wunderfeedENDE

Nº 040 · Technology · 50 sec

The first computer bug was a real moth

Taped into the logbook. Only the word "bug" was already old by then.

A page from the Harvard Mark II logbook with a moth taped to it
Photo: Courtesy of the Naval Surface Warfare Center, Dahlgren, VA., 1988. · Public domain · Original
A page from the Harvard Mark II logbook with a moth taped to it
The Harvard Mark II logbook: the moth is taped next to the note "First actual case of bug being found".Photo: Courtesy of the Naval Surface Warfare Center, Dahlgren, VA., 1988. · Public domain · Original

A moth in the relay

Around 1947 the computer pioneer Grace Hopper was working on the Harvard Mark II. The operators traced a fault to a moth stuck in a relay. They removed it and taped it into the logbook. Hopper later made the story famous.

A pun

The entry was a pun: "bug" for a technical fault had been around for a long time. Thomas Edison used the word as early as 1878 in a letter to an associate.

Sources

Every statement in this discovery is backed by one of these sources and was checked before publication.

  1. Wikipedia: Software bug (accessed 2026-10-05)

Image credits

  • “First Computer Bug, 1947.jpg”, Courtesy of the Naval Surface Warfare Center, Dahlgren, VA., 1988., Public domain