Butterflies and Moths of North America

collecting and sharing data about Lepidoptera

Arrowhead Blue
Glaucopsyche piasus (Boisduval, 1852)


Family: Lycaenidae
Subfamily: Polyommatinae
Identification: Checkered fringes. Upperside of male violet blue with a wide border; female duller. Underside gray with many small black spots. Hindwing with postmedian band of white "arrowheads" pointing inward.
Wing Span: 1 1/8 - 1 3/8 inches (2.9 - 3.5 cm).
Life History: Males patrol during the day near host plants. Females lay eggs on flower buds of host plant; caterpillars eat flowers and fruits. Chrysalids hibernate.
Flight: One brood from March-July.
Caterpillar Hosts: Lupine (Lupinus) and milkvetch (Astragalus) species in the pea family (Fabaceae).
Adult Food: Flower nectar.
Habitat: Coastal dunes and lowlands in California; mountains elsewhere: scrub, openings in woods, roadsides, trails, meadows, clearings, streamsides.
Range: Local and uncommon. British Columbia and southern Alberta south through the mountains of western North America to southern California, northern Arizona, and western Nebraska.
Conservation: Populations in southern California need assessment; elsewhere populations are probably not in jeopardy.
NCGR: G5 - Demonstrably secure globally, though it may be quite rare in parts of its range, especially at the periphery.
Management Needs: Not reported.
Comments: NULL
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