> To keep with the same thread, I am curious to know at what specific time the
> beekeepers shut the upper entrance in the spring and force the bees to use
> the lower entrance.  What motivates the choice?
 
We don't.
 
We have gone to 1 inch auger holes in every brood chamber and leave
them open season round.
 
Only the top one ist open through the wraps in winter, though.
 
We find this reduces drifting.
 
When we had slits in the winter lid (inner cover) that was always a
problem because closing it at a convenient time (for us) often meant
disorienting the bees.
 
Regards
 
Allen
 
W. Allen Dick, Beekeeper                                         VE6CFK
RR#1, Swalwell, Alberta  Canada T0M 1Y0  Internet:[log in to unmask]
Honey. Bees, Art, & Futures <http://www.cuug.ab.ca:8001/~dicka>