The story goes like this:

Back when computers still consisted of vacuum tubes, a system went down one day and people started investigating the cause. They found that a moth was stuck in the computer which fouled it up. When asked what was wrong the tech said "There was a bug in the computer", and since then the term has stuck.

Is that a mostly true story, and if so is that where the terms "computer bug" and "debugging" came from?


1 Answer 1


No; however, this is partly due to semantics, the actual log entry is as follows:

First actual case of a bug being found.

First Computer "Bug"

This is a bit of a tongue-in-cheek reference to the term "bug" that was in use at the time meaning:

The term "bug" is used to a limited extent to designate any fault or trouble in the connections or working of electric apparatus.

Whose definition is courtesy of Hawkin's New Catechism of electricity from 1896. So we know the term was already around at the time and from the log entry we can deduce that other mechanical failures were likely called "bugs" as well.

However, it is apparently the first case of an actual bug being stuck in the computer.

  • 2
    yes, the key word is "actual"
    – Nikko
    Sep 18, 2012 at 19:47
  • 1
    What's with the down vote?
    – rjzii
    Jun 10, 2013 at 22:24
  • 4
    It might be worth mentioning that, contrary to the story as presented in the question, this was before computers started to use vacuum tubes. They used relays (which, being mechanical, were more prone to be affected by insects). Nov 21, 2018 at 15:45

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