Red widow - Red widow

It is an insect belonging to the family Castaneidae in the order Coleoptera of the class Insecta. It is a beetle that is found in stored grains and grain foods, and is distributed widely throughout the world. Its body length is 6 to 10 mm. Its body is elongated and oval-shaped, flat, blackish brown or brown, and its antennae and legs are reddish. Its head is almost semicircular, its prothorax is square and slightly narrower at the back, and its epithelium is long and rounded at the back. The larvae are white, but their head, prothorax, and metathorax are blackish brown, and their tail end, which has a pair of protuberances, is blackish brown. Their body becomes slightly thicker toward the back. They feed on grains, flour, and other foods, but are also known to prey on other pests, making them beneficial insects. Adults live for one year, sometimes two years, and females lay about 1,000 eggs during that time. They may also damage surrounding wood and silk cloth used for flour milling when they hibernate during the winter.

There are over 500 known species of Trogossitidae in the world, mostly found in tropical regions, with around 20 species found in Japan. They are about 2-20 mm long. They range from elongated to ovoid, with many more or less flattened. The giant ovoid, Temnochila japonica , can be found under tree bark, and the larvae are also predatory, with some found on mushrooms and some on grains. In recent years, ovoid species such as Thymalus are often separated into the Peltidae family.

[Takehiko Nakane]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱甲虫目コクヌスト科に属する昆虫。世界に広く分布し、貯蔵穀類や穀類の食品にみいだされる甲虫である。体長6～10ミリメートル。体は細長い楕円(だえん)形で平たく、黒褐色ないし褐色、触角や脚(あし)などは赤みがある。頭はほぼ半円形、前胸は四角で後方がすこし狭まり、上ばねは長形で後方が丸まる。幼虫は白いが、頭と前胸・中後胸の各1対の紋や、1対の突起をもつ尾端は黒褐色。体は後方へ向かってすこし太くなる。穀類や穀粉など食品も食べるが、ほかの害虫を捕食することも知られており、益虫の面もある。成虫は1年、ときには2年ぐらい生き、雌はその間に1000ぐらい卵を産むという。越冬するとき周囲の木材や製粉用の絹布を食害することもある。

　コクヌスト科Trogossitidaeは、世界に500種以上が知られ、熱帯地域に多く、日本には20種近くが産する。体長2～20ミリメートルぐらい。長形から卵形の種が含まれ、多少とも平たい種が多い。オオコクヌストTemnochila japonicaなどは樹皮下にみられ、幼虫も捕食性、キノコにいるものや穀類につくものもいる。近年、セダカコクヌスト属Thymalusなど卵形の種がマルコクヌスト科Peltidaeとして分離されることが多い。

［中根猛彦］

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