Blue Morpho Butterfly

Morpho menelaus is one of about 30 species in the Neotropical genus Morpho, all famous for the brilliant iridescent blue wing color of the males. The blue is not generated by any pigment — there is no blue chemistry in the wing. Instead, microscopic Christmas-tree-shaped ridges arrayed across each wing scale at intervals close to the wavelength of blue light cause constructive interference of light reflected from successive layers, while destroying other wavelengths. The result is a structural color so pure and so bright that flying males are visible from a kilometer above the rainforest canopy. The undersides of the wings are dull brown with eyespots — when at rest, the butterfly nearly disappears. The flight pattern is dazzling in a literal sense: as the male flaps, his wings flash from intense blue to invisibility and back, confusing avian predators that try to track him. Morpho biology has driven a productive research program in 'biomimetic' optics: anti-counterfeiting holograms on currency, color-fast textiles that don't fade, infrared-reflective coatings for energy-efficient buildings, and improved solar-cell architectures all draw on Morpho wing structure. Adults feed on rotting fruit, fungi, and tree sap — they're rarely seen at flowers.