Wyoming ranchers split on opening Mexico border to beef after screwworm outbreak

Wyoming cattle ranchers and agricultural experts say they don’t think the potential return of Mexican cattle to the U.S. will affect the state’s cattle market, but they are divided about whether consumers would see lower beef prices. President Donald Trump’s administration closed the border nearly a year ago after a flesh-eating parasite, the New World screwworm, made its way from Central America to Mexico. The administration has proposed a phased-in approach to reintroduce cattle from Mexico. Trump, who has promised to lower beef prices that have skyrocketed, has said it is part of his plan to meet consumers’ demands.

Mark Eisele, a Cheyenne-area rancher and former president of the National Cattlemen’s Beef Association, said a phased-in approach may be good for consumers because historically, a large share of U.S. beef has come from Mexican cattle. But Dennis Sun, publisher of the Wyoming Livestock Roundup and a Cowboy State Daily columnist, isn’t so sure. “Trump seems to think that more cattle coming in will cheapen the beef at the grocery store,” Sun said. “I’m not sure that it will make much difference.”

New World screwworm is a highly destructive fly, similar in size to a common housefly, that lays its eggs in open wounds. Larvae feed on the flesh of its host—livestock, wildlife, pets and humans—causing the open wounds to grow. The fly was eradicated from the United States in 1966. But a major ongoing outbreak began in Central America in 2023 and has been working its way north ever since. Cases continue to be reported in northern Mexico.

Wyoming Department of Agriculture spokesman Derek Grant told Cowboy State Daily his agency is passively monitoring the news. But Wyoming is so far north that a phased re-opening would not likely lead to any notable increase in cattle numbers for the Cowboy State, nor a risk to Wyoming cattle. “Thankfully, Wyoming is far enough north for it not to be a concern,” Sun said. Eisele agreed, saying a phased re-opening would probably not be of any real consequence to Wyoming. Wyoming cattle ranchers typically don’t get cattle from Mexico, he said, adding that “most of what comes in goes to a Texas feedlot.”

While a phased re-opening could be good news for the cattle industry, which is navigating a record low population, it also presents potential health risks to U.S. cattle. “There are going to be people who are greatly opposed to it,” said Eisele. “If they did find NWS in Arizona or Texas, it would hurt a lot of the transportation to cattle coming out of Texas,” Sun said. “They could quarantine the whole state.” No cases of NWS have been reported in cattle in the U.S. since the 1960s.

One of the strongest defenses against the spread of NWS is the production of sterile flies. Sterile male screwworm flies that mate with fertile females cause the population to decrease until it eventually dies out. The USDA is pumping $750 million into a domestic sterile production facility at Moore Air Force Base near Edinburg, Texas, expected to be fully online by 2027, producing some 300 million sterile flies per week. “If they get this fly facility finished, I think we’re going to be in good shape,” Eisele said.

Sun expressed disappointment at what he sees as Mexico’s lax attitude toward eradicating the pest, saying the United States is doing most of the work to keep the devastating fly at bay. “They just live with it,” Sun said. “They don’t seem to really care.” Eisele agreed, saying the Mexican government has been slow to help Mexican ranchers. “Mexico’s got to get on board,” Sun said.

A phased reopening would do little to curb the nation’s cattle shortage, as less than 4% of the U.S. cattle population historically comes from Mexico. But Sun said the re-opening could help meat packers because they’re having trouble reaching capacity. Before the border closed, U.S. imports of Mexican cattle averaged 1.18 million head annually. As of April 6, there were 1,201 active cases of NWS in Mexico, down from 1,433 cases six days earlier. An isolated case was reported in Nuevo Leon last September about 70 miles from the border, but there have been no cases within 100 miles of the border since. An official announcement about the proposed reintroduction is expected in late April or early May.