For the first time in a year, the U.S.-Mexico border partly reopened to cattle imports following a screwworm infestation across the region. The battle against the flesh-eating fly has only just begun deep in Mexico.

Mexican officials have been racing to combat the first major screwworm infestation in decades, one that has already disrupted a strained cattle industry in both Mexico and the United States. In the town of Metapa, which sits along the Mexican border with Guatemala, a newly refurbished plant has become Mexico's main solution to the parasite that has already resulted in more than 34,000 cumulative cases in all but two of Mexico's 32 states since the first incidence was detected in November 2024. The outbreak is estimated to cost billions of dollars combined in losses and the measures to fight it. The site, inaugurated in late June, is the only such plant in Mexico that produces sterile flies, a process that involves breeding enormous quantities of flies, sterilizing them by exposing them to radiation and then releasing them into the wild. Wild female flies then mate with the sterile male insects and slowly reduce the population size. The goal is to produce 100 million sterile flies a week by November so that the insects can be distributed, starting with Texas and northern Mexico on down, and contain the outbreak.

President Claudia Sheinbaum of Mexico, who originally opposed the border closing and attended the Metapa plant's inauguration, said officials cannot say for sure how long the eradication will take but noted that the plant will help contain the spread. "It was eradicated once before and that is why experts say we can eradicate it a second time," she said. Experts have estimated that eradication could take up to 20 years.