Adelgids are small, dark, soft-bodied insects, somewhat pearshaped like aphids.
Identification of species | Life
Adelgids produce white cottony tufts on the bark, branches, twigs, needles, or cones of their host plants.
Cone-shaped galls or swollen twigs may also appear on infested spruce or fir. High populations can cause
yellowing, early drop of needles, drooping and dieback of terminals, and can retard or kill trees. Vigorous
plants tolerate moderate adelgid populations.
Adelgid galls on spruce are usually harmless
and can be ignored unless the trees are young or galls become
very abundant. To restore the plant's aesthetic quality and
provide some control, clip and dispose of
infested foliage when the galls are green and before the
insects have emerged. Avoid excess fertilization and quick-release
formulations, which can promote adelgid populations. Replace
some spruce with other
tree species to reduce adelgid populations that alternate
hosts. Predators may provide some control. A
forceful stream of water directed at the cottony masses on conifers, especially on trunks, dislodges and
kills many adelgids. High populations, especially on young trees, can be controlled by applying narrow-range
oil (but it will discolor spruce foliage) or another broad-spectrum insecticide in the spring when crawlers
Cooley spruce gall adelgid adult
waxy material and stunting of pine needles caused by pine needle adelgid