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This is a large butterfly with a wingspan of 57-95 mm. Easily distinguished from other admirals in the province because it has extensive white patches on the ventral surface of the hind wing and it does not have a red patch on its forewing tip. Dorsal wings are black with a white median band on both fore and hindwings. The submarginal areas of the hind wing are black. Ventral wing has brown with white markings and the base of the hindwing is grey-white with dark crosslines. The marginal spots on the ventral hindwing are grey-white. Identification may be complicated by hybridization with Limenitis lorquini; however, hybrids usually have the orange wing tip and broader white bands. The eggs are green (Bird et al., 1995). The larvae are very similar to other admirals and resemble bird droppings. They are mottled grey and white and the saddle on their humped back is tan (Layberry et al., 1998). The pupae are light-coloured and have a large projection from the back (enature.com, 2000).

Late instar larvae overwinter in leaf shelters. Males perch on trees and shrubs to watch for receptive females and rarely patrol. Females lay eggs singly on the tips of host plant leaves (Opler et al., 1995) and oviposit on Saskatoon (Amelanchier alnifolia) near Writing-On-Stone Provincial Park (Bird et al., 1995). Larvae eat leaves (Opler et al., 1995) and may take more than a year to develop (Bird et al., 1995).

Only known larval host plant in Alberta is Saskatoon (Amelanchier alnifolia, Lancaster, 1988). In the United States, documented host plants include: willows, poplar, ocean spray (Holodiscus sp.), and shadbush (Amelanchier sp.) (Bird et al., 1995; Opler et al., 1995). In Alberta, adults feed on Western Clematis (Clematis ligusticifolia) nectar (Lancaster, 1988). Elsewhere, they feed on tree sap, carrion, and flower nectar (Opler et al., 1995).

It does not occur in other Canadian jurisdictions (Layberry et al., 1998). Its range extends from southern Alberta and eastern Oregon, south to Nebraska and east-central California, southeastern Arizona and southern New Mexico (Opler et al., 1995).