Around 3700 butterfly species live in Germany. About 95 percent of them belong to the moths. They have the reputation of being much more monotonous in color than their relatives flying during the day. But this first impression is deceptive, as a study by Meng Li from Lund University and her team in the »Journal of the Royal Society Interface« shows: Under the right light, owl, moth or bear butterflies present themselves in iridescent colors.
To this end, the working group examined 82 animals from 26 species and photographed their wing scales using a special technique that detects certain wavelengths of light that are invisible to the human eye. It turned out that the wings literally glow in the infrared range and show a wide variety of colors, while in sunlight they just look brown or gray.
The different types also reflected the light in different patterns: each species has a specific signal. These patterns helped the team to determine the structure of the scales on the wings of the moths. The black and white colored forms of the birch tensioner (Biston Betularia), for example, also differ in the structure of their wing scales. So far, it has been assumed that only the melanin content determines the wing color.
The deviating infrared signatures could contribute to the identification of moths, Li and Co. now hope. After all, the diversity of moths has so far been insufficiently recorded. However, there are reasons why they appear rather monotonous to the human eye. During the day, the moths have to hide from predators: muted tones seem helpful.
