Yesterday morning it was worse and bodies were regularly being dumped outside or carried away by struggling undertaker bees. This continued all day.
It was the saddest day of my beekeeping and I couldn't think of anything useful to do. In all there must have been thousands of dead bees. The strange thing is that they are all sisters - all offspring of the same queen in the lower colony as there hasn't been a queen in the upper half - and they have always been in air contact. I even erred on the side of caution and used newspaper as well but it still didn't work. Dave Cushman's website says the method is usually successful but will fail occasionally. I have used newspaper to unite other colonies successfully but this failure is puzzling. Even though the bees in this hive are very good tempered (to me at least) they certainly behave strangely.