Origin:
Native to Europe.
Biology:
A pest of apple and pear trees, as well as some ornamental trees such as hawthorn or ash, or shrubs such as rose and spiraea. Generally it restricts its feeding in an area to only 1 plant species. Feeding action by clusters of these aphids may cause moderate leaf curl. Eggs are the over-wintering stage, and these hatch to wingless females which are parthenogenic and which produce another generation without fertilization by males. These females produce living nymphs rather than depositing eggs, and up to 15 generations may occur in one season. Winged forms develop in the spring and migrate to other nearby host plants, and these winged females deposit eggs. In the fall both male and female winged forms will be produced, eggs are deposited on twigs of the plants, and these eggs then over-winter.
Identification:
Normally the wingless females will be observed, which is a green aphid with a round body and with black cornicles at the end of the abdomen. The winged forms have a black thorax and 3 pairs of black spots on the sides of the abdomen.
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.
