Beetles are a group of insects which have the largest number of species. They are placed in the order Coleoptera, which means "sheathed wing". The Coleoptera contains more described species than in any other order in the animal kingdom, constituting about 25% of all known life-forms. Forty percent of all described insect species are beetles (about 350,000 species while whirligig beetles simply carry an air bubble down with them whenever they dive.
Evolutionary history and classificationWhile some authorities believe modern beetles began about 140 million years ago, research announced in 2007 showed that beetles may have entered the fossil record during the Lower Permian, about 265 to 300 million years ago.
The four extant suborders of beetle are these:
- Polyphaga is the largest suborder, containing more than 300,000 described species in more than 170 families, including rove beetles (Staphylinidae), scarab beetles (Scarabaeidae), blister beetles (Meloidae), stag beetles (Lucanidae) and true weevils (Curculionidae). These beetles can be identified by the cervical sclerites (hardened parts of the head used as points of attachment for muscles) absent in the other suborders.
- Adephaga contains about 10 families of largely predatory beetles, includes ground beetles (Carabidae), Dytiscidae and whirligig beetles (Gyrinidae). In these beetles the testes are tubular and the first abdominal sternum (a plate of the exoskeleton) is divided by the hind coxae (the basal joints of the beetle's legs).
- Archostemata contains four families of mainly wood-eating beetles, including reticulated beetles (Cupedidae) and the telephone-pole beetle.
- Myxophaga contains about 100 described species in four families, mostly very small, including Hydroscaphidae and the genus Sphaerius.
These suborders diverged in the Permian and Triassic. Their phylogenetic relationship is uncertain, with the most popular hypothesis being that Polyphaga and Myxophaga are most closely related, with Adephaga as the sister group to those two, and Archostemata as sister to the other three collectively.
There are about 350,000 species of beetles. Such a large number of species poses special problems for classification, with some families consisting of thousands of species and needing further division into subfamilies and tribes.
Impact on humans
PestsMany agricultural, forestry, and household insect pests are beetles. These include the following:
- The Colorado potato beetle, Leptinotarsa decemlineata, is a notorious pest of potato plants. Crops are destroyed and the beetle can only be treated by employing expensive pesticides, many of which it has begun to develop resistance to. As well as potatoes, suitable hosts can be a number of plants from the potato family (Solanaceae), such as nightshade, tomato, aubergine and capsicum.
- The boll weevil, Anthonomus grandis, has cost cotton producers in the United States billions of dollars since it first entered that country.
- The bark beetles Hylurgopinus rufipes and Scolytus multistriatus, the elm leaf beetle, Pyrrhalta luteola, and other beetles attack elm trees. The bark beetles are important elm pests because they carry Dutch elm disease as they move from infected breeding sites to feed on healthy elm trees. The spread of the fungus by the beetle has led to the devastation of elm trees in many parts of the Northern Hemisphere, notably in Europe and North America.
- The death watch beetle, Xestobium rufovillosum, (family Anobiidae) is of considerable importance as a pest of older wooden buildings in Great Britain. It attacks hardwoods such as oak and chestnut, always where some fungal decay has taken or is taking place. It is thought that the actual introduction of the pest into buildings takes place at the time of construction.
- Asian long-horned beetle
- Citrus long-horned beetle
- Western corn rootworm
- Coconut hispine beetle, Brontispa longissima, feeds on young leaves and damages seedlings and mature coconut palms. On September 27, 2007, Philippines' Metro Manila and 26 provinces were quarantined due to having been infested with this pest (to save the $800-million Philippine coconut industry).
- The Mountain Pine Beetle normally attacks mature or weakened Lodgepole Pine. Under the right circumstances outbreaks make it the most destructive insect pest of mature pine forests. The current infestation in British Columbia is the largest Canada has ever seen.
- Both the larvae and adults of some ladybirds (family Coccinellidae) are found in aphid colonies. Other lady beetles feed on scale insects and mealybugs. If normal food sources are scarce they may feed on other things, such as small caterpillars, young plant bugs, honeydew and nectar.
- Ground beetles (family Carabidae) are common predators of many different insects and other arthropods, including fly eggs, caterpillars, wireworms and others.
- Plant-feeding beetles are often important beneficial insects, controlling problem weeds. Some flea beetles of the genus Aphthona feed on leafy spurge, a considerable weed of rangeland in western North America.
Some farmers develop beetle banks to foster and provide cover for beneficial beetles.
Beetles in ancient Egypt and other cultures
Several species of dung beetle, most notably Scarabaeus sacer (often referred to as "scarab"), enjoyed a sacred status among the ancient Egyptians, as the creatures were likened to the major god Khepri. Some scholars suggest that the Egyptians' practice of making mummies was inspired by the brooding process of the beetle. Many thousands of amulets and stamp seals have been excavated that depict the scarab. In many artifacts, the scarab is depicted pushing the sun along its course in the sky, much as scarabs push or roll balls of dung to their brood sites. During and following the New Kingdom, scarab amulets were often placed over the heart of the mummified deceased.
Some tribal groups, particularly in tropical parts of the world, use the colourful, iridescent elytra of certain beetles, especially certain Scarabaeidae, in ceremonies and as adornment.
Study and collectionThe study of beetles is called coleopterology, and its practitioners are coleopterists. Coleopterists have formed organisations to facilitate the study of beetles. Among these is The Coleopterists Society, an international organisation based in the United States. Such organisations may have both professionals and amateurs interested in beetles as members.
Research in this field is often published in peer-reviewed journals specific to the field of coleopterology, though journals dealing with general entomology also publish many papers on various aspects of beetle biology. Some of the journals specific to beetle research are:
There is a thriving industry in the collection of beetle specimens for amateur and professional collectors. Many coleopterists prefer to collect beetle specimens for themselves, recording detailed information about each specimen and its habitat. Such collections add to the body of knowledge about the Coleoptera. Some countries have established laws governing or prohibiting the collection of certain rare (and often much sought after) species. One such beetle whose collection is illegal or restricted is the American burying beetle, Nicrophorus americanus.
- Poul Beckmann, Living Jewels: The Natural Design of Beetles ISBN 3-7913-2528-0
- Arthur V. Evans, Charles Bellamy, and Lisa Charles Watson, An Inordinate Fondness for Beetles ISBN 0-520-22323-3
- Entomological Society of America, Beetle Larvae of the World ISBN 0-643-05506-1
- David Grimaldi, Michael S. Engel, Evolution of the Insects ISBN 0-521-82149-5
- Ross H. Arnett, Jr. and Michael C. Thomas, American Beetles (CRC Press, 2001-2). ISBN 0-8493-1925-0
- K. W. Harde, A Field Guide in Colour to Beetles ISBN 0-7064-1937-5 Pages 7-24
- White, R.E. 1983. Beetles. Houghton Mifflin Company, New York, NY. ISBN 0-395-91089-7
- Heteroptera - insect suborder that is superficially similar to beetles
External linkssisterlinks Beetle
- - Coleoptera All what do you need to know about coleoptera, collecting and preparation
- The Beetle Ring - A group of websites about beetles (Coleoptera).
- List of major Beetle collections - worldwide
- Entomology - online insect museum, entomology, tips and tricks, how to spread and pin insects, etc.
- http://www.koleopterologie.de/gallery - Gallery of Central European beetles
- Coleoptera from the Tree of Life, also Beetles Movies
- Australian borers species
- Beetles and coleopterologists Russian site with English version, with information about biology, systematics and paleontology of beetles
- Illustrations from book by G.G. Yakobson "Beetles of Russia"
- North American Beetles from BugGuide
- Bibliography on fossil insects
- Coleoptera Families of the World
- A digital collection of Southeast Asian beetles
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chafer in Simple English: Beetle
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