Shachihokoga (English spelling) the lobster moth

A general term for insects of the Lepidoptera order, family Sychihokomidae, or one of them. The Sychihokomata ( Stauropus fagi ) is native to the Eurasian continent, and is commonly found throughout Japan, from Hokkaido to Kyushu. The wingspan is about 55 mm. The body is thick, with dark purple-gray forewings and a yellowish-white pattern on the front edge, which is not hidden under the forewings when the moth is at rest with its wings closed, but appears on the outside. The larvae of the Lepidoptera order have a strange shape, with abnormally long and developed legs in the mesothorax and metathorax, and when at rest, the cephalothorax is strongly arched backwards, the thorax is folded upwards, and the tail tip is lifted over the back. This appearance resembles the shachihoko (a type of ridge ornament) used for castle ridge decorations, and the moth was commonly called shachihokomushi, which is the origin of the Japanese name. In Europe, this moth is called a lobster moth because it resembles a shrimp. The larvae attach to various deciduous broad-leaved trees in mountain forests, and are often seen on zelkova and maple trees. They are bivoltine and overwinter as pupae, and the moths emerge in May to June and August.

The family Orthopodidae includes many medium to large moths, and there are more than 1,000 known species in the world, mostly found in temperate to tropical forests. Japan has about 120 species. The colors and markings vary depending on the genus and species. The proboscis of adults is often degenerate, and they do not gather around flowers or sap. The larvae are also diverse in form, and while most are green and caterpillar-like, some have protrusions or rows of protrusions on various parts of their backs, some have degenerate abdominal legs at the tail end, and some have long tubular protrusions replacing the tail legs. However, there are only a few species in this family with specialized middle and hind legs, such as the Orthopod moth mentioned above. Most larvae attach to trees, and each species often feeds on a specific plant. In temperate regions such as Japan, most species attach to deciduous broad-leaved trees. The beech green shachihoko that inhabits beech trees often causes great damage to beech forests, while the black-spotted shachihoko that inhabits willows, the young shachihoko that inhabits poplars, and the black shachihoko that eats cherry trees are well-known as pests. In old books, the shachihoko family is sometimes written as the "Heavenly Shrine Moth Family," and in China it is currently called the "Boat Moth Family."

[Shigeo Sugi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱鱗翅(りんし)目シャチホコガ科の昆虫の総称またはそのなかの1種。シャチホコガStauropus fagiは、ユーラシア大陸に産し、日本では北海道から九州までの全土に普通に分布する。はねの開張は55ミリメートル内外。体は太く、前翅は暗い紫灰色で、前縁部に黄白色の模様があり、この部分はガがはねを閉じて静止したとき前翅の下に隠れず、外に現れる。幼虫は鱗翅目の幼虫では珍しく奇異な形態をしており、中胸部と後胸部の肢(あし)は異常に長く発達し、静止時には頭胸部を強く背方に反らせ、胸を上方に向けて畳み、尾端を背面に持ち上げる姿態をとる。この姿を城郭の棟飾りに用いるシャチホコに見立てて、シャチホコムシと俗称されたのが和名の起源である。ヨーロッパではこの姿をエビに見立てて、ロブスターモスlobster mothとよぶ。幼虫は山林の各種の落葉広葉樹につき、ケヤキ、カエデなどによくみられる。年二化性で、蛹(さなぎ)で越冬し、5～6月と8月ごろにガが発生する。

　シャチホコガ科には、中形から大形のガが多く、世界には1000種以上知られ、温帯から熱帯の森林地帯に多い。日本には約120種がすむ。色彩や斑紋(はんもん)は属、種によって多彩である。成虫の口吻(こうふん)は退化していることが多く、花や樹液には集まらない。幼虫の形態も多様で、緑色のイモムシ状を呈する場合が多いが、背面の種々の部位に突起や突起列の発達しているもの、尾端の腹脚が退化したり、これと反対に尾脚が長い管状の1対の突起に置き換わったものもある。しかし、前記のシャチホコガのように、中脚と後脚が特化した種は、本科のなかでもわずかである。幼虫はほとんど樹木につき、種ごとに特定の植物を食べる場合が多い。日本のような温帯地域では落葉広葉樹につく種が大半である。ブナにつくブナアオシャチホコは、しばしばブナ林に大害を与え、ヤナギ類につくセグロシャチホコ、ポプラにつくヒナシャチホコ、サクラを食うモンクロシャチホコなどは害虫として著名。シャチホコガ科を古い書物では「天社蛾科」と記していることがあり、中国では現在「舟蛾科」とよんでいる。

［杉　繁郎］

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