The Beech Blight Aphid

Pest Identification

• Beech blight aphids are sap-sucking pests that belong to the woolly aphid group. The natural range of the pest ranges from Maine to Florida. The beech blight aphid mainly affects the American beech tree, Fagus grandifolia. Pest presence on trees becomes noticeable during early July. If not controlled in time, the insects assume large population by mid fall. The pest is also likely to infest the roots of certain conifers.

Description

• Like all aphids, the beech blight aphid is soft bodied and oval shaped, rarely exceeding 1/8 inch in length. There are two pipelike cornicles that grow from the rear of the body, the distinguishing feature between aphids and other sap-feeding pests. The beech blight aphid is light blue in color and is covered with white waxy filaments that give the pests a fuzzy look. When the pests collect in large number on foliage and stems, the infested trees take on a snow-covered look.

Damage

• Beech blight aphids feed on tree sap and excrete sticky honeydew that falls on tree areas beneath them. This promotes the growth of sooty black mold on infested areas. Though pests are not destructive to the tree in lower numbers, large populations can kill the smaller limbs of trees. Foliage starts to get discolored and distorted by excessive loss of sap. The sooty black mold reduces the aesthetic value of the tree.

Management

• Introduce natural predators like parasitic wasps, lacewings, lady beetles and syrphid flies in trees. Control the presence of ants in the trees, as these protect the aphids from their natural predators. Chemical-control options include the use of horticultural oil sprays and insecticidal soap. The systemic insecticide imidacloprid is also effective against beech blight aphids.