In message <[log in to unmask]>, Bumble
<[log in to unmask]> writes
>In reading my copy of  Snelgrove (10th ed Feb 1956) he shows the screen
>board as having only one layer of mesh in its construction.  However I have
>heard it referred to as a "double screen" board and a beekeeper of over 50
>years experience told me that a single layer of screen will not work and
>that screen should be placed on both sides of the board.  What is the
>opinion of the list?
I have used it successfully by having one area permanently with a single
layer of mesh and the other a piece of queen excluder - mesh (actually
perforated zinc) is put over it once the bees are in equilibrium (enough
young bees upstairs with the eggs, larvae and queen cells). It always
seems to work well. But in all cases I have used it, there are honey
supers between the two parts having the old queen or queen cells and a
queen excluder over the lowest box. Therefore there is a large distance
between queens. I don't always use more than one upper entrance, even
then, usually only 2, not 3 as Snelgrove proposed.

The Horsley version has a moveable slider operated from outside the hive
- closed entrance and open queen excluder - open entrance and closed
queen excluder - but only one entrance.

Both are easy to use without finding the old queen. Shake all bees off
and move frames to the new box which will be put to the top. Fill up as
usual. Re-build and let the bees sort themselves out before closing the
passage between the 2 parts. The value of the temporary access is to
ensure the brood has enough bees. This avoids any potential problems of
having too few nurse bees in the split or even with the old queen. Hence
the value of the double screen. Though this may not be what you meant.
--
James Kilty