My hive swarmed back; see post for the details. Today, I got a frantic call from my wife saying that my hive swarmed again - apparently the air was thick with bees. I drove home, obeying all legal speed limits to find no swarm present. She said that the swarm landed back on the face of the hive and just dissipated. She couldn't tell for sure, but she thinks they went back into the hive. The weekend following the first swarm I checked the hive and could not find a queen or eggs. Some small brood only. There were some swarm cells as well as a queen cell mid-frame in one of the outer frames in the bottom-most brood box. That inspection was about 17 days ago.

My question is: Do bees "practice" swarming? Or might they emerge like a swarm when a virgin queen leaves the hive and then return? Any other theories welcome.