Bug Alchemy: Gold and Silver Beetles

All that glitters is not gold. That metallic glint might be sunlight bouncing off a beetle’s shell. The Chrysina aurigans [top left] and Chrysina limbata [top right] specimens shown here bear such an uncanny resemblance to polished nuggets of gold and silver it may be hard to believe that their exoskeletons are made of the same stuff—chitin—that covers drab cockroaches and crayfish.

These beetles shine not because of chemical pigmentation or the incorporation of actual metals. Instead, a closer look at their elytra—the hard forewings that conceal the beetles’ more delicate hindwings—reveals a multilayer nanostructure that tricks the light in just the right way to create metallic effects.

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