May 16th swarm

At 7 pm, I stepped outside and heard the loud buzz in the backyard.  The buzz was the strongest standing in front of the hive and looking straight up into the tree canopy the blue sky was darkened by bees. I'm not sure what happened:

• Did my hive swarm or abscond then return landing and accumulating on the outside of their hive?   It's hard to imagine that this weak hive had a population this large and certainly 1/2 of the hive population was not this large.  This is where I wished I had a recent baseline hive weight measurement.
  
• Did a neighborhood hive or wild nest swarm and chose my hive boxes over the hanging 40-liter swarm traps.  For the past few days, I watched scout bees investigating my swarm traps.   I suppose 6 boxes filled with drawn comb is more attractive than the swarm traps - a furnished home with all the modern conveniences versus an unfurnished selection!
  

Time will tell what's going on.

Here's a photo the next morning.  I'm so pleased the bees moved in last night and that I did not intervene - the bees executed a plan, a plan that I did not understand.  Previously in my first-hand experience, swarms choose the hanging swarm trap and not a vacant hive.