a mesh bottom board, is one part of an integrated plan.

varroa mites are obligate to brood, so interruption of brood cycle should be integrated into your cultural plan. here we are on the edge of swarming season, which is perfect time for artificial splits of hives.

you intercept swarming by moving roughly half the bees and the queen into a "package", and removing brood from the original hive except for one frame of brood. rehive the artificial swarm after 2 or three days.

this creates a break in brood cycle, allows adult bees to clean and shake free of mites, interrupts the mite brood cycle, and mitigates swarm loss.

some will cage the queen to break brood cycle however this is stressful, and must be accompanied by more hive space, or reduction of bee population.