# Screened bottom board?



## NCSUbeeKEEPER (Feb 28, 2011)

I'm not familiar with the article, but I can already tell that I would disagree with the author 100%. I'm not saying that a screened bottom board will solve all your Varroa problems but they have so many advantages. They improve the ventilation in your hives, they provide a way to monitor your infestation levels, they over-winter better, and they provide a 100% treatment-free reduction in mite levels. I think they are one of the most important developments in modern beekeeping and if you're not using them, you should be! Switching hive bodies during early spring should adequately resolve upward bee movement.


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## NewbeeNnc (May 21, 2009)

This topic has already been beaten into the ground too many times. Do a thread search you'll see.


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## hipbee (Sep 11, 2009)

I disagree with the article as well.......if you live in a cold climate just close the SBB when its cold.

there is no way that all of those mites falling through dosent help at least a little.....when I put in a Sticky board on hives with a high infestation there are hundreds of mites that fall in just a few days, without a SBB they would just wait on the Bottom for another bee to hitch a ride on.


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## valleyman (Nov 24, 2009)

hipbee said:


> I disagree with the article as well.......if you live in a cold climate just close the SBB when its cold.


It depends on what you call cold climate. Here in Ky we just are ending (I hope) a very cold and snowy winter for us. My screened bottom boards have been wide open all winter, as have the vented supers on top. I just last week went thru my 7 hives and found them stronger than I imagined they could be. You know what I didn't find? MOISTURE, NONE. One hive is Queenless I guess the vent could have killed her. Now if I was in one of the real bad winter states I might consider closing them part way during say -20 degree wind chill or below. 
MOISTURE kills bee cold doesn't. Oh and I saw no mites.


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## ArkansasBK (Mar 5, 2011)

I agree with the majority. I can't find a single disadvantage to the SBB. I love 'em. I'm in the south also.


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## MDS (Jan 9, 2011)

No problem with screened bottom boards here in central Missouri. Love them and easy to build after you find an online source for #8 wire cloth.


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## beeup (Apr 10, 2010)

What was the authors reason for being against SBB? Was he in a northern state?


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## Ben Brewcat (Oct 27, 2004)

His main points were technically correct; that only phoretic mites may fall (additionally, and he doesn't mention this, but it's likely that mainly moribund mites fall anyways) , and as a mite-killing tool their efficacy isn't supported by the data. However he studiously ignored the demonstrable and important benefits of ventilation and monitoring. The ventilation is GREAT; I've left SBBs totally open for two winters here in CO with some very cold snaps and haven't had colonies freeze. The main risk is, as noted, chilled brood in early spring. I now close the sliders around 3/1 for that reason. But perhaps the single best reason for the SBB, IMO, is the ease of monitoring for mites and how little that monitoring disrupts the colony. No killing bees, no digging bees out of the broodnest for a dusting, just count without opening the colony.

IPM is pretty much required in today's beekeeping climate, and SBBs are a critical IPM tool. 'Nuff said.


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## hipbee (Sep 11, 2009)

the aurthur compared SBB with opening your house windows in early spring, I guess he thinks the bees keep the whole hive warm.


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## Ben Brewcat (Oct 27, 2004)

hipbee said:


> the aurthur compared SBB with opening your house windows in early spring, I guess he thinks the bees keep the whole hive warm.


Good point, and common misconception. Also, I sure DO open my windows here in Spring... we mountain folk can only breathe so much indoor air before we start getting a twitch .


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## paintingpreacher (Jul 29, 2006)

He was in Ohio. He says a three year study of screened bottom boards (2001-2003) done at Cornell University ended with the conclusion that "screened bottom boards are not recommended for control of V. destructor in the northeast. In addition to being ineffective for Varroa contol, screened bottom boards are also detrimental to spring colony management. 
The article seems to be saying the bees will not build up as well in the spring with screened bottom boards. (In the Northeast)
IMO:: I use mostly screened bottoms here in the south, but I do have a few with solid bottoms. I do not see much difference in their build up accept those on screens seem to stay in the upper boxes until warmer weather. Those on screens seem to get crowded just as quickly as those on solid boards.


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## Mike Snodgrass (Mar 11, 2010)

10 beekeepers, and 14 opinions!!!
Ill do what they all do LOCALLY!!!!!!!! LOCALLY!!!!!!!!!


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## Ueli Hoffmann (Jan 26, 2011)

Experimentation of an Anti-Varroa Screened Bottom Board in the Context of Developing an Integrated Pest Management Strategy for Varroa Infested Honeybees in the Province of Quebec

_"Based on the results obtained during the two years of trials, we are convinced that the anti-varroa bottom board is a good means of slowing the progression of the varroa mite population in the colonies. Our conclusion reinforces those of several other studies, which demonstrate the same tendency. We therefore recommend its use within the Canadian context. The anti-varroa bottom board should however be used with a closed bottom in order to not, contrary to the desired result, encourage an accelerated increase in the varroa mite population which would follow a lowering of the hive temperature. This word of caution is very important. The bottom must be closed by means of a movable drawer that permits, at regular intervals, a cleaning of accumulated hive debris. This drawer is also useful for sampling purposes. We also recommend that the distance between the bottom of the sampling drawer and the screen be at least 4 cm (1 5/8”) to prevent the re-entry of the varroa mites into the hive unless future studies prove that this distance can be reduced."_

For what it is worth I think it is important to remember this study was conducted in Quebec, Canada so the concern of lowering hive temperatures may be different than in warmer climates.


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## NDnewbeek (Jul 4, 2008)

I have never liked the 'open windows in winter' analogy with screened bottom boards. The opening with a SBB is essentially the FLOOR of the hive. Windows open mid-way to 2/3 up on a structure. The physics and their effects (warm air rising) are completely different between these two situations. Heat shouldn't be lost through the open bottom of a hive for the simple fact that heat rises. It might produce a thermocline in the hive, but heat won't be lost.

Additionally, moisture shouldn't be lost through a screened bottom board either because warm air holds more moisture than cold air. The warm air collecting at the top of the hive should be holding all the moisture as well.

Now, if you run an upper entrance, heat WILL be lost, and so will moisture.

How many run both SBB's and upper entrances? This arrangement should produce a flow of air from the bottom to the top of the hive and out. Do bees overwinter well with THIS configuration?


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## valleyman (Nov 24, 2009)

Mike Snodgrass said:


> 10 beekeepers, and 14 opinions!!!
> Ill do what they all do LOCALLY!!!!!!!! LOCALLY!!!!!!!!!


I respectfully disagree. Of the ones on here that have actually used SBBs I haven't seen but mostly all positive. On many other issues it would be more like 10- 20/25 opinions.


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## libhart (Apr 22, 2010)

valleyman said:


> MOISTURE kills bee cold doesn't.


Not trying to hijack the OP's thread, but I've seen this written so many times, and I have to to respectfully disagree. Put a bee in your freezer for a couple hours and then tell me if its still alive because it was just cold, not wet.


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## Ueli Hoffmann (Jan 26, 2011)

NDnewbeek said:


> How many run both SBB's and upper entrances? This arrangement should produce a flow of air from the bottom to the top of the hive and out. Do bees overwinter well with THIS configuration?


:thumbsup: Both are good questions. I am looking forward to reading the responses from those who have used SBB's with upper entrances.


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## RiodeLobo (Oct 11, 2010)

This is my first winter, but that is what i am running. SBB (closed) with a reduced top and bottom entrance. So far so good. No moisture problems, good bulk of bees still, and spring is a month away.

Dan


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## D Coates (Jan 6, 2006)

I run SBB's open all year with bottom entrances as well as have small emergency upper entrances and have for four years. I do it to ensure there is some air movement to haul away excess moisture that isn't absorbed by the emergency sugar I have on top of the frames (Mountaincamp method). It's not perfect, I still lose hives and this year was the worst 4:11 hives, 1:5 nucs. But to me it makes the most sense and that's how I choose to do it.


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## NCSUbeeKEEPER (Feb 28, 2011)

libhart said:


> Not trying to hijack the OP's thread, but I've seen this written so many times, and I have to to respectfully disagree. Put a bee in your freezer for a couple hours and then tell me if its still alive because it was just cold, not wet.


The idea is not that a single bee is freeze-proof, the idea is that a healthy cluster of bees can regulate temperature in harsh winters. A healthy cluster can not regulate moisture, and if they're getting dripped on during freezing conditions they WILL SURELY DIE!!

-I use a screened bottom board and I place tongue depressors along the rim of my inner cover to create a small gap between it and the top cover. Another trick I've adopted is to place a few pennies on the inner cover during late fall. During my first inspection of the season (late winter/early spring) I take note of whether or not the copper on the pennies has oxidized (green color). If the pennies have oxidized heavily then the moisture content of that hive was high during the winter. A monitoring technique that will only cost you a few cents!! Can't beat that...:thumbsup:


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## Barry (Dec 28, 1999)

I guess when I start to see SBB on bee trees, soffits and wall cavities, I'll give them a second look. These are the places and conditions bees choose to live all on their own.  Where I'm at cold winters and moderate summers, haven't seen a need for them. Certainly don't need them for mites.


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## NDnewbeek (Jul 4, 2008)

D Coates said:


> I run SBB's open all year with bottom entrances as well as have small emergency upper entrances and have for four years. I do it to ensure there is some air movement to haul away excess moisture that isn't absorbed by the emergency sugar I have on top of the frames (Mountaincamp method). It's not perfect, I still lose hives and this year was the worst 4:11 hives, 1:5 nucs. But to me it makes the most sense and that's how I choose to do it.


Now THAT is interesting to hear! I run the same setup (screened bottoms/small upper entrance) and, most years, the bees overwinter fine, but always with some losses. 

This year though, I have the same kinds of losses (4:12 and 1:8 nucs). After reading the article, I am wondering if I need to change/improve my setup.


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## jmgi (Jan 15, 2009)

I think SBB function better as a ventilation tool rather than a means of lowering varroa numbers. Sticky boards or oil pans under the SBB will catch mites, dead ones and lives ones, but I don't think in the long run they keep a hive from becoming infested, they just tell you whether you have mites and maybe the degree of mite infestation if kept track of regularly. I use SBB on my top bar hives but don't use them yet on my Lang's. My screens are not open to the air though all the time, I have a hinged board that can be opened or closed under it. John


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## libhart (Apr 22, 2010)

NCSUbeeKEEPER said:


> The idea is not that a single bee is freeze-proof, the idea is that a healthy cluster of bees can regulate temperature in harsh winters.


I'll buy that but only to a certain extent. But I think (keyword=think  ) if a SBB is open to an area of cold wind, even cold breezes I think, the bees on the outside of the cluster will eventually get cold enough to become torpid and fall off the cluster. I know the bees rotate in and out of the cluster's core, but I'm not sure this can happen fast enough to keep the outter bees from dying off when an open sbb allows the cluster to be exposed to cold moving air.

I know it's nearly impossible to control hives enough to do an experiment that tries to pinpoint a single variable, but in anyone aware of a study of many hives in a cold, breezy location with open vs closed sbb?


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## Kingfisher Apiaries (Jan 16, 2010)

Read my thread, Are screened bottom boards essential to treatment free beekeeping
I hate those things! 

mike


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## Merlyn Votaw (Jun 23, 2008)

I used SBB this past winter with goodrsults but I like them best for summer venelation.It gets cold here


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## Kingfisher Apiaries (Jan 16, 2010)

Oh, did I fail to mention no losses from about Oct to now?


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## hoodswoods (May 15, 2009)

If ANY pests fall thru my SBB into the (enclosed) pan below and dies, it's that many fewer (can you use those words together:s) the bees have to attend to. This is not any sort of plug for the company, since I construct all my own speciality woodenware, but the fact that purchasing #6 screen (which for me is the optimum size for SBBs) is nearly impossible in small amounts is why I have used this product (they advertise on beesource).

http://greenbeehives.com/ipk-small-hive-beetle-trap-assembled-unpainted.html

Something else to pay for, but for me, more valuable than my gloves.

Only if I removed the pan and left the pan entrance open could it provide any sort of ventillation (good or bad). I ran both top and bottom entrances this winter which worked perfectly, as the bees use both equally. I run only the bottom entrance the rest of the year to cut down on unguarded invasion by critters & use other (screened) methods for ventillation.


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## Kingfisher Apiaries (Jan 16, 2010)

Could someone cite a research paper that says that SBB work? As far as I am concerned, there is no conclusive evidence for or against them. Seems like folks claim that everyday something new these things can do...
Mike


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## Adrian Quiney WI (Sep 14, 2007)

Mike, see post #14 in this thread.


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## D Coates (Jan 6, 2006)

Kingfisher Apiaries said:


> Oh, did I fail to mention no losses from about Oct to now?


Don't crawl up too high on the soap box, life has a way of teaching you it's never really stable up there. 

Are you directly attributing your reported success with not having SBB's? Can you directly prove the that failures you experienced and discussed on your linked post are because of SBB's? I'm not discounting your personal claims but if it was as easy as insinuated we wouldn't be having this conversation would we?


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## hoodswoods (May 15, 2009)

Kingfisher Apiaries said:


> Could someone cite a research paper that says that SBB work? As far as I am concerned, there is no conclusive evidence for or against them. Seems like folks claim that everyday something new these things can do...
> Mike


I see the proof every time I pull the pan out to clean/refill. BUT, as I said in a previous discussion re SHB, I really haven't spent the time to verify if the medium I use in the pan (veg oil) is drowning the pests, or if they are arriving there in a deceased condition (I'd like to use pest glue trap glue if anyone can ID the type glue they use).

I believe that the whole idea behind the I-part (integrated) of IPM is that multiple methods are used together - whatever those might comprise of for each keeper and their philosophy. If I'm diminishing the number of pests in my hives that fall thru (it's not the Dyson vortex vacuum cleaner, by the way) by 25%, then a SBB is successful by that percentage.

Since my SBB's cannot act for ventillation, I won't comment.


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## NCSUbeeKEEPER (Feb 28, 2011)

Kingfisher Apiaries said:


> Could someone cite a research paper that says that SBB work? Mike


I would ask you to elaborate on the word "work". Do they work as an effective means of monitering infestation levels? Yes. Do they improve ventilation in the hive? Yes. Do colonies over-winter better with or without them? Debatable. Are they an absolute solution to Varroa mites? No.

Bottom Line: When you consider the pros and cons it's hard to argue against them.


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