It was pushed out of North America by releasing large amounts of sterile flies, so that they’d mate and die without producing new generations. They pushed the range of the fly down slowly, until they hit Panama.

That is a very narrow strip of land connecting North and South America, allowing for a ‘wall’ of sorts to be made, by continually releasing batches of the sterile flies from sites in the area.

With Covid disruptions, and associated cuts to the department though, they’ve been creeping past the barrier, and there wasn’t a funding increase to push them back down. DOGE accelerated this by firing a bunch of the people involved.