Green Apple Aphid
Biology: Overwinter as eggs in protected areas on limbs and start hatching at half-inch green. Green apple aphids remain on apples all season.
Symptoms: Curled leaves; honeydew.
Monitoring: Look for shiny black eggs in early spring. If aphids are a problem later in the season, start after petal fall and select a random shoot on the major cultivar in the block and count the number of leaves that have one or more wingless aphids; repeat on 10-20 more shoots, and determine an average number leaves/shoot that have aphids.
Treatment Threshold: Delayed dormant oil will usually take care of this aphid. Otherwise, 4+ leaves/shoot infested with aphids during the season will require treatment.
Degree Day Model: None
Management Considerations: Numerous beneficial insects including lady beetle adults and larvae, lacewing larvae, and syrphid fly larvae help suppress aphid populations.