The cover picture shows the mechanism of structural color in the famous Morpho butterflies ranging over Central and South America. Their wings are covered extensively with iridescent scales, on which a lot of ridges bristle with regular projections at both sides. In their Review on page 1442 Kinoshita et al. demonstrate that these regular structures assist the selective reflection of blue light through interference, while their irregular heights give the diffusive light through diffraction. Thus the cooperation of regularity and irregularity generates wavelength-selective, highly reflective, and spatially diffusive light in the blue region.