Al Needham was kind enough to share with the list some comments concerning
use of a screen to prevent mites that drop from the brood nest from climbing
onto a bee and re-entering the brood nest.  I personally use such a screen
and value it highly but want to remind list members of three points from
last years discussions on this subject:
* creating a space between the screen and the bottom board that cannot be
assessed by bees provides a wonderful breeding ground for wax moths!  Pollen
also falls into this space, and the moth larvae feel like they are in
heaven.  Several list members commented on having this difficulty, and I was
among them.
* Once a beekeeper decides to have a screen, and I am among those, there is
no good reason to have a bottom board!  Let the mites fall through to the
ground.  There is no reason to put on a bottom board during he winter...at
least as far north as Albany, New York.
* Studies done in 1998 and published in ABJ during early 1999 showed summer
mite reduction of up to 25% when using screens in place of bottom boards.
However, by fall mite counts in hives with screened bottoms were equal to
those in control hives.  These studies were repeated during 1999 by Dr. Nick
Calderone at Cornell, and verbally reported at the Empire State Honey
Producers meeting during November, 1999.  This means that screens should
best be looked at as method of deferring the time when Apistan or other
treatments need be applied, rather than a means of avoiding such treatments.

For those who want to put a screen over bottom boards, Betterbee, as well as
Brushy Mountain, sell such items.

Lloyd
Lloyd Spear, Owner, Ross Rounds, Inc.  The finest in comb honey production.
www.rossrounds.com