THE ancient Egyptians worshipped it and strove to duplicate its iridescent colours. Now physicists have laid bare the secret of the scarab beetle’s unusually vibrant shells.
Gymnopleurus virens beetles have shells that change from red in the centre to green around the edges or from green to blue. To understand why, John Brink of the University of Pretoria in South Africa and his colleagues examined the shell under an electron microscope. They found that the shells are made of thousands of ultrathin layers, with each successive layer slightly twisted in relation to the one above. “It’s a corkscrew effect,”…
