The ash leaf cone roller is a moth that is a relatively new pest in Calgary. It affects ornamental ash trees, principally Green and Manchurian Ash.
Young caterpillars feed within the leaf tissue. As the caterpillar grows, it emerges from the leaf, migrates to a new leaf, and rolls the leaf into a characteristic cone shape. The larvae will continue to feed within this enclosure until the pupal stage. Larvae feed until mid or late June and the adult moths will emerge from the leaf cone starting about mid-July.
Although the insect can be quite prevalent on individual trees, the damage to individual trees is minor and does not interfere with overall tree health. The rolled leaves remain attached to the tree and actual leaf damage is minimal.