Some feed on the undersides of leaves, causing stunting, curls, and folds in the leaves. Trees with poor vigor or with branch and crown dieback should be examined closely for aphids. Typical soft-bodied aphid on pine. Sooty mold and ants frequenting a tree are good indicators of an active or recent aphid attack. Eggs hatch and live births usually occur in the spring, and nymphs begin feeding on selected parts of the plant.
Some aphids require alternate hosts in alternate generations.
However, insecticides are often used to protect high value trees and are most effective against the nymphs.