Some butterflies have beautifully colored wings that can be change depending on the angle at which you look at them. In one South American species of butterfly, the wings are so intensely colored that they can be seen from a distance of 800 meters! How come butterflies have wings of such beautiful and bright colors?

The remarkable feature of the Indonesian green swallowtail butterfly (Papilio Blumei) is that it contains rows of very small concave surfaces that reflect light in many ways. For instance, the center of the concave surface reflects a yellow-green light and the edges reflect a blue light.

At the center of the concavity, light is reflected directly but when light hits the edges, it bounces off into forming many layers, which amplifies and rotates the waves of light.

The final blend that are created in this complex process are called structural colors.

Papilio Blumei can be found only on the Indonesian island of Sulawesi. It is sometimes confused with the more widespread Papilio palinurus, but that species is smaller and has mostly black tails (in Papilio blumei, the upper surface of the tails is mostly bluish-green).