BUTTERFLIES have a hitherto unknown way of making black on their wings. Instead of relying solely on light-absorbing pigments, as it was thought every black animal did, the insects use specially structured wing scales to absorb light.
Different scales absorb, scatter and diffract light in ways that produce colours, such as the intense blue of the male Papilio ulysses (above). On this species these blue areas are enhanced by a black frame, which Pete Vukusic of the University of Exeter in the UK and his colleagues have found reflects only about 5 per cent of light that hits it. “It’s…
