Its underside is purer dust -grey, the black spots are smaller, more compact, sharper, more regularly arranged, less distorted or widened; the anal red of the hindwing beneath is usually reduced to one or 2 sharply defined spots, not being smear-like or dull as in true optilete.

However, the individuals from the High Alps and the High North appear to incline more towards cyparissus, while the form flying on the Sphagnum-swamps of the warmer plains — particularly in North Germany — is the most normal optilete — In the Ural there flies a form with the ground-colour beneath black-grey; this is uralensis Courv.

— Larva pale green, densely clothed with minute silky reddish yellow hair, and adorned with a light-yellow black-bordered lateral stripe; until June on Vaccinium myrtillus.

Pupa rounded, obtuse, anteriorly dotted with small yellowish red hairs, green with yellow abdominal segments.

The butterflies from the end of June towards September, locally plentiful, on moors, also in woods of high trees, where it is usually the only Blue found.

The butterflies occur there mostly on more open places where there is a bush in the centre from which the males make short excursions.