A globetrotting quest to find blue in the natural world and to understand our collective obsession with this bewitching colour. Blue is a rare colour natural blue that is. From morpho butterflies in the rain forest to the blue jay flitting past your window vanishingly few living things are blue and most that appear so are doing sleight of hand with physics or complex chemistry. Flowers modify the red pigment anthocyanin to achieve their blue hue. Even the blue sky above us is a trick of t