Insects That Hurt Pine Trees

European Pine Sawfly

• The European pine sawfly produces larvae that feed in groups upon the needles of pine tree and shrubs. The larvae are a gray or green color, with one dark and two light stripes on each side of the body. These pests typically appear in mid-May and move into adulthood by Memorial Day, at the latest. The European pine sawfly consumes only old needles of the tree, so the pine typically survives, although it may be damaged aesthetically.

Pine Needle Scale

• The eggs of the pine needle scale spend the winter hiding beneath the protection of the adult female scale, before hatching in May and beginning the process of sapping fluids from the foliage of a pine tree. Gardeners who wish to control these immature scales -- known as crawlers -- at an early stage of the season before they begin to multiply rapidly, should immediately apply soapy water or horticultural oil to the needles of the pine.

Pine Aphids

• Pine aphids begin to infest trees in the fall, when females deposit groups of five or six eggs in a row on the needles of a pine. Hatching commences in the spring, with the aphid identifiable by two extremities that stretch backward from the abdomen. They feed on the plant sap, stunt the growth of branches and can kill immature trees. Additionally, their feeding produces honeydew that leads to a black, sooty mold appearance on the tree.

Pine Bark Adelgids

• Covered with a white, waxy secretion, the pine bark adelgid is a tiny, dark-colored insect that lives within the branches and bark of the pine, causing the tree to look as if it is covered with a cottony mold. Occasionally, the insects may be discovered on needles, but the pine bark adelgid feeds exclusively on bark. Although as many as five generations are produced annually, these pests cause no significant injury to the tree. Insecticidal soaps help to control the population.