While not particularly injurious to either of its hosts, this aphid can become a nuisance because its white, woolly threads accumulate under heavily infested trees. This insect is commonly called the Hemlock Woolly Aphid even though it is not in the scientific family of true aphids. Its correct name is the Hemlock Woolly Adelgid. Underneath the wax, adelgids resemble tiny, plump aphids without cornicles. The pine bark adelgid is also commonly called an aphid.
Similar adelgids feed on spruce, larch, and other conifers.
Twigs, large branches, and trunks of heavily infested pine trees may become nearly white with wax from pine bark adelgids. though light infestations cause little damage, persistent heavy infestations can seriously weaken a tree and may eventually lead to its death.