Leafcurl ash aphid (Prociphilus fraxinifolii)
Pest description and damage Leafcurl ash aphids cause significant curling and twisting of leaves which provide protection for the white waxy aphids inside. The woolly ash aphid is woolly and curls ash leaves. The consensus is that damage substantially disfigures leaves but does no lasting damage as the leaves continue to photosynthesize sugars for the plant.
For biology, life history, monitoring and management
See "Aphid" in:
For more information
Rosetta, R. Woolly ash aphid. PNW Nursery IPM (http://oregonstate.edu/dept/nurspest/woolyashaphid/introduction.htm)