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Close-up photo of live adult Northern Blue butterfly

Catherine Cr Rd, Wallowa Co, July 8


Plebejus idas

Size: 1.0 - 1.25 inch wingspan

Key ID features:  Male deep violet-blue above with black marginal band and white fringe. Female brown above with scalloped orange marginal band, clearer and bolder on HW.  Below, light bluish gray with black spots, with row of marginal spots that are black inwardly, then orange, and outwardly black with a patch of iridescent blue, lighter and less clear on FW.

Similar species: Male Acmon and Lupine Blues have orange band on HW above, and females of those species have no orange on FW above. Melissa Blue has brighter orange borders and bolder iridescent patches on HW below. Anna's Blues don't occur east of the Cascades in NE Oregon.

Host plant: May be using plants in the pea family and/or heath family.

Habitat: Moist, cool montane meadows and forest openings, and dry meadows among conifers. ​

Range: Found from Ochocos to Wallowas and Blue Mtns in NE Oregon.

Season: Early June to late August

Abundance: Common 


Conservation Status: Secure

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