In last year's drought some species of butterfly did poorly, but many of the forest dwelling species did exceptionally well. The shade provided by the trees seems to have helped reduce the impact of the lack of water on the habitat. This year, however, with the cold and damp, they are not doing nearly so well, so you might be lucky to see an Emperor Apatura spp or one of the white Admirals Limenitis spp.
One of the loveliest of the arboreal species is the Lesser Purple Emperor Apatura ilia (or le Petit Mars changeant in French). The males of this large (in European terms) butterfly are a gorgeous irridescent purply blue on their upper sides. Generally they are not all that common, but will often visit gardens in areas with suitable damp woodland (I have seen them at Villandry, for instance). Their main caterpillar host plants are poplars (including aspen), willows and occasionally alder. Their numbers are threatened by modern forestry practices, which clear out all non-commercial tree species (such as aspen and willows).
like the way it shows the butterfly's yellow tongue.