Paul,
 
The story I have heard is that the banging of pans to settle a swarm goes back to Olde England.  There were many more beekeepers among the populace in those days and a swarm was a valuable piece of property.  When a beekeeper noticed a swarm issuing forth from a hive he would bang on a pan to announce his claim to it as he followed it until it eventually settled.  From this practice came the notion that the noise induced the swarm to alight.  Maybe there is even some truth to this old wives tale, I really have never tried it.
 
Bob Roach