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Trombiculidae ( (also called berry bugs, harvest mites, red bugs, scrub-itch mites and aoutas) are a family of mites. The best known of the Trombiculidae are the chiggers. The two widely recognized definitions of "chigger" are the scientific (or taxonomic) definition and the common definitions found in English and medical〔(Medical Definition from Merriam-Webster, Chigger ), 2; "...and causes intense irritation" Retrieved March 7, 2014〕 dictionaries. According to most dictionaries, the several species of Trombiculidae that bite their host in their larval stage and cause "intense irritation"〔(Merriam-Webster's Online Dictionary, chiggers ) cause intense irritation〕 or "a wheal, usually with severe itching and dermatitis,"〔(chigger: Medical dictionary: ) "produces a wheal, usually with severe itching and dermatitis"〕〔(Chigger: ) American Heritage Dictionary〕 are called chiggers.〔chigger: Dictionary.com, http://dictionary.reference.com/browse/chigger〕 The scientific definition seemingly includes many more, but not all species of Trombiculidae. Trombiculidae live in forests and grasslands and are also found in the vegetation of low, damp areas such as woodlands, berry bushes, orchards, along lakes and streams, and even in drier places where vegetation is low, such as lawns, golf courses, and parks. They are most numerous in early summer when grass, weeds, and other vegetation are heaviest. In their larval stage, they attach to various animals, including humans, and feed on skin, often causing itching. These relatives of ticks are nearly microscopic, measuring 0.4 mm (1/60 of an inch) and have a chrome-orange hue. There is a marked constriction in the front part of the body in the nymph and adult stages. The best known species of chigger in North America〔''Eutrombicula (Trombicula) alfreddugesi'' is the in North America."〕 is the hard-biting ''Trombicula alfreddugesi'' of the southeastern United States, humid Midwest〔"Eutrombicula alfreddugesi." "...(from the Atlantic coast to the Midwest and southward )..." Encyclopædia Britannica Online, 2011. Web. 10 Aug. 2011.〕 and Mexico; in the UK, the most prevalent chigger, called the "harvest mite", is ''Trombicula autumnalis'', with distribution through Western Europe to Eastern Asia.〔''N. autumnalis'' "has not been found in the Nearctic region...." http://www.vetstream.com/lapis/Content/Bug/bug00357〕 Trombiculid mites go through a lifecycle of egg, larva, nymph, and adult. The larval mites feed on the skin cells of animals. The six-legged parasitic larva feeds on a large variety of creatures, including humans, rabbits, toads, box turtles, quail, and even some insects. After crawling onto their hosts, they inject digestive enzymes into the skin that break down skin cells. They do not actually "bite", but instead form a hole in the skin called a stylostome and chew up tiny parts of the inner skin, thus causing severe irritation and swelling. The severe itching is accompanied by red, pimple-like bumps (papules) or hives and skin rash or lesions on a sun-exposed area. For humans, itching usually occurs after the larvae detach from the skin. After feeding on their hosts, the larvae drop to the ground and become nymphs, then mature into adults which have eight legs and are harmless to humans. In the postlarval stage, they are not parasitic and feed on plant materials. The females lay three to eight eggs in a clutch, usually on a leaf or under the roots of a plant, and die by autumn.〔 ==History== Trombiculidae, from Greek ("to tremble") and Latin ''ラテン語:culex'', genetive ''ラテン語:culicis'' ("gnat" or "midge"), was first described as an independent family by Henry Ellsworth Ewing in 1944. Then, when the family was first described, it included two subfamilies, Hemitrombiculinae and Trombiculinae. Womersley added another, Leeuwenhoekiinae, which at the time contained only ''Leeuwenhoekia''. Later, he erected the family Leeuwenhoekiidae for the genus and subfamily, having six genera; they have a pair of submedian setae present on the dorsal plate. References to chiggers, however, go as far back as sixth-century China, and by 1733, the first recognition of trombiculid mites in North America was made. In 1758, Carl Linnaeus described a single species, ''Acarus batatas'' (now ''Trombicula batatas''). However, most information about chiggers came from problems that arose during and after World War II. 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「Trombiculidae」の詳細全文を読む スポンサード リンク
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