As I understand that post, boric acid kills bees, but only if they get it on them. Is that right?
I have seen SHB traps where you put checkmite or some other chemical in what looks like corrugated cardboard, but it's plastic. Has anybody tried something similar with boric acid traps inside hives. Maybe a sealed, dark container where beetles might go to hide with holes small enough for beetles but too big for bees. I have seen designs for similar traps with oil that drowns them.