screened bottom boards

[Zookeep]

getting rid of the last of them, for me they are a complete fail, every hive I have inspected with the screened bottom board has done the same thing. they have abandoned the bottom half of every frame in the bottom box and yet the hives with solid boards are brood right to the board, I am so glad I did not go hole hog and buy a bunch of them.

[Cracker]

I've been having the same problem since day one and went on year round,but didn't have a clue why.Thanks Bill!!!!!

[robo]

I also stopped using SBB many years ago and have no regrets.

I know many folks believe that the screened bottom board (SBB) helps reduced varroa population because the mites fall through the SBB and can not climb back up or grab onto a passing bee.  This does seem logical, and most people can visualize this process and easily buy into it. The basic premise that they take for granite is that the natural fall off rate of varroa is significant.  I personally do not believe it is.  There are studies that show the proposed benefits of the SBB can be outweighed by the temperature drop if the SBB is left open for ventilation, both in the brood nest where the mites breed,  and in the rate of falling off bees.  So if you're using open SBB, inserting empty frames in the brood nest, using top entrance, or any other method that reduces the hive temperature, are you are helping the population of varroa grow?

I have attached two PDF files showing results of the studies if you want to read them in their entirety.

Temperature seems to have more of an impact on Varroa reproduction than most people thought. While 95ºF is "brood nest temperature," that temperature fluctuates some with climatic conditions. By carefully controlling temperature, Varroa were found to reproduce best at 93ºF. Performance was a bit worse at 88-91 and 95º. At the lower than brood nest temperatures, the post-capping period is extended about one day per 2ºF. At higher temperatures the post-capping period is not shortened significantly. However, at "brood nest" and higher temperatures, mite reproduction drops way off. In the same study it was shown that 53% of the mites on brood held at 59-68% RH (normal) reproduced normally but at humilities of 79-85% only 2% of the mites reproduced. Hot, humid brood nests are tough on Varroa. Studies of Apis cerana brood nests showed drone brood is reared at 92ºF (perfect for Varroa) and worker brood is incubated at 96-98ºF (too hot for Varroa). Purposely cooling the brood nest in Apis mellifera colonies by using a "thin" hive lid, open bottom board, simulative feeding to spread brood out, and splitting the brood nest with frames of foundation doubled the numbers of mites on the bees.

The antivarroa bottom board must never be used with its bottom hole opened as this leads to a lowering of cluster temperature resulting in ideal conditions for varroa development. As confirmed in 2000, this situation not only negated the beneficial effects of the bottom board, it also resulted in a net increase in the mite infestation rate (29.2% more varroa mites, non significant) as compared to the control group.

[Perry]

Nice link.
I stopped using them and am trying to cycle out the ones I have. I seem to recall only a 15% benefit would be realized (natural drop) in the reduction of mite levels using them.
I also started to find wax moth becoming a problem in the last couple of years as a result of debris below the screen where the bee couldn't gain access.

[G3farms]

Same here, mine are all being slowly worked out of the system too. I find it also gives ants another entrance that is hard to control along with the stray weed growing up through it.

[robo]

I also started to find wax moth becoming a problem in the last couple of years as a result of debris below the screen where the bee couldn't gain access.

Yes,  I like the refer to SBB as "wax moth heaven".  Food falls from the sky and they are protected from the bees by the screen.  I have heard of quite a few cases of weak hives that where taken over by wax moths that multiplied from under the SBB.

[LazyBkpr]

  Know of a couple that swear by their SBB's. They claim you need to use a slatted rack to get the bees using the entire lower brood box...   I've never said anything to them about it.. but it always made me think...   Isn't that defeating the entire purpose?    Being CHEAP.. I cant see buying SBB's and then buying racks..   Maybe if I only had three or four hives...

[Crofter]

Thanks for that info Robo.

I am in a rather cool location compared to a lot of you. My thought is it lowered hive temps for too much of the day to a point where wax making was reduced and the foragers could not get going as early in the day as they were needed for covering brood. I keep my bottom entrances small until they are crowded. Buildup is quicker on solid bottoms.
The screened bottoms are good for doing mite drop counts but they have drawbacks I think.

[blueblood]

I'm with ya Zoo....I have went all solid since my second season.

[Finally Home]

New keeper here.  Can one of you post a decent list of pro's and con's so we can learn.  I've heard of the SBB but never used one.  Any other downfalls besides whats been posted?? 

[riverbee]

i don't use them finally, and never have, so i can't give any advice or opinion on them.  i'm an old fashioned keep, so i use solid bottom boards.  i tend not to try and fix something that isn't broken and works for me.......lol 

[Slowmodem]

I have changed from the open SBB to the SBB with the oil tray because of SHB.  I did that last summer, so I don't have a full year's worth of info on that type yet.  I guess I'll use the SBBs on swarm traps and such, since I don't want to throw them away.

[rcannon]

I've gotten rid of my screen bottoms,also. When the bees chased the hive beetles,they would run thru the screen and hang out under the hive until they could sneak back in. I never used the oil trays,just open bottoms for "ventilation", which I thought was a good thing at the time.
I also found that the queens avoided laying near the screen bottom, I suppose because the temperature wasn't as well regulated there.
I'm much more satisfied with solid bottoms and the bees seem to be, too.

[Jen]

All your comments are very interesting. I use a sbb because of the ever controversial ventilation thing, and I can get an idea of my mite count with a plastic board smeared with crisco. And after a formic acid treatment, I can easily estimate the carnal damage. I don't like doing the sugar roll, or the ether roll. This next season I'll watch for how the queen broods down on the bottom of the frames.

[blueblood]

Another reason I like solids is because they are easier to build.  Screens involve so much more when building them.

[Finally Home]

Very good info.

[Jacobs]

I have had another problem with screened bottom boards.  On a couple of occasions my hives have requeened.  After her mating flight, the queen went under the screened bottom board rather than into the hive.  I wound up with a hive full of highly polished cells and content workers who felt queenright.  I also had a large cluster of bees under the bottom board.  The first time I saw it, it took me awhile to figure out what was going on.  I broke down the hive and dumped the cluster into the hive and reassembled it all.  It was fine after that.  I have seen it one or two times since, and now use sbb only when I temporarily don't have enough solids.

[Bakersdozen]

Has anyone seen this product?  www.bluebees.com.au  Is there any difference between this and slatted bottom boards?

[iddee]

My opinion. it is a lot of words used to say nothing. Kinda like a politician talks.

[Riverrat]

Slatted bottom boards around here have went to the way side years ago. I think the SBB is not far behind it.