Hemlock woolly adelgid (Adelges tsugae) or HWA is an invasive insect that develops, reproduces and feeds on all species of hemlock trees. Both Carolina hemlock (Tsuga caroliniana) and eastern hemlock (Tsuga canadensis) are vulnerable to infestation and are currently suffering widespread mortality in the eastern United States. Unfortunately, hemlock woolly adelgid was discovered in Kentucky during the spring of 2006.

Hemlock woolly adelgid is an insect species native to Asia that was introduced first in the 1920’s to the Pacific Northwest region of the United States, and introduced again in the early 1950’s to the Washington DC and Richmond, Virginia areas. States such as Virginia, New Jersey and Connecticut have reported devastating mortality rates between 42 and 90 percent of the hemlock species.

Take the limbs of your hemlock tree and turn them over. You are looking for white cotton like masses along the twigs and at the base of the needles. The image in the upper right shows the underside of an infested branch.