I heard Tom Seeley talk about this during a presentation several years ago. For the life of me, I can't remember what the message was that they were communicating. He played a video tape of this sound coming from the hive. Maybe Seeley didn't know either. Seeley also said that a returning forager will ram others working inside the colony to communicate "Wake up! There's work to do." According to him, if there is a good nectar opportunity, a forager will recruit receiving bees to join them in gathering nectar. If there are more foragers than receivers and the flow gets out of balance, bees will return to their role of receiving and storing.
