How Buckeye butterflies produce wing color

Today’s Video of the Day from the National Science Foundation describes a study led by UC Berkeley and the Marine Biological Laboratory. The researchers found that Buckeye butterflies and other Junonia species can produce a rainbow of colors by changing the thickness of the bottom layer of the wing scale.

The experts explained that structural color is created by microscopic structures which interact with light to project certain colors and inhibit others. 

On the other hand, pigmentary coloration is created by the absorption of specific wavelengths of light. This type of coloration typically produces yellow, orange, and brown.

“It was a surprise to find that the lamina, a thin sheet that looks very simple and plain, is the most important source of structural color in so many butterfly wing scales,” explained study first author Rachel Thayer. 

“In each Junonia species, structural color came from the lamina. And they are producing a big range of lamina thicknesses that create a rainbow of different colors, everything from gold to magenta to blue to green. This helps us understand how structural color has evolved over millions of years.” 

“The color comes down to a relatively simple change in the scale: the thickness of the lamina,” said study senior author Nipam Patel. “We believe that this will be a genetically tractable system that can allow us to identify the genes and developmental mechanisms that can control structural coloration.” 

Video Credit: NSF

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By Chrissy Sexton, Earth.com Staff Writer