Screened bottom board utility questions. Or, does the Emperor really have clothes?

[TooFarGone]

I am just getting back into (hobby level) beekeeping after a many year hiatus. I am located in the Deep South and are subject to virtually year round pest attack. New major pests have forced reevaluation of many old apiary practices. One of the “new” ideas is the screened bottom board. It appears to me that this became popular with the arrival of the Varroa mite as a tool to assess colony infection levels. It has morphed in to a variety of other applications including a holder for a small hive beetle trap oil pan. SBB use raises a number of questions in my mind:

1) Does the screen in fact create easy access to wax moths and SHB’s? It creates a giant opening in the bottom of the hive which might be facilitating infection. Many seem to create a space under the hive that is not patrolled by bees. It appears that many of the screens would hardly slow down wax moths and beetles. Data has been published that the SHB’s are attracted to alarm pheromone. They enter the hive and infect the hive pollen stores with a yeast that creating fermentation products that include attack pheromone, which in turn attracts a lot more hive beetles! Until the bees develop the genetic selection to adequately control the beetle (as the AHB’s do), we need to try to stop the beetles before they enter the hive entrance via various traps. It just seems that having such a hole in the hive defenses is a bad thing.

2) The SBB is used for Varroa mite sampling. This method is reportedly not as accurate as an ether roll or sugar roll, so is the large screen really needed?

3) Increased Ventilation- This may be a double edged sword. The bees may have difficulty regulating the amount of airflow through the hive and there is the potential for too much ventilation, decreasing their ability to control the temperature and humidity inside the hive. If extra ventilation is desired from below, some 1 inch holes in the bottom board that were screened with fine mesh and could be propolized as desired by the bees might be the an alternate answer.

I would be very interested in the thoughts and experiences of others, particularly those who have tried it both ways.

[dusanmal]

Most of your concerns are true for some of screened bottom board designs but there are some that are fully enclosed with tray of liquid in that may be removed (I like http://www.greenbeehives.com/ipk-sma...unpainted.html but there are others) which remove the concerns.
As for does the screen need be so large - idea is that bees knock down small pests from the whole hive volume, those fall down on the whole bottom surface. If screen for them to fall through is not over the whole bottom, mobile ones would just climb back and undamaged larvae could complete the life cycle there on the bottom.

[Colleen O.]

TooFarGone, I have been wondering the very same things. I am a new beekeeper and have two top bar hives, one is a temporary hive that I put together and has a window screen bottom board, the other has the normal size mesh. To me they are a bit of a double edged sword. I have started thinking they are the way the pests are getting in, because the entrances are well guarded. They do, however, seem to also let the bees clean pests out of the hive. It has also allowed me to shut them in for the day but still give them adequate ventilation.

I have a cedar hive nearly built (need to put the observation window in it and make a decision on the bottom board) to take the place of the temporary hive. I think I am going to forgo the SBB on this one and see which fares better. I'm really not sure which way to go on this, but it seems the bees can go after the pests and close off the hive better without the screen.

I'll be following this thread closely to see what others with more experience think about this topic.

[BeeCurious]

From what I've read, it seems that SBB's are not reducing the mite populations by a significant amount. Some very knowledgeable beekeepers have begun using solid bottom-boards again.

The Google search on the http://www.beesource.com/ page will allow you to search "SBB". If you can't find what you're looking for, try Bee-L. There was a recent discussion about SBB's.

http://community.lsoft.com/scripts/w...exe?A0=BEE-L&X

[Vance G]

I doubt there usefulness. Every time I here a hobbyist newbee in the cold country bemoaning his colonies inability to build up, my first thought is are they SBB religionists. I believe in ventilation and when a couple pounds of bees are hanging out I will supply more for my bees, until then, I want them building up and not fighting to climate control.

[xcugat]

limited utility for most beekeepers unless you are in a hot/humid climate like the south
See my huge thread here

http://www.beesource.com/forums/show...e-not-worth-it

[cerezha]

1) Does the screen in fact create easy access to wax moths and SHB’s? It creates a giant opening .... It just seems that having such a hole in the hive defenses is a bad thing. ==> I always assume that SBB is accompanying by solid bottom board, so there is no complete opening. If oil pan inserted between solid board and screen, it creates very effective barrier for all small "visitors".

2) The SBB is used for Varroa mite sampling. This method is reportedly not as accurate ... ==> to me, sticky board is a good indicator of general health of the beehive. If mites counted regularly, it gives you a baseline. Comparison with baseline gives you an idea what is the mite situation in the hive? Sudden (or steady) increase in mite count would be alarming to me. Baseline would be specific to the hive.

3) Increased Ventilation ==> this is very controversial subject. Couple of things:
- in order to have a "ventilation" we should have entrance and exit for the airflow. In another words we need some air coming from outside and exiting at another end. If one out of two does not exist - there is no "ventilation" in common sense. One could remove bottom board completely and if there is air-tight top - there is no "ventilation", simple physics. But, sure, air could move by convention even in close volume.
- if there is an exit to the air at the top,than we have a chimney effect, too much ventilation. So, technically, amount of ventilation would depends from the size of the exit hole if any.
- My bees have SBB and the screened hole in the inner cover (chimney). They regulate "ventilation" two ways - (1) block the hole in the inner cover by their bodies when necessary; (2) block screened bottom. It seems to me, they have no problem adjusting "ventilation" as they like. At some point, I noticed that they reduced the hole in the inner cover with propolis. Now, when it's hot - they removed propolis and use chimney effect instead fanning. My bees never beard and they do not fan often - instead, they just have good time on the landing deck letting physics to take care of the ventilation issue. Bees are very instrumental!

As for wintering with SBB - I saw the pictures of beehives in snow with completely opened bottoms... I have no experience with this since we are in southern Ca and our problem is heat, not cold. In this sense I agree with xcugad that for worm climate SBB probably is useful. Personally, in cold climate I will just block the screen with piece of board, not a problem at all! The bottom line - to me, it is very useful to use SBB and sticky board as a diagnostic tool - less invasive to the beehive. Sergey

[Keefis]

Screen is supposed to be 1/8" grid. Moths are going to have much difficulty getting in that. Normally the moths come in the entrance.
Supposedly the mites that are groomed off the bees will fall through the screen, out of the hive. If you have a sticky board underneath then you can count the mites. (If your hive is on the ground this point is moot because they will climb back in.)
As far as ventilation, the top can be sealed and the bottom screened and the convective currents created by the heat of the bees will move air around regardless. The cluster is 90 + degrees and the outer reaches of the hive are cooler, therefore creating air movement.
Too much ventilation means that the bees will have to make more trips to get water. In a perfectly balanced hive the water evaporated from the honey and bees will condense on the interior walls of the hive giving the bees distilled water to use. (without being too moist)

[TooFarGone]

Thanks to all for responding. Th point about the SBB with the oil pan that completely closes the space is noted- this gets past much of my concern about having an uncontrolled ingress of critters through the bottom board. One of the big problems with beekeeping is too many variables to control them all...as a control freak, this really bothers me!

Xcguat- I missed your thread when I did my initial search, thanks.

[EastSideBuzz]

From what I've read, it seems that SBB's are not reducing the mite populations by a significant amount. Some very knowledgeable beekeepers have begun using solid bottom-boards again.

So if you want to use SBB for checking mites then do it. For a year round board use solid. SBB cools the hive and then the pests take a better hold. Just be careful the ++'s you get can also be your downfall. Know why you are using them and don't count on them being the only solution.

One of the big problems with beekeeping is too many variables to control them all...as a control freak, this really bothers me! .

The bee's have been around a lot longer then us and they instinctively know whats best. If you mess with them to much you will do more harm. If they die of something then they might be better off. The strong survive and the traits in that survivor hive are the ones that you want to continue.

On a side note. The stupid gene is not getting bread out of our race either because........... You know maybe I should not have gone there. OH forget this last thought. Focus on fixing them bee's.

[Laurence Hope]

I use SBB, although I still have some solid bottom board hives. I originally went to the SBB for ease of testing mite drop and the ability to use powdered sugar as a miticide. I know of no other necessity for them in my operation, but they are there and work well when I want to do as stated above. There is a hassle involved when I must shut them off to use thymol gel or MAQS or whatever else demands shut SBB.