Flesh-eating screwworm is spreading in the US, threatening livestock and wildlife – hunters can be the first line of defense

A devastating infestation of the flesh-eating screwworm (Cochliomyia hominivorax) has returned to the United States mainland after a 50-year hiatus. This fly, known for attacking all warm-blooded animals, including deer and elk, threatens livestock and wildlife. As a new infestation spreads, hunters may play a crucial role in spotting and reporting any signs of this destructive parasite.

Experts urge hunters to remain vigilant while in fields and wooded areas, as they could serve as an early warning system for the screwworm. Unlike other blowflies, New World screwworm larvae feed on living tissue, making them particularly hazardous. The larvae lay eggs in open wounds or mucosal openings, which later hatch into destructive maggots that burrow into the animal's flesh, causing infection and eventual death.

Historically, the U.S. eradicated screwworms in the 1950s by treating infected animals and releasing sterilized male flies to disrupt the population's life cycle. This method proved effective and led to the complete eradication of the screwworm from the mainland in 1966.