The First Computer Bug...

In 1945, Grace Murray Hopper was working on the Harvard University Mark II Aiken Relay Calculator. On the 9th of September, 1945, when the machine was experiencing problems, an investigation showed that there was a moth trapped between the points of Relay #70, in Panel F. The operators removed the moth and affixed it to the log. (See the picture above.) The entry reads: "First actual case of bug being found."
Grace Murray Hopper, who lived from 1906-1992, found the first computer bug while working in a temporary World War I building at Harvard University on the Mark II computer where a moth had been beaten to death in the jaws of a relay. She glued it into the logbook of the computer and thereafter when the machine stops (frequently) they say that they are "debugging" the computer. The very first bug still exists in the National Museum of American History of the Smithsonian Institution. The word bug and the concept of debugging had been used previously, perhaps by Edison, but this was probably the first verification that the concept applied to computers.
Moth found trapped between points at Relay #70, Panel F, of the Mark II Aiken Relay Calculator while it was being tested at Harvard University, 9 September 1945. First actual case of bug beeing found.

Kivonat

A mai napon (-64 év) megtalálták az első valódi számítógépes „bugot” (magyarul: bogár): a Harvard Egyetemen működő Mark II hibás működését egy, az egyik relé érintkezői közé szorult molylepke okozta. Az operátorok a rovart eltávolították, és beragasztották a gép naplójába. A legenda szerint azóta hívják bugnak a számítógépes hibákat (eltávolításukat pedig debuggingnak), ám valójában a szót az angol műszaki szakzsargonban már a 19. század óta használták ilyen értelemben.