Excluders

[LazyBkpr]

I also use a top entrance year round.  I used the notch in the inner cover to start out with, and then started building the reversible inner covers with a 1 inch notch in them..  I also typically dont remove the entrance reducer.   I leave it with the 3 inch opening side down unless it is going to be one of those summers where it decides we need to be 105 degrees for three months.
   The bees come and go at both entrances.  I put an excluder on if I find a queen that wants to go up top. she gets moved down and the the excluder goes on.  Normally the queens remain where they belong, but every so often.. there is that recalcitrant female that thinks she HAS to do things her way...     

[tecumseh]

a Jack snip...
Hey tec, how would closing the bottom entrance, put a queen excluder above the brood box and a top entrance above the super work for swarm prevention? They would have to really slim the queen down to go anywhere.

tecumseh..
I have always cheated here and do leave a very small bottom entry.  as far as LIMITING swarming what you notice in the primary brood nest is several things.... 1) the field bees do not pass thru the brood nest and therefore do not crowd the brood nest when they come and go and 2) they also tend to deposit nectar above the excluder and therefore don't back fill the brood nest with incoming nectar. < both of these changes should limit swarming somewhat.

I use top entrance all year long and most of these are built into my modified migratory covers.  in some hives without these I build upper entrances by using building shims place between upper super bodies.