly in a 3-week-old bovine in Zavala County, Texas."

As expected, @USDA_APHIS confirmed the detection of a New World Screwworm (NWS) fly in a 3 week old bovine in Zavala County, Texas. @USDA and Texas Animal Health @TAHC officials are taking immediate action to contain and eradicate NWS from the area.

For more… https://t.co/GJkUJl0XEI

— Secretary Brooke Rollins (@SecRollins) June 4, 2026

USDA states that there is currently no evidence that NWS has become established in the U.S., but the agency is moving quickly with quarantines, movement controls, surveillance within a 12-mile zone of the detection area, and the release of sterile flies to contain any spread.

The detection of NWS in the U.S. would be a direct biological and economic shock to the cattle herd if the spread were rampant, given that the nation’s herd is already at a 75-year low, beef prices are at record highs, and meatpackers are under pressure from fewer and more expensive animals.

If NWS were established in the U.S., this could delay herd rebuilding at the worst possible time. Reuters notes that a spreading outbreak could further hit the herd and expose Texas livestock alone to roughly $1.8 billion in estimated economic losses.

A spread of NWS would be bullish for live cattle futures and beef prices, bearish for meatpackers, such as Tyson Foods, that need cattle heads, and supportive of animal-health names tied to treatments and parasite control.

Perhaps the U.S. importing 60% of its live cattle from third-world Mexico is not the best idea.