Polarized iridescence of the tropical carpenter bee, Xylocopa latipes

Abstract

The tropical carpenter bee, Xylocopa latipes, has metallic-reflecting, iridescent wings. The wing reflectance spectra for TE- and TM-polarized light depend on the angle of light incidence in a way characteristic for dielectric multilayers. Anatomy indicates the presence of melanin multilayers in the wing’s chitinous matrix. A simple optical model of melanin multilayers explains the angle dependence of the wing reflectance spectra. The wing reflections that occur upon oblique illumination exhibit colourful and strongly polarized light patterns, which may mediate intraspecific signaling and mutual recognition by conspecifics.