| Rhinoceros Beetles | |
|---|---|
| Adult male Chalcosoma caucasus (Dynastini) on an adult human's hand |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Coleoptera |
| Suborder: | Polyphaga |
| Infraorder: | Scarabaeiformia |
| Superfamily: | Scarabaeoidea |
| Family: | Scarabaeidae |
| Subfamily: | Dynastinae MacLeay, 1819 |
| Tribes | |
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6-8, see text |
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The Rhinoceros Beetles or Rhino Beetles are a subfamily (Dynastinae) of the scarab beetle family (Scarabaeidae). Other common names – some for particular groups of rhino beetles – are for example Hercules beetles, unicorn beetles or horn beetles. There are over 300 known species of rhino beetles.
Many rhino beetles are well-known for their bizarre shapes and large size. Famous species are for example the Atlas Beetle (Chalcosoma atlas), Common Rhinoceros Beetle (Xylotrupes ulysses), Elephant Beetle (Megasoma elephas), European Rhinoceros Beetle (Oryctes nasicornis), Hercules Beetle (Dynastes hercules), Japanese Rhinoceros Beetle or kabutomushi (Allomyrina dichotoma), Ox Beetle (Strategus aloeus) and the Unicorn Beetle (Dynastes tityus).
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They are among the largest of beetles, reaching 150+ millimeters in length, but are completely harmless to humans because they cannot bite or sting. They have been documented to support items that are up to 850 times their own weight. Their common names refer to the characteristic horns borne only by the males of most species in the group. They have a horn on the thorax and another horn pointing forward from the center thorax. The horns are used in fighting other males during mating season, and for digging.
The body of an adult rhino beetle is covered by a thick exoskeleton. A pair of thick wings lay atop another set of membranous wings underneath, allowing the rhinoceros beetle to fly, although not very efficiently, owing to its large size and large horns. The best protection they have from predators is their size and stature. Additionally, since they are nocturnal, they avoid many of their predators during the day. When the sun is out, they hide under logs or in vegetation to camouflage themselves from the few predators big enough to want to eat them. If rhino beetles are disturbed, some can release very loud hissing squeaks. The hissing squeak is created by rubbing their abdomen against the ends of their wing covers. Rhino beetles are rather well-protected, and the adults usually live 2-4 months, occasionally longer.
A rhino beetle's larval stage can be several years long, and is very time consuming. The larvae feed on rotten wood and the adults feed on nectar, plant sap and fruit. First, the larvae hatch from eggs and later develop into pupae before they reach adult status (see picture at left). The females lay 50 eggs on average. Contrary to what their size may imply, adult rhino beetles do not eat large amounts, unlike their larvae, which eat a significant amount of rotting wood.
Rhino beetles are popular as pets in parts of Asia. This is in part due to their being clean, easy to maintain and safe to handle. Also in Asia, male beetles are used for gambling fights.[1] Since males naturally have the tendency to fight each other for the attention of females they are the ones used for battle. In order to get the two male beetles to lock in combat, a female beetle or a small noisemaker is used to duplicate the female's mating call.
Entomologist Séverin Tchibozo suggests the larvae contain much more protein (40%), than chicken (20%) and beef (approximately 18%) and that larvae could become a protein source for a large [human] population.[2]
Some species can become major pests e.g. in tree plantations. Usually however, rhino beetle population densities are not as high as in some other pest insects, and food trees which are typically already sick or dying from some other cause are preferred. Some species' larvae, however, will attack healthy trees or even root vegetables, and when they occur in large numbers can cause economically significant damage. The fungus Metarhizium anisopliae is a proven biocontrol agent to control this infestation in crops in an environment friendly way.
Agaocephalini Burmeister, 1847 (disputed)
Cyclocephalini Laporte 1840
Dynastini MacLeay, 1819
Hexodontini (disputed)
Oryctini Mulsant, 1842
Oryctoderini
Pentodontini Mulsant, 1842
Phileurini Burmeister, 1847