Now surrounded by a healthy herd of longhorn cattle, Dove is anticipating the return of screwworm, the parasitic fly that eats livestock and wildlife alive. Female screwworm flies lay hundreds of eggs in wounds on any warm-blooded animal. Washington has halted cattle imports from Mexico and invested millions in setting up a new sterile fly production plant in Metapa, Mexico. Treatment is low-tech and onerous: vets and ranchers must scrape each worm out of the infested animals by hand before spraying the wounds with an insecticide. In 1973, Dove was a child who could rope cattle for treatment until 2 a.m. and head to school the next morning.