# OA and brood



## cdanderson (May 26, 2007)

Obviously many of you use OA Vaporization throughout the year even when there is brood. However, I keep reading studies that say it harms brood. Am I missing something ?

Thanks, Charlotte


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## bugman2 (Apr 9, 2014)

Vaporization does not hurt brood or queen, The dribble method can hurt both from what I have read.


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## Mike Gillmore (Feb 25, 2006)

I agree, the studies you are reading are most likely referring to the liquid "dribble" method. If you do happen to find a study claiming that "vaporization" harms brood please let us know.


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## camero7 (Sep 21, 2009)

Been using it for several years... never had any brood problems.


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## snl (Nov 20, 2009)

cdanderson said:


> I keep reading studies that say it harms brood. Am I missing something ?


Yes, those studies relate to dribbling not OAV.......... Have never seen a study that states OAV harms brood.........


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## JWChesnut (Jul 31, 2013)

I accidentally killed hives outright using a double-dose of OA in a "crack-pipe" vaporizer (2009?).
Yes, you can overdose hives with OAV.
The dose response curve for OA shows increasing mortality at 2x dosing.


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## dsegrest (May 15, 2014)

I know that varroa can kill brood.


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## snl (Nov 20, 2009)

JW........... I believe we're talking normal doses here.......one gram per brood chamber.


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## deknow (Jul 17, 2006)

I thought you had posted previously that an overdose of several times didnt harm the bees?


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## crofter (May 5, 2011)

JWChesnut said:


> I accidentally killed hives outright using a double-dose of OA in a "crack-pipe" vaporizer (2009?).
> Yes, you can overdose hives with OAV.
> The dose response curve for OA shows increasing mortality at 2x dosing.
> View attachment 16112



The chart attached seems to apply to OA in sugar syrup dribble not vaporization.


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## snl (Nov 20, 2009)

deknow said:


> I thought you had posted previously that an overdose of several times didnt harm the bees?


No Dean, I previously posted that consecutive doses (such as 1 time per week for 4 weeks) did not harm bees).


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## camero7 (Sep 21, 2009)

I have more that double dosed hives [nucs] with the Heilyser vaporizer without any noticeable problems with bees or brood.


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## snl (Nov 20, 2009)

camero7 said:


> I have more that double dosed hives [nucs] with ..... vaporizer without any noticeable problems with bees or brood.


I'm sure you have as you have stated so, but I believe that we're discussing here 1 gram gram doses per brood chamber (normal, correct doses) harming bees..........and that dosage does not...... 

I have not tried to find the amount of OA overdose (using vaporization) that it would take to harm bees


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## johno (Dec 4, 2011)

Is it possible that using a 'crack pipe' you could overheat the OA and produce FA and by over dosing by OA you might produce enough FA to damage the hive. Just a thought.
Johno


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## snl (Nov 20, 2009)

johno said:


> Is it possible that using a 'crack pipe' you could overheat the OA and produce FA and by over dosing by OA you might produce enough FA to damage the hive. Just a thought.
> Johno


I'm not sure. I've heard that won't happen unless under "lab conditions" and also heard otherwise. I'm trying to find out. I don't believe the formic that is produced would harm the bees as that is the basis for other mitecides; it's the carbon monoxide that would harm (kill) the bees.


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## seapro220 (Mar 14, 2013)

I've heard that due to the oxidation process (smoking up the hive) that sometimes the queens stop laying for a while? I've been thinking about starting the OA process, and this is one of the 'keys' that I'm interested in. Anybody experience this issue? From what I understand the OA process only kills the 'present' mites also - not the ones that are sealed-inside capped brood. Isn't this true also? I presume that you don't want to do this while the honey flow is on also - and does this affect the dreaded SHB any? It'd be nice if it killed them also?


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## snl (Nov 20, 2009)

seapro220 said:


> I've heard that due to the oxidation process (smoking up the hive) that sometimes the queens stop laying for a while? I've been thinking about starting the OA process, and this is one of the 'keys' that I'm interested in. Anybody experience this issue? From what I understand the OA process only kills the 'present' mites also - not the ones that are sealed-inside capped brood. Isn't this true also? I presume that you don't want to do this while the honey flow is on also - and does this affect the dreaded SHB any? It'd be nice if it killed them also?


I've not experienced the queen to stop laying using OAV or have read that may happen. You are correct, the OA only kills phoretic mites (those on the bees). No, you do not use OA with supers on. Unfortunately, it does nothing to kill SHB. Wish it did!


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## zhiv9 (Aug 3, 2012)

My understanding is that the dribble isn't that harmful to brood either - it is just ineffective when there is brood present as it also only work well against phoretic mites. The dribble is also unsuited to the repeat applications that would make it effective other than a broodless period. It is hard the bees carapaces 

Virtually any treatment is hard on the queen - just because it doesn't kill her and the bees don't supercede her doesn't mean it isn't harming her.


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## sterling (Nov 14, 2013)

Zhiv9. Do you have any evidence showing harm to queens??


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## zhiv9 (Aug 3, 2012)

sterling said:


> Zhiv9. Do you have any evidence showing harm to queens??


No, but it seems to be well accepted that queen lifespan has decreased with the pressures of varroa, viruses, etc. Repeated exposure to high concentrations of organic acids or any other insecticide can only we contributory.


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## Mike Gillmore (Feb 25, 2006)

zhiv9 said:


> My understanding is that the dribble isn't that harmful to brood either - it is just ineffective when there is brood present as it also only work well against phoretic mites.


That's the reason most beekeepers who use the dribble method only apply "one" time per year, usually in early winter when there is no brood present.


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