Butterflies: Alcon Blue

The Alcon blue (Phengaris alcon), gentiaanblauwtje in Dutch, is a very rare butterfly in The Netherlands; I have only seen one once, and I didn't even find that one; my GF did and pointed it out to me.

They only deposit eggs on gentians, rare in The Netherlands, and the larvae depend on the presence of ants (of the genus Myrmica, not that common either) to take care of them:

"The larvae emit surface chemicals that closely match those of ant larvae, causing the ants to carry the Alcon larvae into their nests and place them in their brood chambers."

The ants protect and feed the larvae/caterpillars. After pupating a butterfly emerges that is recognised by the ants as an intruder, so it has to make its way out of the ants' nest as fast as it can.

In short: where there are no gentians or no Myrmica ants, there will be no Alcon blue population.

As I said, I only ever saw one, but I did manage to get five photos of that female, first inspecting a gentian, and then depositing eggs on it:

^{Olympus Stylus 1s, 300mm, ISO125, f5.6, 1/500s}