Rosy Apple Aphid
Overwinter as eggs in protected areas on limbs and start hatching at half-inch green. Migrate to alternate weed hosts during summer.
Curled leaves; honeydew; saliva of rosy apple aphid is toxic to fruit cells, resulting in deformed fruit.
Look for shiny black eggs in early spring. Starting at open cluster stage, examine at least 10 trees, spending 3 minutes/tree, and look for colonies.
Delayed dormant oil will usually take care of this aphid. Otherwise, an average of more than one colony per tree may result in fruit injury.
Degree Day Model
Numerous beneficial insects including lady beetle adults and larvae, lacewing larvae, and syrphid fly larvae help suppress aphid populations.