Smaller lantana butterfly
The smaller lantana butterfly, also known as the lantana scrub-hairstreak (Strymon bazochii), was introduced to Hawaii in 1902 to control lantana species. I don’t believe it has been terribly successful in that regard, but it has managed to establish itself in Hawaii. At least it hasn’t turned out to be a deadly scourge like the mongoose and several other species. For that we can be grateful.