Black Cherry Aphid
Description and life cycle
Adults and nymphs are readily identified by their shiny black coloration. The adults are 1∕8 inch long and have both winged and wingless forms. Nymphs are similar in appearance, but smaller.
Although the aphid can survive on most cherries, it prefers commercial cherry varieties, greatly preferring sweet cherries. Napolean, Black Tartarian, Schmidt, and Windsor are most susceptible to injury, while Dykeman and Yellow Spanish are not very susceptible. Alternate summer weed hosts include water cress, peppergrass, and members of the mustard (Brassicaceae) family of plants.
The black cherry aphid overwinters as an egg on the bark of small branches. The eggs begin to hatch as soon as cherry buds break, with young aphids moving to new green tissue. After 3 to 4 weeks wingless, stem mother females have established large colonies on growing shoots. Two to three generations occur on cherry trees by early July when most of the aphids move to alternate hosts for the summer. In September or October winged males and females return to cherry trees, mate, and lay eggs.
Feeding causes curling and stunting of leaves and stems. Heavy infestations may kill young trees and reduce crop quality and quantity and return bloom on mature trees. Honeydew from these aphids also causes the growth of black sooty fungus.
Monitoring and management
Trees should be scouted in early spring to detect the presence of stem mothers on actively growing shoots. It is important to determine aphid severity before the leaves curl. While no thresholds have been established for mature trees, young trees cannot tolerate even low numbers of aphids. Delayed dormant applications of oil and insecticides applied to control other cherry pests usually control the black cherry aphid. Aphid natural enemies including syrphid flies, lacewings, and lady beetles are often abundant enough to control this species.