In my apiary, when the bees have excluder at entrance of hive they don't
swarm. Don't swarm and don't work. They wait for a moment when the excluder
is removed. This is a good way to avoid swarming when I have to go away for
a week to two. At least ones a week the excluder must be removed for a 1 to
2 hour because drones plug it.
 
Andrzej, Poland