The first bug was a moth

In 1947, Harvard's Mark II started failing. When the team opened the machine, they found the culprit: a moth trapped in one of the relays. They removed it with tweezers and taped it into the logbook.

Underneath they wrote, with an engineer's humour: "first actual case of bug being found". The joke was that the word bug had already been used since Edison's day to talk about technical faults. That day, for once, the fault was literally a bug.

The anecdote became famous thanks to Grace Hopper, a programming pioneer who was working on that team. And the moth still exists: the logbook, with the insect taped inside, is kept in a museum in Washington.

Source: Smithsonian National Museum of American History