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KINGDOM : Animalia
PHYLUM : Arthropoda
CLASS : Insecta
ORDER : Coleoptera
FAMILY : Scarabaeidae
SUBFAMILY : Cetoniinae
GENUS : Chalcothea
SPECIES : C. Smaragdina
 EUROPEAN CHAFER BEETLECLICK FOR DOWNLOAD |
The body of this flower chafer grows up to 3 cm in length, with all dorsal regions distinctly metallic green in appearance.Contrary to many other scarabaeid beetles, the body is elongated and features a pronounced, angular pronotum.The body is oblong, with distinct "neck" between head and pronotum. Elytra are metallic green and much broader than pronotum. The shimmering colour effects we see on many insects are not the result of pigments, but of special nanostructures in their body. A research team at the University of Fribourg has now discovered Chalcothea smaragdina is able to produce its metallic green colour. They investigated the chafer's chitin exoskeleton using electron and atomic force microscopy, and found a helicoidal structure in the outermost layer. This so-called exocuticle has roughly 70 layers of the finest fibres (micro-fibrils) on top of each other, staggered at regular intervals. It's precisely this arrangement that is needed to reflect a single, unique colour. In this case it's green. When light is reflected off it, it adopts a specific direction of oscillation, known as being circularly polarised. A grate-like structure on the surface of the exocuticle also helps to mitigate the reflection of non-polarised light. The researchers have also shown that when viewed through a polarisation filter, the chafer appears even more luminescent. Many insects can perceive this polarisation of light, but birds and mammals can't. By creating polarised light, the chafer probably catches the eye of others of its species, while at the same time remaining camouflaged from predators.
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