The first computer bug in history was a real moth trapped in a computer in 1947.
Why it is true
Programmer Grace Hopper and her team found a moth trapped in a relay of the Harvard Mark II computer. They taped the insect into the logbook with the note first actual case of bug being found, popularizing the term to describe flaws in computer systems.
Source: Computer History Museum
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.