By sucking sap from the young twigs, the insect retards or prevents tree growth causing needles to discolor from deep green to grayish green, and to drop prematurely. The loss of new shoots and needles seriously impairs tree health. Defoliation and tree death can occur within several years. Egg masses produced by overwintering adults. Discolored foliage and twig dieback caused by feeding nymphs.
Hemlock stand heavily damaged by hemlock woolly adelgid.