[log in to unmask] takes just about every major and minor beekeeping
supply company to task for providing screened bottom boards.

Well that's what vendors do!  They're in it for the money.  As far as the
time frame (And now almost one year later we hear reports claiming the
results are basically non-noticeable), indications that open bottom boards
were not all they were being touted to be is old news.  The first indication
on BEE-L can be found in the archives as far back as January '99.  So don't
fault the vendors.  It's their job to sell what the consumer will buy.

Aaron Morris - thinking Caveat emptor!