Blue morpho butterfly iridescence. Blue morpho butterfly (Morpho peleides) about to be dipped into water to show the difference it makes to the appearance of its iridescence wings. This colouration is not due to pigmentation, but the diffraction of light by microstructures on the scales. It is thought that this iridescence is used for long-distance communication. This butterfly lives in the canopies of South American rainforests. For an image showing the change in wing colour when submerged in water see Z355/1431.