Why is an Earwig called a "Coach-bell?"

Your correspondents, although both kind and learned, do not appear to have given any satisfactory answer to my former query —why a lady-bird is called Bishop Barnaby? Probably there will be less difficulty in answering another entomological question —Why do the country-people in the south of Scotland call an earwig a "coach-bell?" The name "earwig" itself is sufficiently puzzling, but "coach-bell" seems, if possible, still more utterly unintelligible.