Large 21-spotted ladybird - Large 21-spotted ladybird

An insect belonging to the family Coccinellidae in the order Coleoptera of the class Insecta. It is found throughout Japan (mountainous areas in warmer regions), as well as in eastern Siberia, the Korean peninsula, and China. It is a major pest that feeds on potato and eggplant leaves. Its body length is 6.5-8 mm. Its body is hemispherical, covered with short reddish brown or gray hairs, and has many black spots. Adults appear in early summer and lay eggs on the undersides of leaves. The larvae are spindle-shaped and pale yellow, with 2-3 pairs of long, branched black projections on each body segment, and reach about 9 mm when mature. Both adults and larvae feed on leaf flesh, forming a net-like structure on the leaves. Pupae can be found on the undersides of leaves.

The large 24-spotted ladybird, H. pustulosa , which is very similar to this species, feeds on thistle leaves, but is also found in potato fields and is distributed throughout Hokkaido except for the southern part. Furthermore, from southern Hokkaido to Honshu, there are closely related species of the previous species that feed primarily on thistles and russet butterflies, and the complex relationships between them are an interesting subject in research into classification and ecology.

[Takehiko Nakane]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱甲虫目テントウムシ科に属する昆虫。日本全土（暖地では山地）および東シベリア、朝鮮半島、中国に分布する。ジャガイモやナスの葉を食害する大害虫。体長6.5～8ミリメートル。体は半球形で赤褐色ないし灰色の短毛に覆われ、多くの黒色斑点(はんてん)を備える。成虫は初夏から現れ、葉の裏に産卵し、幼虫は紡錘形で淡黄色を帯び、枝のある黒くて長い突起を各体節に2～3対もち、成熟すると9ミリメートルぐらいになる。成虫、幼虫はともに葉肉を食べて葉を網状にする。蛹(さなぎ)は葉の裏にみいだされる。

　本種によく似たコブオオニジュウヤホシテントウH. pustulosaは、アザミの葉を食べるが、ジャガイモ畑にもみられ、南部を除く北海道に分布する。さらに北海道南部より本州にかけて、アザミやルイヨウボタンを主食とする前種の近縁種が産し、それらの間の複雑な関係は分類や生態などの研究上、興味のある対象となっている。

［中根猛彦］

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