The brimstone butterfly (Gonepteryx rhamni) is unique in several ways. Firstly, it has an almost unpronounceable and unspellable scientific name, Gonepteryx rhamni!
Secondly, its larvae feed exclusively on alder buckthorn and purging buckthorn which are generally found in open chalk downland areas and yet the brimstone is plentiful here in Purbeck where these buckthorns are not common. They are frequent visitors to our garden where there is certainly no buckthorn at all and it is believed that they do travel great distances.
Thirdly, whilst some species like the red admiral, peacock and small tortoiseshell do hibernate most of our main early specimens of these species are immigrants from Europe. The brimstone, however, is a specialist at hibernating and our first sightings in early spring are those that have seen the winter through in hibernation. When at rest the wings have a remarkable resemblance to ivy leaves and it is generally in ivy that they hibernate undetected thanks to this camouflage.
Brimstone is the old name for sulphur and the male's vivid bright yellow colouring gives rise to the common name. The female is white and is often assumed to be an early large white but, of course, it lacks the black on the wings that the large white has.
What a lovely sight these butterflies are on a warm spring day; a true joy to behold.