Wordorigins.org

Most of us have encountered bugs in hardware or software, those defects that prevent computers from operating properly. But the term existed long before the age of computers. It has its origins in the shop of perhaps the greatest innovator of the industrial age.

The term was coined in the lab of Thomas Edison, perhaps by the man himself. Edison is the first to be recorded using the term, in Josephson’s Edison of 1878:

“Bugs"—as such little faults and difficulties are called—show themselves and months of anxious watching, study and labor are requisite before commercial success...is reached.