Blue

The reds, yellows and browns in this picture of a butterfly’s wing are the result of pigments in the scales on the wing’s surface – but not the blue.

Blue is rare in the insect world. Red and yellow pigments have evolved hundreds of times in thousands of different invertebrate species but the chemistry of blue is more complicated and harder to achieve.

The scales in the peacock’s wing that appear blue are, in fact, transparent and ridged. We see right through them to the under layer of the wing. That under layer reflects blue light back through the transparent scales and the complex ridges scatter the blue into an iridescence. Beautiful!