This is a good season for butterflies – still warm, and all their food plants still growing well with the last of the Wet season – and several species besides the Cairns Birdwing and Ulysses are still around in good numbers. The lady above is a Common Eggfly, Hypolimnas Bolina, also known as the Varied Eggfly. The males are consistently dark with blue-white eye-spots but the species earns its alternate common name through the wide variation in the females’ upper wing coloration. The one pictured is one of the darker forms; visit this set of my photos on flickr to see the males and other female colour schemes. We also have another closely related species, the Blue-banded Eggfly, Hypolimnas alimena. They are much the same size and their undersides are much the same colours – standard dead-leaf camouflage colours with some white markings – but the males’ upper wing surfaces are quite different.
The apparent colour of all these butterflies changes with the viewing angle, as seen in the photo above, in which the two wings are seen from different angles and almost look as though they belong to two different butterflies. The effect is due to the physical structure, not the pigments, of the scales on the wings and Wikipedia’s Structural Coloration page is a good starting point for anyone wishing to learn more about it. Males of both these species are aggressively territorial so I was quite surprised by these two seen amicably sharing the same creeper: