Hawthorn aphid
Dysaphis crataegi
15 host plants
Last updated
In spring as hawthorn buds expand, small reddish or dark-colored aphids gather on new growth and tender leaves, causing them to curl inward and distort. The affected leaf curling creates shelter for the aphids as they feed throughout spring and early summer on Crataegus species. You notice the distinctive curled, thickened leaves in April through June. Populations diminish as leaves harden.
Prune out heavily curled shoots during early leafing to remove colonies. Monitor new growth starting in April for curl symptoms and spray with water to dislodge aphids. For recurring concerns, apply dormant oil in late winter to suppress overwintering eggs. Once leaves fully harden, populations typically self-regulate through natural enemies. Horticultural oil or insecticidal soap can help.
Quick Reference
All these aphids are light green in color. Spirea aphid is very difficult to separate from apple aphid without high magnification, whereas apple grain aphid can be distinguished by a yellowish green stripe down the middle of the back. Apple grain aphids infest pear only in the early part of the season, while apple aphid is present all summer. Aphids suck plant sap and live in colonies on new shoots. Populations are damaging only sporadically. Damage appears as rolled leaves, stunted terminal...
Cultural Controls
- Hand-wipe or prune to control small, localized infestations when practical.
- Wash aphids from foliage with a strong stream of water.
- Encourage natural enemies including ladybird beetles, lacewings, syrphid (hover) fly larvae, and parasitic wasps.
- Avoid use of broad-spectrum insecticides which kill these beneficial insects.
- Control honeydew-feeding ants, which may protect aphid colonies from predators.
- Provide proper nutrition.