Fireweed control moth
The fireweed control moth (Secusio extensa) was deliberately introduced from Madagascar in 2012 because its larvae feed on fireweed. Unlike many other introductions, the moth was first confined to a study area to make sure it would not wreak havoc on native species. Having passed that test, it was released into the wild.
I’m not sure how much impact the moth is having on the fireweed, but I think it’s a pretty and quite striking moth.