Slatted racks: how should the slats be arranged?
My inbox was full of questions about slatted racks this morning. One of the questions concerned the direction of the slats. The slats should go the long way—they should run from the front of the hive to the back of the hive. The idea here is that the slats should line up with the frames and–more importantly—the spaces between them should also line up. This way, mites that are dislodged by the bees have a better chance of falling down between the frames, falling between the slats, and then falling through the screened bottom. This continuous space also allows for better air flow.
Is this a perfect system? No. Not all mites will fall through: some will get caught on rough parts of the comb, some will intercept bees on the frames, and some will land on slats and eventually find their way back up into the hive. But if there were no spaces to fall through, all the mites would make it back—so it is better than nothing.
I think the main virtue of the slatted rack is the extra room it provides for bees to “hang out.” The hive becomes very congested in the spring and summer and worker bees can congregate in this space without making the brood nest excessively warm. An overly warm brood nest may stimulate swarming.
My hives are up off the ground about two feet and I can climb under the hive stands and look up into the hives through the screened bottom. In the summer, I am always amazed to see how the bees cluster on the slatted racks. The warmer the day, the larger the cluster. I would probably be unconvinced about the utility of the slatted rack if I hadn’t seen this again and again. It is fascinating.
Another beekeeper asked me how to get the slats to line up if you are using nine frames in a ten-frame brood box. Although I am always reluctant to endorse particular products, I have to say that Brushy Mountain Bee Farm has the perfect slatted rack in its catalog. You have to assemble it yourself (it is easy to do) and you can put in either nine or ten slats according to what you have in your brood boxes. Also, if you are using nine frames and two follower boards you can position the slats to accommodate that arrangement as well.
In the winter slatted racks provide some dead air space below the brood nest that provides a little extra insulation. I leave slatted racks in all year long and I strongly believe they have increased the health of my hives.