Mexican flesh-eating worm causing shortage in U.S. beef supply

Juan Manuel Fleischer, whose family has managed ranches in the borderlands long before the United States existed, has seen his Arizona-based cattle import business face unprecedented disruption. For decades, his operation, which brings Mexican cattle across the border, has weathered political disputes and the construction of the massive border wall. But now a renewed threat is rattling both U.S.-Mexico trade and the American beef market: the New World screwworm, a parasitic fly larva that feeds on living flesh, has resurfaced in Mexico more than sixty years after being largely eliminated in the U.S.

Normally, around 1.2 million young Mexican cattle are imported annually through several border ports to be raised in U.S. pastures or feedlots. However, most crossings have been suspended since November, when a cow in southern Mexico tested positive for the parasite. The screwworm larvae burrow into animals flesh, causing painful wounds and potentially fatal weight loss. As more cases appear further north, including one in September just 70 miles from the border, Mexican cattle imports have dropped to roughly 230,000 in 2025.

Were hurting, Fleischer said. Were basically going broke. The closure comes at a time when the U.S. cattle herd is shrinking and beef prices are near record highs. Officials from both the Biden and Trump administrations have agreed on the urgency of preventing the parasite from spreading. Agriculture Secretary Brooke Rollins described it as a national security priority.

The shutdown has disrupted long-standing cross-border relationships and caused financial strain for Texas cattle feeders, New Mexico importers, and Arizona ranchers. Jorge Maldonado, mayor of Nogales, Arizona, emphasized the impact on his community. With livestock pens empty, the city has seen a significant drop in tourism revenue and struggling local businesses. Maldonado himself sold cattle at much lower prices than usual, and smaller operations across the border in Sonora are similarly affected.

Fleischer recalls that in a good year, he would bring in 80,000 cattle from Mexico, sorting them by size as they passed through the border. When I heard about the closure, I said, Oh, my god, its going to kill us. This will break us, he said. Now, he relies on savings while his family takes on substitute teaching jobs.

The New World screwworm was once a devastating problem in early 20th-century U.S. ranching, killing thousands of deer and costing millions of dollars. It was eradicated in the 1960s by releasing sterile flies, although occasional outbreaks have occurred since then in livestock and endangered wildlife. While experts do not expect it to wipe out U.S. cattle, the costs of controlling an outbreak could be massive. USDA estimates suggest a potential $1.8 billion economic impact in Texas alone.

Hunter Ihrman, spokesperson for the National Cattlemens Beef Association, supports the border closure but urges faster development of an $8.5 million sterile fly production facility in Texas. Mexican President Claudia Sheinbaum has pushed for reopening the border, yet USDA officials remain cautious, indicating the closure may continue at least through the end of the year.

The blockade also affects cattle producers like Mark Rogers in Dimmitt, Texas. Once relying heavily on Mexican cattle, his herd has been reduced and workforce cut. Ive laid in bed at night thinking, What the heck? he said, hoping the border will eventually reopen.

Texas Agriculture Commissioner Sid Miller notes that 15% of the states feeder cattle come from Mexico and has suggested trial openings, but federal authorities have rejected these proposals. Some industry members acknowledge the need for caution, yet the economic toll is undeniable. Alvaro Bustillos, head of Vaquero Trading in El Paso, saw his $400 million annual business come to a halt, emphasizing the deep cross-border connections of the trade.

At the Santa Teresa port in New Mexico, normally a bustling hub for 500,000 livestock yearly, pens remain empty and half of the staff laid off. Truckers and businesses reliant on cattle imports are also struggling. There are people selling homes, people selling semis. Its created such a disaster for so many people, said Daniel Manzanares, director of the livestock crossing, reflecting the bleak outlook amid this ongoing crisis.

Author: Olivia Parker