Gall Adelgid

Gall adelgid refers to adelgid species that produce galls in spruce trees, conifer species. Such galls can be produced by an infection by Adelges cooleyi (Adelges is the genus, and Adelgidae is the subfamily), a species of aphid-like woolly adelgids (order Homoptera). These infect the new buds of native spruce trees (Cooley Spruce gall adelgid) in the foothills of the Rocky Mountains in the spring. They also attack blue spruce to a lesser degree. The parasite completes two generations within the year. The parasite requires two different trees for its life cycle, the second being the Rocky Mountain Douglas-fir. They may also attack Sitka, Engelmann, or white spruce. There are many different species of adelgids that produce different galls on different spruce species.