Oct. 28, 2021

Bottom Boards (045)

Bottom Boards  (045)

Every kind of hive has some kind of bottom board. Typically, Langstroth type hives have a bottom board that is removable. Many are reversible, too. That is one side has a ridge going around three sides that is only 3/8th of an inch tall, leaving an...

Every kind of hive has some kind of bottom board. Typically, Langstroth type hives have a bottom board that is removable. Many are reversible, too. That is one side has a ridge going around three sides that is only 3/8th of an inch tall, leaving an opening so small in the front that a mouse should not be able to get into the hive. These are used this way in the winter. The other side of this bottom board has a ridge that is 3/4th of an inch tall, to be used in the summer for better ventilation and traffic control out front.

For awhile, bottom boards with a screen were common, developed to help control varroa that would fall through if they fell off a bee above. Some people would put cardboard sticky boards under the screen to catch the varroa and give an idea of how many a hive had. These had to be covered in winter, which was sometimes a problem because of lost covers, warped covers or bent screens. They are still around, but mostly for ventilation, not varroa control.

Polystyrene Bottom BoardMostly, we use what we have, because that’s the way we’ve always done it.

But now there are several styles of bottom boards to use. Many are now heavy duty plastic, some with built in screens and a cover, some are insulated for winter use, and some will fit an 8 frame or 10 frame hive, so no matter what kind of hive you have they will fit just right. Bottom boards are getting to be as technical as the rest of our bee hives. Finally.


We welcome Betterbee as sponsor of today's episode. BetterBee’s mission is to support every beekeeper with excellent customer BetterBeeservice, continued education and quality equipment. From their colorful and informative catalog to their support of beekeeper educational activities, including this podcast series, BetterBee truly is Beekeepers Serving Beekeepers. See for yourself at www.betterbee.com


Honey Bee Obscura is brought to you by Growing Planet Media, LLC, the home of Beekeeping Today Podcast.

Music: Heart & Soul by Gyom, Walking in Paris by Studio Le Bus, original guitar music by Jeffrey Ott

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Honey Bee Obscura

Episode 45 – Bottom Boards


Kim Flottum: Hey, Jim, you know that a while ago we were talking about getting ready for winter. We talked about wrapping and things, but we didn't really talk about the bottom board.

Jim Tew: We didn't talk about bottom boards much, Kim. When I brought that up, I surprised myself. What do you do with bottom boards? I don't know?

Kim: [chuckles] Well, it depends on what bottom board you got. There's a lot of different ones out there that are subtly different. What you do with them is subtly different also.


Hi, I'm Kim Flottum.

Jim: I'm Jim Tew.

Kim: Today, we're going to talk all about bottom boards.

Introduction: You are listening to Honey Bee Obscura brought to you by Growing Planet Media, the folks behind Beekeeping Today Podcast. Each week on Honey Bee Obscura, host Kim Flottum and Jim Tew, explore the complexities, the beauty, the fun, and the challenges of managing honeybees in today's world and engaging in informative discussion meant for all beekeepers, long-timers, and those just starting their journey with bees. Sit back and enjoy the next several minutes as Kim and Jim explore all things honeybees.

Jim: I have this situation, Kim when you've been keeping bees a long time and you're an old guy, I keep using the same old equipment. Just like driving a 1966 Chevrolet because you've always had it. I've had bottom boards now that must be 30, 35, 40 years old. I had a guy who wrote me. I had a picture to Bee Journal. He wrote me and said, "My equipment was always interesting." He said, "There you are using a 40-year-old inner cover."

The guy was almost right to the year it was. That inner cover was about 40-years old. A lot of my bottom boards are old. They have been around for long, long before the screen bottom board. I use them, Kim because I've always used them. They've just always been a part of my bee business.

Kim: Well, I went through the screen bottom board phase and phased out the solid ones that I had that were older than that, older than about 20, 25 years ago. Got all screens because that was going to save the bees because of ventilation and because of varroa and all these things. After a few years, I phased out the screen and I'm back to solid. There's lots of things that even your screen or even your bottom boards go, you got a shallow side and a deep side.

Jim: Yes. Since you brought that up, Kim, I'm going to tell you that I just leave my bottom boards on the 3/8 inch side all the time. Why don't you explain in case we are not being clear here? Why don't you explain the different depths from the different on each side of that?

Kim: Well, I'll tell you why I don't because I don't know.

Jim: Okay.


One side is 3/8 of an inch deep. That ostensibly would keep mice from getting inside of the hive. The other side, if you flip the reversible bottom board over is 3/4 of an inch deep. The kit usually comes with an entrance reducer that you have to keep up with that you would then put in that entrance to keep the mice out. Those are called reversible bottom boards, one side, 3/8, the other side, 3/4. I just leave mine on the 3/8 year-round. Then I don't do much entrance reducing to keep out mice.

Kim: I've got mouse guards that I put on. Not the wooden ones, but these are heavy-duty metal things that-- Going back to screen, there's a lot of people that still use screen bottom boards. A lot of the kits that come with them, come with a piece of that corrugated plastic that you're supposed to slip in the winter to reduce the cold airflow in the hive. I got to tell you something about those sheets of plastic, almost always, they're not perfectly flat.

Jim: No. They're not.

Kim: You slip them in and one side is curled up, or the backs curled up, or the front gets weird. When I was using screen bottom boards and I had that sheet of plastic, I took them off. I took the bottom board off the hive. I took that piece of plastic and I laid it on the inside of the hive there. I thumbtacked it down so that it was as flat as it could get and as tight as it could get to reduce or eliminate any airflow and to make sure that the bottom or the entrance stayed open.

Jim: I understand that because when you were talking, you were hurting my feelings. That insert that you're describing is mine, is the one that has mildew you on it. It has wax and propolis stuck to it. It's over in the near the hive but behind it. I tend to use those covers - either the plastic corrugated board or the metal strips. You've not mentioned that. Some of those screen bottom boards that are wooden have sheet metal inserts that go in. I've always had to, what do you do to keep up of these things because they blow all over the yard if they're not inside the bottom board? All I've ever done was just put it on top of the hive and put a brick on it.

You have to move that brick and that piece of sheet metal when you open the colony, but it's always there. It was always readily available, put that back on. I have not phased anything in or out. Half of mine, right now, I probably got 15, maybe 20 colonies, give or take, who's alive, who's dead. Probably half of those are screen and the other half of the traditional 30-year-old wooden bottom boards. I lean toward having both. I was going to say one or the other. Here's this, let me tell you, Kim. Can I talk just for a second? I'm talking too much, but when I put on old equipment, I purposely leave out that bottom board divider.

I can monitor under the hive, how quickly the bees are cleaning that equipment by the detritus that drops out. I use that as a measurement. Are they really working in that top deep that I put on that has some wax moth damage in it or are they're not doing anything yet? Reading the garbage that comes through that screen wire is helpful at times. Of course, I have mine that sit on flat platforms. There's no grass under my colonies right there. But monitoring that colony litter - that's an odd thing that I do.

Kim: Well, I guess that would work in the summer. If you've got anything approaching winter, you're going to want to close that screen up. I've got all my hives on hive stands. What I want to do even more is, I want to make dead airspace underneath that hive stands so that no matter what bottom board you get, it's not going to fluctuate with colder or warmer temperatures.


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Jim: This is why we're having this discussion because I think we surprised each other. What do you do with the bottom board in the winter? I have not been doing very much. You were, at least, going down to the bottom board, tacking down the insert so that it was solidly in place. I wonder should I be doing anything more? Do you put a sheet of insulation under the bottom board? Does that help those of us in cold climates? Does it matter if you're in a cold climate or a warm climate or this is just busywork? Don't do anything. Bottom boards are fine.

Kim: I think if you can make that dead airspace under a hive stand, if you got them on a hive stand, that's as far I've ever gone. That seems to work because any heat that comes into that hive is going to go up. The warmest part of the hive is going to be way above the bottom board. What I do, when I wrap hives in the winter though, is I bring that wrap that I do down, so it extends beneath the bottom edge of the bottom board.

Jim: Let's say, yes. I see what you would mean. It's wrapped all the way around.

Kim: Yes. Except for the front, which is got one small opening in it. The whole rest of the front is then insulated also. The insulation comes down from the super above it and extends down below the edge of the bottom board. I've got them as about as snug as I can get.

Jim: I don't know that I want to do a lot different. Number one, I love hive stands. I don't like stooping over almost to the ground on those really low, those low stands, I guess they were hive stands. They were just a few inches off the ground. I like colonies now closer to 20 inches, so I don't have to lean over so far. That does mean that, as you've been describing, that my bottom board screen are solid. Especially, the screens are not exposed to airflow, so I guess I'm asking for an opinion, Kim. What would I do? If I’ve got the tear them all the way down to the bottom, the way you do, to do a better job, or can I just slip in that distorted piece of corrugated plastic board and not feel guilty about it?

Kim: You can do that and not feel guilty but ask your bees next spring which they liked better.

Jim: Sometimes it's tricky in any of those, the metal, or the corrugated board. I have to really work to tease those inserts back in. They bind up, but once you got them in there -- You haven't mentioned this, but one of the reasons early on that I had mixed emotions about screen bottom boards is that the tongue of my hand truck when I moved them would sometimes slip or move or tear that screen as I had the colony on a hand truck. When I was having to move bees more than I am now, I had some issues with me tearing up my own screen on the bottom boards.

Kim: Yes, I can see that. I never used a hand truck so that was an issue I've never had to worry about.

Jim: More and more, I don't want to ever want to use one again either.


We haven't said specifically that those screen bottom boards exist for varroa control. I don't think you said that in this discussion. The reason they existed - at all - was for those clumsy varroa mites that happened to drop off a bee, but not just drop off to the bottom board and hitch a ride back up. No, they drop outright through the screen bottom onto the ground. They must deal with ants and centipedes and whatever else. They're pretty much done once they dropped out of the colony. How was that finally rated, Kim? How effective were screen bottom boards for varroa control?

Kim: I don't know that anybody ever came up with a good number to say, "Yes, we've got good control, some control, no control." They were useful in terms of monitoring population because you could count how many dropped in a 24-hour period if you caught them underneath that screen. I've still got some of those sticky grids that you put under your bottom board to count how many dropped in 24 hours.

Anymore, it's not how many do you have, it's, yes, you have them, and what are you going to do now, or you've been selecting for resistance, or tolerance or something. I think the screen bottom board's life of being a varroa control has passed.

Jim: I'm sure it doesn't hurt. Since I've got them, I'll probably use them. They're interesting but I don't know-- probably passed. The sticky boards. Do you remember all the sticky boards we used to use?

Kim: Oh, yes, I do.

Jim: If you didn't have sticky boards, you made your own.

Kim: That too has passed, I think.

Jim: We went through our beekeeping history; we would just been enamored with slanted bottom boards. Some of the old design beehives had bottom boards at a 25, 30-degree angle. The objective was - speaking of these mites falling through the screen - was that when wax moth larvae would….Why did wax moth larvae fall? I don't know. But, if a wax moth larvae fell off the comb, and hit that slanted bottom board, it would roll right out the front of the hive, and the chickens would eat it.

It probably made sense to an old beekeeper someplace, but that slanted bottom board was still a concept as recently as the '70s and early '80s when I started beekeeping. The bottom boards were slanted it the bottom board side rails so they weren't reversible. It was higher in the back than it was in the front. That was so wax moth and hive litter and whatever else would roll down the front and fall out the front of the colony.

Kim: The other thing for those if I recall was if you got a lot of rain, you wouldn't have water running into your hive-

Jim: That's correct.

Kim: -or melting snow in the spring. You wouldn't have water running into your hive. It would let it roll out. I think that too is passed.

Jim: That's a good point and I had forgotten that. Those were complicated construction procedures. To take that sideboard rail and cut the bottom board groove at an angle, that's going to take some complicated jig construction, compared to just cutting a straight groove down that rail side. We, as we've always done in beekeeping, took a very simple concept and tried to make it complicated and impractical.


We probably achieve that with slanted bottom boards. Bottom line, Kim, you got to have some kind of bottom board.

Kim: Yes. You have to have a bottom board. You got to take care of it in the winter. You got to take care of it in the summer. It's different things to do with it, different seasons, but you got to have one. I like solid and lots of people like screen.

Jim: I'm going to stay with chocolate and vanilla.


I use what I have. The next time we talk, I will sit here and say, "Well, the screens are good for this, and the solids are good for that." I'll just stay wishy-washy on the subject, but I do have a bottom board under every one of my colonies right now of some kind.

Kim: Keep them high and keep them dry.

Jim: Hey buddy, I'll talk to you next Thursday. Everybody who's listening, thank you so much for doing that.

Kim: Okay. Take it easy.

Jim: All right.

[00:16:03] [END OF AUDIO]