Gonepteryx rhamni - Brimstone. Family Pieridae. This butterfly is widely distributed throughout Europe with the exception of northern Scandinavia. In the British Isles it is found in England, Wales and Ireland, but becomes less common further north and is absent from Scotland. It occurs up to 2000 meters on open ground and in light woodland. The caterpillar is bluish-green with a pale line low down along each side. It feeds on buckthorn (Rhamnus catharticus) and alder buckthorn (Frangula alnus) and when full grown pupates on the foodplant. The enlarged, green wing-cases of the pupa resemble a curled leaf. The butterfly is on the wing from July to September and after hibernation from as early as February until June. This species is single-brooded but individual specimens may live for more than ten months. It is a common sight in gardens and has been well known since the mid seventeenth century. It seems quite probable that its yellow colour gave rise to the name butter-coloured fly which has since been contracted to 'butterfly'.
Text from: Butterflies and Moths in Britain and Europe (1982) David Carter. Pan Books
