Analysis of the optical properties of the silvery spots on the wings of the Gulf Fritillary, Dione vanillae

Andrés Dolinko,Candela Szischik,Marina Inchaussandague,Pablo Tubaro,Diana Skigin,Ana Barreira,Ernest Ronald Curticean,Irene Wacker,Hendrik Hölscher,Christian Lutz,Yidenekachew Donie,Luisa Borgmann,María Sol Vidal

doi:10.1038/s41598-021-98237-9

Abstract

The ventral face of the wings of the butterfly Dione vanillae is covered with bright and shiny silvery spots. These areas contain densely packed ground- and coverscales with a bright metallic appearance reflecting more than 50% of light uniformly over the visible range. Our analysis shows that this optically attractive feature is caused by the inner microstructure of the scales located in these areas. Electron microscopy of cross sections through the scales shows that upper and lower lamina, supporting trabeculae, and topping ridges can be approximated by a ‘circus tent’-like geometry. By simulating its optical properties, we show that a moderate disorder of this geometry is important for the uniform reflection of light resulting in the silvery appearance.

Highlights

The ventral face of the wings of the butterfly Dione vanillae is covered with bright and shiny silvery spots
Our experimental analysis of the silvery spots of D. vanillae shows that they consist of densely packed ground- and coverscales
Our simulations evidence that their metallic appearance is caused by broadband reflections of the disordered three layer system which consists of upper and lower lamina and the air layer in between

Summary

Introduction

The ventral face of the wings of the butterfly Dione vanillae is covered with bright and shiny silvery spots. These areas contain densely packed ground- and coverscales with a bright metallic appearance reflecting more than 50% of light uniformly over the visible range. Colours in nature are so numerous because they serve many purposes ranging from camouflage and courtship to thermoregulation and protection against ultraviolet (UV) radiation In many cases these colours are caused by pigments and dyes. In recent years scientists have become interested in such structural colours because they have several advantages compared to pigments and dyes They are extremely bright and attract attention even when displayed in a colourful environment. Colour mixing leads to broadband silver reflection, the detailed scale structure is different to that of Argyrophorus argenteus

Methods

Findings

Conclusion