Amazing World of Insect-Wing Color Discovered [Bugs]

A closer study seemingly drab, transparent insect wings has revealed realms of previously unappreciated color, visible to the naked eye yet overlooked for centuries.

Until now, the wing colors of many flies and wasps were dismissed as random iridescence. But they are as distinctive and marvelous as the much-studied, much-celebrated wings of butterflies and beetles.

” Given favorable light conditions, they display a worldwide of brightly patterned wings which can be apparently unnoticed by contemporary biologists,” wrote researchers led by University of Lund entomologists Ekaterina Shevtsova and Christer Hansson in a December 3 Proceedings of the National Academy of Sciences paper.

Wasp and fly wings are made out of two compressed layers of transparent chitin, with light bouncing off both layers and mixing to provide color. An identical is right of oil slicks and soap bubbles, and scientists considered transparent wing coloration ” a soap bubble iridescence effect, with randomly changing colors flashing over the wing surface,” wrote the researchers.

Instead, the researchers found that surface variations in chitin filtered out the iridescence. Remaining colors proved to be stable, and were visible from almost any angle. They differed consistently between species and sex.

Generations of biologists seem to have missed this partly because they didn’t search for it, and partly because the colors are most obvious against a depressing background. Against a white background, they’re invisible – that’s exactly how most entomologists study transparent wings.

” You hold the wing up against the light, so you will discover the veins,” said study co-author Daniel Janzen, an evolutionary ecologist at the University of Pennsylvania. ” Whenever you’re searching through a microscope, you are trying to get a clear view behind the wing. It’s the antithesis of getting wing color.”

The researchers studied wings under microscopes, against black backgrounds. But once Janzen, who breeds wasps for his research on caterpillar-parasite symbioses, started to appear, colors may be seen by the naked eye as wings omitted insects’ black bodies.

” They flash like little diamonds,” he said.

The researchers think the coloration has specific functions, particularly for mating, just as it does in butterflies and beetles and other insects with better-appreciated markings.

The patterns can even help scientists distinguish between species difficult to distinguish in alternative routes. Already the researchers used transparent wing colors to identify three new species of wasp.

According to Janzen, no less than a dozen other orders of insects, spanning dragonflies and cockroaches and grasshoppers, have transparent wings prone to be as colorful as those of wasps and flies.

” I envision taxonomists going back to their animals, and looking out at them in a new light,” he said. ” It’s like discovering an entire new piece of the animal.”

Images: 1) Fruit fly against white and black backgrounds./PNAS. 2) Patterns in fly wings (top half) and wasp wings (bottom half)./PNAS. 3) Composite image of fly against white and black bacgrounds./PNAS. The photographs are all true-color, modified only by a 10 percent increase in color saturation.

Citation: ” Stable structural color patterns displayed on transparent insect wings.” By Ekaterina Shevtsova, Christer Hansson, Daniel H. Janzen, and Jostein Kjærandsen. Proceedings of the National Academy of Sciences, Vol. 108 No. 1, January 4, 2011.

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This post is tagged: evolutionary ecologist, national academy of sciences, proceedings of the national academy, proceedings of the national academy of sciences, university of lund