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It is a medium sized butterfly (46-72 mm wingspan). Adults are sexually dimorphic. Males are milk-white with black checks, grey patches, and red spots on hindwing. The adult female is similar to the male, but wings have transparent areas, there are large grey patches on the outer forewing and occasionally there are red spots near the inner hind wing edge. A large waxy white pouch, known as a sphragis, is found near the ventral tip of mated female abdomens (Acorn, 1993; Bird et al., 1995). The entirely black antennae of both sexes distinguish this Parnassian from the only other Parnassian in the province of Alberta, Parnassius smintheus, which has alternating bands of white and black on its antennae (Acorn, 1993; Bird et al., 1995). Another distinguishing character of P. clodius is the absence of red spots on the forewing (Layberry et al., 1998). Eggs are white to pale brown, round and are flattened on the top and bottom (Guppy & Bird, 2001). Early instar larvae have small tubercles (McCorkle & Hammond, 1985). Later instar larvae are usually black with rows of yellow or reddish spots and are covered with fine hairs. In mountain passes in Washington and California, larvae are another colour form. They are grey-brown to pink-grey, with cream yellow lateral spots and dorsal rows of narrow chevron markings (McCorkle & Hammond, 1985; Layberry et al., 1998; Guppy & Bird, 2001). Pupae are dark red brown, oval and smooth and are formed within a sturdy cocoon (Guppy & Bird, 2001).

Unknown for Alberta. Eggs or larvae overwinter in decayed leaf litter and pupate in thin silken cocoons in the spring in British Columbia (Guppy & Shepard, 2001). Males patrol habitat to find females; after mating they attach a pouch (sphragis) to the female to prevent multiple matings (Acorn, 1993; Bird et al., 1995). Females scatter single eggs on or near the host plant (McCorkle & Hammond, 1985; Guppy & Shepard, 2001). Larvae may feed at night or during the day at the base of host plant and may be parasitized (McCorkle & Hammond, 1985). Larvae pupate in a loose silk cocoon above ground (Guppy & Shepard, 2001; enature.com, 2002).

Unknown for Alberta. Larvae feed on bleeding heart (Dicentra formosa) in the rain forests of the Pacific Northwest, D. uniflora in the Sierra Nevada Mountains and D. pauciflora is consumed elsewhere (Opler et al., 1995; Guppy & Shepard, 2001). Adults feed on flower nectar (Opler et al., 1995).

Endemic to North America. The Alberta records are on the northern periphery of its range. In Canada, it also occurs in British Columbia (Layberry, et al. 1998). Its range extends south to the western states including northern California, Idaho, Montana, Wyoming and Utah (Opler et al., 1995).