Used in monitoring and fighting against varroa infestations, our varroa screen is placed on top of a regular bottom board and includes a wooden entrance closure. A certain percentage of varroa mites will accidentally fall off bees or out of the hive when transferring from bee to bee.With just a bottom board in place, the fallen mites will just hitch a ride on a bee entering the hive. When a varroa screen is on the hive, the mites will fall through the screen and onto the bottom board. Because the front entrance to the bottom board is closed off, it forces the bees to enter above the screen and keeps mites trapped on the bottom board, where they consequently die. Researchers indicate that mite falll may be as high as 30% .