Overview info and resource documents for the hemlock woolly adelgid, originally from Asia, which was first discovered in the eastern U.S. in the 1950’s. It has since spread throughout the range of hemlock in the East, and caused extensive mortality of mature hemlock – especially in the Appalachian Mountains.

Hemlock trees in eastern forests are late successional tree species that provide shade for the forest understory. Globally, there are ten hemlock species, with populations located in Asia and eastern and western North America12. Eastern hemlock (Tsuga canadensis) and Carolina hemlock (Tsuga caroliniana) grow in the eastern U.S. These trees have great ecological and cultural value in forests. However, the invasive hemlock woolly adelgid (Adelges tsugae or HWA) is decimating hemlock populations throughout much of the trees’ native range, altering landscapes, and threatening these iconic tree species in both rural and urban areas.

Important dosage information for treating infestations of hemlock woolly adelgid.

Important dosage information when treating for hemlock woolly adelgid.