Val d'Aran, July 1999

I am not 100% certain this is Plebejus pylaon, mainly because the books say that the species is not found in the Pyrenees, as well as that the Spanish subspecies is quite rare. However, I know no other male blue that sports pink around the spots towards the anal angle of the hindwing. If it is not P. pylaon it is one of the other three in that group : idas, argus or argyrognomon. If anyone can confirm the likelihood of one of these from the locality and/or appearance of the butterfly, I would be grateful. Unfortunately I did not study the underside - the butterfly was flying with Polyommatus eros and when I photographed it I thought it was eros. It was only on getting the pictures back I discovered it was definitely not eros.

UPDATE : Simon Coombes, whose own butterfly website, Captain's European Butterfly Guide, I can recommend, suggests that a subspecies of Plebejus argus is more likely - possibly P. a. hypochonius, although the distribution of this subspecies, too, does not extend to the Pyrenees. More suggestions would be welcome.

UPDATE : A Spanish correspondent, with considerable experience in the area, confirms that pylaon does not reach the Pyrenees and suggests a subspecies of idas blue, Plebejus idas degener, which does occasionally show the pink spots and flies in the Pyrenees. He has also found it in association with eros blues. I think I have to knock Zephyr blue off my life list, but LISTS ARE NOT EVERYTHING. It is (was) a lovely butterfly...

UPDATE : Another Spanish correspondent, whom I met in the Val d'Aran, is quite confident it is argus ; he has speciments from the area showing the pink markings.

Note : This is a difficult group to identify, principally because of the range of variation within each species. Normally idas blues have narrower dark margins than silver studded (P. argus) and this is apparent in the picture of idas I have put under that name on this site (from Norway). The real clues, which are not given in this picture, are :

Zephyr blue : no 'silver studs' in the submarginal spots on the underside of the hindwing.

Silver-studded blue : silver studs + spine on fore-tibia.

Idas blue : silver studs but no spine on fore tibia.