(Gonepteryx rhamni)
What's in a name
Brimstone, meaning "burning stone" was the name for sulphur from the 14th century, referring to how easily sulphur burns. This beautiful butterfly was given it's common name from the vivid sulphur colour of the upper wings of the male. The underwings are a greeny yellow, and the female is a much paler green. Slightly confusingly, there is also a yellow moth with the same common name (Opisthograptis luteolata).
The genus "Gonepteryx" means angled wing and the species name "rhamni" refers to one if it's food plants, Buckthorn.
It's believed that the word 'butterfly', or 'buttered colour fly', originates from the yellow colour of the male Brimstone.
Range and habitat
Bucking the butterfly trend, this species is increasing in both range and abundance. It is common in England and Wales, less so in Ireland, and rare in Scotland. It can also be found across Europe, Asia and North Africa. The caterpillars feed on Buckthorn (Rhamnus cathartica), and Alder Buckthorn (Frangula alnus), which aren't currently suffering from human induced threats. It can be found in woodland and scrub where these plants occur.
The adults feed on nectar and are particularly attracted to purple flowers including Thistle, Devil's-bit Scabious, Teasel, Bluebells and Bugle. They also feed on yellow Cowslips, Primroses and Dandelions in the spring.
Life cycle
Adults hibernate amongst Ivy, Bramble or Holly between October and April. When the adults emerge in spring, they mate and lay single eggs on the underside of young Buckthorn or Alder Buckthorn leaves.
After 1-2 weeks, the green caterpillars emerge. They feed on the upperside of the leaves where they're well camouflaged, and can mainly be spotted by looking for leaves that are nibbled all around the edges. After a month, it pupates on the underside of a leaf, but not on it's foodplant. The pupa looks like a curled leaf and lasts about 2 weeks before the Adults emerge in August and feed before going into hibernation in Autumn.
Notice nature
Whilst the striking adults are beautiful to spot in flight and feeding, there is something special about discovering a tiny egg, pupa or other wonder of nature hiding under a leaf. So get looking under those leaves!
The Brimstone is one of the species that makes an appearance in 'The Tree That Held The Moon' to inspire curiosity in the wonders of nature.
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