Researchers Discover Optical Secrets of Beetles' Metallic-like Appearance

Posted on April 25, 2011

Why are some beetles so metallic and shiny? A team of researchers at the University of Costa Rica believe the metallic appearance of some species of beetles may help them go unnoticed by potential predators. The brilliant gold- (Chrysina aurigans) and silver-colored (Chrysina limbata) beetles have also given optics researchers new insights into the way biology can recreate the appearance of some of nature's most precious metals. The blinged-out beetles above were captured in the University of Costa Rica's Alberto Brenes Mesen Biological Reserve, a tropical rainforest environment.

Physicist and study leader William E. Vargas, says in a statement, "The metallic appearance of these beetles may allow them to be unnoticed, something that helps them against potential predators. The surface of their elytra reflects light in a way that they look as bright spots seen from any direction. In a tropical rainforest, there are many drops of water suspended from the leaves of trees at ground level, along with wet leaves, and these drops and wet leaves redirect light by refraction and reflection respectively, in different directions. Thus, metallic beetles manage to blend with the environment."

The beetles have a cuticle which contains 70 separate layers of chitin. Each of the chitin layers have different refractive indices. Light reflected through a sequence of these chitin layers creates the beetles' metallic look.

The researchers say the discovery of how the beetles produce a metallic appearance could potentially lead to new products or consumer electronics that can perfectly mimic the appearance of precious metals. The full research article can be found here in OpticsInfoBase.

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