Switzerland, May 2006
Large wall brown on left and northern wall brown on right, for comparison.
The northern wall brown is very similar to the dark form of the large wall brown, but can be identified by the dark irregular line across the hindwing. It is also generally smaller and darker. The butterfly has a strange distribution, being found, as its name suggests, in Scandinavia, but also, quite separately, in the Alps, where these were photographed.