Some butterflies can be seen from as far as half a mile away. What makes metallic colors on the wings so intense and pure? The colors change depending on the angle you see it from. The wings have tiny concave surfaces which reflect light in various ways. In Papilio blumei (green swallowtail) the center of each concavity reflects yellow-green light, while the edges reflect blue light. The light at the center is reflected directly. Also light striking the sides first bounces through a surface of multiple layers which amplifies, polarizes and rotates the light waves. The final mix produced in such a complex way is called structural color. Researchers are trying to replicate the butterfly's wing surface. This technology could be used to produce credit cards, bank notes that are harder to forge and solar cells that are more efficient. Despite the detailed scientific understanding of optics, the astonishingly varied colour palette found in nature often surpasses the optical effects that can be generated by technological means. writes Professor Ullrich Steiner of Cambridge University’s Nanoscience Centre.
Source: Awake Magazine March 2012 and Eye of Science/Photo Researchers, Inc.

Mountain Blue Swallowtail Butterfly (Papilio ulysses)

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To contact Marco Peña go to: marcop@ag.arizona.edu

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.