In general, the blues are grassland butterflies. They are fond of visiting flowers and lay their eggs on various flowering plants. The blues can be roughly divided into two groups, one in which the males have a blue upperside to their wings, and the other where it is brown or black. Most of the blue "blues" are conspicuous by the sheen on their wings. ( P. daphnis 02)

The tint of blue, especially for the experienced observer, is a good help in identification. The females are more modestly coloured, and are nearly always brown.
In most cases, there is no real dependence on the ants. However, there are a few species, such as the Large Blue and some other Maculinea species that are true parasites.

Examples:
Common Blue (Polyommatus icarus),
Brown Argus (Aricia agestis),
Chalkhill Blue (Polyommatus coridon).