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This is our most common sulphur. The submarginal spots along the fore- and hindwing underside and lack of orange on the forewing upperside will generally distinguish this species. The underside discal spot is double-ringed, giving it a 'halo' effect. The spring generation tends to be smaller and darker. The subspecies status of our populations is unclear; they have been variously assigned to the nominate form (Layberry et al. 1998) or eriphyle (Guppy & Shepard 2001). It may be best not to assign a subspecies (Bird et al. 1995) until further study sheds light on this situation.

The eggs are elongate with tapered ends and longitudinal ribs, and are red in colour several days after being laid (Guppy & Shepard 2001). Mature larvae are dark green with a dense covering of short, fine hairs, and have a dark dorsal and white-and-pink lateral line (Guppy & Shepard 2001). Pupae are green with three red dashes on the abdomen (Guppy & Shepard 2001). In favourable years (with adequate moisture and warm spring weather), there may be three broods in southern Alberta, and occasionally at least as far north as Edmonton. Individuals of the third brood, flying in late September to early October, are smaller and darker than the summer (second) brood, and resemble the spring brood. Northern (and possibly mountain) populations likely only have one annual brood. Single-brooded populations in the Peace River region of BC (subspecies vitabunda) may be a species distinct from philodice (Guppy & Shepard 2001). This taxon should also occur throughout the Peace River region of Alberta.

Many species of legumes are larval hosts, including native and cultivated species. In southern Alberta, larvae feed on clover (Trifolium sp.) and alfalfa (Medicago sativa). Adults visit legume flowers and males will often congregate to mud-puddle.