Adelgids are aphid-like insects in the genus Adelges (family adelgidae) that feed mainly on conifers.
Conifers are trees and shrubs that bear cones such as Pine, Spruce, Hemlock, Douglas Fir, True Fir, and many other valuable landscape and forest species.
Like aphids, adelgids feed by tapping into their host plants and withdrawing plant sap.
Infestations can cause branch dieback, growth deformation and in severe outbreaks even death of the host plant. Entire forests can be killed by certain adelgids such as the hemlock woolly adelgid.