> >"I have been telling folks for years: the bees don't heat the hive, they heat the cluster. Insulation does very little in such a case."

>    1. What about stores consumption to keep warm?   2. What about during brood buildup, plenty of heat generated here to be used or lost.   3. How come colonies stronger in spring with styro boxes than with wood.

Good call, Alden.  You are right to point this out.  

We have been met with this this half-truth over the years and I have written about it at great length, but it still gets trotted out again and again.

Here we go again...  Hopefully this is clear.  While the claim is true, it is not the whole truth.

When in a defined cluster, the bees heat the cluster, and *if* the space surrounding the cluster is warmed by that heat, that is incidental, unless that cluster is in a cavity which is reasonably matched to the colony size.  I won't go into that here.

*However*, warming in an occupied cavity increases bee activity and heat production, and that in turn again increases the warming inside the cavity further. 

When/if the space surrounding the cluster becomes warm enough to reach above clustering temperature -- either through the heat given off by the bees or by ambient conditions, or a combination of the two and hive geometry -- the bees become more active and the cluster becomes looser yet.  

Obviously, the size of the cluster, the baseline metabolism rate, the geometry and material of the cavity and the amount of ventilation and absorbed/radiated heat from the sun, will combine to determine equilibrium temperatures on the cluster periphery.  

If the equilibrium is above clustering temperatures, then the bees will heat the entire cavity, since the cluster limits will be defined by the dimensions of the cavity.  If the temperature is less than cluster temperature, then a defined cluster will form that is smaller than the cavity.  

If the cavity is large, then the cluster forms at night and breaks if the days are warm.  If the cavity is smaller, then the cluster may never form.  There is also a hysteresis effect due tot eh feedback mechanism in that the raised metabolism and cluster activity lags the ambient warming and also subsequent ambient cooling, say at night.

When brood rearing is ongoing and increasing, the baseline metabolism rate is increased and the bees will occupy more space to the point where they heat the entire box if the cavity is insulated, warmed, small in comparison to the number of bees, etc.

Much of the art of beekeeping is choosing the correct amount of space for the time of year and the state of the colony.

It's not that simple, but that is all the4 time I have right now.  See the archives for more...

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