>Why a single bee?  All the outer bees on the lower part of the cluster would be the coldest , so first to use up food in tummies due to greatest shuddering to keep warm.  So a whole wave would need to press their way inside to re-fuel.  The following wave would push them always in the same direction, upwards, setting up a persistent 'convection' current. 
Robin

Do you have reference supporting that outer bees
push to the center of the cluster?  I would love to 
see any related info. Thanks 

All I can find is references that state bees on the mantel
of a cluster are unaware of conditions at the core of the
cluster, therfore, how would they know that they need
to press their way inside?

"....Bees on the mantle are
not aware of the conditions of the bees in the core\ and
those in the core do not produce excess heat in order
to warm the bees on the mantle[ The regulation of the
core temperature near a set point results from each bee
attempting to remain at a comfortable temperature
within the..."

http://each.uspnet.usp.br/sistcomplexos/SC1/Thermoregulation_in_bee_hives/SelfOrganizationHoneyBees.pdf

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html