Cupido minimus - Small Blue 

This charming tiny butterfly is very common in the Alps, but less so in the UK where I have to travel distances to either East or West coast to see it.

 

The males show varying amounts of blue upper-side scaling and the females sport a very attractive blue iridescent sheen. 

It was a long time before I found it in the UK, and I still enjoy achieving a good butterfly photograph of this species.