Image courtesy Vinod Saranathan
Resembling a patch of reptile skin, these green-orange structures are actually wing scales of the emerald-patched Cattleheart butterfly, as seen under a microscope.
Scientists have long known that the insect's vibrant green wing colors are due to complex crystals in the scales called gyroids, which bend and refract light in specific ways.
(See picture: "Glowing Butterflies Outshine LEDs.")
But since these gyroids are only a few hundred nanometers across, scientists had only captured the structures in fuzzy 2-D snapshots.
Now, thanks to an x-ray imaging technique, "we were able for the first time to unambiguously diagnose the 3-D structures of these complex materials," said study co-author Vinodkumar Saranathan, a biologist at Yale University.
The research appears this week in the journal Proceedings of the National Academy of Sciences.
—Ker Than
Published June 24, 2010
Image courtesy Vinod Saranathan
The wing scales of the juniper hairstreak butterfly shimmer with a green iridescence thanks to crystals called gyroids.
But not all butterflies use gyroids to produce wing color—most get their color from pigments or simpler structures, said study co-author Saranathan. (Watch a video of monarch butterflies congregating in Mexico.)
"Evolutionarily speaking, each of these butterfly families have independently stumbled upon this," Saranathan said. "By using these butterflies as templates, we could reproduce [the gyroids] for artificial technological purposes."
For example, gyroids could be used to produce fade-resistant fabrics that don't require pigments and are visible from all directions.
Published June 24, 2010
Image courtesy Richard Prum
The green patches on an emerald-patched Cattleheart butterfly (pictured) are the result of gyroids embedded in the wing scales.
"The green color is very similar to the leaves [in the butterfly's environment], so we think it helps with camouflage," study co-author Saranathan said.
Scientists think the gyroids only form during the butterflies' cocoon phase, and can't be replaced once the adult insects emerge from their cases.
Published June 24, 2010
A yellow butterfly hit my windshield while driving and left a small yellow mark on glass. Three days later, after rain, while I was driving in bright sunlight I saw the colors of a prism in the spot where the wing had hit. It was beautiful! All remnants of the yellow were gone but the "gyroids" remained on the glass and bent the sunlight as it passsed throught the glass.
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