Double screen boards are a very handy tool for a number of beekeeping needs! This is a simple wooden frame with two screens separated by 1/8" hardware cloth. A 3/8" entrance is included on one end for the upper colony to go in and out (the lower colony uses their bottom board entrance).
The double screen board is useful in the following situations, to name a few:
1. Overwintering and/or spring buildup of weaker hives. Place a weaker colony on top of a stronger one with the double screen board in between. Warmth and energy from the stronger colony below can provide quite a boost to the weaker hive!
2. Combining two hives. Place the double screen between the two colonies for a couple of days, so they can adjust to each other before fully combining. Less stressful for the bees!
3. Resolving a laying worker situation. In some cases, you can dispel a laying worker scenario by placing the laying worker colony on top of a strong queenright colony, with the double screen separating them. Over time, the pheremones from the queen below will shut down the laying worker. Doesn't always work, but worth a shot!
4. It can also serve as a vented inner cover or moving screen!