In article <001a01c282c8$e2adb460$70ae73d1@pii266>, Allen Dick
<[log in to unmask]> writes
>One thing about polystyrene is that it does not breathe at all.

I am led to believe (from a Danish friend) that this is not actually
true, and that moisture permeates out through the walls, and in
particular the roof. I have probably finished that idea off by applying
exterior gloss paint to all external surfaces. However, it seems to have
made no difference to the bees.

Moisture certainly can get into the material. I wondered why our
polystyrene feeders were turning black on the outside and clumps of bees
and wasps were hanging about on them. I asked the maker and was asked in
return if I had painted them. My answer was, at that time, 'No, I had
not but would clean them, stack them up, and spray them next spring.'  I
was then told, the its not the outside you should be painting, its the
inside, as the syrup migrates into, and right through the polystyrene
between the beads. If I had not painted them before I had put feeding in
them there was little point doing it later as this would just be over
the top of syrup in the material and that it would not stick long term.
The second batch we painted inside and out and no problems whatsoever,
plus they will be a pound or two lighter today than the unpainted ones.

Roofs taken from store in spring are surprisingly noticeably lighter
than those on the hives, but as summer comes on they are about the same.
I would guess that this is due to water being absorbed into the fabric
of the polystyrene in winter, and coming back out again once the sun
heats up the hives during the active season.

> I wonder
>what kind of entrance4 reducers you use and if you use top ventilation
>and/or flight holes.

No entrance reducers (all are on 3/8" anyway), and no upper entrances.
Plentiful ventilation comes through the mesh floor.
  It remains relatively warm inside the hive, and condensation forms
against the hand hold areas, runs down, and exits the bottom board
through the mesh.

I am not in Canada of course! My minimum temperature for sustained
spells is not greatly below zero, a good bit warmer than you, but
central Norway and Sweden would be comparable, and they seem to do it
just the same as I do out there.

> What are your thoughts?  Maybe Mats and P-O and others might comment too.

Anthony Morgan would have a good input to make too.

The bees in them are always strong, clean, and not apparently suffering
from the moisture sometimes found in our ( all unwrapped) wooden hives.
--
Murray McGregor