The Large Blue
Last month a correspondent wrote in the English language newspaper - 'What am I doing here?' Here is my answer. Here in France I am delighted to see the Large Blue butterfly alive and well within a few hundred metres of my house. Though now re-introduced to Britain, it became extinct there through the destruction of its habitat. That it is still possible to enjoy the sight of wild creatures here in a state that England enjoyed a hundred years ago is my Reason for France. This butterfly has a complex life history. It lays its eggs on the flowers of thyme. The young caterpillar, which is a dull pink, matching the flowers of the thyme, eats happily for a while, but with luck (for it itself, as we shall see) an ant of a particular species will find it and apparently having a taste for the sweet 'goo' which the caterpillar exudes, takes it into the communal nest. Once there, the caterpillar takes a change of diet and begins to feed on the larvae of the ants! This is continues to do until the winter, when after a rest, it commences again in the spring. In June to July they pupate and crawl out of the ants' nest to become the full adult.
The ants themselves, have a particular predisposition to living in a certain kind of terrain. It must be more or less open ground without a dense cover of tall grasses or scrub. the stony causse around here with low vegetation is just right. If this is destroyed, perhaps simply by being allowed to overgrow through lack of grazing, then the ants can die out and the butterfly with them.
The butterfly is instantly recognisable, because it is a noticeably larger butterfly for a 'blue' and also the black spots on the upper wing are very characteristic. It also flies rather more lazily than most of the blues and you can approach it near enough as in this case to take a photo!