Admiral Grace Murray Hopper was a pioneer in the computing profession,
and is known to be the person who coined the phrase “debugging”. Her
anecdote has been published in many sources, including the Internet.
The following is transcribed in “Banquet Anecdotes,” ACM SIGPLAN History
of Programming Languages Conference, Los Angeles, June 1-3, 1978 and published
in “Annals of the History of Computing,” Volume 3, Number 3, July 1981, 285-286.
 
 
 In the summer of 1945 we were building Mark II [an early
 electromechanical computer]; we had to build it in an awful
 rush--it was wartime--out of components we could get our 
 hands on. We were working in a World War I temporary building 
 [on the campus of Harvard University]. It was a hot summer 
 and there was no air-conditioning, so all the windows were 
 open. Mark II stopped, and we were trying to get her going. 
 We finally found the relay that had failed. Inside the relay-
 -and these were large relays--was a moth that had been beaten 
 to death by the relay. We got a pair of tweezers. Very 
 carefully we took the moth out of the relay, put it in the 
 logbook and put Scotch tape over it.
 
 Now, Commander Howard Aiken had a habit of coming into the 
 room and saying, “Are you making any numbers?” We had to have
 an excuse when we weren’t making any numbers. From then on if 
 we weren’t making any numbers, we told him that we were
 debugging the computer. To the best of my knowledge that’s 
 where it started. 
 
 See picture below: