Phengaris nausithous - Dusky Large Blue 

Phengaris-nausithous-dusky-large-blue | PTKbutterflies
Phengaris-nausithous-dusky-large-blue | PTKbutterflies
Phengaris-nausithous-dusky-large-blue | PTKbutterflies

I was shown this species, in Switzerland where it appears to thrive on Greater Burnett flower-heads, from where it doesn't seem to stray far. It is very attractive, if not very blue, and does not open it's wings for butterfly photos very often.