In Japanese, a "stomach bug" isn't a sickness, but rather "a bug that stirs up one's feelings."

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I'm sure you know 虫 means "bug" or "insect," but idiomatically, it also can represent that something inside us that stirs feelings up. Think of it as a "non-bug bug in one's gut" that stirs up emotions.

Today, we'll look at a few idiomatic expressions involving 虫 (the non-bug bug in one's gut)

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The 虫 bug here refers to the Taoist belief that three worms lived inside the human body. The worms keep record of their host's misdeeds and report the transgressions to heaven. You can learn more about it here:  https://en.wikipedia.org/wiki/Three_Corpses

Knowing this, you can see why most of the idioms using 虫 are negative.

Let's hit on a few useful "non-bug bug" idioms.


selfish; asking too much; take too much for granted


He is always asking for too much.

  • 彼は as for him, he…
  • いつも always
  • 虫がいい take too much for granted
  • こと matter [creates a noun phrase]
  • 言っている saying

And here is the same form but いい is conjugated with すぎる to mean “too good”:


asking too much; very selfish


Don’t you think that’s a little selfish?

  • それは as for that
  • 虫が良すぎるん too selfish [The ん is used to both soften the criticism and ask for agreement]
  • じゃないか isn’t it?


staying angry; cannot contain one's anger; can't contain myself


Even though his friend apologized profusely, he was still angry.

  • 友達 friend
  • 一生懸命に with all one’s might
  • 謝っても even (if he) apologized
  • 彼 he
  • 腹の虫がおさまらなかった wasn’t appeased; still angry

  • (むし)()らせ

    feeling in one's bones; foreboding; premonition


    I had a feeling this might happen.

    • 虫の知らせ feeling in one’s bones
    •  があった there was


    to be disgusted; to be repulsed; to get the creeps


    Just thinking of that pervert’s face gives me the creeps.

  • 痴漢の the pervert’s; the groper’s
  • 顔 face
  • 思い出した  thought
  • だけで just the (thought of…); even just (thinking)
  • 虫唾が走る to be disgusted [虫 (bug) + 唾 (saliva; spit) + が (subject marker) + 走る (to run]
  • わ (usually feminine ender for emphasis)

  • (むし)居所(いどころ)(わる)

    irritable; bad-tempered


    Mom was irritated so dad quietly snuck out for a walk.

  • お母さん mother
  • 虫の居所が悪かった was irritable
  • ので therefore; because of that
  • お父さん father
  • こっそり secretly; quietly; stealthily
  • 散歩に for a walk
  • 出かけた left for (a walk)

  • (むし)()かない

    disliking; having an antipathy to


    No matter how hard I try, I just don't like Tanaka.

  • 田中さん Tanaka
  • のこと about (Tanaka); the matter of (Tanaka) [the こと here creates some distance rather than directly saying “Tanaka.”]
  • どうも for some reason; despite my best efforts [どうも in this context is hard to translate, but it indicates the speaker’s difficulty]
  • 虫が好かない to dislike
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