| | Beetles | Beetles (Coleoptera) are the largest order within the Class of insects. They are grouped in 166 families and hundreds of new species are discovered every year. Beetles are found throughout the world except in Antarctica. Central Europe has around 8,000 different beetle species. The oldest beetle fossils date from about 265 million years ago.
Beetles’ bodies are significantly different to other insects’ in that they do not solely comprise head, chest and abdomen. The second section consists solely of the prothorax, of which only the neck shield on top of the body is evident. The remaining two sections of the chest, together with the abdomen, form one unit, which is overlaid by the first pair of wings (the cover wings).
Beetles can vary enormously in size ranging from 170 mm in length (Titan beetle in Brazil) to lengths of 0.5 to 75 mm (European species). The largest beetle in Germany and Central Europe is the stag beetle. | | |
| | | Beetles’ body shapes are very diverse as a result of adaption to environment. They can be long, lean, short and stocky as well as flat and sometimes streamlined. The structure of the beetle’s surface is an important criterion for classification. The surface can be smooth, ridged, shiny, grooved or with cavities and bumps. Beetles are sometimes bizarrely shaped as a means of camouflage.
Another important distinguishing feature is the color of the beetle, which varies as greatly as the body shape. While most beetle species are dark or brownish in color, there are species whose surface has a luminous pattern or metallic sheen. | | |
| | | All beetles use virtually any organic food source however the larvae have a completely different diet to the adults. Beetles can be classified according to what they eat. There are two types coprophagous and necrophagous. The former feed on excrement (earth-boring dung beetles) and the latter on carrion (Silphidae).
The excretions of both species are from great importance at the remineralization of the soil. Beetles, like all living creatures, are dependent on water. There are species that live under or near the water like hygrophiles or predaceous diving beetles.
Depending on which species they are, beetles fly shorter or longer distances. There are also species that are not capable of flight because (as is the case for most ground beetle species) their wings are missing. There are beetle species producing sounds by moving parts of their bodies. Some beetles are able to generate light (such as fireflies). | | |
| | | The larval stage for most beetle species is the longest period of their lives and can last several years, with the living of the larvae is often similar to the living of the adult beetles. The living of the larvae affects the duration of their larval stage.
In the Palearctic beetles mostly overwinter as pupa and slip off during the spring. Some species overwinter as adult beetles (for example: ladybirds and Hydrophilidae).
The most important natural enemies of the beetles are pathogens (viruses, bacteria, protozoa, fungi), parasites (Ichneumon wasps, tachina flies, Acarina) and enemies like birds, hedgehogs, shrews, bats, reptiles, spiders, fish, amphibians and even other species of beetle which feed on them.
Beetles are often divided by humans into two groups: those that are harmful and those that are beneficial. Sitophilus oryzae and wheat weevil can cause significant damage to cereal stocks, while the Colorado potato beetle, Meligethes aeneus and Western corn rootworm are able to destroy entire harvests. Furthermore Bark beetles, Ips typographus, the Old-house borer and Mountain pine beetles destroy wooden structures, forests and woods. The Asian ladybird is among those considered useful , as it is the enemy of many pests in agriculture and forestry. | | |
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