Forest Pests: Insects, Diseases & Other Damage Agents

Importance. - This aphid occurs in the Eastern United States and west to Colorado. Heavy aphid infestations cause premature defoliation and stunt growth. The distorted foliage, along with accompanying honeydew and sooty mold, mar the beauty of ornamentals and make nursery plants unsalable.

Identifying the Insects. - Aphids are 2.0 to 2.5 mm long, soft bodied, and pear shaped to globular, with a pair of tubes projecting from the abdomen. They are yellowish green to pale yellow with brown head and legs. Both winged and wingless forms occur. White, waxy secretions often cover the aphids, giving them a "woolly" appearance.

Identifying the Injury. - Aphids suck the sap from the undersides of tender, developing leaves of terminals and branch tips. Feeding causes leaves to curl downward. Unfolding the tightly curled leaves will reveal clusters of aphids. Heavily infested leaves may drop prematurely. A whitish, sticky honeydew produced by the aphids frequently coats the foliage and supports the growth of black, sooty mold.

Biology. - Overwintering occurs as eggs in bark crevices. The eggs hatch in the spring into wingless females that reproduce without mating. Several generations are produced each year. During fall, winged adults deposit the overwintering eggs. The largest populations are usually present during early summer.

Control. - Natural enemies routinely keep most aphid populations under control, but insecticides may be needed to protect nursery stock and ornamentals.