Hello Vivian, and Gang,

Vivian, a simple way is to use bricks on the edges of the bottom boards.
They are relively cheap, last a long time and easy to install.
Just place a brick under each corner of the screen bottom board and
it is done.

I use pallets obtained for free just for the asking. The OMBB, open
mesh bottom boards sit on these to provide ventilation and mite dropping
space. I do have one hive on concrete half blocks that are set in the
earth. The OMBB is then set on bricks for ventilation.

I made the OMBB myself and designed it to have a screen board which
is removable from the back of the hive. This faciltates mite drop
testing and cleaning. The hive remains on the OMBB while the screen
board is pulled out from the rear of the hive. The bees hardly notice
that the screen portion of the OMBB has been removed.

I use freezer paper sprayed with Pam cooking oil for the mite drop test.
I leave it there for 24 hours and pull it out the next day and return
the scren board to is place. The in and out takes less than 30 seconds.

Ernie Gregoire

Grist Mill Apiary

Canaan, NH
The paper is viewed indoors with a magnifying glass,( old eyes ).