Iolas is an exceptionally large blue, the largest in Europe, being rather larger than the Phengaris (previously 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 upperside is a clear bright blue and the female blue with wide dark borders.

The flight period is said to be mid-May (there is a suggestion of a possible second brood), although the first male I saw in 2011 was looking rather worn on 20 May. 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.

A superb video of the life-cycle of iolas has been produced by Filming VarWild and can be viewed on YouTube here: www.youtube.com/watch?v=62mGXCiQNfM

ref

sex

observations

alt. m

29333

M

a male, showing the clear blue colour.

480

29120

M

a male, showing quite well-developed marginal markings.

480

29340

M

a male, nectaring on the Colutea - note the proboscis enters at the base of the flower.

370

29152

Colutea arborescens, the larval hostplant.

370