Notice the clear drop on the left side of this picture. Ants, bees, and wasps collect honeydew for food. Black and brown fungi, appropriately called sooty molds, cover leaves and other objects below aphid colonies where honeydew collects. Sooty mold problems can be prevented by controlling the resident aphids. A variety of insecticides are registered for aphid control.
Some aphids produce a protective coat of white waxy filaments.
Woolly alder aphids feed and reproduce on silver maple in spring and early summer, then produce winged forms which migrate to alder to start new colonies. 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.