The Emerald Swallowtail is the chameleon of the butterfly world, as its wings change color depending on the way the light hits them. This is caused by the tiny scales on the wings.
According to the American Museum of Natural History, “When the scales reflect blue and yellow light, their tight arrangement allows the colors to mix together and be perceived as the iridescent green bands from which the butterfly takes its common name. But when its wings are viewed from another angle, the human eye will see the bands as only yellow or blue, respectively.”
