Quoting from Mobus: "In fact, the bees were dehydrated and had flown en mass for reason of dire thirst! And, coming from a warm cluster without having to contribute to heat generation, they chilled by the thousands before reaching their goal: water."
But that quote is distinctly out of context and should be brought more into focus to understand what he documented. He combined 4 strong colonies to produce 2 super strong colonies each in a highly insulated hive. This is an abnormal condition and was meant to elucidate information on an observation by Jeffree that very large and very small colonies suffered inordinate losses during winter. He weighed individual bees and whole colonies to derive the result which is that very large colonies are out of balance. They do not need to consume very much honey in a highly insulated hive to maintain cluster temperature. The result is that they become water starved.
The highly insulated hive was constructed out of polystyrene with floor 30 mm thick and walls and roof 50 mm thick. The hives were put on very accurate scales which showed that no brood was reared during the period investigated and honey consumption was minimal at less than 1 mg per bee per day.
He showed that bees near the outside of the cluster produce most of the heat. Bees in the middle of the cluster lose more water than they produce eventually becoming water deficient. Bees from the middle then cycle to the outside of the cluster where they metabolize enough honey to replenish their water reserves. In a highly insulated hive with a very large cluster, this cycle does not occur. Bees in the middle of the cluster as well as bees on the outside suffer alike from loss of water.
What was interesting was the behavior of small clusters. They consume large amounts of honey to stay warm accumulating fecal matter until dysentery sets in. This is where a highly insulated hive becomes beneficial allowing a small cluster to maintain temperature without triggering dysentery.