Large Aspen Tortrix

Not of concern.

Adult flight period from late May to early August but mainly from mid June to mid July.

Occurs along with its principal host (trembling aspen) from the Pacific to the Atlantic and from Alaska to California, Arizona, and New Mexico (Furniss & Carolin 1977).

Larvae initially pale yellowish-green. As they mature, larvae darken to deep green or almost black with reddish brown to black head capsule and reach 15-21 mm in length. Pupae spindle-shaped, 9-17 mm in length, initially bright green and eventually turn brown or black. Adults brownish gray in colour with basal, middle, and outer brownish patches on forewings and fringe of hairs along posterior edges of hind wings. Wingspan of 25-35 mm (EPPO 2004, Cerezke 1992).

Trembling aspen (Populus tremuloides) forests.

Pale green eggs are laid from June through July in large, flat masses on upper surface of aspen leaves. Larvae hatch 7-10 days after oviposition (EPPO 2004). First instar larvae congregate between flat surfaces of leaves they weave together. Although larvae skeletonize the foliage, their damage is not conspicuous at this time. In August, larvae find protected locations on the tree trunk to spin cocoons for hibernation, then molt and overwinter as second instar larvae. Larvae emerge in spring at time of bud break, climb the tree and begin mining expanding buds which can cause complete defoliation before buds open (Furniss & Carolin 1977, USDA 1979). Most of the defoliation occurs from late third instar until pupation when larvae roll leaves into shelters, feed, eat all but the larger leaf veins, and then pupate. Pupation occurs mainly in June and adults emerge 7-14 days later. One generation per year (EPPO 2004).

Main host is trembling aspen but will also feed on other associated broad-leaved trees when endemic (Furniss & Carolin 1977).

Choristoneura conflictana, the large aspen tortrix, is a moth of the family Tortricidae. The species was first described by Francis Walker in 1863. It is found from the Pacific to the Atlantic coast and from Alaska to California, Arizona, and New Mexico.

Eggs Caterpillar Pupa Damage

The wingspan is 25–35 mm. Adults are on wing from May to August.

The larvae feed on Populus tremuloides.