Transparent insect wings actually rainbow-colored

Insect wings that look transparent and drab to our eyes – like the wings of small flies and wasps – apparently look more like peacock feathers to other insects. That’s according to a new study, published this week in the Proceedings of the National Academy of Sciences. Ekaterina Shevtsova of Lund University in Sweden, lead author of the new PNAS study, told us:

People used to think of them as not very attractive, but they’ve got all these colors and exciting patterns.

By looking at transparent insect wings in a new way, under the microscope – against a black background instead of white one – Shevtsova and her team discovered that these wings display a rainbow-variety of color. She said:

These colors are the same like we have when we look at soap bubbles, or we have a film of oil on water on a surface. We see colors like magenta, green, and yellow. These liquids, they are very thin so they produce colors as an optical effect. Insect wings work the same way, because they are very thin.

Shevtsova said the colors in the wings of wasps and flies are partially created by physical microstructures of the wings — things like specialized membranes and hairs.

She said that she suspects that very tiny insects, much like butterflies, use the colors on their wings to communicate. She said:

Of course mating behavior and courtship behavior when they flash wings and show colors. These colors might be involved in signaling.

And might even be used to scare tiny predators, like spiders.

Shevtsova clarified that, while the colors in insect wings do resemble the rainbowed looked of an oil slick, there’s a difference between the color patterns in an oil slick and the color patterns in the wings of wasps and flies. The colors in insect wings are fixed. In other words, they don’t move around. She said:

These colors, it’s not like just any colors, it’s certain colors in certain sequence. And even if you have magenta, green, blue yellow colors, we do not observe red.

She said that’s likely because small insects with transparent wings – flies and wasps, for example – don’t see red. Very fittingly, they don’t produce red on their wings. But they do have quite a bit of blue. Shevtsova said a pattern that came up repeatedly in the wings of flies and wasps was a blue dot.

Blue colors seem to be stable in many many specimens and its in the same area of the wing. All males have a blue spot and they might show it in courtship behavior to females, for example.

On the other hand, butterflies – which are also insects -see things a little differently. While wasps and flies perceive blue very well – things near the ultraviolet end of the spectrum – butterflies have special receptors for the color red in their eyes. Accordingly, they tend to have lots of red in their wings. And, as a consequence, probably use red as a special color for communication.

Shevtsova indicated that her research could help contribute to understanding of how genes control wing development in insects.

Insect wings that look drab to us (left side) look rainbow-colored to other insects (right side.)

Related: Jaap de Roode: Monarch butterflies use plants for medicine

January 5, 2011

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Beth Lebwohl

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