Origin:
Believed to have originated in Europe, brought to North America with nursery stock of apple trees with the earliest settlers, and it now can be found throughout the world.
Biology:
Primary hosts are apple, pear, and plum trees, hawthorn, and a variety of grasses and grain crops during the summer. Over-wintering eggs on the trees hatch to dark green nymphs as the new buds on the trees are developing, and new aphids tend to cluster on these buds. These mature to wingless stem mothers after about 2 weeks, and they begin producing living nymphs in the next 24 hours, exuding around 75 nymphs over a 30 day period. Most of this second generation will develop wings and fly to new host plants. Subsequent generations commonly infest grasses and grain crops, and the final generation of winged adult males and females mates, with the females returning to the primary host trees to deposit eggs.
Identification:
Nymphs are dark green with a lighter green patch down the back. Antennae, legs, and cornicles are dark colored. Mature females reach about 2 mm in length and have a darker green stripe down the middle of the back.
Characteristicts Important to Control:
Winter applications of dormant oils will kill eggs on the twigs or branches. A soil or trunk applied systemic insecticide can be very effective in killing the feeding aphids, which ingest the active ingredient as they ingest plant fluids. The systemic may provide longer control than sprays applied to the leaves, but sprays may provide rapid kill when needed quickly. Sprays should be applied prior to the occurrence of leaf curling, which inhibits the ability to contact the insects with the spray.
