Hemlocks infested with wooly adelgid (Adelges tsugae) aren't really big news in the world of invasion ecology any more. But then there's this article from the Erie-Times News, describing how the wooly adelgid is teaming up with the elongate hemlock scale (Fiorinia externa) to devastate forests of hemlock (Tsuga canadensis) in the northeastern U.S. The attacks of these two species of sucking insects, combined with recent drought conditions, have led to a strong decline in the number of hemlock trees in the forest. While they have had some luck with biological controls for wooly adelgid, there is as of yet no treatment for elongate hemlock scale.
