I made a little bird house a few years ago, for bluetits, on the side of the summerhouse, but they never occupied. This year, bees have moved in and it's adjacent to where we eat on the veranda of the summer house, so not fun at all and their numbers are increasing dramatically. The first sign of their arrival, was lots of 'material', pouring out of the round hole - bluetit door. What can we do about them?