What is the insect pest?
Ash leaf curl aphid, a type of woolly aphid.
What is the sticky material?
Aphids are not able to digest all the sugars they consume when feeding on plant sap. They excrete the excess as waste material, which is also known as honeydew. Ash leaf curl aphid produces large amounts of this sticky substance.
How likely is the tree to be seriously injured from this damage?
Despite the injured leaves, ash leaf curl aphid feeding has little impact on a healthy, mature tree. Infestations are also rarely found in sufficient numbers to be very damaging.
What are the pest management options?
Since this aphid is rarely a threat to the health of trees, one option is to just ignore them. Natural enemies will help keep ash curl aphids reasonably under control. If one wishes to protect the tree's appearance, leaves may be treated with a systemic insecticide, such as acephate (Orthene). However, once leaves are curled, they remain that way for the remainder of the season. To help preserve natural predators and parasites, be careful not to over-apply an insecticide.
