Nature gifts us with a tantalizing array of phenomena, which can make us go bonkers owing to the complexity of the same. One of these awe-inducing aspects of nature includes the creation of the dazzling colours of butterflies. They get their colours from two sources: ordinary and structural colour. The ordinary colour comes from chemicals that absorb certain wavelengths of light while reflecting the others. Most of the butterflies are brown or yellow in colour due to their melanin pigments, just as the melanin in human skin gets tan in summer. But it is the structural colour of the butterflies which differentiates them rest of the animal kingdom when it comes to patterns and colourful overlays on the bodies. Their structural colour is due to the specificity of the structure of their wings.
Their colour changes as the light passes through a transparent, multi-layered surface of the wings and is reflected more than once, each of these multiple reflections intensifying the colour. This effect is known as iridescence, commonly found in mother of pearl seashells, fish, peacock’s feather and many more birds and animals. The wings of the butterfly and the way they move are a key factor in changing their colour. The wings with more degree of layers show a higher effect of iridescence, allowing the light to penetrate and then pass through them. This, indeed, provides an opportunity for these light waves to hit the wing, interact with them, reflect and, in turn, get magnified. The combination of all such reflection forms very intense colours as found in many species of the butterfly.
When these insects fly, the upper surface of their wings continuously changes its color from bright blue to dull brown. This is due to the angle of the light striking the wing getting changed, and the dark undersides of their wings strengthening this effect. Thus, combined with an undulating pattern of flight and having the ability to change color in the blink of our eyes, these butterflies make it tough for predators to pursue them in spite of their vibrant colors. The open apparent secret here lies in the inherent way in which light reacts with a physical object and creates the patterns on the object according to the way in which the object moves and reciprocates to light as a whole.
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