Tomoega - Tomoega

A moth belonging to the family Noctuidae, order Lepidoptera, class Insecta. Also known as male black tomoe. A large-sized species with a wing span of about 65 mm. It is known for producing distinct seasonal forms and sexual dimorphism. It is trivoltine, and in summer moths from the second generation onwards, large flame patterns appear on the surface of the forewings, which are black-brown in males and reddish-brown in females, and have numerous wavy horizontal lines. In the first generation of moths that emerge in spring, there is almost no difference between males and females, and the flame-shaped patterns on the forewings have almost disappeared, leaving only traces. The larvae are nocturnal and looper-shaped, feeding on the leaves of the silk tree. During the day, they gather in large numbers at the low parts of the tree trunks. The two seasonal forms of this species were long considered to be separate species, but rearing of the larvae proved that they are the same species. It is also widely distributed in Southeast Asia, and in Japan, Aomori Prefecture is the northernmost limit of its distribution.

[Shigeo Sugi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱鱗翅(りんし)目ヤガ科に属するガ。別名オスグロトモエ。はねの開張65ミリメートル内外の大形種。顕著な季節型と雌雄異形を生ずることで知られる。年3化性で、2化以降の夏のガでは前翅表面に大きなともえ紋が現れ、雄では黒褐色、雌では赤褐色で、波形をした多数の横線をもつ。春に出る1化のガは、雌雄の差異はほとんどなく、前翅のともえ状の紋はほとんど消失し、痕跡(こんせき)をとどめる程度である。幼虫はネムノキの葉を食べる夜行性で、シャクトリムシ状である。昼間は樹幹の低い所に多数集まっている。本種の季節的2型は、長らく別種として扱われていたが、幼虫の飼育によって同一種であることが証明された。東南アジアにも広く分布し、日本では青森県が分布の北限である。

［杉　繁郎］

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