I feel that, by this approach we can immitate more closely,
the conditions that prevail in a "hollow tree" natural nest and
hopefully deter the sort of wax moth attack that is so often
associated with the sliding panels that are used for mite monitoring
and to reduce ventilation.
18 mm Woodwork
19 mm Woodwork
I have to apologise for appending my name to this device,
but I could not think of a cryptic or descriptive title for it.
It is an attempt to retain the varroa shedding qualities of
the "Open Mesh Floor" but at the same time, reduce the excessive
ventilation that causes the bees to treat the lower 100 mm or so of
their comb, in a different fashion to what they would if the
ventilation was not present.
As timber is available from DIY stores in 18 mm or 19 mm thicknesses,
this design suits either.
The details of the dimensions are due to the existance of
a jig for the manufacture of queen excluder grids. This jig is one of
the manufacturing aids of B.J.
who are manufacturers of metal components for beekeepers and the
beekeeping appliance trade. (You should consult them if you wish to
purchase the metal floor insert.)
shown left is with the frame made from 18 mm thick timber, if
19 mm is used the gap between the frame and the grid is reduced by
1 mm all round.
It is important that the gap is never more than 3.5 mm
otherwise there may be trouble with robber bees or wasps.
The dotted green line represents the edge of
the entrance if an 18 mm
is used instead of the conventional one.
Whichever size of entrance block is used, a pair of staples
should be fitted into the side walls so that the block cannot fall
inside the floor. This is illustrated for a 21 mm square entrance
block, below left.
If an 18 mm
entrance block is used it will align with the frame material.
The illustration depicts the entrance block as a grey "ghost".
The 18 or 19 mm frame width was chosen owing to the use
in Britain of "cold way" and "warm
way". The design will shed just the same amount of varroa
whichever method is in use.
Assembly is by gluing and screwing, using six, #6 x 50 mm
twinthread screws and two #6 x 30 mm screws. The two smaller screws
that are used vertically should have their tips filed, or ground,
down so that they do not interfere with the longitudinal screws.
The ventilation is much less (about 85% less) than a
comparative area of "8" mesh.
The principle is simple... varroa mites will fall either
by accident or due to chemical narcosis. The radius of the fold at
the top of each strip is small and the sides are particularly steep.
Any falling mite is doomed to fall through one or other of the gaps.
The only place where they may possibly ledge is the small welded tabs
on the tie bars and that represents less than one percent of the area
of the floor.
Operation is completely passive and the floor can be left
in position at all times during the year. No provision is made for
monitoring mite drop, but it envisaged that the user will place a
sticky board, with a mesh screen covering, directly on the ground
between the legs of the stand.
This floor should not be considered a "treatment" for
varroa, however it should be used as a part of "Integrated pest
This metal version may be sterilised by wiping a gas flame
over it, but could be subject to corrosion if organic acids are used
as part of your management. If the item proves popular enough a
redesign would be possible using an injection moulded plastic grid
that would withstand such acids.
Cost is a big issue with most beekeepers but this version
will compare favourably with an open mesh floor made from galvanised
"8" mesh, which is a relatively expensive item. It should prove durable
if the wooden parts are coated with
linseed oil, the metal grid should not be oiled as that
might arrest a falling mite.
Various estimates have been made in the past about the
number of mites that will lose their grip and fall from the bees. I
am not concerned what the actual figures are, all I am prepared to
say is that around 99% of mites that would have fallen on to a
conventional floor, will meet their doom by this method.
Many beekeepers express concern that an open mesh floor
will be too draughty for the bees. I personally think that the bees
cope admirably but they do re-arrange their nests in the lower
portion of the frames if they are used. This floor has considerably
reduced ventilation compared to mesh and should satisfy those
beekepers that are concerned, and should cause less alteration to the
way the bees use their comb.
This document links back to "British Standard Beehive and
Frame types" and thence to both the "National" menu and the "Rational"
menu as the device is equally valid for both top bee space and bottom
bee space use.
Written... 01 June 2001
Revised... 04 February 2002