How to say "pest" in Japanese

• 害虫がいちゅうCommon
  nounThe word for 'pest' in the literal sense: a harmful, noxious insect, one that damages crops, plants, or goods; it also serves for 'vermin'. Use it when you mean an actual destructive insect.
  残飯ざんぱんの屑くずは害虫がいちゅうの住処すみかになる。↗

  Garbage harbors vermin.
• 毛虫けむしCommon
  nounLiterally a caterpillar. Its 'pest' sense is the one used of a person: an annoying, bothersome person, a nudnik — so this is the word when you want to call someone a pest.

Use 害虫 for the literal 'pest', a harmful or noxious insect (also 'vermin'); 毛虫, literally a caterpillar, is the match for the 'pest' that means an annoying person, a nudnik.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 害虫がいちゅうharmful insect
• 害獣がいじゅうharmful animal
• 鼠疫そえきplague
• 困ったちゃんこまったちゃんperson oblivious to the fact they are irritating or inconveniencing others
• 病害虫びょうがいちゅう(insect) pest
• 毛虫けむしpest
• バチルスpest (e.g. to society)
• 疫病神やくびょうがみjinx