We were a bit busy this autumn and all the hives still had the entrance blocks in and set to the narrowest door sizes from the wasp problems in September, so, I had thought I could get away without fitting the mouse guards. I have often forgotten the guards in the past and have only ever once had a problem. Therefore I was quite shocked to find that 2 out of 3 of our empty hives had mice nests in.
But here's the real problem: its now too cold to check the active hives and so I have no idea if they have also had mice invading. The mice produce quite a lot of wax debris so I suppose I could try and scrape a stick along the hive floor and see what I can drag out. But even that would involve removal of the entrance blocks and disturbing the bees.
I think I just have to wait until Spring now and keep my fingers crossed.
This was also the first year we have had any problems with wax moths. They make quite a mess too but I think this is a symptom of hives being empty.