BIOLOGICAL OBSERVATIONS AND LARVAL DESCRIPTIONS OF ENARGIA DECOLOR (LEPIDOPTERA: NOCTUIDAE) ON TREMBLING ASPEN IN NORTHERN ALBERTA

Abstract The life history and the immature stages, especially the ultimate larval instar, of Enargia decolor (Walker), are described and illustrated. This insect has only one generation a year in northern Alberta. It overwinters in the egg stage. The first two larval instars roll leaves and feed on the mesophyll. The last four larval instars feed on the edge of the leaves, and construct flat cases by webbing two leaves together. Pupation occurs in the soil during July. Adults emerge from late July until late August; the eggs are laid in August. Fifteen species of parasites and one species of hyperparasite were reared from larvae of E. decolor. Five of the parasites are known to have issued from other lepidopterous species feeding on aspen.