Emerald-patched Cattleheart Butterfly WingResembling 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

Image courtesy Vinod Saranathan