One of my largest hives, now that the weather has turned off hot and humid
(over 100 degrees F today), has bees completely covering the alighting board
and up about 9 inches high on the face of the hive about an inch thick
everywhere.  They seem to have left a small opening at one edge of the
entrance, but the entrance is completely covered everywhere else and bees are
not going in or out of the hive (this happens in the evening and night).
 
I know there is space inside the hive for them to build more comb (this one is
a long horizontal top bar hive).  Is this behavior a heat dissipation
mechanism?  or are these the foragers that just can't wait to get a head start
on the new day and so are waiting the night outside? or does my hive have too
many bees for all of them to fit inside?  Or is this behavior a precursor to
swarming?  Are the bees "trying to tell me something" by this behavior?  Is
this a "read flag" or a "green flag", a bad sign or a good, or indifferent?
 
Layne Westover
College Station, Texas