The hemlock woolly adelgid (Adelges tsugae) is a sap-sucking insect originally from Asia and a major pest of eastern hemlock (Tsuga canadensis) and Carolina hemlock (Tsuga caroliniana) in eastern North America. Its is recognizable for its distinctive white, waxy wool coating. Here, woolly adults as well as dark-colored, uncoated nymphs, are visible. (Photo credit: Bruce Watt, University of Maine, Bugwood.org)