Apart from a few small whites there really are very few butterflies around at the moment. I don't know whether they are simply late because of the cold weather this Spring, or absent because of last year's dismal weather. However, there are some brimstones in the woods. These are very fidgety butterflies. When a male and a virgin female meet they perform a spiral dance up into the canopy, whirling around feverishly before falling to the ground (in a swoon?) to mate (see link). In this photo the female is above the male who is obviously much more yellow. It makes a very attractive sight in the yellowish light under the emerging canopy.