Mystery of butterfly research resolved

High-resolution X-ray tomography reveals how butterflies form their iridescent wing scales.
It has only been one year since the material scientists around Prof. Erdmann Spiecker from the Center for Nanoanalysis and Electron Microscopy (CENEM) at the FAU Erlangen-Nuremberg had been granted funding for one of the World’s best X-ray microscopes, and they could already contribute with fascinating 3D analyses to unravel an open question in butterfly research. Their results have recently been published in the renowned scientific journal Science Advances.

Fascinating colors generated by photonic crystals
Who is not fascinated by the wonderful iridescent colors of butterfly wings? If you try to understand this phenomenon, you will find out that most often the color is not generated by pigments but rather by periodic structures made of chitin, a structure-forming polysaccharide. These so-called photonic crystals give rise to structural col-or by only reflecting specific wavelengths of the incoming solar spectrum. The re-sulting color is not random, but rather serves as camouflage or signalling. But how do millions of these photonic crystals form within the tiny scales of butterfly wings? The opinions of scientists differ in this matter.