成 虫(せいちゅう)

せいちゅう

noun

adult insect; imago

1. adult insect; imago; fully grown insect

An insect that has completed all stages of metamorphosis and reached its final, mature form. Contrasts with larva and pupa stages.

幼虫(ようちゅう)が成虫(せいちゅう)になる。

The larva becomes an adult insect.

カブトムシの成虫(せいちゅう)は夏(なつ)にしか見(み)られない。

Adult rhinoceros beetles can only be seen in summer.

セミは成虫(せいちゅう)になってからの寿命(じゅみょう)が非常(ひじょう)に短(みじか)い。

Cicadas have a very short lifespan after becoming adults.

成虫(せいちゅう) is the final stage in an insect's life cycle — the fully developed adult form capable of reproduction.

Life cycle stages

卵(たまご): egg
幼虫(ようちゅう): larva
蛹(さなぎ): pupa, chrysalis
成虫(せいちゅう): adult insect (imago)

Common collocations

成虫(せいちゅう)になる: to become an adult (insect)
成虫(せいちゅう)の寿命(じゅみょう): adult insect's lifespan
成虫(せいちゅう)に羽化(うか)する: to emerge as an adult (from pupa)

Forms

成(せい) (mature, complete) + 虫(ちゅう) (insect).

Used in science education (理科(りか)) and nature observation. Japanese children often learn this vocabulary through カブトムシ (rhinoceros beetle) and セミ (cicada) life cycles.

general

Added 2026.3.23 11:01 · Revised 2026.9.2 13:01

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