blind as a bat/beetle/mole

blind as a bat/beetle/mole

Totally blind, or, figuratively, unseeing. None of these animals is, by the way, truly blind. The bat flies about in the dark in seemingly erratic paths (see bats in one’s belfry), and the beetle and mole burrow through the ground. Nevertheless, these similes are quite old and have become clichés. The bat analogy dates from the sixteenth century at least (John Harvey); the mole and beetle similes come from Roman times and were cited in translations by Erasmus.
See also: bat, beetle, blind, mole