West banner

East banner

Central banner

Acmon-lupine blue butterfly

Eastern Washington

Acmon or Lupine Blue (Plebejus) butterfly basking on buckwheat flowers
Acmon/lupine blue butterfly nectaring on buckwheat

Acmon and lupine blue butterflies can be seen throughout the spring and summer months, having multiple broods through the season, and can be found across eastern Washington.

Both acmon and lupine blue butterflies are adapted to rely on various wild buckwheats as host plants for their caterpillars to feed on, and acmon caterpillars also eat lupines (oddly, lupine blues don't eat lupines though). Adult butterflies gather nectar from various flowers including western clematis, white forget-me-not, and host buckwheats.

Acmon-lupine blue identification

The easiest way to identify acmon-lupine blue butterflies is to look at the pictures and compare with similar butterflies. Acmon-lupine blues are small, having a wingspan of about an inch more or less, and the upper wing surface on males is powdery blue while females are brownish. Both males and females have an ornate orange and black-dot arc on their dorsal (upper) hindwing. The ventral hindwing (underside) also has the orange and black-dot arc, with blue scintillae (glittery scales) encircling the black dots. The ventral hindwing is otherwise bluish gray with black spots. Square-spotted blue and dotted blue butterflies look similar but lack the glitter and are smaller, while Melissa's blue butterflies have the glitter but also have an orange arc extending up the ventral forewing edge.

Picture of a male acmon - lupine blue butterfly nectaring on buckwheat
Male acmon/lupine blue butterfly
nectaring on parsnip-flower buckwheat

Picture of female acmon - lupine blue butterfly nectaring on buckwheat
Female acmon/lupine blue butterfly
perched on snow buckwheat - August

Picture of acmon or lupine blue butterfly in snow buckwheat
Acmon/lupine blue butterfly
crawling deep into snow buckwheat

Acmon - lupine blue butterfly nectaring on white forget-me-not
Acmon/lupine blue butterfly
nectaring on white forget-me-not - May

Acmon - lupine blue butterfly picture
Acmon/lupine blue butterfly

Acmon-lupine blue butterfly nectaring on snow buckwheat
Acmon-lupine blue butterfly
nectaring on snow buckwheat