Arnold asked about robbing with mesh floors.

No robbing takes place because you keep very, very small entrances, as
little as one bee-space if needed. You won't get any overheating simply
because the whole floor provides an air inlet. When I first started using
these floors, about 1990, I had the same fears as Arnold - would the wasps
hang in clusters below the mesh floors fighting to get in. Well they don't,
hardly see a wasp, or other bee, underneath them. Maybe they try when I am
not looking but quickly appreciate there is no-way they can chew through
that steel wire.

But the importance of mesh nothing larger than 8 wires to the inch cannot be
over emphasised, a larger mesh easily allows access to any invader.

My normal entrances using mesh floors are about 4" wide and 3/8" high. When
we have had associations visits to my apiaries some had said, "I want a big
entrance to allow my bees easy exit/access". I have always replied they
should witness one of my swarms (which I never (!!!!!) experience) emerging.
Even using a very small entrance they still pour out like water, hundreds
and thousands at a time.

One word of warning, be careful with the bucket feeders, make sure they have
formed a vacuum before placing onto the crown (cover) board, otherwise you
will see a couple of cupfuls flowing through the mesh.

Ken Hoare