Structural Layers Origin Of The Blue Colour Reflections On The Wings Of The Junonia Orithya Madagascarensis

Abstract

This article is devoted to the study of the structural layers origin of the blue reflections on the scales of the wings of the Junonia orithya madagascarensis, a butterfly of the Nymphalidae species. We proceed by spectrophotometry and scanning electron microscope (SEM) characterization of these layers to explain the origin of the blue color of the wings. We also made numerical calculations to simulate the structural nature of these layers which help to support the experimental results. Indeed, from the measurements using the spectrophotometer, a main peak of reflection was obtained at 483 nm. From our calculations results we get a 515 nm for the dominant length in reflection and 510 nm for the numerical reproduction of the reflectance spectrum, respectively. These results confirm that the multilayer structure is at the origin of the blue colour of the dorsal scales of the wings of the Junonia. A very thin membrane is responsible for it. This membrane diffuses sunlight at its upper and inner surface. Therefore, it is called structural coloration. It is possible to consider artificial reproduction for the multilayer through a process of deposits in order to manufacture materials at nanometer scale with selective reflection.