Male, France, August 2008
Male, Switzerland, July 2009
Female, Switzerland, July 2012
Male, Switzerland, April 2014
Very approximate distribution. The species occurs as a rare vagrant further north.
In much of Europe, north of the Alps and
the Pyrenees, this is one of the two common clouded yellows - the other
being the clouded yellow, Colias crocea. In the south it is largely replaced by Berger's clouded yellow, Colias alfacariensis,
though the area of overlap is extensive. As a rule of thumb, the
further south you go, the more likely (on geographical grounds alone)
an individual is to be Berger's clouded yellow and the further north
you go, the more likely to be pale clouded yellow.
Thee is no real risk of confusion with the
clouded yellow as the normal ground colours of these species are so
different. In the case of f. helice - the white form of the female clouded yellow - it may be necessary to have a view of the upperside to be sure. In helice
the pale submarginal spots towards the trailing edge of the forewing
(often there is just one spot) are more or less completely enclosed
within the dark band. In pale clouded (and more so in Berger's clouded)
the dark band tapers, leaving these spots open to the yellow ground.
Differentiating between pale clouded and Berger's clouded yellows is
more difficult and it
probably impossible to be 100% certain of identity in the field (unless
a laying female or a caterpillar is found). The wings are slightly more
pointed at the apex in pale clouded and the colour of the male is less
bright. In the hand (or looking through the wings into the sun) more
dark can be seen around the wing edges in pale clouded yellow and the
dark basal area of the forewing upperside is more fanshaped (rather
than extending predominantly along the trailing edge). The orange spot
on the upperside of the hindwing is also much brighter orange in
Berger's.None of these features is diagnostic on its own.
Berger's clouded yellow is the
predominant species in the Alps
and on calcareous soils, where it forms relatively sedentary colonies
associated with horseshoe vetch. Pale clouded yellow is more mobile and
may be found on almost any terrain. The caterpillars also take a wider
variety of foodplants. Nevertheless, it does seem to have a strong
preference for clover and I habitually locate temporary colonies by
searching clover fields in June and later, especially in areas where I
know Berger's does not fly. I am confident of the identity of all the
insects shown above.
This species hibernates as a young larva.