Typical aphid species in Alaska are greenish in color, however many aphid species occur in Alaska or have been brought in with trees and shrubs by the nursery industry that are yellow, black, reddish, or tan. One common group, woolly aphids, produces an abundance of flossy, waxy threads that cover their bodies. Figure 1 . Damage Aphids feed on plants by sucking plant sap from the leaves, twigs or stems. When abundant, aphids remove large quantities of sap, reducing plant growth and vigor.
Aphids feeding on developing leaves also can produce leaf curl injuries.
This is most frequently observed on birch, mayday, lilacs, honeysuckle, crabapple and roses. Most aphids excrete large quantities of a sweet, sticky substance called honeydew. At times, excessive honeydew dropping from trees can be an extreme nuisance. Also, sooty mold fungus may grow on the honeydew, producing a black, unattractive covering of the leaves. Sooty mold is not damaging to the trees except when it covers leaves and temporarily reduces photosynthesis.