In 1947, computer scientists working on the Harvard Mark II, one of the earliest electromechanical computers, noticed a malfunction in the system. Upon inspection, they found the cause: a dead moth lodged between relay points.

The team carefully removed the insect, taped it into the logbook, and labeled the entry: “First actual case of a bug being found.” Thus, the term “computer bug” was born — and it stuck.

Though “bug” was used earlier in engineering circles, this incident made it iconic in computing history. The original logbook is still preserved at the Smithsonian Institution, moth and all.

It’s a reminder that the most advanced machines can still be undone by the smallest glitches — especially when they fly in through the window.