Ash Leaf Cone Roller (Caloptilia fraxinella) is the larval stage of a small grey moth which lays its eggs on green and black ash leaves in the spring. The small (3mm) caterpillars are most noticeable when they dangle on silken strings to move within the tree canopy, startling homeowners and passersby. This insect is aesthetic only, and causes no damage to healthy trees.
- The larvae that hatch spend several weeks mining tissue between the upper and lower leaf surfaces.
- In June, they move to neighboring leaflets where they use silken threads to roll and secure a leaflet in place to spin a cocoon.
- This pest is not to be confused with cottony psyllid, which is fatal to black ash trees and is currently at outbreak in Grande Prairie. Cottony psyllids are extremely small, cause massive leaf deformation and make cottony nests in curled leaves.
No control is necessary, as this insect does not pose a risk to the health of the tree.