Fall Cankerworm

No concern; often reaching pest status.

Adults fly after the first fall frosts have occured, peaking in mid October.

Nova Scotia west to Alberta, south to Colorado and California (McGuffin 1988). In Saskatchewan and Alberta, this species is associated with Manitoba Maple shelter belts in the southern parts of the province. It did not occur historically in the Edmonton region, but is now established here and is often common in October on city Elm trees.

Males have an even brownish grey forewing with jagged white and dark PM and AM lines, occasionally with a visible dark discal spot. The hindwings are light grey, with a dark discal spot and a faint pale PM line. The females are wingless and stout-bodied, looking very unlike a lepidopteran.

Wooded areas including city parks, ornamental plantations and shelter belts.

The larvae are often a serious pest of many tree species elsewhere, although it rarely reaches densities high enough to do damage in Alberta. The eggs are laid in clusters on tree branches and trunks by the wingless females and hatch the following spring, synchronized with the flush of leaves. There are four larval stages, which are described in detail by McGuffin (1988). Larvae pupate in the soil and delay their emergence until fall, spending about four summer months as a pupa. Females in at least some populations are able to reproduce parthenogenetically (without mating). (McGuffin 1988).

Larvae feed on a large variety of deciduous trees and shrubs, especially elm (Ulmus spp.), ash (Fraxinus spp.), and maple (Acer spp.), which are non-native to Alberta but often planted in cities and as shelterbelts.