[Derbasti]

But isn't that basically where the term came from? Actual insects frying on circuits and shorting contacts?

[brazzy]

Not really, it was always largely figurative. The famous Mark II logbook with the moth taped to it had the note "First actual case of bug being found." - so that clearly indicates that A) the term had been in use for a while (a very long while, there is a record of Edison using it) and B) Real insects were typically not involved.

[gaius]

Yes http://en.wikipedia.org/wiki/Grace_Hopper#Anecdotes tho' it was jamming a relay.

[cadab]

There was a article on HN a few weeks back, the link escapes me. But there was the first ever bug, an actual moth. It was taped to the error log i believe.

Edit: Brazzy explains it better and indeed seems more informed :)