Not just another pretty face

Cover illustration: Not just another pretty face

The Union Jack butterfly (Delias myisis) is found along the tropical northeast coast of Queensland, Australia, including the Cape York Peninsula, and has the typical languid and random flight of most butterflies. But the behaviour of these solitary creatures belies their dynamic physiology, surprising learning abilities, and truly sensational visual mechanisms.

Investigators seeking further understanding of the visual mechanisms found members of a closely related species to be quick studiers when learning the whereabouts of food. Moreover, through behavioural techniques, these same investigators proved that butterflies definitely have colour vision, and even have colour constancy. This ability allows the neurological system of butterflies to draw conclusions about colour (and food sources) when the same wavelength may be not presented. For example, a flower that appears red in broad daylight may appear to be a dark maroon on an overcast day and/or when blooming in the shade of a tree. Any animal that relies on colour perception for food must have some degree of colour constancy or would not be able to recognise food sources in differing light. As with many other insects, butterflies also see into the ultraviolet, and can even detect polarised light. Many butterflies have inborn preferences for certain colours. Although not evaluated in many butterfly species, some species are known to have preferences for yellow and/or blue.

Usually when you see a butterfly, though, you don't think of colour constancy. …