How to Manage Pests
Pests in Gardens and Landscapes
Pest identification and confirmation—Adelgids
There are about 14 adelgid species in the U.S. in two genera, Pineus and Adelges.
Pine bark adelgids
White material on pine
Most pine bark adelgids form harmless but sometimes unsightly galls on spruce. Their alternate
hosts are pine, or pine and spruce. Adult females are purplish black, soft-bodied insects. Females
and yellowish pink masses of eggs occur in cottony, wax-covered colonies on pine. Crawlers resemble
tiny pepper grains on the cottony egg masses. The adelgids overwinter as eggs and have several
generations a year.
Damage to Douglas fir
Cooley spruce gall adelgid
The Cooley spruce gall adelgid alternates generations between spruce and Douglas fir. Their life
cycle is completed in two years. Nymphs on spruce overwinter under bark or buds and move to the
base of needles in the spring and suck plant juices. This initiates the formation of a light green
to purple gall. About midsummer the nymphs emerge from the galls and molt into winged adults.
The adults feed and reproduce on spruce or migrate to Douglas fir. They give birth to wingless
nymphs. This generation overwinters on Douglas fir. Some of these adelgids develop wings and migrate
back to spruce. There the migrants produce males and females that mate, and the females lay eggs.