I wrote this six years ago and bumped into it recently while editing some previous writing that I did in the past. I think its important to remind everyone that much of what we have, use, or “discover” already exists in nature. We seem to forget that we are so advanced that we can mimic all natural processes. Take photosynthesis for example. Imagine what we could do by recreating that process!
One of the miracles of late summer in temperate climates is the large fields of wild flowers that can be found as the end of summer approaches. In much of the northern United States and Canada many of these fields are dominated by the many different species of goldenrod. This beautiful plant produces nectar used by countless species, including but not limited to, bees, wasps, and of course, butterflies.
On one bright sunny August day I found myself in a large stand of goldenrod examining galls along the stems of the plant. As I looked ahead across the sea of yellow, I noticed the many different insects collecting nectar from the golden flower heads. My eyes were attracted to the largest of these insects, a butterfly who bounced from plant to plant in search of sweet nectar. I noticed that the wings would appear black and brown, and then blue, green, black and brown depending on the angle it positioned itself on the flower. The blue, green, black phase was absolutely striking. It reminded me of a peacock feather, which from one direction appears black with mottled brown markings on the feather, and from another angle where bands of florescent greens and blues dominate the black background on the feather. When in the correct position the black, blue, and green butterfly stood in remarkable contrast to the bright yellow goldenrod feathers.
African swallow tail butterfly had amazing structures on their wings that manipulate light in such a way that it appeared, at certain angles, as blue and green pigment in distinct patterns on the wing. I have not been able to confirm that this process is utilized by other butterflies that inhabit North America, but it makes sense that this might be a trait shared by butterflies on different continents.
In part, the African swallowtail butterfly uses its brightly colored wings to communicate with other butterflies at long distances. The wings may attract other butterflies with regards to food supplies, mating, and survival. The wings employ a sophisticated method of manipulating light, so that the light can be directed and produce colors. For butterflies that have this color capability, the wings are covered with microscopic scales that absorb ultraviolet light. The scales contain very small photonic crystals that act as mirrors which prevent the light from scattering in a sideways direction. These mirror like structures concentrate the light upward through florescent pigments that emit a blue and green color. To see this color the observer has to be close to ninety degree angle, the direction that the light is reflected.
This is almost the exact same process that modern LED (light emitting diode) lights use to emit the bright blue light that we are familiar with in modern flashlights. The LED light first came out in the 1960’s, and although it used very, very little energy, it simply was not that bright. After many different experiments one clever inventor utilized a system where tiny patterned holes filled with crystals above a multilayered mirror emitted six times as much light as the original efforts.
It proves that once again man often does not invent new technology he simply discovers what nature has already accomplished. This is just one more example of biomimcry, a topic frequently discussed recently by the well known ecologist Janine Benyus, and in the past by Loren Eisely.
That being said, one of the newspaper articles about LED’s that I found had the headline “Butterfly Wing Structures Matches High Tech Light”. A better headline would have been “High Tech Light Matches Butterfly Wing”.
Let us give credit where credit is due.