Mustard White

Not of concern.

Two broods, flying in June and again in late July to August.

Found throughout Canada from Newfoundland west to the western Northwest Territories, and in the northeastern United States (Opler 1999). In Alberta, this species is restricted to the boreal and foothills region (Bird et al. 1995). There is an outlying population in the Cypress Hills of Saskatchewan, but it has not been found on the Alberta side (Layberry et al. 1998).

This species and the Margined White (P. marginalis) are very similar. The Mustard White has well-marked, narrow and dark green markings along the veins of the hindwing underside, not broad, diffuse, and greyish-green as in marginalis. The second (summer) brood of oleracea often has these markings faint or absent. These two species occur together only in the foothills region. Alberta populations are the nominate subspecies (Layberry et al. 1998).

Moist mixed-wood forest.

The eggs are conical and yellow, with longitudinal ridges. Mature larvae are green with a dark dorsal stripe and numerous blacks dots. They are covered with short, dense hairs (Guppy & Shepard 2001). Pupae have dorsal and apical projections, and vary in colour from pale green to white to brown (Guppy & Shepard 2001).

The larval hostplants are unknown in Alberta. In BC, Mustard Whites feed on wild mustards (Brassicaceae) such as rock cress (Arabis spp.) (Guppy & Shepard 2001). In the right habitat, females will also lay eggs on cultivated mustards such as cabbage (Hooper 1973). Adults will also nectar at flowers of mustards (Nielsen 1999).