The rather special brimstone butterfly

At last I've seen a slightly unusual creature. Usually when I turn to a guidebook on butterflies, flowers etc, my cherished specimen is described as 'so common as to be not worth bothering with' or words to that effect.

On a Monday run around that same tiny nature reserve, yellow butterflies were in evidence which surely must have been the brimstone, known to frequent the reserve which lies towards the Northern limits of its breeding territory. Whilst not exactly rare, I'm not aware that I've ever seen one before. It carries the distinction of being one of the few species which hibernates as an adult and therefore is one of the first butterflies to be seen in Spring. These early ones are last year's adults, which will live until July, when the new adults hatch.

Sadly they were too flighty for me to catch on camera but here's a photo I didn't take:

It might not be rare but it looks pretty special to me.