Blue morpho butterfly iridescence. Blue morpho butterfly (Morpho peleides) showing the iridescence of its wings. This colouration is not due to pigmentation, but the diffraction of light by microstructures between the scales. Hence, when the wing is submerged in water it changes its iridescence. It is thought that this iridescence is used for long-distance communication. This butterfly lives in the canopies of South American rainforests.