I have been asked to solve a problem.  A family in a town of 5,000
people in Northwest Iowa presently has a problem that in the latter
part of an afternoon, bees are flying and congregating on brass door
knobs on the east side (shade) of a house during the warmth of the
afternoon.  The bees are quite agitated.  The bees are not foraging
and they are not attracted to warmed corn syrup left in a lid below
the knob.  (The syrup was placed there to see if the bees would be
attracted to the syrup - they were not.) The bees are gone in the
evening.  As a beekeeper, I see nothing that is attracting the bees
(the knob has been cleaned).  The bees are not attracted to other
neighbors.  This has occurred for a week with the bees being
especially nasty at temperatures above 65 degrees F.  There are no
swarms in the house.  No other neighbors have reported any swarms in
homes or nearby trees.  I am perplexed as to what is drawing the bees
to the particular location.  The clusters formed are about the size
of a softball.  There are no beekeepers in town that would have
extracted honey that bees would be flying without a home hive.
 
Does anyone have any theories as to the cause of this situation?