Butterflies of Keele
The Brimstone Gonepteryx rhamni
There is little to compare with a handsome yellow male flying in the spring sunshine. Male Brimstone butterflies (left) have sulphur-yellow forewings and hindwings with an orange central spot. The female's fore- and hindwings (right) are a delicate yellow or pale green with an orange central spot. Both butterflies have greenish veined underwings. At rest, they always hold their wings above the body.
The term "butterfly" is thought by some to derive from "butter-coloured fly" but there is some debate over this.
There is a single generation during the year with the larvae feeding on Buckthorn Rhamnus catharticus or Alder Buckthorn Frangula alnus. Neither of these plants has been found at Keele so this butterfly is rarely seen. It is, however, a common species in the limestone dales of Staffordshire and Derbyshire where its foodplant is more frequent. As a single established bush can support a viable colony and the butterflies do wander widely, it is always worth looking out for.
Brimstones fly from June/July to September (or into October), then hibernate until the spring. They emerge in March/April and May to lay eggs which will quickly give rise to the adults that emerge in the summer. It is a butterfly of gardens and woodlands.