Peter Borst <[log in to unmask]> asked:

> Have you compared them side by side with hives on regular
> bottom boards to determine the difference in the same apiary
> the same year?

You should ask this question of someone at Beltsville Bee Lab,
where the screened bottom board (called "The Beltsville Screen"
at first) was developed.  Their opinion would carry more weight than
mine, and they likely can back up their view with excellent data.

In my own experience, the first year I used screened bottom boards,
I had 5 hives with screened bottom boards, and two without, all
within a few yards of each other at the same site.  (The two "without"
were being used for pollen collection, and one can either have a
pollen trap or a varroa screen, but not both. )

While I can't represent my limited data as "publication quality" at all,
there was little or no difference in any of the key factors (brood, honey,
etc) that I noticed.  Yes, I do keep written records, so this is not merely
an impression.

But I think you are missing the point.  The general consensus
is that screened bottom boards work.  If there is an impact
on the "overall productivity" of the bees, it is so minor, it has
escaped the notice of many attentive beekeepers.

Even if there was some minor disadvantage, the advantages
(better hive survival) outweigh any possible disadvantages.
An overwintered hive will always out-perform a split or package,
by a wide margin, and one must replace a dead-out with a split
or a package.

I consider screened bottom boards to be cheap insurance.
They are cheap to make, they work well, and the way they
work is both well-understood and easy to verify yourself.


        jim

        farmageddon