Concept of insects getting into computing machines is likely as old as such machines; oldest I'm aware of might be the Antikythera mechanism, which some estimate to be as old as 200BC.
As for the "correctness" of "bug" - appears you agree this is the first historically documented reference to an insect being the source of a computing error and the "quotes" infer this means insect, though agree this might not be obvious to some.
As for the "correctness" of "bug" - appears you agree this is the first historically documented reference to an insect being the source of a computing error and the "quotes" infer this means insect, though agree this might not be obvious to some.