I’m in love with all the ventilation aids I’ve added to my hives lately. Judging only from preliminary observations, I’d say the screened bottom board is #1 on my Gotta Have ‘Em list. The ventilation rim ain’t too shabby either. But the one I love the most, purely for the This Is So Cool factor, is the screened inner cover. It provides a handy view of the hive that doesn’t require tearing the hive apart or wearing any protective clothing. Check it out:
This is just a prototype. Screen with a wider mesh might be more ideal, but still… I’ve watched the bees quickly fill this honey super since I added the screened inner cover not too long ago, and it’s great to be able to just pull the top off the hive and look down through the screen and observe what’s going on without disturbing the bees. This is exactly the kind of thing many first time beekeepers would love, because you know they’re looking for any excuse to poke around inside the hive to see what’s happening. And it’s good for the bees, so why not?
I don’t see harm in any of these ventilation aids for my hives in St. John’s, Newfoundland, at least during the peak of summer. I’m not sure I’ll stick with them over the winter months, though.
February 2019 Postscript: I don’t use screened inner covers anymore, but I do remove the regular inner covers from my hives sometimes when it’s really hot, placing an empty moisture quilt on top, which is basically the same thing. Full-on ventilation with a view of the bees through the screen. I don’t do that when it’s cold at night, though.