Pest description and crop damage Aphid-like, with a covering of white, woolly exudate. Cone-like galls are formed at ends of twigs.
See "Spruce" in:
Christmas Tree Plantation Pests
Chemical Control of Nursery Pests
Apply when new growth is unfolding in the spring. Once galls are forming, spraying will not control adelgids.
For more information
Johnson, W.T. and H.H. Lyon (1991), Insects That Feed on Trees and Shrubs, 2nd ed., Cornell University Press (p. 112).