This is a high-altitude
butterfly of
sheltered, grassy and flowery slopes, not found below about 2000m in
the Alps, though apparently flying lower in the Apennines. Its
distribution within its range is patchy; thus, in Switzerland, it flies
commonly in Valais but is absent near me, in Vaud. It may or may not be
a coincidence that the meadow fritillary flies near me in Vaud but not
in Valais. I have never seen both species in the same place.
The Grisons fritillary is very variable. The female, in particular, may
be bright orange, like the male, or almost completely dark, resembling
a little fritillary (Melitaea
asteria).
Males are weakly marked above, with the post-discal line in particular
very thin and sometimes vestigial or even absent. The markings are
generally regular and grid-like. The dark, discal mark in s.1 of the
forewing is often club-shaped and never oblique (distinguishing this
species from the meadow fritillary).
The caterpillars feed on alpine plantain and spring gentians. Like
those of other Melitaea
species, they are gregarious while young and hibernate together,
dispersing in later instars. Butterflies are on the wing from the end
of June through to August, though the start of the flight period varies
from year to year depending on when the snows melt.