Female, Switzerland, July 2006 (under the wing of a small
Male, Switzerland, July 2006
Upperside of a male found dead, Switzerland, July 2006
The moorland clouded yellow is more
local than the mountain clouded yellow,
preferring rather more remote, heathy sites where bilberries grow.
Until recently I thought it did not occur near where I live
in Switzerland but in the last few years have found it on my local
mountains. I have also found it in many places in Valais and in the
Jura. Unlike the mountain clouded yellow, which is strictly a butterfly
of high mountains, the moorland clouded yellow will fly at
lower altitudes if the foodplant is present, even in the southern parts
of its range. Like most alpine butterflies with a Scandinavian
distribution it generally flies at low altitudes in the north.
The male is a much
butterfly than the mountain clouded yellow; the female is whiter. Both
sexes lack white spots in the border of the forewing and the discoidal
spot on the forewing underside is neatly etched in black with a pale
centre. The species is actually
easily identifiable in flight, when the characteristic plain border is
very obvious. It occasionally settles but does have a useful habit
flying close to watchers, as if to watch them, so gives plenty of
opportunity for a firm identification even when it is restless.
The larvae feed on bilberry (Vaccinium
uliginosum or V. myrtillus).
This means the butterfly is often found in the company of cranberry
blues and cranberry fritillaries, which use the same hostplant. It
hibernates as a young larva, completing its development in the spring
when the snow melts.