Galls are produced by insects called Cooley spruce gall adelgids, or woolly aphids.
The galls usually do not cause any serious harm to the tree. However, extremely heavy infestations may cause minor retardation of tree growth and some distortion. In most cases, old galls are covered by new growth the following season and become almost unnoticeable a few years after they form.
Commonly found on the new growth of spruce trees. Appear early in the season as light green cucumber shaped growths. By mid July the growths typically brown and are often mistaken for seed cones.