Any of various insects that feed and form galls on conifers

Usage examples of adelgid.

You can see patches of dead hemlocks, probably killed by the wooly adelgid, which is infesting so many of our forests.

In the Smokies, over 90 percent of Fraser firs--a noble tree, unique to the southern Appalachian highlands--are sick or dying, from a combination of acid rain and the depredations of a moth called the balsam woolly adelgid.