Horsefly - Horsefly

An insect belonging to the family Tabanidae, suborder Brachyceratops, order Diptera, class Insecta. A large-sized horsefly commonly found throughout Japan, with a body length of 22-29 mm. Its body is purple-brown in color. It lacks an eye, has a linear mid-brow rump, and an elliptical lower brow rump. The tips of the antennae are orange-red, and the base joints are black. There is a yellowish-white triangular spot in the center of the abdomen. Adults appear from July to September, and attack grazing livestock such as cows and horses to suck their blood. They also like to gather on sap in mixed forests along with rhinoceros beetles and stag beetles. They lay triangular pyramid-shaped eggs on the grass of pastures and wooden fences of pastures. The eggs hatch in about a week, and the larvae are carnivorous, preying on small animals such as earthworms in the soil. The larval stage is long, and they pupate and emerge in the following summer.

[Hiroshi Kurahashi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱双翅(そうし)目短角亜目アブ科に属する昆虫。日本各地に普通にみられる大形のアブで、体長22～29ミリメートル。体は紫褐色を帯びる。単眼は欠失し、中額瘤(がくりゅう)は線状で、下額瘤は楕円(だえん)形。触角の先端鞭節(べんせつ)は橙赤(とうせき)色で、基部関節は黒色。腹部中央には黄白色の三角斑(はん)がある。成虫は7～9月に出現し、ウシやウマなど放牧中の家畜を襲撃して吸血する。一方、カブトムシやクワガタムシなどとともに雑木林の樹液にも好んで集まる。卵は三角錐(さんかくすい)状の卵塊で、放牧地の草や牧舎の板塀などに産み付けられる。卵は約1週間で孵化(ふか)し、幼虫は肉食性で、土中でミミズなどの小動物を捕食する。幼虫期は長く、翌年の夏に蛹化(ようか)し、羽化する。

［倉橋　弘］

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