Chris Womack is one of a dwindling number of Texas ranchers who can remember fighting the New World screwworm, a once-vanquished pest threatening to make an unwanted encore in the US after its recent return to northern Mexico.
“You never forget the smell,” Womack, 60, said of his first encounter with a calf being devoured by screwworm maggots. It was one of many he and his father would treat in the early 1970s as an outbreak of the parasite — which can kill cattle in less than two weeks — devastated Texas ranchers.
More than 50 years later, Womack and ...