Screened bottom board?

[paintingpreacher]

Article in March ABJ. Managing Varroa, IPM Realities. The author really seemed to discourage screened bottom boards. I have most of my hives on screened bottom boards but even here in the south I have trouble getting the bees into the bottom box. I know there are many opinions but what do most think. Are screened bottom boards helping or hurting?

[NCSUbeeKEEPER]

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.

[NewbeeNnc]

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

[hipbee]

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.

[valleyman]

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.

[ArkansasBK]

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

[MDS]

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.

[beeup]

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

[Ben Brewcat]

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.

[hipbee]

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

[Ben Brewcat]

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 .

[paintingpreacher]

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.

[Mike Snodgrass]

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

[Ueli Hoffmann]

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.

[NDnewbeek]

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?

[valleyman]

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.

[libhart]

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.

[Ueli Hoffmann]

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?

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

[RiodeLobo]

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

[D Coates]

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.