It might sound like something out of a horror movie — millions of flies being dropped from planes over Texas — but this surprising strategy could be the key to stopping a dangerous outbreak already inching toward the U.S.

A flesh-eating parasite called the New World screwworm is spreading rapidly through Central America, threatening cattle, wildlife, and even people. It’s already reached southern Mexico — and the U.S. is scrambling to stop it before it crosses the border.

The solution? Sterile male flies. Lots of them.