Hive E was showing some unusual activity today, given that it's supposed to be empty. There were bees coming and going from the entrance and a large amount of debris on the hive floor. There were wax moth larvae; large bits of comb and wax which had been nibbled from white and heavily propolised comb
The obvious explanation for the activity is that the empty hive is being cleaned out by robbers. The new occupants in Hive C, colony 11, are building up just after the Horse Chestnut blossom has finished. Pollen in Hives G and D shows a change in colour to bright orange which vividly illustrates the transition. I find it difficult to follow the bees flight path when they leave the hive. I've always found it hard to follow a tiny black dot as it moves quickly across a variegated background. Maybe they are robbing?
The pattern of debris makes me doubt robbing. We're in peak swarm season now, and how often do robbers evict 2 or 3 wax moth larvae? Then there is the wax on the hive floor. The cappings are seldom very dark, even in the brood area, but the floor had very dark material. It looked more like cell cleaning.
Time will tell.