At bugle, its favourite plant. Switzerland, May 2009.
This species is very similar to the small pearl-bordered fritillary but
in my experience is more strictly a woodland species (though their
habitats do overlap). The classic diagnostic feature is the single
pearl in the middle of the underside hindwing, with yellow spots in the
rest of the band. This is clearly visible in the second picture above.
Other points of distinction are the very reddish underside and the
yellow ring around the black spot in the cell of the underside hindwing.
In England this used to be called the April fritillary, though
rarely if ever flies in April there - possibly this was a throwback to
the Julian calendar! The small pearl-bordered fritillary flies a little
later and was called the May fritillary. In the wood where I
photographed the first two above, small pearl-bordered does certainly
succeed pearl-bordered as the year goes on.