Icaricia icarioides, or Boisduval's blue, is a butterfly of the family Lycaenidae found in North America. This butterfly has 25 recognized subspecies.

This species has been classified in at least four different genera since it was named by Jean Baptiste Boisduval in 1852. It started out in Lycaena, was transferred to Icaricia by Nabokov (Hodges et al., 1983), moved to Aricia by Bálint and Johnson (1997), merged with some other genera in the supergenus Plebejus by Gorbunov (2001), which was accepted by Opler & Warren (2003) and Pelham's Catalogue (as of 2012); however, Lamas (2004) among others use Aricia. More recently, it was moved back to the genus Icaricia, which was reinstated as a result of molecular studies (Vila et al., 2011; Talavera et al., 2013). Synonymy, subgenera, and subspecies vary considerably depending on the author.

Their range extends throughout the western US and Canada from southern Saskatchewan to British Columbia. Its habitats include dunes, mountains, meadows, streams, and sage-lands. It is also found in open areas or openings in woods near its larval host.

Larvae feed on species of lupines (Lupinus). Adults feed on nectar from flowers of Eriogonum species and other composites.

Wingspan: 21 to 32 mm.