US Set to Release Billions of Flies to Fight Flesh-Eating Parasite

The United States is preparing to release billions of sterilized flies over southern Texas and northern Mexico in an urgent effort to control the spread of a deadly flesh-eating parasite that threatens livestock, wildlife, and even humans.

This large-scale biological program, led by the US Department of Agriculture, targets the New World screwworm, a parasitic larva that invades the tissue of warm-blooded animals, causing severe infections and, in many cases, death.

The government’s strategy involves breeding male flies, sterilizing them using radiation, and releasing them into affected areas by aircraft. Once in the wild, the sterile males mate with native females, resulting in infertile eggs and a dramatic reduction in the screwworm population over time.

Experts say this technique is highly effective and environmentally safe, avoiding the widespread use of chemical insecticides.

It has been successfully used in the past, helping to eradicate the screwworm from the United States and other countries north of Panama. A dedicated sterile fly production facility in Panama has supplied flies to contain outbreaks for decades.

However, the reappearance of the parasite in southern Mexico late last year prompted new action. In November, the United States temporarily halted Mexican livestock imports after detecting the parasite but resumed shipments in February under stricter inspection protocols.

Despite these measures, the parasite has continued advancing northward, raising alarms among US agricultural authorities.

The screwworm, scientifically named Cochliomyia hominivorax, poses a severe threat to livestock industries. It can also affect wild animals and humans, burrowing into skin and causing life-threatening damage.

With the current outbreak, the USDA is accelerating fly distribution to prevent a repeat of past infestations, which once took decades and billions of dollars to overcome.