I was gifted a lovely cedar bee-hotel a couple of years ago. It's been really successful, each year it's been mostly filled up. Except last year.

Last summer while sat enjoying the sunshine and watching the hotel, I noticed they were acting differently. There were plenty of interested bees, but almost none of them were actually going into any of the tubes. They would get as far as sticking their heads in the door and then fly off.

At the end of the season almost none of the tubes had been used (the image above is from a previous year). They could sense something was off, but what?

I think I figured it out. The ends of the tubes are no longer totally sealed, holding it up to the sun showed a little gaps at the end of almost all the tubes. My theory is that the bees won't nest in a tube which has a gap 🙁. They poke their heads in, see some light at the end of the tube and reject it.

The gaps are probably the result of two things: Not closing it up tightly enough when I last cleaned it out and the wood warping slightly.

This year while cleaning it out, I gave each layer a light sanding. This helped reduce the gap a lot. To completely close it up, I added a small paper shim to the back. That did the trick.

Hopefully this coming season the bees will use all the tubes once more.