Male, Switzerland, July 2005

Male, Val d'Aran, July 2005

Female, Rhône Valley, May 2006

Male, Val d'Aran, July 2002

Male, Val d'Aran, July 2003

Male, Val d'Aran, July 2003

Male, Rhône Valley, May 2004

Male, Rhône Valley, May 2004

I once thought this species was rarer than short-tailed blue. However, I have since found it commonly in the Val d'Aran and even in my home town of Barboleuse in Switzerland in 2003. It is separable from the short-tailed blue by the lack of orange on the hindwing. The tail on the hindwing may be vestigial or apparently absent, but there is always at least a kink in the black marginal line and there seems always to be half-chequering on the margin of the hindwing upperside in the male, distinguishing this from the Osiris blue.