Hemlock Wooly Adelaid

These pests infest Hemlock trees and gradually kill them. Discoloration occurs in the needles of infested trees, transforming them into yellow or green-gray; infestations also cause the needles to fall off and the branches to dry out. Hemlocks die two to ten years after infestation, depending upon the strength of the tree. Wooly adelgids are so small that they tend to be invisible to the naked eye, but infestations can be spotted by the white fluff they leave at the base of the tree's needles.

Shown here is the white fluff that adelgids spread.