The beetle that wears every colour at once

There is no green pigment in this beetle. Its shell is built from thin layers that reflect some wavelengths and cancel others, so the colour changes as the light moves — gold at the shoulders, green down the back, a blue that only appears at the edges.

I spent a week trying to paint one in gouache and failed every time, because paint gives you one colour per place and the beetle gives you three. What finally worked was to stop blending: flat patches of gold, green and blue laid side by side, the way a mosaic does it, and let the eye do the mixing.

It is the same trick the Impressionists used on water, and it is humbling to find a beetle doing it better.