The Swiss brassy ringlet is
restricted
to the Alps, where it is locally common from medium altitudes right up
to the summer snowline. It is said that only one species of brassy
ringlet flies at any site, and in my experience this is largely true.
On my local mountain, the common brassy ringlet flies and I have never
seen Swiss brassy ringlet. But not far away, on the Massif du Muveran,
only the Swiss brassy ringlet flies. The butterflies appear on the wing
in July and fly through into September in a single generation -
seemingly commoner later in the year, perhaps suggesting individuals
are long-lived (so the numbers grow cumulatively).
Males have a strong brassy reflection, very visible in some lights and
at some angles. Females generally appear plain, though there are slight
brassy reflections. The two eyespots on the forewing are generally
small and separated, and there are no - or tiny - spots on the
hindwing. Both these features help to separate this species from the
common brassy ringlet (apical eyespots touching, and strong spots on
the upperside hindwing) and de Lesse's brassy ringlet (apical spots
separated by a hair, and spots on hindwing always present but not as
strong as those of common brassy ringlet). The grey marbling of the
underside hindwing - characteristic of brassy ringlets - is very
variable and may be highly contrasting or essentially plain.
The foodplants are grasses, including mat grass and sheep's fescue. The
caterpillars hibernate, completing their development in one seasonal
cycle - like the common brassy ringlet but unlike de Lesse's brassy
ringlet, which takes two.