Hello Kent,
Anyone having a colony WITHOUT an upper entrance 365 days of the year are only
hurting their bees heath, increasing swarming possibilities, and hurting
their honey crop.

You are in Ontario which has a good bit of snow, and an upper entrance is
very important for your colonies.  If snow or ice blocks the bottom board
entrance, an upper entrance give the bees a chance to take a cleansing flight
on a sudden warm afternoon.  More important, an upper entrance allow the
warm, DAMP exhaled air from the cluster to go UP and OUT of the colony rather
then going up and condensing into water droplets on the cold inner cover and
then RAIN down on the cluster.  Further,
during a nectar flow, foraging bees utilizing the bottom board entrance just
cause increased CONGESTION in the lower brood chamber, which is the number
one cause of swarming.  An upper entrance provides a secondary entrance to
the colony so that
foragers can go directly in and out of the upper entrance rather than use the
bottom
board entrance.

For 100 years or more, some drilled holes in their supers, or staggered their
position on top of each other in order to provide the colony more entrance to
supers and more ventilation.  Not like that approach is why I started using
my IMIRIE SHIM about 40 years ago, now sold by "the hundreds" by Brushy
Mountain Bee Farm.  Every inner cover
should have an upper entrance cut in the front edge of the cover, so bees and
damp air
can get out of the colony 365 days of the year.  Brushy Mountain sells inner
covers with an entrance cut in the edge, or you can cut one in your covers
yourself.

I hope I have helped.

George Imirie
Certified EAS Master Beekeeper
Starting my 70th year of beekeeping in Maryland
Author of George's PINK PAGES at www.cybertours.com/~midnitebee/
 or

www.beekeeper.org/george_imirie/index.html