Insect Pigments

The colours of insects are as varied as those of a fashion designer's dress show; from the satiny black of the elytra of some beetles and cuticle of black wood ants, through the gaudy colours of some butterflies, to the pinstripes of the Colorado potato beetle (Leptinotarsa) and the polka dots of the ladybirds. Some insect colours are due to the physical effect of interference, such as found on the wings of some butterflies and the surface of scarab beetles; these colours are called schemochromes. The beautiful irridescent blue of some butterflies like Morpho rhetenor and M. didius is due to schemochromes. Chemical substances in the cuticle, on scales or in the haemolymph that cause colours are called chemochromes. The colours may carry a message for the species (recognition, mating, camoflage) or for predators (warning colours of aposematic species). Strictly it must be remembered that the spectra of colours seen by vertebrates and insects are different, that of insects being shifted about 100-150 nm towards the ultraviolet. Carotenes in insects have already been considered in Chapter 7. They are the most widely distributed of all natural pigments.

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