Alcon Blue (Phengaris alcon)

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2017 photographs highlighted in yellow. Click on any photograph to go to an enlarged picture, or simply scroll down the page.

13564_female_Vienne_15Aug08 13479_female_Vienne_15Aug08 13505_female_Vienne_15Aug08

Alcon is very closely related to the Mountain Alcon Blue (P. alcon (rebeli)). It was only recently that rebeli was considered to be a separate species and older reference books record rebeli as a subspecies of alcon. They are very similar in size and colouring and the undersides are almost indistinguishable, although the altitude is the best differentiator - if it's at high altitude, it's almost certainly rebeli. In the recent re-classification of scientific names rebeli is now considered to the higher altitude subspecies of alcon and no longer a separate species.

Both rebeli and alcon are reportedly quite rare and their habitat is threatened, especially alcon. I have, however, seen rebeli in a number of places, only ever in small numbers, so maybe I've just been lucky. I have only seen alcon in one place which I was taken to, for the first time in 2008, and would never have chanced upon the location (thanks are due to Neil Wilding). The females were constantly egg-laying on Gentiana pneumonanthe, so were easy to photograph, whereas the males were whizzing around, never settling, chasing after females that generally weren't interested.


This species was previously known as Maculinea alcon.

ref sex


alt. m
13564 F

a female underside, probably the underside of 13479.

13479 F

a female, with almost no blue scales, and with a clearly visible upf discoidal spot and a faint post-discal mark in s2.

13505 F

a female egg-laying on G. pneumonanthe.

13492 ovum

two ova on G. pneumonanthe.