R-CALF USA Responds to New World Screwworm Case Near U.S.-Mexico Border

September 22, 2025 - BILLINGS, MT - R-CALF USA has issued a statement addressing a recent development in the ongoing battle against the New World Screwworm (NWS), a devastating livestock pest now detected alarmingly close to the United States border. The U.S. Department of Agriculture (USDA) announced that Mexican authorities confirmed a case of NWS in Sabinas Hidalgo, in the state of Nuevo León-less than 70 miles from the U.S.-Mexico border. This follows a previous case, confirmed on July 9, roughly 370 miles from the border, suggesting a troubling northward progression of the pest within Mexico.

The New World Screwworm: A Looming Threat

New World Screwworm is a parasitic fly whose larvae feed on the living tissue of warm-blooded animals, causing severe wounds that can be fatal if left untreated. The pest's historic presence in Mexico has long been a concern for livestock producers on both sides of the border due to its potential to devastate herds and inflict serious economic damage.

According to the USDA's latest update, the recently identified case in Nuevo León involved an 8-month-old cow that had been transported from a region in southern Mexico with ongoing NWS activity to a certified feedlot in the north. This movement of potentially infected livestock highlights the risk of further spread toward the United States.

R-CALF USA's Response and Recommendations

Bill Bullard, CEO of R-CALF USA, released a statement commending USDA's proactive measures to prevent the introduction of NWS into the United States. He specifically recognized Secretary Rollins for a series of actions, including:

• Closing U.S. ports to imports of cattle, bison, and horses from Mexico

• Supporting efforts to halt the pest's spread within Mexico

• Maximizing American preparedness through updated emergency management plans

• Expediting the production of sterile NWS flies to reduce pest populations in Mexico and push the infestation south of Panama

• Backing innovative research to enhance eradication strategies

Bullard emphasized that, given the new evidence linking the northernmost case to cattle moved from the south of Mexico, additional steps are needed. He called on Secretary Rollins and U.S. authorities to urge Mexico to:

• Immediately stop the northward movement of all livestock within Mexico until the pest is eradicated

• Halt any unlawful trafficking of cattle from South America to Mexico

Protecting American Livestock

The statement underscores the gravity of the threat to U.S. livestock. Both cattle and sheep herds are already at historically low levels, as are the number of U.S. cattle and sheep farms and ranches. The introduction of NWS into the United States could have disastrous consequences, further threatening the nation's agricultural sector and food security.

Bullard stressed the necessity for continued vigilance and preventive measures: "We must, as the Secretary is doing, take every precaution to prevent this pest's introduction into the United States."

Looking Ahead: Rebuilding America's Cattle Supply

R-CALF USA expressed encouragement at Secretary Rollins' announcement that the USDA will soon unveil a new plan to help rebuild America's cattle supply. The organization pledged its support for these efforts, recognizing the importance of a robust and resilient livestock industry.

Conclusion

As the New World Screwworm advances toward the U.S. border, livestock producers and government agencies face a renewed challenge. R-CALF USA's statement calls for coordinated, decisive action to safeguard American herds and maintain the strength of the nation's agriculture. The coming weeks will be critical in determining whether the pest can be kept at bay and the integrity of U.S. livestock preserved.