Hi:

After 7 years of running bee hives with flight counters and simultaneous
weather measurements, up to 50 hives at locations in MT, MD, TX,
Mississippi - we offer the following:

1.  Bees know when a thunderstorm is approaching and head home about 20
minutes ahead of the RAIN.

2.  They reportedly can sense barometric pressure changes, but the pressure
does not always drop before the clouds open and dump, yet the bees still
come home.  Overall, we can only make a weak case for barometric pressure.

3.  Bees respond to strongly to solar radiation (and not simply light
intensity).  Whether this is a direct stimulus or a secondary effect
because of the influence of solar radiation on plants and things like
nectar release is unknown.  But, under good flight conditions (reasonably
calm and warm with flowers in blossom), the overall flight activity of a
colony seems to almost synchronize with changes in solar radiation levels.

4. Turn a colony away from the sun in the morning and it will start to fly
30-60 minutes later than a colony with the entrance facing the sun.

5. We suspect that bees sense an array of weather variables, don't just key
on one or two. So, if the winds picking up, temp dropping, solar radiation
decreasing AND THE BAROMETRIC pressue is dropping, like you and I, it adds
up to a storm on the way.  No reason why they'd make decisions about
whether to fly out of the hive or return based on ONE variable.  And, our
data and models indicate that sometimes bees just don't know, anymore than
we always make the right prediction.


In other words, some days, all of the colonies race home before the storm,
or all of them ignore the clouds on the horizon -- and the storm sweeps
around, missing the yard.  But on some days, some of the colonies race
home, others don't, and some mill about (can't quite decide whether to make
another trip or not).

Cheers

Jerry
Jerry J. Bromenshenk
[log in to unmask]
http://www.umt.edu/biology/bees