Source: Science News
This is a narrative about camouflage, but don’t think of mud-blob brown, mealy beige, or dismal green when you think of camouflage. Scientists investigate the phenomenon of mirror glitter and the counterintuitive concept that there is a bright side to the mask.
According to visual ecologist Amanda Franklin of the University of Melbourne, mirrorlike surfaces have developed in open-ocean fishes and spiders, butterfly chrysalises, and most branches of the wide variety of beetles. In one standard theory, these living mirrors’ reflections of water, leaves, or twigs might confuse predators, causing them to flee in fear.
Franklin and her colleagues resorted to a spectacular collection of roughly 40 species of scarab beetles for a test of dry-land mirrors, some of which had a natural sheen to their scales. They dress in golds, bronzes, greens, and blues and climb up eucalyptus trees to flirt and mate at the peak of summer in their native Australia, which is December. “Christmas bugs are prevalent,” Franklin explains.
Anoplognathus parvulus (bright) and Anoplognathus prasinus (matte) are two greenish Christmas insects that Franklin set out to produce nubs of clay about the form of two greenish Christmas beetles, one with a mirror finish and one with a matte finish, to investigate whether excellent reflection provides protection (dull). It was simple to create a “brushed-metal” effect, but she required faux bugs with a total muscle car metal sheen to complete the image. She also needs something that could be made quickly. ‘If you have to sand it for the rest of the day, you aren’t going to earn a thousand dollars,’ Franklin explains.
However, prototype after prototype fell short of expectations. The result of around six weeks of frustration was that “we probably had hundreds of items in the trash bin.” Working with a specialist at a hobby store where her father had been purchasing supplies for constructing model World War II aircraft for years, she was able to solve the enigma of the mirror.
To achieve beetle-grade reflectivity, it was necessary to locate precisely the correct super-smooth resin to cover the models before spraying them with reflective paint. Then, the mirror-like models could approximate the relative difference between the mirror species and its drabber counterpart with a bit of sanding.