And God Created: Beauty And Functionality In Butterfly Wings
David Everson
As the cool days of spring give way to the warm and sunny days of summer, one of the delights of the season is the arrival of butterflies to blooming flowers. As they visit the flowers, gathering nectar to fuel their flights as they migrate and travel to places unknown, their patterns of flight fascinate with randomness and delicateness. Yet, as a child or an entomologist with a butterfly net knows, catching one of these elusive creatures is not as easy as you would think. Scientists studying the wings of butterflies have now found that much of their erratic flight patterns are controlled by the second set of wings, the hind wings. Let us look at some of the amazing details about the nanotechnology God has created in the seemingly simple, delicate structure and beautiful colors of a butterfly’s wings.
All butterflies have two sets of wings, the fore wings and hind wings. The wings are very fragile structures. They have a frame work of veins covered with scales made of a protein called chitin (pronounced “kite en”). It is the arrangement of different types of scales that give the colors and patterns by which we recognize butterflies and moths. There are three basic types of scales: pigmentary scales, structural scales, and androconia.
The pigmentary scales are mostly flat. Their color is the result of the presence of melanins, pterins, and other chemical pigments. These compounds come from plants that the larva ate on its way to becoming an adult. These pigments account for the basic colors found in butterfly wings: black, red, yellow, and white. The arrangement of the various colored scales over each other and the amount of pigment they contain create the illusion of additional colors such as orange, cream, and green. In some butterflies, very subtle variations in the density and pigmentation of scales can create other illusions, such as texture or shading, which help to give the wings a 3-dimensional appearance.
The next type of scale is the structural scales. Many of the most beautiful and striking colors found on the wings of butterflies are created, not by pigments, but by refraction, or bending of light. This is comparable to the way rainbow hues reflect from thin films of oil in puddles on a rainy day. The really bright reflective colors, however, are produced by a different means - diffraction. In this case light is broken up into its various colors after being bent by prism-like ridges on the surface of the scales. Many of the golden-yellows, the glittering metallic greens, and the almost blindingly reflective blues of many tropical butterflies are produced this way. These diffractive scales can cause some wings to look, from one angle, to be green, and, from another, to be turquoise.
Almost all butterflies and moths have a mixture of pigmentary and structural scales. In combination, these can produce any color ranging from metallic gold to fluorescent orange, iridescent green, sapphire blue, or any other color seen on butterfly wings. They can even display colors beyond the visible spectrum. Most butterflies, in addition to the colors and patterns visible to humans and birds, also have a "hidden" ultra-violet pattern that can be detected only by other butterflies.
The third type of scales, the androconia, is found mainly on male butterflies. They usually exist as slightly raised dark streaks or patches on the forewings. At the base of the androconia are tiny sacs containing scent (pheromones). These scents are disseminated by tiny hairs or plumes on the edges of the scales, and used to attract females for reproduction.
Each of these scales is now known to have three layers in each scale. There is a top layer of cuticle with most of the pigments. The middle layer is an air space, and the lower layer has an Oreo cookie-like arrangement, with two protein layers and an air space in the middle. So, the more we enlarge the microscopic structures of the wing, the more we marvel at the wisdom of our Creator.
While the colors amaze and fascinate, the speed of flight and the elusiveness of these creatures is studied by flight engineers looking to create better airplanes. Both sets of wings are used in flight by butterflies, but only the hind wings help it to turn in such a quick fashion. High speed cameras used to film their flights have shown that the hind wings scope air and provide extra force for quicker turns when the butterflies are being pursued. Removing the hind wing did not affect the ability to fly but did cut their turning acceleration by 50 per cent.
So, when God designed the wing of the butterfly, He showed that incredible functionality and beauty can go side-by-side. As we watch these creatures flit from flower to flower this spring and summer, we should remember to praise our Creator for the marvels of His creation. –Rt 1 Box 116A, Belington, WV 26256. aedeverson@yahoo.com