Butterfly of the Month - October 2022
The Blue Triangle (Graphium choredon) is a striking butterfly, easily recognisable by appearance and size. The female’s wingspan reaches 60mm while the male is slightly smaller at 57mm.
What makes this butterfly stand out are the bright turquoise-blue wing markings on black background on the upper side. Please note the three spots at the apex of the forewing finishing off the triangular shape. That central turquoise-blue band extends across the hindwing to the dorsal (inner) edge. Four halfmoon shaped blue spots stretch across the outer margin of the hindwing concluding the arrangement with a fifth white one. The male Blue Triangle can be distinguished by its sex markings which take the shape of very fine hair of a surprising length, arranged along the inner edge of the hindwing. Sorry, no image available.
The wing underside is very similar. However, the markings are a little lighter and the background takes on a dark brown colour Additionally, the hindwing shows a short red stripe at the base and a series of markings of the same colour flanked by black spots.
Spherical cream-coloured eggs of less a 1mm start off the life cycle of a Blue Triangle. They are smooth in appearance and shiny. The larvae appear in different shades of green. All instar stages are sprinkled with the tiniest of yellow dots and carry a white or yellow line along the lower part of the larva’s body. The thorax is humped which is especially pronounced in early instar stages. The foremost segments of the thorax carry pairs of small black spines, the upper middle segment has a pair of slightly longer spines which are connected via a yellow line. The anal thorax segment show a short pair of white spines. The pupa blends perfectly into the background camouflaged by colour and pattern. Narrow yellow ridges appear to mimic leaves.
Many of us associate the butterfly with the exotic Camphor laurel (Cinnamomum camphora). While larvae are known to feed on this widespread weed tree, there are plenty of native alternatives available in Brisbane. Among them members of the Laurel family (Lauraceae) like Blush Walnut (Beilschmiedia obtusifolia), Brown laurel (Cryptocaryia triplinervis), and White bolly gum (Neolitsea dealbata) as well as others including Broad-leaved scrub wilga (Geijera salicifolia), Lolly bush (Clerodendron spp);
Images: DM – Deborah Metters; PC – Peter Chew/Brisbane Insects; SA – Sylvia Alexander