In my JLPT workbook, it has a section which gives a list of idioms that use [虫]{むし}.

仕事{しごと}の (worker bee)

点取{てんとり} (derogatory term for a student who tries too hard)

がいい (selfish)

泣{な}き (cry baby)

弱{よわ} (weakling)

腹{はら}のがおさまらない (extremely angry)

が知{し}らせる (forebode)

が好{す}かない (antipathy to)

の居所{いどころ}が悪{わる}い (in a bad mood)

娘{むすめ}に悪{わる}いがつく (daughter has a lousy boyfriend)

I'm curious about the origins of the "bug" being used in these phrases.

In one sense, some of them are evocative of a sort of character, a "bug" that is present when things are bad, when there's a sense of foreboding, when one feels down. Almost like the bug is an entity that causes trouble wherever it goes.

In another sense, sometimes the person being described is the "bug", as if they have become the "bug" by being weak, by being a drone, by being a whiner, or whatever the case is.

So, do some or all of these uses of come from the same origin?

What exactly is "the bug" when it's the first sense of a character that is present, such as when it's "in the stomach"?

Bonus questions:

Is there any connection in terms of origins between the phrases 「腹{はら}の虫がおさまらない」 and 「腹が立つ」?

Is 「仕事{しごと}の虫」 equivalent to "workaholic"? Or does it not have negative connotations of over-work?

Is 「点取{てんとり}虫」 equivalent to "teacher's pet"? Or does sucking up to the teacher having no relation?

  • Only peripherally related to the question, but regarding 'worker bee' (as a figurative way of describing a hard-working salaryman), I'm more familiar with '働き蜂'/'働きバチ' (which also seems closer to the literal meaning). Maybe there's a nuance between the two expressions...
    – Dave
    Jan 11, 2012 at 10:08
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    I don't have the capacity to write a full answer now, but here's something to consider: 虫 can be used as a (derogatory) diminutive suffix in the Chinese language. (The parenthesis is because sometimes it can be used in a cute-sy way to poke fun at others but not as a full insult).
    – Flaw
    Jan 11, 2012 at 10:28
  • from a lesson I got a while ago, but can't link to.... 虫が 好すかない this 虫, that deals with emotions, refers back to a pre-modern concept of "bugs" in the stomach. (maybe one can think of them as bacteria or maybe like the english equivalent of butterflies). So, if the bugs in your stomach don't like something/someone , you don't either.
    – yadokari
    Jan 11, 2012 at 17:17

3 Answers 3


According to the Wikipedia article for :

  1. 体内の架空、仮想の生物の意味で用いるもの。
    Used for the meanings of "imaginary inside the body, imaginary creatures":

    • 三尸{さんし}の虫: A 庚申{こうしん} belief originating from Taoism from China that inside the bodies of humans there are three bugs.

    • 虫の知らせ: A premonition. As if given a prediction by the inner-body "bugs", a feeling about things that aren't generally known and events that will occur in a distant place.

    • 虫が(の)いい: Only think about oneself (selfish.)

    • 虫の居所が悪い: In a bad mood. This is because it was believed that unless the inner-body "bugs" settled down, the person's mood would worsen.

    • 虫が(の)好かない: Something (you) don't like.

    • 獅子身中の虫: Though a friend, has an element that does harm (treacherous friend.)

    • 腹の虫が治まらない: Cannot contain one's anger.

    • 腹の虫が鳴く: The sound which comes out of your stomach when you're hungry.

  2. 実際の虫のイメージで用いるもの。
    Used the way the image of bugs is in reality:

    • 虫の息: At death's door. Originates from the the fact that breath is small like a small bug or creature, but isn't necessarily used to refer to breath in reality.

    • 悪い虫が付く: To get involved with an unsavory/bad person.

    • 虫酸が走る: To be disgusted.

    • 虫も殺さぬ: Obedient and quiet ("wouldn't hurt a fly.")

    • 飛んで火に[入]{い}る夏の虫: Jump into failure, things that are dangerous to oneself. ("like a moth flying into the flame.")

    • 蓼食う虫も好きずき: "To each their own (taste)." From that the leaves of 蓼{タデ} have a characteristic harsh taste and there virtually aren't any bugs which eat them, but there are some which are fond of their taste.

    • 一寸の虫にも五分の魂: Even if small, has power and presence ("tread on a worm and it will turn.")

  3. 他に、嫌な人の意味で使う事もある。
    Otherwise used to refer to a detestable person:

    • 弱虫: A weak-hearted person.

    • 泣き虫: Someone easily moved to tears.

    • 点取り虫: A derogatory term for someone who gets high scores in school exams (I'm guessing it doesn't mean "teacher's pet". Space ALC defines it as "grade grabber" and "obsessed with grades".)

The Gogen-allguide article for 虫の知らせ seems to back up the Wikipedia article. It says that the in those expressions refers to the 三尸{さんし}/三虫{さんちゅう} bugs that influence subconscious awareness and feelings/emotions and corroborates that 虫の知らせ, 虫がいい and 腹の虫が治まらない have that etymology.

According to the etymology page for 虫唾が走る, 虫唾 comes from the acidic liquid that comes from your stomach out of your mouth while feeling nauseous in your chest, and the 走る refers to it coming out of your mouth. In other words, something that's as unpleasant as the acidic liquid coming out of your mouth. There are theories of the etymology coming due to saliva that comes up out of your stomach output by parasites as well as acidic liquid due to parasites. For that reason, it can be written as 虫唾 (bug saliva) and 虫酸 (bug acid) and historically has been written as both むしづ and むしず.

The page for the etymology of says that in ancient times it was thought that one's mind was inside the abdomen/stomach, so it says a lot of words use to mean emotions/feelings and I think it's likely that might be the root of 腹が立つ rather than .

EDIT: Removed the Kanjigen section as I wasn't sure of it's accuracy and added a section on 虫唾が走る.


I might furnish the answer in future. But here's what I have tentatively:

  1. 虫 can be used as a (derogatory) diminutive suffix for certain types of people that exhibit an arbitrary trait that is commonly collocated with . 点取虫, 泣き虫, 弱虫 belongs to this usage.

  2. I think 虫が知らせる is based on the different behaviours of insects due to different environmental conditions. For example, insects react to weather change. If it's about to rain one would suddenly notice more flying insects indoors. So one way to "predict the future" would be to observe the natural adaptive behaviour of insects. So in a way, insects forebode and provide us with a presentiment of things to come.


This should be tracked back to 7th century where Kanji first came to Japan due to China's influence. Those phrases mentioned are actually from the Chinese Language, where when it's used, 「虫」has the meaning of " something alive and active ", " something bad and irritating ".

  • 1
    This is a bad answer. Where is the evidence of a link to Chinese at all, let alone 7th-century Chinese? (A vague resemblance of metaphor is meaningless.) It is possible that some of these expressions derive from Chinese, but it can't be asserted that this is the case just because both languages use the concept of a "bug" as a metaphor.
    – Matt
    Jan 12, 2012 at 0:20
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    @DaveMG OK, point taken. I should have put the first sentence more tactfully.
    – Matt
    Jan 13, 2012 at 0:52
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    I'm sorry if I wasn't clear in my previous answer. During 7th century, Chinese's economy is at their peak. Then, after Japaneses were influenced by Chinese, it gave birth to Kanji and Katakana. @Matt , I guess you can find this in any history book as evidence. In both languages ( Chinese and Japanese ) many metaphors are used to express themselves. Well, you can say it too as a vague "entity" of sorts. It's just basically that, not as a representative of themselves.
    – Chizuru
    Jan 19, 2012 at 11:39
  • @Chizuru thanks the reply. I'm not saying that Japan didn't import its writing system and a lot of its lexicon from China -- that obviously happened. But that doesn't mean that every vague resemblance of metaphor must indicate a borrowing from China. If you aren't offering evidence of specific connections (a la cypher's answer), you're just speculating wildly. Even this can sometimes be useful and even correct, but it should not be presented as settled fact ("This should be tracked back to...").
    – Matt
    Jan 20, 2012 at 8:06

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