The colour patterns on the wings of Lepidopterans (butterflies and moths) are costructed from thousands of scales. The sunset moth, Chrysiridia rhipheus have unique, iridescent patches which are produced not by pigmentation, but by microscopic adaptations to the structure of the scales themselves. Each one is made up of multiple layers, held separated by randomly located cuticle blocks and air-filled gaps. This generates optical interference, strongly reflecting specific wavelengths of light. The curvature of the scales is also unusual and increases reflectance within and between scales and enhancing the colour-changing effect.
Image courtesy of Linden Gledhill. See more of Linden’s work here.