Re:Historical notes. (Score 3, Informative)

In his book Why Things Bite Back, Edward Tenner cites two stories that connect Thomas Edison with "bugs'. In 1878, Edison described his style of invention: "The first step is an intuition and it comes with a burst, then difficulties arise -- this thing gives out and then that -- 'Bugs' -- as such little faults and difficulties are called -- show themselves, and months of intense watching, study and labor are requisite before commercial success -- or failure -- is certainly reached."

Separately, Tenner points out that 'bug' was used by telegraphers as the name for hidden faults in circuits, and that it also had a literal meaning for operators, since Western Union offices were notoriously dirty and insect-infested. In 1868, Thomas Edison, who started as a telegraph operator, invented an early version of an electrical zapper to debug his desktop.