> > I just bought another 110 of them - enough for the 440 hives that
> > had received my alternate treatment last year.  They seem to work
> > well and last forever - some of mine are 15+ years old and are just
> > like new in spite of often being left out in the summer sometimes and laid
> > on by cattle.
>
> All of my wraps are custom made 6 mil poly blankets with R12 fibregalass.
> The biggest
> problem for lengevity is the breakdown of the mateial when exposed to the
> sun.  To avoid the sun, I alternate between putting the joint on the
> North, then the South, then turning it inside out.  Before I did this, I
> was discarding wraps that had completely broken down in one area.
 
I gather that the wraps are made from black plastic.  This is
interesting to know because I assumed that this stuff is UV resistant
and would last as long as the material that Inland Plastics uses.
 
I just am in the process of finishing making some plastic bags of top
insulation from this stuff and was contemplatng making some bags that
I could stuff the rolled up wraps into.  The plan was to use them for
for outside summer storage so that the wraps would  last even longer
and not get water into them or have the top  bags exposed to the sun.
 
Maybe I should reconsider.
 
>
> If I rotate the area exposed to sun and avoid cattle and skunks, they
> last a long time.  I suspect I have some that are 10 years old.  When the
> plastic breaks down I open it up and salvage the insulation.  The good
> stuff goes into a new wrap and the other goes into a pillow for the top.
> Often I can simply patch the plastic if the insulation is still OK.
 
> > They are a trifle costly - $31 Cdn  (about $23US) for a wrap that
> > covers a four pack of hives.  And you still need a bag of top
> > insulation and plywood sheet on top (1/3 sheet)
 
(I am starting to think this is cheap after experiencing  the amount
of work that goes into getting the top pillows aready and making the
upper entrance holes in the wraps.)
 
BTW we've now eliminated the plywood by having larger flaps put on
the wraps themselves.
 
> > I guess the real question that I was trying to answer was  - how much
> > insulation is *needed* on top?  We presently vary from R5 to R25.
 
<snip>
 
> I am sure there is an optimal insulation for the top when looking at the
> cost effectiveness.  However, I don't think there can ever be too much.
> As long as the bees can circulate the air they will not overheat because
> of too much insulation.
 
This brings up the questions: How big should the hole be?  And when
should one unwrap?  How much feed could be consumed by excess
fanning?  And How many bees will fly out in inclement weather if the
hive gets too warm?
 
I've gone to unwrapping earlier (March) in cases where the bees
bother the neighbours.  It noticably cuts down the bees flying around
when there is nothing to gather.
 
>
> Any thoughts on what the insulation does?  We know that the bees cluster
> and maintain the temperature in the cluster, allowing the balance of the
> hive to become cold.  So what good does the insulation do?  Here is my
> hypothesis - I think the insulation simply moderates the rapid changes in
> temperature and allows the bees time to organize.  In the spring the top
> insulation may be of more use.
 
Well, I agree with that, but would add that the insulation allows
the cluster to be larger than it would otherwise be bt twice.  Top
insulation allows the cluster to form a half basketball form aginst
the lid instead of a basketball shape below the lid - in effect by
mirroring back the heat.
 
This is readily observable on opening hives with and without top
insulation.
 
We also often fail to distinguish between the winter dormant state
with no or little brood,  and the phase whare the bees ramp up to
maximum possible brood rearing.
 
I believe that the insulation does little in the former state, but
is very crucial in the latter.  In the latter the bees _will_ heat the
whole hive as much as they can and insulation and controlled
ventillation will help a lot.
 
This latter activity happens to coincide witht a time when the bees
are old, populations are decreasing due to age, food is scarcer, and
diseases are increasing in the hive.
 
> Here is another hypothesis I would like to hear about - Feed left in the
> hive is important to eat but it is equally as important as a heat simk.
 
I would prefer to use the words 'heat reservoir', because the heat
flow is two way, but that is just being picky; I agree with you.
 
Anything that slows the changes of temperature in the hive helps 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>