Lepidoptera - Rinshirui

In insect taxonomy, the order Lepidoptera is simply called Lepidoptera. They belong to the same family as butterflies and moths, and without exception, they undergo complete metamorphosis, going from egg → larva → pupa → adult. Their most noticeable feature is that their four wings are covered in scales, from which the name Lepidoptera (order) comes. The mouthparts of adults are specialized into an absorbing mouth for absorbing liquids, but a few primitive small moths still retain chewing mouthparts, a vestige of their ancestors.

In general, daytime butterflies have bright, eye-catching wing colors and markings, but nocturnal moths often have colors similar to those of other moths. However, there are also daytime moths with gorgeous colors, and it is thought that the color of their wings is closely related to the time of their activity.

The mouthparts of the larvae are chewing-type, unlike those of the adults, and they mostly feed on plant matter, with some feeding on leaves, flower buds, fruits, and fallen leaves, others attaching themselves to mushrooms, moss, and lichen, and some burrowing into the pith or trunks of plants. The carnivorous ones are thought to have evolved secondarily from the plant-eating ones, and include those that prey on aphids and scale insects, and some like the cicada parasite moth that parasitizes adult cicadas externally.

They are found wherever plants grow, from the tropics to the polar regions, but the number of species is greater in places with abundant plants and less in places with poor flora, such as around the poles and in semi-deserts. Globally, the most species are found in the tropics and subtropics of Southeast Asia and Central and South America, followed by Africa.

There are about 150,000 known species of Lepidoptera found worldwide, of which there are only about 20,000 butterfly species, due to insufficient research on moths in unexplored areas, and the actual number is probably over 200,000. Butterflies have been relatively well surveyed, so it is unlikely that the number of species will increase significantly in the future.

[Takashi Shiramizu]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫分類学上の鱗翅目Lepidopteraのことを平易に鱗翅類という。いわゆるチョウ・ガの仲間で、例外なく、卵→幼虫→蛹(さなぎ)→成虫の経過をとる完全変態の昆虫である。4枚のはねが鱗粉で覆われているのがもっとも目につく特徴で、鱗翅類（目）の名称はこれからきている。成虫の口器は特殊化して、液状物をとる吸収口となるが、原始的な少数の小ガ類はそしゃく型口器で、祖先の名残(なごり)をとどめている。

　一般に昼間活動性のチョウ類は、はねの色彩や斑紋(はんもん)が鮮やかで人目をひくが、夜間活動性のガ類はじみな色合いのものが多い。ただし、ガ類でも昼間活動性のものは華美な色彩のものがあり、はねの色彩はその活動時刻にかなり関連があるものと考えられる。

　幼虫時代の口器は成虫と違いそしゃく型で、その食べ物は植物質のものが多く、草木の葉、花蕾(からい)、実、落ち葉などを食べるもののほか、キノコ、コケ、地衣につくものがあり、草木の髄や樹幹に潜入するものもある。動物質食のものは、植物質食のものより二次的に転化（進化）したと考えられるもので、アブラムシやカイガラムシなどを捕食するもの、またセミ類の成虫に外部寄生するセミヤドリガのようなものもある。

　熱帯から寒帯まで植物の生える所であればどこでも分布しているが、その種類数は植物の豊富な場所に多く、極地周辺、半砂漠のような植物相の貧弱な場所には少ない。世界的にみれば、東南アジアおよび中・南アメリカの熱帯から亜熱帯にもっとも種類が多く、アフリカがこれに次ぐ。

　全世界に産する鱗翅目の既知種類は約15万種、そのうちチョウは約2万種、これは未開地のガの研究が不十分なためで、実数はおそらく20万種を超えるものと推定される。チョウの場合は調査が比較的によく行き届いているので、今後種類数が大幅に増える可能性は少ない。

［白水　隆］

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例