Iolas is an exceptionally large blue, the largest in Europe, being rather larger than the Maculinea species. It is also exceptionally scarce and probably in decline. It occurs in two or three known locations in Var (maybe more sites are yet to be discovered) although more widespread in the Alpes-de-Haute-Provence, and is very much tied to the larval hostplant Bladder Senna (Colutea arborescens). The male is a clear bright blue and the female blue with wide dark borders.

The flight period is mid-May (there is a suggestion of a possible second brood) and the one individual, a male, I have seen was looking rather worn on 20 May as this photo shows. It occurs in very low densities, usually only ones and twos, but it has a very powerful soaring flight and is apparently capable of wandering long distances from the Colutea.

observations