The USDA and its partners maintain an invisible but permanent sterile fly barrier at the Darien Gap. What this means is that every week, airplanes fly over the Darien Gap, dropping sterile males by the millions to keep screwworms out of North and Central America.
The permanent sterile fly barrier just underscores the mind-boggling work it takes to not just eradicate an insect from a country, but to keep it away forever.
Increased trade with Cuba might have brought the little buggers back.
If the U.S. continues to open up trade and travel with Cuba, the screwworm is likely to cross those few hundred miles of ocean again. The best thing to do, says Hendrichs, is partner with Cubans to eradicate screwworms in their country, too. Screwworms don’t care about international relations, but they’ll exploit any holes in it to survive.