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A large yellow-tan fall-flying geometrid. The extent of the forewing dark markings are extremely variable, the AM and PM lines ranging from thin and well-defined to broad and diffused into the basal and terminal areas. The wingless females are white with two rows of dorsal black dots, matching lichen-covered tree trunks in contrast to the large dead-leaf mimicking males. E. vancouverensis, which was considered to be a subpsecies of tiliaria following Rindge's (1975) revision, appears to be a species separate from tiliaria. The distribution and differences between these two species in Alberta are currently unclear, although McGuffin (1977) maintains that vancouverensis occurs together with tiliaria in the central part of the province. McGuffin's records of E. vancouverensis are based on his examination of specimens in the Bowman collection at the University of Alberta (McGuffin 1977). Edmonton area Erannis show variation in wing markings from typical, light tiliaria to dark, vancouverensis types, and we consider all these to be variants of tiliaria. The presence of vancouverensis in central Alberta, without intervening records in western Alberta, further suggests true vancouverensis does not occur east of the Rockies in Canada. This interesting situation warrants further study.

The Linden Looper larva is immediately recognizable with its brown, pin-striped dorsum and wide, bright-yellow sides. Localized outbreaks can defoliate deciduous trees and shrubs (particularly aspen and hazel in the Edmonton area). Eggs overwinter in bark cracks. Male moths come to light.

Larvae are generalist feeders on deciduous trees and shrubs. Reported hosts which occur in Alberta include paper birch (Betula papyrifera), trembling aspen (Populus tremuloides), willow (Salix spp.), choke cherry (Prunus virginiana), and hazel (Corylus sp.) (Prentice 1963).