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Cockroaches are insects of the order Blattodea, which however also includes the termites. About 30 cockroach species out of 4,600 are associated with human habitats. About four species are well known as pests. The cockroaches are an ancient group, dating back at least as far as the Carboniferous period, some 320 million years ago. Those early ancestors however lacked the internal ovipositors of modern roaches. Cockroaches are somewhat generalized insects without special adaptations like the sucking mouthparts of Hemiptera; they have chewing mouthparts and are likely among the most primitive of living neopteran insects. They are common and hardy insects, and can tolerate a wide range of environments from Arctic cold to tropical heat. Tropical cockroaches are often much bigger than temperate species, and, contrary to popular opinion, extinct cockroach relatives and 'roachoids' such as the Carboniferous ''Archimylacris'' and the Permian ''Apthoroblattina'' were not as large as the biggest modern species. Some species, such as the gregarious German cockroach, have an elaborate social structure involving common shelter, social dependence, information transfer and kin recognition. Cockroaches have appeared in human culture since Classical antiquity. They are popularly depicted as dirty pests, though the great majority of species are inoffensive and live in a wide range of habitats around the world. ==Taxonomy and evolution== Cockroaches are members of the order Blattodea, which includes the termites, a group of insects once thought to be separate from cockroaches. Currently, there are 4,600 species described and over 460 genera worldwide.〔(【引用サイトリンク】year=2014 )〕〔(【引用サイトリンク】url=http://anic.ento.csiro.au/INSECTFAMILIES/order_overview.aspx?OrderID=42509&PageID=overview )〕 The name "cockroach" comes from the Spanish word for cockroach, ''cucaracha'', transformed by 1620s English folk etymology into "cock" and "roach". The scientific name derives from the Latin ''blatta'', "an insect that shuns the light", which in classical Latin was applied not only to cockroaches, but also to mantids. Historically, the name Blattaria was used largely interchangeably with the name Blattodea, but whilst the former name was used to refer to 'true' cockroaches exclusively, the latter also includes the termites. The current catalogue of world cockroach species uses the name Blattodea for the group.〔 Another name, Blattoptera, is also sometimes used. The earliest cockroach-like fossils ("blattopterans" or "roachids") are from the Carboniferous period 320 million years ago, as are fossil roachoid nymphs. Since the nineteenth century, scientists believed that cockroaches were an ancient group of insects that had a Devonian origin, according to one hypothesis. Fossil roachoids that lived during that time differ from modern cockroaches in having long external ovipositors and are the ancestors of mantises, as well as modern blattodeans. As the body, hindwings and mouthparts are not preserved in fossils frequently, the relationship of these roachoids and modern cockroaches remain disputed. The first fossils of modern cockroaches with internal ovipositors appeared in the early Cretaceous. A recent phylogenetic analysis suggests that cockroaches originated at least in the Jurassic.〔 The evolutionary relationships of the Blattodea (cockroaches and termites) shown in the cladogram are based on Eggleton, Beccaloni & Inward (2007). The cockroach families Lamproblattidae and Tryonicidae are not shown but are placed within the superfamily Blattoidea. The cockroach families Corydiidae and Ectobiidae were previously known as the Polyphagidae and Blattellidae. |2= }} |2=Mastotermitidae }} |label2=Cryptocercoidae |2=Cryptocercidae (brown-hooded cockroaches) }} |2=Blattidae (Oriental, American and other cockroaches) }} |label2=Blaberoidea |2= }} |label2=Corydiodea |2= }} |2=Mantodea (Mantises) }} }} Termites were previously regarded as a separate order Isoptera to cockroaches. However recent genetic evidence strongly suggests that they evolved directly from 'true' cockroaches, and many authors now place them as an "epifamily" of Blattodea.〔 This evidence supported a hypothesis suggested in 1934 that termites are closely related to the wood-eating cockroaches (genus ''Cryptocercus''). This hypothesis was originally based on similarity of the symbiotic gut flagellates in termites regarded as living fossils and wood-eating cockroaches. Additional evidence emerged when F. A. McKittrick noted similar morphological characteristics between some termites and cockroach nymphs. The similarities among these cockroaches and termites have led some scientists to reclassify termites as a single family, Termitidae, within the order Blattodea.〔 Other scientists have taken a more conservative approach, proposing to retain the termites as Termitoidae, an epifamily within the order. Such measure preserves the classification of termites at family level and below. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cockroach」の詳細全文を読む スポンサード リンク
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