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I was looking for some figures on the thermal conductivity of beeswax for a topic related to queen cells, when I came across the following paper. If you're anything like me, you'll most probably have thought that there wasn't a whole lot to know about beeswax - but not so - it's a highly complex subject. Here are a few tid-bits:
DSC [Differential Scanning Calorimetry] studies indicate that beeswax melts over a relatively wide temperature range, with the onset of melting occurring at a temperature well below the temperature at which melting is first observed visually. For example, Apis species wax begins melting at approximately 37°C although capillary tube measurements describe the melting point onset at about 61°C. Honeybees actively maintain ambient nest temperatures between 34 and 35°C via evaporative cooling and other methods (Seeley and Heinrich, 1981). Not only are the animals themselves sensitive to temperatures above 35°C (Hepburn, 1986) but also the wax that forms their nest actually begins to melt at these temperatures, as evidenced by the DSC thermograms. The low onset of melting also illuminates previous findings regarding the mechanical properties of honeybee waxes. Hepburn et al. (Hepburn et al., 1983) found that the weight of wax comb loaded with honey, pollen and larvae would exceed the yield strength of beeswax above 40°C. This is due to the fact that strength properties significantly decrease as material temperature increases and the sample reaches the onset of melting.
Beeswax comprises hundreds of chemicals in at least nine principal compound families (Aichholz and Lorbeer, 1999), and multicomponent materials typically display depressed melting points compared with the melting points of their components in pure form (Callister, 2007). The need to maintain nests at specific temperatures for proper brood development has probably served as a selective pressure that kept the onset of melting above these thresholds.
Honeybees are unique among the social insects in using essentially unmodified wax for nest construction. Even though Apis cocoons remain in the comb after brood emergence, these cocoons are not essential to the structural integrity of the comb, as comb can bear the full weight of a brood and food before the first brood enters the pupal stage.

"The thermal properties of beeswaxes: unexpected findings", Buchwald et al., Journal of Experimental Biology, 2007.
I'd take issue with the last point, as old black, highly propolised wax comb is a lot tougher than newly-drawn white comb, and more resistant to melting at the lower temperatures cited - that is, in my experience.

A paper well-worth reading. imo.
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