# OAV and screened BB and effect on queens



## Mosherd1 (Apr 17, 2011)

I used MAQS a couple years ago and was disappointed with a couple colonies going queenless after the treatment. Does this seem to be a problem with OAV? Also, how do most people close the screened bottom boards for the treatment? My SBB are open too the ground below. The sticky board (when inserted) is not air tight, so do most of you just slide a piece of cardboard in through the entrance and place the wand above it to cover the screen? Thanks,
-Dave


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## iluvicecream (Jun 2, 2014)

I have a SBB and I always have a sticky board inserted. When I use OAV I just slide the vaporizer through the landing board so it sits on top the screen, I stuff the bottom opening with a wet kitchen towel and try to close the upper notch with a wet wash rag. I don't think there's a way to get it totally air tight when doing OAV, but it's been very effective despite some vapors escaping here and there.


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## vdotmatrix (Apr 5, 2014)

Its a 13 minute process....I slide the IPM board in the bottom and close off the inner cover...I slide the vaporizer in the entrance and then shove a rag in around it to make it air tight....cook it for 90 seconds, pull out the vaporizer and then replace the rag and keep the hive plugged up for 10 minutes and then open it up. Air tight just has to be pretty closed up you can stick a piece of cardboard or something to press the IPM board up against the SBB...i have the same issue with one of my NUCs... I don't like MAQS, i think it is too harsh so I switched to using 50% soln. of FA and the treatment is over in 24 hours...easy-peasy.


Mosherd1 said:


> I used MAQS a couple years ago and was disappointed with a couple colonies going queenless after the treatment. Does this seem to be a problem with OAV? Also, how do most people close the screened bottom boards for the treatment? My SBB are open too the ground below. The sticky board (when inserted) is not air tight, so do most of you just slide a piece of cardboard in through the entrance and place the wand above it to cover the screen? Thanks,
> -Dave


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## Stephenpbird (May 22, 2011)

I use only OAV now, twice a year. I too have SBB open to the ground and don't bother sealing the hive at all and the mites still die.


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## vdotmatrix (Apr 5, 2014)

of course they still die, but more would die if the fumegation of the hive were more thorough right?; but YMMV. OAV has been used in Europe for a long time so who knows more than you-all! What kind of bees do beeks mostly use where you live? thanks


Stephenpbird said:


> I use only OAV now, twice a year. I too have SBB open to the ground and don't bother sealing the hive at all and the mites still die.


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## Stephenpbird (May 22, 2011)

vdotmatrix said:


> of course they still die, but more would die if the fumegation of the hive were more thorough right?;


It does not matter if a few mites survive the summer treatment. Not many treatment methods get rid of 100% and that's one of the reasons a second treatment in the brood less stage in winter is recommended.




vdotmatrix said:


> but YMMV.


???????



vdotmatrix said:


> OAV has been used in Europe for a long time so who knows more than you-all!


True, but there are very few countries where OAV is legal in Europe and not many treat with OAV in summer as is done widely in the States. 



vdotmatrix said:


> What kind of bees do beeks mostly use where you live? thanks


Carnica (Carniolan) and Buckfast.


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## vdotmatrix (Apr 5, 2014)

YMMV: your mileage may vary

I know local beeks who say they are keeping treatment free hives and going organic....they are also buying new bees every year because they don't treat and their bees do not suvive the winter.


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## enjambres (Jun 30, 2013)

Just a point of note about OAV: Vdotmatrix uses burns 90 seconds long undoubtedly because that's the correct timing for his particular wand. But burn times are wand-specific, so be sure to follow the appropriate instructions for your particular equipment. (For example my wand, a Varrox, is powered on for 2 min and 30 secs, and the left inside the hive for a further 2 min to finish the sublimation and cook off the remaining OA, before removing it.)

Regarding the SBB, I have both SBB and solid boards on each of my stacks so closing them up isn't a problem, other than the front entrance around the wand, which I seal with paper towels. I have a friend with only SBB and he made himself metal trays to slide in that cover the bottom of the SBB. 

What didn't work successfully for me is trying to do it under the SBB. The screening caused the vapors to re-crystalize and not propagate well into the hive. I had initially though it would be better to do it under the screening to keep all the bees safe from being caught in the pan. In practice (now, obviously, on top of the screening) I only very, very rarely find dead a bee in the pan when I withdraw it.

Enj.


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## Stephenpbird (May 22, 2011)

enjambres said:


> What didn't work successfully for me is trying to do it under the SBB. The screening caused the vapors to re-crystalize and not propagate well into the hive. I had initially though it would be better to do it under the screening to keep all the bees safe from being caught in the pan. In practice (now, obviously, on top of the screening) I only very, very rarely find dead a bee in the pan when I withdraw it.
> 
> Enj.


Yes, I had exactly the same experience. I used to use aluminum screening but that does not stand up to organic acids to well so now use stainless steel screening.


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## Stephenpbird (May 22, 2011)

vdotmatrix said:


> YMMV: your mileage may vary


Thanks


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## BernhardHeuvel (Mar 13, 2013)

Concerning the queens: I never had an issue with it. Some Austrians claimed to have queen losses, but it never turned out what the real cause was. They used 5 grams of oxalic acid per vaporization in a selfmade pan. I use only 0.5 gram per hive through the Italian heat gun thing. 

In studies they've found, that everything beyond 2 grams doesn't kill more mites. 1-2 gram oxalic acid is pretty much the standard. Don't know why they chose the 5 gram.

The most sophisticated device is the Oxamat. See:





https://www.youtube.com/watch?v=-HZ6u8Bkoew

It is only very time intensive.


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## vdotmatrix (Apr 5, 2014)

SPOT ON! My motorcycle battery cooks a scoop of OA off in about 90 seconds.


enjambres said:


> Just a point of note about OAV: Vdotmatrix uses burns 90 seconds long undoubtedly because that's the correct timing for his particular wand. But burn times are wand-specific, so be sure to follow the appropriate instructions for your particular equipment. (For example my wand, a Varrox, is powered on for 2 min and 30 secs, and the left inside the hive for a further 2 min to finish the sublimation and cook off the remaining OA, before removing it.)
> 
> Regarding the SBB, I have both SBB and solid boards on each of my stacks so closing them up isn't a problem, other than the front entrance around the wand, which I seal with paper towels. I have a friend with only SBB and he made himself metal trays to slide in that cover the bottom of the SBB.
> 
> ...


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## vdotmatrix (Apr 5, 2014)

Dang!! that is the coolest contraption ever!!! too bad I don't read Italian.....LOL !


BernhardHeuvel said:


> Concerning the queens: I never had an issue with it. Some Austrians claimed to have queen losses, but it never turned out what the real cause was. They used 5 grams of oxalic acid per vaporization in a selfmade pan. I use only 0.5 gram per hive through the Italian heat gun thing.
> 
> In studies they've found, that everything beyond 2 grams doesn't kill more mites. 1-2 gram oxalic acid is pretty much the standard. Don't know why they chose the 5 gram.
> 
> ...


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