Shedding new light on nature's brightest signals

Most colour in nature arises from pigments, but the most brilliant, deeply saturated visual signals have structural origins. These colours are generated from nanoscale structural arrays that interact with incident light to produce specific optical effects. Perhaps the most dazzling of nature's signals, the iridescent colours of tropical butterflies, have long been known to originate from such structures. However, new research by Vukusic and colleagues reveals the true depths to which evolution has crafted these fascinating optical devices.