Pest description and crop damage White, cottony masses on bark of trunk, branches, or twigs.
See "Pine" in:
Christmas Tree Plantation Pests
Chemical Control of Nursery Pests
Spray in early spring at or near bud break. Thorough coverage is necessary. Difficult to control with anything other than high-pressure spray equipment.
For more information
Johnson, W.T. and H.H. Lyon (1991), Insects That Feed on Trees and Shrubs, 2nd ed., Cornell University Press (p. 76).