Maculinea alcon

Vaud, Switzerland, August 2006

Alcon Blue
Maculinea alcon

Distribution: Distribution is unclear due to the identification problems with the Mountain Alcon Blue, M. rebeli. The combined distribution of these two species (if they are separate species) is: N Portugal, W Pyrenees, much of France and eastwards across Germany and to northern Greece.

Identification: Fairly large blues, undersides are uniform brown with small black spots circled white. Male uppersides of a violet blue. Females with limited blue basal areas, occasionally large enough to show the underlying shady spots on the upperside reminiscent of the other Maculinea species. See also the Maculinea identification page for more information. Separation from M. rebeli is by the narrower black margins of the upperside male and limited blue basal areas in the females.

Flight time: From my experience, the flight time appears to be rather short. I W Switzerland where I found the species, but no adults, the eggs were laid over a period lasting about 10 days in early August. This appears to be the same flight time as for N Italy and NW France, but in Slovakia and E France I found them in mid July - I just wonder if these would be better considered as M. rebeli???

Habitat: In contrast to the Mountain Alcon Blue, M. rebeli, this species (or form) appears to like damp places at low levels, particularly at the edges of marshes. Larvae feed on Gentiana pneumonanthe, Marsh Gentian.

Behaviour: Larvae are tended by ants in the later instars.

Additional notes: The photographs of the eggs are the only photos I have of this butterfly upto the end of the 2006 season. The butterfly appears to be elusive, even if the eggs are relatively easy to find. I think this indicates just how threatened the species is, at least in its few remaining colonies in W Switzerland.

Vaud, Switzerland, August 2006

Vaud, Switzerland, August 2006