Look for hemlock woolly adelgids on the underside of the lower branches of your hemlocks. Adelgids secrete masses of white, fluffy protective wax that make them easy to spot. The vulnerable stage of the woolly adelgid is the crawler stage.
Crawlers are small, brown, and oval and hatch in early spring.
They migrate to the new growth where they may be found at the base of the needles. Tap infested branches over a white piece of paper to determine if crawlers are present. Wait to treat hemlocks until the crawlers have hatched and spray them thoroughly with horticultural oil. Don't fertilize hemlocks with woolly adelgids since extra nitrogen increases the adelgid's rate of reproduction. Monitor your oak trees for tan, cottony egg masses of the gypsy moth.