Hi Everyone,

Allen Dick asks regarding mesh bottoms:
"*  8 mesh is recommended, but 6 mesh harware cloth is cheap and strong
   and widely available.  Is it satisfactory?  Or does the mesh need
   to be finer?

*  Is a bottom entrance necessary?  Some of us have auger holes in the
   brood boxes.  Would they suffice for entrances?

*  Does debris build up on the screens?  Is there wax or dead bees
   after winter?  Or do the bees seem able to make everything fall
   out the bottom?

*  Has anyone noticed any adverse effect on spring build-up?"

There are two requirements for mesh size as far as I know.  They are small enough that bees can't get through and large enough that varroa fall through.  Any mesh that will fulfill these requirements will work fine.  Note that window screen is too small for varroa to drop through so will provide ventilation but not varroa control.  Here in the US window screen is usually about 16 mesh to the inch.

Bottom entrances:  I like them as it is easier to work colonies that continue to orient and fly to the bottom entrance as you work the hive.  As far as I can determine the bees don't care as long as they have an entrance to use.  With the mesh bottoms I use a smaller entrance that is short enough that mice can't get into the hive so there is no need of a mouse guard.

Overwinter here in Minnesota USA dead bees do pile up on the mesh just like on a bottom board but no mold etc like you get on solid bottomboards.  I still need to clean the bottom in the spring just like with solid bottoms.

I have noticed spring buildup problems.  Colonies with mesh bottoms raise more brood a little later in the spring at least compared to those on solid bottoms and will raise brood right down to the bottombars of the lower broodchamber.  ( I am using two deep broodchambers ) They will also raise queen cells ( swarm cells ) on the bottombars right above the mesh.  This is different than solid bottoms where they prefer to raise swarm cells between the boxes rather than on the bottom of the lower chamber.  Yes you have to check down there for swarm cells or they will leave before you know what is going on.

These are my observations from using 8 mesh hardware cloth bottoms since mid 1999 on only a few colonies.  The bees seem to do well with them and build up fine.  I do go light on upper entrances but do use them overwinter.

FWIW

blane


******************************************
Blane White
MN Dept of Agriculture
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