Coleoptera

The Coleoptera (koleón = sheath, ptéron = wing), with over 350 thousand known species, are by far the most numerous Order in the whole animal kingdom. Their main characteristic, from which their name derives, is that of having hardened (sclerotised) forewings, called elytra, which cover the membranous hindwings like a sheath. They are insects with complete metamorphosis and are generally divided into two large Suborders: Adephaga and Polyphaga. The Adephaga, less numerous, are usually predatory and carnivorous, both in the larval and in the adult stage; they comprise a small number of families, whose chief representatives are the Carabidae and Cicindelidae, together with some families of predatory aquatic beetles. The Polyphaga, far more numerous, are mostly omnivorous and above all vegetarian (phytophagous); some feed on wood (xylophagous) or on dung (coprophagous).

Because of their extremely varied diet, the Polyphaga often prove very harmful to the human economy. A well-known example is that of the Colorado potato beetle (Leptinotarsa decemlineata), native to North America, which since 1922 has become permanently established throughout Europe (in Italy it appeared in 1943), causing considerable damage and sometimes irreparably devastating potato crops. Thanks to the extreme variability of their forms and colours, the Coleoptera represent a unique phenomenon in the animal world: from the smallest forms, almost invisible to the naked eye, we come to the giants of the Insect kingdom, 15 centimetres long and more. The elytra, this natural armour, often have bright, metallic colours, such as to have earned many Coleoptera the description of “living gems”; in some tropical countries, in fact, they are often used as ornamental motifs in necklaces and jewellery.