Arrowhead blue butterflies, Glaucopsyche piasus
Arrowhead blue butterflies fly in May but may be seen through spring and summer. This butterfly evolved to rely on lupines and milk vetches as the host plant its caterpillars feed on, and adult butterflies feed on nectar from spring-blooming flowers including mustards and thistles.
Arrowhead blues or Glaucopsyche piasus have a wingspan of 1-1/8 to 1-3/8 inch. Their upper wing surface on males is violet blue-- duller on females-- with a dashed white fringe. The underside is gray with black dots and a light row of "arrowheads" points inward on the hindwing, giving the arrowhead blue butterfly its name.
Arrowhead blue butterfly
Arrowhead blue butterfly on western wallflower
Arrowhead blue butterflies mating
