that confusing bugs with beetles is far from being a linguistic problem only.

Sure a valid point, but the thing is, that in English the word bug has this two ways of being used. Also in Germany there are a lot of people who have no clue about the different insects. May be they know a house fly and a wasp and a spider. But they won't call everything else Wanze, or Käfer. They might say Viecher (critters) or something like that.