The first recorded computer bug was an actual moth stuck in a relay.
Why it is true
In nineteen forty-seven, Grace Hopper and her team found the insect in the Harvard Mark II. They taped it into the logbook and coined the term debugging.
Source: Computer History
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.