Emerald-patched Cattleheart Butterfly Wing
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.
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.