My TBH wasn't worth blowing up until I put cardboard and then a real board under the SBB to close it off. It's too off the ground in a TBH and it's too long so it lets in a lot of light. Bees plan to live in a tree trunk in the dark, so shining all that light into their home doesn't entice them to stay, it encourages them to go. I agree with Iddee - cover it or they'll leave again every time.
Linda T
