Structure of Iridescent Lepidopteran Scales: Variations on Several Themes1

Abstract

Although there are many types of iridescent colors among the scales of butterflies and moths, the structures responsible for the iridescence are for the most part achieved by relatively small or minor elaboration of certain architectural elements present in all ordinary or unspecialized scales. These elements include notably the ridges and their associated lamellae and microribs, and the trabeculae, the pillars normally acting as spacers between the two surfaces of the scales. The apparent ease with which these structures can be shaped into complex and elaborate color generators, and the convergence of these specialized structures in unrelated organisms, suggest that the developmental processes shaping the specialized scales are basically simple and may represent small variations on standard patterns of scale development.