Merriam-Webster Collegiate Dictionary - woolly adelgid

 noun  Etymology: adelgid ultimately from New Latin Adelges, probably irregular from Greek adelos unseen  Date: 1987 either of two aphids (genus Adelges) with a white woolly coating that have been accidentally introduced into North America:  a. one (A. piceae) native to Europe that is a serious pest of fir trees  b. one (A. tsugae) native to Asia that is a serious pest of hemlocks