About Adelges cooleyi (Gillette, 1907)
Scientific name: Adelges cooleyi (Gillette, 1907)
Identification: Signs of infestation by Adelges cooleyi are most visible on Cooley spruce from spring, between May and June, when galls develop. This infestation is often misidentified as damage caused by worms or grubs, and the galls are sometimes mistaken for reproductive structures of the spruce tree. Spruce pollen is released from smaller structures that do not have needles, which distinguishes these pollen structures from the galls formed by this insect. The galls have a distinct pineapple-like shape, and range in length from 0.5 cm to 8 cm, with size depending on the tree’s growth capacity. Most galls develop pink, red, or deep purple coloration, while the spruce needles on the tree typically stay green. The new bud segments that develop these galls die after the adelgids leave the gall in summer. When Adelges cooleyi infests Douglas fir, the insects feed on the needles of the tree and do not form galls.
