Glossary
A beehive bottom board featuring a wire mesh screen instead of a solid floor. Screened bottom boards serve two primary functions: passive varroa mite monitoring (mites that fall through the screen land on a removable tray where they can be counted) and improved hive ventilation (warm, moist air exits downward).
When a varroa mite loses its grip on a bee or is dislodged by grooming behavior, it falls downward. On a solid bottom board, the mite lands on the floor and can re-attach to a passing bee. On a screened bottom board, the mite falls through the mesh onto a removable monitoring tray (sticky board) below and cannot return to the colony.
Beekeepers count mites on the sticky board over a 24-72 hour period to estimate infestation levels. This natural mite drop count provides a non-invasive monitoring method that does not require opening the hive or handling bees.
Screened bottom boards provide significant ventilation benefits in warm climates: hot air rises and exits through the top of the hive, drawing cooler air in through the bottom screen. This convective flow reduces the colony's cooling workload and can prevent overheating in southern summers.
In cold climates, some beekeepers close off the screen in winter (using a solid insert board) to reduce heat loss, while others leave screens open year-round, relying on the cluster's ability to thermoregulate.
No. Screened bottom boards provide passive mite removal (mites that naturally fall cannot return) and monitoring capability. They reduce mite populations by an estimated 10-15 percent at most. They are a monitoring and supplementary control tool, not a standalone treatment.
This depends on your climate and management philosophy. In moderate climates, leaving the screen open provides moisture ventilation. In very cold climates, a partial or full closure may help retain warmth. Experiment and observe what works for your conditions.
A white or yellow plastic or cardboard insert coated with a thin layer of petroleum jelly or cooking spray, placed under the screened bottom board to catch falling mites. Count mites on the tray after 24-72 hours to estimate infestation level.
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