The Hemlock Woolly Adelgid is a tiny, sap-sucking insect that primarily affects Eastern Hemlock and Carolina Hemlock trees. Native to Asia, it was first discovered in the United States in the 1950s. The adelgid feeds on the tree's sap, weakening it and often leading to its death. This pest is recognizable by the white, woolly masses it produces on the underside of hemlock branches. The spread of the Hemlock Woolly Adelgid poses a significant threat to hemlock forests, impacting local ecosystems and wildlife that depend on these trees for habitat and food.