The tree or shrub looks gray, off-color, and lacks new growth. Eventually the needles turn yellow. Branches and possibly the whole plant die back. The foliage is covered with clusters of tiny, yellow-and-white scaly bumps. A shiny, sticky substance, possibly with black sooty mold growing on it, may coat the needles.
Prune out heavily infested branches. Apply an insecticide labeled for this pest, following label directions.