also: とぎょ
noun
silverfish; bristletail
Refers to small, wingless insects that feed on paper, starch, and fabric. Sense 1 is the broader taxonomic term; sense 2 specifies the common Oriental silverfish (Ctenolepisma villosa). In everyday use, しみ usually means the household pest.
古い本を開いたら、しみが出てきた。
When I opened the old book, a silverfish came out.
しみは紙や衣類を食い荒らす害虫だ。
Silverfish are pests that eat paper and clothing.
noun
bookworm (derogatory); someone who can't apply what they read
Derogatory term for a person who reads a lot but cannot put the knowledge into practice. Often used in the set phrase 紙魚の虫 (しみのむし).
彼は紙魚の虫で、知識はあるが実践が伴わない。
He's a bookworm who has knowledge but can't put it into practice.
Alternate reading for 蠧魚; rarely used.
本の虫 is a neutral or affectionate term for a bookworm, while 紙魚 is derogatory and emphasizes inability to apply knowledge.
The kanji 紙魚 (literally 'paper fish') and 衣魚 ('clothing fish') are jukujikun applied to the native Japanese word しみ, which originally referred to the insect. The derogatory sense derives from the image of a silverfish that lives in books but gains nothing from them.