First Computer Bug
In 1947, Grace Murray Hopper was working on the Harvard University Mark II Aiken Relay Calculator (a primitive computer).
On the 9th of September, 1947, 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."
(See the link at the bottom of this page for a much larger version of this picture.)
The word went out that they had "debugged" the machine and the term "debugging a computer program" was born.
Although Grace Hopper was always careful to admit that she was not there when it actually happened, it was one of her favorite stories.
One of the most common stories about the moth, and a story I often repeated, was that the moth was on display at the Smithsonian.
A correspondent for the Online Hacker Jargon File decided to check on it and guess what . . . it wasn't there.
In 1990, the editor of the Online Hacker Jargon File did some investigating. Turns out that the log, with the moth still taped by the entry, was in the Naval Surface Warfare Center Computer Museum at Dahlgren, Virginia. They had tried to donate it to the Smithsonian, but that the Smithsonian wouldn't accept it.
The 1990 curator of the History of American Technology Museum (part of the Smithsonian) didn't know all of this, agreed to accept it, and took it in 1991. It took years to be actually exhibited due to space and money constraints.
As the Online Hacker Jargon File notes
Thus, the process of investigating the original-computer-bug bug fixed it in an entirely unexpected way, by making the myth true!
So, where did the term "bug" come from?
Well, the entry ("First actual case of bug being found.") shows that the term was already in use before the moth was discovered. Grace Hopper also reported that the term "bug" was used to describe problems in radar electronics during WWII.
The term was use during Thomas Edison's life to mean an industrial defect. And in Hawkin's New Catechism of Electricity, an 1896 electrical handbook from Theo. Audel & Co.) included the entry:
The term "bug" is used to a limited extent to designate any fault or trouble in the connections or working of electric apparatus.
In discussing the origin of the term, the book notes that the term is
said to have originated in quadruplex telegraphy and have been transferred to all electric apparatus.
Common folk etymology says that the phrase "bugs in a telephone cable" was used to account for noisy lines. There is no support for this derivation.
However, the term "bug" was used in the early days of telegraphy. There were the older "manual" keyers that required the operator to code the dots and dashes. And there were the newer, semi-automatic keyers that would send a string of dots automatically. These semi-automatic keyers were called "bugs". One of the most common brands of these keyers, the Vibroplex, used (and still does use) a graphic of a beetle.
These semi-automatic "bugs" were very useful, but required both skill and experience to use. If you were not experienced, using such a "bug" would mean garbled Morse Code.
Radio technicians also used the term "bug" to describe a roach-shaped device consisting of a coil of wire with the two ends of wire sticking out and bent back to nearly touch each other. This device was used to look for radio emissions. This term "bug" was probably a predecessor to the modern use of "bug" to mean a covert monitoring or listening device.
But, lets go way, way back to Shakespeare. In Henry VI, part III, Act V, Scene II, King Edward says "So, lie thout there. Die though; and die our fear; For Warwick was a bug that fear'd us all."
Samuel Johnson's first dictionary includes a definition of "bug" to mean
a fightful object; a walking spectre
For a more detailed and careful discussion of the etymology, see
"Entomology of the Computer Bug: History and Folklore", American Speech 62(4):376-378, 1987, by Fred R. Shapiro