蚯蚓(みみず)

蚯蚓(みみず) is the common word for earthworm. Usually written in hiragana (みみず) since the kanji 蚯蚓 is rarely used.

Ecological role

• Aerate soil and improve drainage
• Break down organic matter into compost
• Enrich soil nutrients through castings
• Widely valued in gardening and agriculture

Common expressions

• 蚯蚓(みみず)腫(ば)れ: a welt or linear swelling on the skin (literally "earthworm swelling")
• 蚯蚓(みみず)のような字(じ): illegibly scrawled handwriting (literally "letters like earthworms")

Usage

• Counter: 匹(ひき)
• Used as fishing bait (釣(つ)りの餌(えさ))
• Children often encounter them when digging in soil

Cultural note

In traditional folk medicine, dried earthworm (地竜(じりゅう)) was used as a fever reducer. The expression 蚯蚓(みみず)に小便(しょうべん)をかけると腫(は)れる is a folk superstition warning children not to urinate on earthworms.