Hello Mike & All,
All beekeeping is local so hard to answer without looking at your situation
close up. You are farther north than me but in the last week the henbit
started blooming. Bees bring in a huge amount of pollen from henbit if the
weather is warm like it has been (several days close to 80F.)
The maples are about done in our area. Some pollen has been coming in almost
every warm day in our area.
You need to get a pollen trap and learn the colors of different pollen in
your area. Then you can tell if your bees are bringing in something other
than pollen. My guess is they are not.

General answers to your questions as would pertain to  my area.

  1.  What are the odds that the bees are bringing in something other than
pollen?

Happens rarely when bees are brooding up and running out of pollen for
feeding brood. A sign would be tossing dead brood from entrance and the
eating of brood plus no stored pollen around the
young brood.

  2.  Is there a field-test to find out?  (I'm afraid I don't have access to
a chemistry lab or even to a particularly powerful microscope.)

Sure. However most beekeepers are familiar with the taste (and color) of
fresh pollen. Get a trap and do as I suggested if you are worried.

  3.  Is it a reasonable hypothesis that bees kept in more built-up
environments may be at greater risk of bringing in non-pollen?

I suppose but I think what you are seeing is excellent flight days with only
pollen to work on (although some early trees also provide nectar). Bees want
to start the spring work. If your hives are pollen bound I suspect most was
brought in last fall instead of last weekend.


The early spring pollen is mostly from trees. A period exists after early
tree pollen but before dandelions when bees are needing pollen. A pollen
patty helps during this period in many areas.

  4.  If I do nothing, will they eventually discard the  non-pollen?

Many bee supply houses will not like what I am about to say. I have had to
pull frames of pollen suppliment simply stored and not used. The powder
packed in cells. I have never had the same problem with patties made with
real pollen.

The pulling of pollen bound frames is common in my area. Also honey bound
from a strong fall flow. You have to pull these frames (not all and maybe
simply move to the outside of the nest) and replace with empty drawn comb to
get the swarm working. Especially true of Russian bees.

Bob

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