Hi:
 
As regards bees knowing that a storm is coming due to barometric pressure
changes - as always, the answer is not that simple.
 
We now have 21 hives (in gruops of 7 at 3 locations) fitted with counters
that monitor every bee coming and going from each hive.
 
Yes, bees do come home before the thunderstorm.  No, it is not
necessarily a drop in barometric pressure.  We have an electronic weather
station at each site.
 
Barometric pressure does not always drop before a storm, yet the bees
still come home.  We suspect multiple triggers for this behavior -
temperature drops, wind speed increase or calm before the storm, changes
in light intensity, and maybe some things bees detect that we can't -
such as the electrical charge in the air.
 
Just as you and I pick up on more than one indicator of the approach of a
storm, bees may do the same.
 
Jerry Bromenshenk
The University of Montana
 
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http://grizzly.umt.edu/biology/bees