Ancylis discigerana (Walker) is a univoltine leaf folder of yellow birch. Final instar larvae overwinter in litter and pupate from mid-April through mid-May. Adults emerge in early June and deposit single eggs on the upper surface of a leaf, usually on a major leaf vein or other small depression in the epidermis. The first two instars skeletonize the lower surface of a leaf, beneath a sheet of silk that is constructed between two lateral veins. Third-instar larvae move to the upper surface of a different leaf and fold it lengthwise. Larvae feed on the upper epidermis within the fold until leaf-fall. Life stages are described.
An egg parasitoid, Trichogramma minutum Riley, and a larval parasitoid, Apanteles polychrosidis Viereck, were the major natural enemies in the population studied.
A key is presented for three species of Ancylis found on yellow birch.