Cooley spruce gall adelgid

Cooley spruce gall adelgids create distinctive cone-shaped galls on spruce new growth, becoming miniature pinecones by late summer; galls range from light green to deep purple and measure one and a half to three inches long. You will see these galls at branch tips and along new shoots from spring into early fall on various spruce species in the Puget Sound. Though rarely harmful to tree health, heavy infestations can disfigure branches by destroying buds and distorting tree form.

No cultural control needed; most trees tolerate galls. Prune heavily galled branches on ornamental specimens if appearance is critical. Natural predators usually keep populations light. Apply horticultural oil during dormancy only if gall disfigurement significantly affects landscape value.