The Diamond Weevil, Entimus imperialis, inhabits Southwest Brazil. Its name comes from the brilliant green diamond spots on its body. The color is not a pigment, but a structural color. A group of Dutch Scientists* has been measuring the reflective properties of the beetle.
The beetle has a black cuticle dotted with pits. The pits contain photonic crystals that reflect the color. The black cuticle breaks up the outline of the weevil making it more difficult to spot. Housing the crystals in pits prevents the crystals from being scratched or damaged in the environment which might affect the structural color.One property of structural colors is that the color can change depending on the angle of view. When viewed from afar, the crystals on the weevil reflect a green color that allows the weevil to blend with the green color of the foliage. When viewed from close range, the angle of viewing changes as do the colors. Instead of a camouflage green, a brilliant color pattern is observed. At close range, the color pattern is useful for mate recognition.
*Bodo D. Wilts, Kristel Michielsen, Jeroen Kuipers, Hans De Raedt and Doekele G. Stavenga. Brilliant camouflage: photonic crystals in the diamond weevil, Entimus imperialis. Proc. R. Soc. B 7 July 2012 vol. 279 no. 1738 2524-2530