What Is It?
The adult of the ash leaf cone roller (Caloptilia fraxinella) is a small gray moth with a 12 mm wingspan. This insect is native to North America.
What's the Problem? Early stages of the caterpillar are leafminers, feeding on the tissue between the upper and lower surfaces of the leaflet. In early to mid June, the caterpillar migrates on a silk line to a different leaflet. Once on a new leaflet, the caterpillar folds the leaflet into the characteristic cone, and spins its cocoon inside.
What Can I Do?
Spraying is not required as this rolling up of leaflets appears to have little effect on the health of the ash trees. The rolled leaflets remain attached to the tree. While a small part of a rolled leaflet will rot, most of it appears to remain undamaged.