In my operation in the Calif foothills, around 5% of my Italians curtain
off the lower entrance (I have no upper entrances).

So interesting the great variation in bees propolizing entrances!
It appears that the bees don't have a strong behavior to close off all
upper entrances during winter, which I find of interest.

Those interested in further discussion should review "How Bees (Apis
Mellifera) Reduce Humidity in the Beehive by Means of Active Ventilation",
available at ResearchGate.
Also Mobus' articles, available at
http://scientificbeekeeping.com/suggested-readings-and-resources-for-serious-beekeepers/

Those of you with sensored hives could perhaps confirm whether ventilation
actually occurs at the top of the cluster, or only from below.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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