How Butterfly Wings Display Brilliant Colors

Ever wonder how butterflies flash brilliant colors from their wings? It's not done with pigment. Instead, butterflies use a trick of light that sounds like something out of Star Trek: "photonic crystals."

Photonic crystals are precise arrangements of geometrical patterns at microscopic scales.
On butterfly wings, these patterns might be bumps, holes, ridges, hexagonal arrays or other shapes, often in 3-D arrangements. The shapes are spaced very close to the wavelengths of light i...