# Oxalic Acid Vaporizing vs. Dribbling



## GaSteve (Apr 28, 2004)

Apparently both methods can achieve an efficacy rate in the mid-90s if done correctly. Pros and cons as I understand them:

Vaporizing is fast but requires a heating element and an energy source and fumes may not be healthy for the beekeeper. Dribbling only requires mixing OA (3.2% I think) in 1:1 sugar syrup and a large syringe but must be done while bees are clustered and broodless in cold weather and takes longer per hive. I have also heard the dribble method may be a little more harmful to the bees but that may have been due to inaccurate dosing.

FWIW, I have heard rumblings that the EPA is very close to officially approving OA for use in beehives. Apparently they will "hold the license" which precludes a commercial entity from having to pay a huge amount of money to get the approval. Although the folks I talked to weren't sure which method would be approved, they expected it would be the dribble method probably due to the danger of OA vapors.

Curious what folks experienced with these methods think about one vs. the other.


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## Bob J (Feb 25, 2013)

Randy Oliver has done some pretty extensive work that might be worth taking a look at.....

articles-by-publication-date


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## snl (Nov 20, 2009)

As a seller of vaporizers, I can tell you this. Most commercial folks use the dribble method. It's quick and easy. 2 workers can quickly do a yard. They don't necessarily use a syringe, but a hand sprayer. Open the hive, spray & close. Vaporizing takes longer, but does not require that you open the hive. Many hobbyists and some side-liners use it as again, you need not open the hive. Some use 2 and sometimes more vaporizers. Quick and easy for one person. Used with the proper safety equipment, OAV is not a health hazard. 

I've also heard that the EPA will approve OA for use in beehives. Not sure what method, OAV or OAD........but probably OAD.


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## antonioh (Oct 15, 2014)

Here in "guidelines pdf", you have a study about oxalic in the dribbling method, doses and way for application (sorry, its in portuguese) :

http://www.dzoo.uevora.pt/index.php...co_guia_de_utilizacao_na_luta_contra_a_varroa

Oxalic acid is not approved in all EU countries (in Portugal we are still waiting...) , but some beekeepers as I, are using it, mainly in the dribbling form. I have never used it in vaporizer, as I do not have the equipment and I thing it´s a little more complicated.

Dribbling is very easy and there is not the risk of inhaling the fumes. I do it alone, and it does not take more time per hive than putting strips of Apistan or Apivar. 

I apply it in the first week of January, as is the month that the hives have less brood but, the rate of success is low as in all countries of southern Europe, because there is , even in that month, 2 to 3 frames of brood and oxalic only kills foretic mites.
Even so, is useful to lower the count for one more month, so we can have higher temperatures to use another product (usually formic).

When diluting oxalic, you must pay attention to whether oxalic type you are using, if dihydrated CAS No. : 6153-56-6 or anhydrous CAS Nº. :144-62-7 and take that in account for the weight of acid you use.

The first time I used it , there was a mistake in the lab and they sold me anhydrous for dehydrated. As a result the concentration was higher, with heavier bee mortality . I only do one treatment and only once tried a second one 15 days apart. The second one had higher mortality. There is always adult bee mortality, and a delaying of the activity of the queen, but in middle spring they are to the point. In 12 years of use, never had problems with queens.

OA is very good in countries of central / north Europe where brood is suspended in winter. In south Europe, where there is brood all year round, is not so good... but it gives us time to have temperatures to use more efficient methods, and indeed the only one we can use in low temperatures.


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## cerezha (Oct 11, 2011)

GaSteve said:


> ....Curious what folks experienced with these methods think about one vs. the other.


 My understanding is that dribbling method can be applied only for broodless colonies at the end of season and once (smaller total dose). Evaporation can be used anytime during the active period, often a few times in the row to address the brood issue. In terms of efficiency, both methods are about the same, but keeping in mind that dribbling is used once and vaporizing 2-3 times, the absolute efficiency of dribbling is higher (my opinion). 
I have to admit, that I personally do not treat, but I did quite extensive analysis of available treatment options in case I need to treat. For myself, I choose OA vaporizing because in my climate (SoCal) we have no brood break. For colder climate I would choose dribbling because it is much more controllable and easy. There is another great anti-varroa method for cold climate so called "Thermo-camera." Bees are heated up to 48(???)oC in special camera, which caused mites to drop. I believe, originally, it was invented in Japan, than Russians improved it and now Germans are selling commercial apparatus (same principle, but different from classical "Thermo-camera"). Please, search internet for details. You may try Russian: пчёлы термокамера


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## Bob J (Feb 25, 2013)

I prefer the OAV as it is effective and my understanding is that it is less risk to the colony..... Breathing is no problem as I always stand upwind... Only downside is that you have to do multiple treatments to as it doesn't get the mites under capped cells... No problem for me since I am a backyard beek but would be a hassle if I kept outyards....


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## dsegrest (May 15, 2014)

Bob J said:


> I prefer the OAV as it is effective and my understanding is that it is less risk to the colony..... Breathing is no problem as I always stand upwind... Only downside is that you have to do multiple treatments to as it doesn't get the mites under capped cells... No problem for me since I am a backyard beek but would be a hassle if I kept outyards....


The jury isn't in for me on the efficacy of OA, but I used it and will be checking the hives in about 2 weeks. I still have 1 hive that gets treatment #3 today. It seems to be that the exposure to the beek from the vaporizer is less than from the dribble. I haven't tried the dribble, but I know that it involves mixing the chemicals and handling them in liquid form.


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## Mbeck (Apr 27, 2011)

GaSteve said:


> FWIW, I have heard rumblings that the EPA is very close to officially approving OA for use in beehives.


I guess this means pure OA will be taken off the shelf and unavailable in the USA.

Hoard now or you'll be stuck ordering it from Australia.


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## cerezha (Oct 11, 2011)

dsegrest said:


> ...I know that it involves mixing the chemicals and handling them in liquid form.


 Dissolving OA in syrup is much-much less dangerous procedure than breathing vapors. Proper PPE for dribbling would be simple nitrile gloves and some splash protection for your eyes. In case of vapors PPE would be (my guess) face mask with respirator, gloves and some coveralls to minimize skin exposure to the vapors. The biggest danger from OA vapors would be to your lungs and eyes.


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## snl (Nov 20, 2009)

cerezha said:


> The biggest danger from OA vapors would be to your lungs and eyes.


With adequate protection and standing "up-wind" both of those dangers are alleviated............


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## AstroZomBEE (Aug 1, 2006)

Mbeck said:


> I guess this means pure OA will be taken off the shelf and unavailable in the USA.
> 
> Hoard now or you'll be stuck ordering it from Australia.


Haha


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## Nabber86 (Apr 15, 2009)

Although I have never tried it, dribbling sounds messy and I don't like the idea drenching my bees, especially if it is cold weather when no brood is present. I am also not sure how it can be faster than OAV, per treatment; you don't have to take the hive apart and it only takes a few minutes per hive. I guess the 3 application thing makes dribbling faster in the long run though. I only treat 4 to 5 hives, so I dot see OVA as a problem. 

Breathing OVA is awful and dangerous. I treat on nice warm fall days when little breeze is present, have a long wire on my vaporizer, and stand far up wind. Just a whiff is enough to make you choke; badly. I have never taken a full-blown hit of white vapor, but I imaging doing so would cause sever problems. That said, I don't wear a respirator, even though I have several.


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## HarryVanderpool (Apr 11, 2005)

Mbeck said:


> I guess this means pure OA will be taken off the shelf and unavailable in the USA.
> 
> Hoard now or you'll be stuck ordering it from Australia.


Now THAT was funny!


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## antonioh (Oct 15, 2014)

> dribbling sounds messy


 No . It´s easy and simple.



> I am also not sure how it can be faster than OAV, per treatment


 Taking out the roof, the inner cover, filling the syringe, dribbling 50 ml of the solution, and closing the hive takes one minute.


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## HarryVanderpool (Apr 11, 2005)

Nabber86 said:


> I am also not sure how it can be faster than OAV, per treatment; you don't have to take the hive apart and it only takes a few minutes per hive.


Several years ago, I hurt my hand and had it all bandaged up just as I was getting ready to dribble.
I called a LARGE and very well known beekeeper who told me to just dribble from the top. Don't take the hives apart.
I realized that it was going to be that or nothing, so away I went.
I was very happy with the results!
So that's how we have done it every since.
Pop the lid, 7 - 9ml per seam of 3.4% Knock 'em dead!
And now you want to talk about fast?!!!
Try it on a few pallets and do your own testing.
I think you may be surprised!


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## cerezha (Oct 11, 2011)

snl said:


> With adequate protection and standing "up-wind" both of those dangers are alleviated............


Yes, the key words are *adequate protection*


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## papar (Apr 10, 2007)

What is the mixture ratio using sugar syrup?


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## PAHunter62 (Jan 26, 2011)

Papar - 

Randy Oliver's site has lots of info on OA treatments. 

http://scientificbeekeeping.com/articles-by-publication-date/

The link entitled "Oxalic Acid - Part 1" talks about the dribble method. There is a link off the part 1 page to a treatment table showing formula's for mixing. Following is the link to the treatment table:

http://scientificbeekeeping.com/oxalic-acid-treatment-table/

I used the weak mix (2.5%) last winter. 

PAHUnter62


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## blackandtan (Aug 20, 2014)

HarryVanderpool said:


> Several years ago, I hurt my hand and had it all bandaged up just as I was getting ready to dribble.
> I called a LARGE and very well known beekeeper who told me to just dribble from the top. Don't take the hives apart.
> I realized that it was going to be that or nothing, so away I went.
> I was very happy with the results!
> ...



So if I use all mediums and the brood nest is 2 or 3 boxes I don't need to take the hive apart? I can just dribble straight down from the top? 
That is really simple. I was under the assumption that I'd have to take my hive apart and do each separate. The idea of that makes me nervous in the cold weather.


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## WBVC (Apr 25, 2013)

If you dribble OA in the winter..early Jan...does the cold moisture cause issue in the hive? I ask as there much discussion of methods to minimize moisture in hives in cold weather.





HarryVanderpool said:


> Several years ago, I hurt my hand and had it all bandaged up just as I was getting ready to dribble.
> I called a LARGE and very well known beekeeper who told me to just dribble from the top. Don't take the hives apart.
> I realized that it was going to be that or nothing, so away I went.
> I was very happy with the results!
> ...


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## blackandtan (Aug 20, 2014)

WBVC said:


> If you dribble OA in the winter..early Jan...does the cold moisture cause issue in the hive? I ask as there much discussion of methods to minimize moisture in hives in cold weather.


What he said. I'd like to hear an answer on this too.


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## antonioh (Oct 15, 2014)

blackandtan said:


> What he said. I'd like to hear an answer on this too.



For the twelve years I had dribbled oxalic, I didn´t had any problems. Here the average temperatures in January are from min of 5~7º C and max of 10~12º C.

True that you are putting syrup in the hive - 5 ml in each space between frames to a max of 50 ml per hive.

It may seem a lot but it´s not. If you put the 50 ml, remember that it represents only 25 ml water. Condensations inside the hive represent much more than that.

Also the syrup (1 water+1 sugar) has an osmotic concentration that still absorbs moisture. 

And some of this syrup is taken by the bees (is not the goal but nevertheless they do it, as is proved by the gut necroses in bees treated with oxalic).

Just keep your hive in a sunny place with entrance fully opened and good ventilation and you will have no problems.


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## blackandtan (Aug 20, 2014)

antonioh said:


> For the twelve years I had dribbled oxalic, I didn´t had any problems. .


Thanks for your insight. I have a dumb question for you. If you are running double brood boxes do you just dribble in the top box or do you separate the boxes and treat each box separately?


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## thebeemanuk (Oct 16, 2014)

The University of Sussex UK did a study and said

An amazing 97% of the varroa were killed by using 2.25g of oxalic acid per hive, and colony survival 3 months later in spring was close to 100%.
http://www.sussex.ac.uk/lasi/sussexplan/varroamites


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## snl (Nov 20, 2009)

The University of Sussex UK did a study and said

The results came to a clear and encouraging conclusion. Application of OA via sublimation, where OA is applied in its pure form by vapourising the crystals with a special heated tool, was superior to application as a solution via either spraying or dribbling. Sublimation gave a greater kill of varroa at a lower OA level and showed no increase in bee mortality. In fact, 4 months after treatment, the hives treated via the sublimation had more brood than the 10 untreated colonies.
The sublimation method is quick and easy, as the hives do not need to be opened. To confirm the results obtained by LASI researchers early in 2013, the sublimation technique was retested one year later in December 2013, just before Christmas, in broodless honey bee colonies. An amazing 97% of the varroa were killed by using 2.25g of oxalic acid per hive, and colony survival 3 months later in spring was close to 100%.


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## antonioh (Oct 15, 2014)

blackandtan said:


> If you are running double brood boxes do you just dribble in the top box or do you separate the boxes and treat each box separately?


 Dribble only on the top box. You don´t need to separate the boxes. The oxalic will flow over the bees and will get the lower box.

Only water can be used, but you get better results with the 1+1 mixture, as the solution gets more "sticky" to bees and prevails longer.


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## antonioh (Oct 15, 2014)

> An amazing 97% of the varroa were killed by using 2.25g of oxalic acid per hive.[


 In the study I pointed out earlier made in Portugal, in the Évora University, they got in a hive without brood, with the dribbling method, a somewhat lower success = 95%, with a solution at 3.5 % with 50 ml per hive, which means a little bit less than 2 g of oxalic per hive.


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## WBVC (Apr 25, 2013)

How much oxalic acid...just the standard stuff for bleaching wood...do you add to 1:1 syrup. Guess i am asking for ratios to give the correct concentration? I do have a varox vapourizer but do half the hives with that and half by dribbling and compare.

If 5 frames wouldn't that be 4 spaces between the frames plus 1 space on each end for a total of 6 spaces at 5 ml each?


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## blackandtan (Aug 20, 2014)

Here is a link to recipes I found

http://www.mtbakerbeekeepers.org/wp-content/uploads/2014/03/Oxalic-Acid-Instructions-Rev1-3-131.pdf


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## HarryVanderpool (Apr 11, 2005)

Here is a very simple and easy to remember recipe that we have used for years.
One gallon of heavy syrup = 12lbs
One gallon of distilled water= 8.34lbs
12 oz of oxalic crystals = .75lbs

Bring distilled water to a boil.
Dump it in a clean plastic bucket.
Dump 12 oz of crystals into water and stir with wood or plastic stick.
Dump mixture and heavy syrup into 4 gallon square bucket and mix well.
The 4 gallon square bucket's square corner makes filling you plastic garden sprayer really easy!

O.K. Please check my math:
12 + 8.34 +.75 = 21.09lbs total weight.
Now divide .75 by 21.09 to find the portion of the mixture that the crystals comprise = .036 (rounded)
Change decimal to percentage = 3.6%

Make sure to wear eye protection and gloves when handling crystals.
When ever handling any type of acid I always have lots of fresh water handy in case of an OOPSY when you will need to quickly rinse off.
Be careful!


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## antonioh (Oct 15, 2014)

As I said before, you must pay attention to whether oxalic type you are using, if dihydrated CAS No. : 6153-56-6 or anhydrous CAS Nº. :144-62-7, as you may end up with a difference in concentration of about 20% !


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## WBVC (Apr 25, 2013)

What do you consider "heavy" syrup?
If you use a garden sprayer how do you measure 5 ml?
Could one use Sheep drencher doser as you can set the volume dispensed with each pull of the trigger?



HarryVanderpool said:


> Here is a very simple and easy to remember recipe that we have used for years.
> One gallon of heavy syrup = 12lbs
> One gallon of distilled water= 8.34lbs
> 12 oz of oxalic crystals = .75lbs
> ...


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## thebeemanuk (Oct 16, 2014)

WBVC said:


> What do you consider "heavy" syrup?
> If you use a garden sprayer how do you measure 5 ml?
> Could one use Sheep drencher doser as you can set the volume dispensed with each pull of the trigger?


Use a Syringe and dribble it between the seams with bees on


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## Rusty Hills Farm (Mar 24, 2010)

WBVC said:


> What do you consider "heavy" syrup?


Traditionally heavy syrup is 2:1. Personally I use 1:1 with excellent results. I am only treating a dozen hives, so my formula looks like this:

1.2 oz oxalic acid (I use Savogran Wood Bleach #10501)
16 oz warm distilled water
16 oz cane sugar

Dissolve the acid in the warm water; add the sugar. Using a 50 mL syringe, dribble 5 mL into each seam of bees. I treat doubles without separating them and get good results. I always remove any supers and I discard any leftover solution within 24 hours. I never use more than 50 mL per colony no matter how big it is.

HTH

Rusty


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## Rader Sidetrack (Nov 30, 2011)

Note that the recipe that Harry posted had 1 gallon of "heavy" syrup (2:1), _plus_ a gallon of water. That will end up pretty close to 1:1 anyway.


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## WBVC (Apr 25, 2013)

This may be a very stupid question but chemistry is not my forte...are the OZs a weight or liqid measure?

Thanks...the oxalic acid wood bleach i have are crystalline.


Rusty Hills Farm said:


> Traditionally heavy syrup is 2:1. Personally I use 1:1 with excellent results. I am only treating a dozen hives, so my formula looks like this:
> 
> 1.2 oz oxalic acid (I use Savogran Wood Bleach #10501)
> 16 oz warm distilled water
> ...


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## Rusty Hills Farm (Mar 24, 2010)

WBVC said:


> This may be a very stupid question but chemistry is not my forte...are the OZs a weight or liqid measure?
> 
> Thanks...the oxalic acid wood bleach i have are crystalline.


I weigh everything on a digital kitchen scale.

HTH

Rusty


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## antonioh (Oct 15, 2014)

For those in Eu or Canada that work in grams and ml...

Di-hydrated oxalic acid is usually acquired in powder or small crystals with a concentration of 97% or above, with no more than 0,0005 % of heavy metals, like lead.

Procedure :

Mix 1 Litre of slightly warmed water with 1 Kg of white sugar . 

Then ad 84 grams of di-hydrated oxalic acid (97% purity) 

Mix well until it solves completely 

This solution will have more
solução or less 3.5% of oxalic and is enough for 25 to 30 hives with 10 deep frame fully occupied with bees. For each space between frame dribble 5 ml with a syringe, to a maximum of 50 ml / hive.

Once again, be sure you are dealing with di-hydrated oxalic. If you have anhydrous, you must reduce the total powder weight accordingly.

Also if the purity of your acid is higher than 97% ( I got 99% pure), you must reduce the total powder weight accordingly.

Have a good dribble .


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