Cranberry Blue (Vacciniina optilete) (Knoch, 1781)

Diagnosis: The upperside is deep purplish blue, with no dark borders in the male and wide dark borders in the female, often with only a trace of purple at the base of the wings. The underside is pale grey with two rows of large spots on both wings; the inner row is black, white-ringed, and the outer row is dark grey, with the largest one of the spots having a large orange spot over it; there is usually also some orange shading over the adjacent dark spots. Wingspan: 18 to 24 mm.

Subspecies: The nominate subspecies optilete occurs in the Old World; only subspecies yukona is found in North America.

Range: Vacciniina optilete occurs in the Old World from central Europe to Siberia and Japan. In North America it ranges from Duck Mountain Provincial Park, Manitoba, to northern British Columbia, Nunavut, the Northwest Territories, Yukon, and Alaska.

Similar Species: The large orange spot on the underside of the hindwing near the lower corner of the wing is diagnostic for the Cranberry Blue; other similar species have a band of orange spots along the outer margin of the hindwing.

Description of this image follows.
Cranberry Blue (Vacciniina optilete yukona). Churchill, Man. J.T. Troubridge

Early Stages: The larvae feed on Ericaceae, especially blueberry and cranberry (Vaccinium spp.) and hibernate half-grown.

Abundance: The Cranberry Blue is common in Yukon, the Northwest Territories, and northern British Columbia, but becomes much scarcer farther east.

Flight Season: There is one generation per year, in July.

Habits: The Cranberry Blue occurs in bogs and wet tundra, where the foodplants are found; in the northern Prairie Provinces it sometimes occurs in dry sandy coniferous forest areas. Adults have a weak flight, very close to the ground.

© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.