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The uniform brown-grey underside with a single row of white-edged submarginal dots, and complete absence of marginal markings, make this an easily identifiable blue. Subspecies couperi occurs throughout most of Alberta, and oro is found in the extreme south (Bird et al. 1995). The larger, paler, populations in the southwestern Mountains are subspecies columbia (C. Schmidt, unpubl. data).

Eggs are laid on the unopened flower buds of the host plant, and larvae feed on recently opened flowers (Layberry et al. 1998). The colour of the larva is dependent on the type and part of the plant being eaten, ranging from green (when feeding on leaves) to whitish or purple when feeding on flowers (Layberry et al. 1998). Larvae always have a darker dorsal and lateral stripe and pale oblique lateral bands and are usually tended by ants (Layberry et al. 1998). The pupa hibernates. The Silvery Blue is one of the few species able to take advantage of non-native plants seeded along roadsides, where the larvae feed on alfalfa (Layberry et al. 1998). It is equally at home in native prairie grasslands and alpine meadows, and males sometimes form large mud-puddling congregations.

The larval food plant is not reported in Alberta. In eastern Canada, a number of legumes (Fabaceae) are used, including introduced species such as cow vetch (Vicia cracca), white sweet clover (Melilotus alba), trefoil (Lotus spp.) and alfalfa (Medicago sativa), and natives such as wild pea (Lathyrus spp.) and milk-vetch (Astragalus spp.) (Layberry et al. 1998).

The Silvery Blue occurs as several subspecies across most of Canada and the USA, from Alaska to northern Georgia and Baja California, Mexico (Opler 1999). Further research may show that some of these populations may actually be different species (Dirig and Cryan 1991).