For the sake of completeness, I'd like to show the girlfriend of
This female Common Blue is not typical of this species, as in our region, they usually are brown, with only some blue at the base of the wings - but always with those orange-red spots along the edges that you can see in the picture. Depending on the temperatures during the development of the insect, however, the amount of blue in the wings varies - the colder it was at that time, the more blue the adult females show.
The plant in the picture is Medicago lupulina, or Black Medic. This is one of the plants the larvae of the Common Blue feed on.