On Mon, 27 Nov 2000, Allen Dick wrote:
 ... As we have learned repeatedly on this list, what is true in one
geographical area, may be seriously false in another region. We
sometimes have very long winters up here in Alberta.  In my experience
around here, bees will look good and survive until late February when
wintered without wraps and with excessive air flow -- as described....

It may be of interest to the group to see a short article I wrote for
the "Alberta Bee New" last summer. It details my experience with
overwintering hives with screened bottom boards. Note that although
the screened bottom boards were left open to the ground the hives were
insulated with 1" of styrofoam everywhere else. They were on 2X6 rails
in rows of 5.



Open Screen Bottom Boards in Central Alberta

Recently there have been a number of articles written suggesting
the use of screened bottom boards for control of Varroa mites.  A
comprehensive article in APIS written by Malcolm T Sanford is
available on the University of Florida website at :

http://www.ifas.ufl.edu/~mts/apishtm/apis99/apaug99.htm#1

The advantages claimed for the boards are:

1. Mites which fall from adult bees go through the mesh and are
unable to reattach themselves.
2. Brood rearing ends sooner in the fall and starts later in the
spring. This provides a longer broodless period which aids in
mite control.
3. A space under the mesh is provided for easy installation of a
sticky board for Varroa testing.
4. Upper entrances for wintering are not required.
5. Entrance reducers are not required. The bottom board is
provided with a 5/16” x 3” entrance which is sufficient for bee
passage during the honey flow and ventilation is provided via
the screen.
6. Bees do not cluster outside the hive in hot weather.
7. Bees can be moved without providing extra ventilation.
8. Wintering results are better due to the prolonged broodless
period. The wintering bees are not stressed by having to keep
brood warm and fed. More pollen is available for spring
buildup.
9. Wet debris does not plug up the bottom boards at the end of
winter.
10. The bees are claimed to be nicer to work with, possibly due to
there being continuous light through the screen.

The only downside mentioned is increased use of winter feed and,
of course, the cost of building and installing the new boards.

I thought it would be good to try a few of the boards last fall. Six
were made and installed under fairly weak hives made up from late
swarms and combined weak colonies. The results were
encouraging, as all the screened hives survived the winter.

I checked them in early April and found that the claim of late
spring brood rearing was justified. The hives with screened bottom
boards had only one or two frames of largely unsealed brood,
while comparable hives with solid bottom boards and top entrances
had two or three frames with sealed brood. In early May, the
screened hives had an average of 3 frames of sealed brood. As of
May 16 they had an average of 6 frames of sealed brood. The
bottom boards did not require any cleaning while some of the solid
ones were plugged with wet grunge. The bees did not seem any
nicer to work with than those with regular bottom boards.

I have been using sticky boards to monitor for mites under the
screened hives. They are easy to install and remove (no mites so
far!). My hives are located about 10 miles north of Edmonton.

Since the article was written our honey has been extracted. The over
wintered osbb hives produced about 10% less than conventional hives. I
put three more hives on the osbb system in the spring and these hives
produced about the same as the conventional ones. With a sample size
of only six and three the honey figures probably don't mean much.



Best regards,

Donald Aitken
Edmonton Alberta Canada