Size: 1.0 - 1.5 inch wingspan
Key ID features: Male bright blue above with charcoal wing borders. Female brown above with orange-brown highlights on FW, often with blue shading basally and vague or no orange band along trailing margin of HW. Both sexes may have dark cell end bars on FW. Male blue-gray below with very small black spots with wide white halos and marginal row of small black triangles. Female below brownish-gray with similar spot pattern.
Similar species: Separated from Greenish blues by tiny black spots below having broad white halos, especially on the hindwing, and lack of orange edged triangles at anal angle.
Host plant: Many lupine species (Lupinus). Fender's Blue subspecies uses Kincaid's Lupine (Lupinus oreganus var. kincaidii).
Habitat: Mountain meadows and roadsides, subalpine slopes, and occasionally lower elevation meadows (Fender's), always near lupines.
Range: All of eastern Oregon, plus central Coast Range, and southern Willamette Valley (ssp. I.i. fenderi).
Season: Late May to early July
Abundance: Common east of Cascade Range, locally common at scattered sites in Willamette Valley.
Conservation Status: Fender's Blue listed as Endangered federally.