Hemlock woolly adelgids (Adelges tsugae) on a hemlock branch. The actual insects (black dots) are tiny but infestation is easily recognized by the cotton-like egg sacs they produce at the base of the needles on the branches of infested trees. Unfortunately, infestation will eventually kill the tree within 3-6 years here in the Southern Appalachians, leading to the loss of hemlocks all over the area.