Screened Bottom Board
Convert a standard bottom board into a screened bottom board assembly to monitor and/or reduce varroa mite population levels.
- # 8 mesh hardware cloth – size 16 1/2″ x 19 3/4″
- 2 wooden frame pieces – size 19 1/4″ x 7/8″ x 3/4″ each
- 2 wooden frame pieces – size 19 1/4″ x 1/2″ x 3/4″ each
- 1 wooden frame piece – size 16 5/8″ x 7/8″ x 3/4″
- 1 wooden frame piece – size 16 5/8″ x 1/2″ x 3/4″
- Rear opening block, used to seal the area at the back, beneath the screened board – 1 wooden piece sized 14 7/8″ x 1 1/4″ x 3/4″, bevel top edge 10 degrees (will fit the width of most standard bottom boards, it should also fit snuggly from top to bottom)
- 1 1/4″ galvanized nails
- 5/16″ staples
- 2″ galvanized nails
Approximately 5 feet of 1″ x 2″ pine (or 1 5/8″ x 3/4″) is required to complete the construction of one screened bottom board. It is suggested that the 19 1/4″ (#2, #3) and 16 5/8″(#4, #5) pieces be cut to length first and then rip/cut those pieces to the proper widths. A piece of masonite, 18″ x 14 5/8″ x 1/8″ (or to fit the bottom board you have) can be used as a tray below the screen so that it can be removed and cleaned.
The standard bottom board will need to be reversed end to end so that the usual “entrance” is now at the rear of the hive. The screened bottom board will sit on top of the reversed standard bottom board, with the bees entering at the front of the assembly. Cutting the standard bottom board to 20″ in length is recommended so that it is flush with the brood chamber. This prevents water from accumulating in the hive and extends the lifespan of the bottom board.
Join the 7/8″ side pieces to the 7/8″ end piece (pieces #2, #4) (do not nail) and staple the hardware cloth to this 7/8″ frame. Place the 1/2″ frame on the screen in the opposite orientation as the 7/8″ frame (Fig. 1) and nail it to the 7/8″ frame with 1 1/4″ nails. Use two 1 1/4″ nails at overlapping joints to prevent racking. Keep the screen taut and the frame square during assembly. Drive two 2″ nails into pre-drilled holes at the ends of the 7/8″ (#4) part of the frame to secure the 16 5/8″ piece to 19 1/4″ sides (Fig. 2).
Design and plans compliments of Paul Kelly and The University of Guelph