> Dobson, A.P. (2023) Flaws of nature : the limits and liabilities of natural selection 

Thanks for the tip! One of the examples that he gives is a species of ant which closes the entrance to the nest at night. Mostly it is done from inside but there is always a group of ants who finish the job from the outside. These ants typically die, being exposed and unprotected. In other words, they are sacrificed for the good of the colony. I suspect the same would apply to honey bees on the outside of a cluster in winter. Even if they are dead, they provide insulation with their bodies.

Southwick again:
> Bees, birds, and mammals all insulate their body surfaces with hair, feathers, or fur. In extreme cold, even animals with a thick layer of fur or feathers must generate additional heat to maintain high body temperatures. The effectiveness of surface insulation is inversely related to body size (Scholander et al. 1950), therefore the bee clusters, as well as smaller mammals and birds, have to rely primarily on heat production to compensate for heat loss in the cold. — Bee colonies are able to tolerate more extreme cold temperatures than most mammals and birds. A bee cluster's cold-temperature tolerance of at least -80°C is as good as that of winter-hardy homeotherms (Southwick 1987). Large arctic foxes and Eskimo dogs can tolerate -80°C

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