Gonepteryx rhamni (Linnaeus, 1758)

Description: Wingspan 60-74mm. The word butterfly is believed to be a contraction of butter-coloured fly a name which is considered to have been used for this species. The name Brimstone has been in use for over 300 years. Adults are large and have pointed fore and hind wings, giving the resting insect a leaf-like appearance. The wings are bright yellow (male) or greenish-yellow (female) with no black markings. The antennae and the hairs on the head are pinkish-brown.

Similar Species: The combination of large size, colour and wingshape is unique amongst Irish butterflies. The Clouded Yellow is smaller with prominent black borders to the wings.

Key Identification Features:

• Wings yellow (male) or green (female) with no black markings
• Wing shape

Sets:

Flight Period: Adult Brimstone are the longest-lived of our butterflies. They appear in July and enter hibernation by mid-September. They emerge in late spring and may live to June or early July. In N. Ireland most records have been in spring and early summer.

Status: Presently considered extinct as a breeding species in N. Ireland. Reports are received in most years of a few adult Brimstones, but these are considered to be wandering individuals of unknown origin. Adults and larvae were seen widely in Fermanagh for a number of years up to 1985 but this population has died out.

Ecology: This is a wide-ranging non-colonial species associated in most of its range with woodland edge and scrub, damp heath and fens. In Ireland it is particularly associated with scrub growing on calcareous soils and the shores of large lakes. When they emerge in summer the adults of both sexes feed on nectar sources prior to entering hibernation. Favoured plants are purple, nectar-rich flowers such as Teasel Dipsacus fullonum, Buddleja Buddleja davidii, Purple-loosestrife Lythrum salicaria and thistles. Adults hibernate under the leaves of bushes including Ivy Hedera helix, Holly Ilex aquifolium and Bramble Rubus fruticosus in woodland. After emergence in spring, males patrol the habitat searching for females. When a female is located both sexes spiral into the sky in a courtship flight before mating. Females then wander, searching for suitable foodplant on which to lay her eggs. The only larval foodplant used in Ireland is Purging Buckthorn Rhamnus cathartica which in N. Ireland is confined to the Lough Erne basin in Fermanagh.

World Distribution: North-west Africa, Europe from Spain and the Mediterranean northwards into southern Scandinavia and eastwards to W. Siberia and Mongolia.

Bradley & Fletcher number: 1546 Agassiz number: 58.013

Additional information:

UK Butterflies account

Caterpillar: