芋虫

1. Origins, structure, and basic meaning

• Structure: 芋虫 (いもむし) is a noun for a caterpillar or larva before it becomes a pupa.
• Basic usage: It appears when finding a caterpillar on a leaf or observing it turn into a pupa.
  • 葉の裏に緑色の芋虫がいた。 — A green caterpillar was on the underside of the leaf.
  • 子どもは芋虫がさなぎになる様子を観察した。 — The child watched the larva turn into a pupa.

2. Common pitfalls and similar expressions

• Larva and pupa
  • 芋虫 identifies the feeding, crawling larval stage, while さなぎ is the later pupal stage before the adult emerges.