Living in central Massachusetts, I remember the gypsy moth explosion back in the early 80s. It was truly disgusting. You couldn't walk outside without stepping on them, they hung by silk threads from trees so bicycling was–let's just say–interesting, they could cover sides of houses and many people actually entered therapy to deal with the incessant chewing they could hear at night.
There were dire warnings that this would be repeated every umpty-something years, but since then I've heard little about them, and the boom/bust cycle thankfully never seemed to materialize. I think they used B-t bacteria against them, though I guess they're still around as a pest.
How practical would it be to slowly advance this pheromone barrier towards the northeast, surround them and completely eradicate them?