# Oxalic Acid Trickle report



## acbz (Sep 8, 2009)

Thanks for your report.
Were the hives broodless the first time you trickled? 
Was the strength of the first batch the same as the second batch, or weaker?


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## snl (Nov 20, 2009)

Commercial guys just use a pump sprayer. Adjust the nozzle to a steady stream and spray the OA between the frames........ quick & easy....no syringe.........


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## HarryVanderpool (Apr 11, 2005)

Your recipe results in a rather weak ( 2.8%) concentration.
We shoot for 3.4%
Also use distilled water so as to not cause interaction of acid & minerals.


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## Tim B (Apr 16, 2009)

The first hives had only a small amount of brood. The current hives are broodless. I believe the amount of oxalic total volume was the same. Either my syrup was more or less diluted than it should have been or I didn't mix it enough.


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## Mike Gillmore (Feb 25, 2006)

Harry,
Good point. I forgot to mention that I use distilled water only. 
My formula I believe is about 2.9% 
For a 3.4% concentration you would use about 20.4 g. of OA crystals with the same amount of water and sugar. 
I've always had excellent knock down results with the formula I use, but the higher concentration might be better. Never tried it but it sounds like it works.


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## snl (Nov 20, 2009)

Ok Mike,
So what's the final mixture all in one post?

Larry


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## Mike Gillmore (Feb 25, 2006)

Most formulas seem to be targeting 3.2% - 3.5% concentration.

If you only have a handful of hives and want to mix up less than a quart, try one of the following. 


3.2% concentration
OA - 19.2 g.
Sugar - 300 g.
Water - 300 ml.

3.5% concentration
OA - 21.0 g.
Sugar - 300 g.
Water - 300 ml.

A target of 20 g. of OA would put you somewhere in the middle.


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## sfisher (Sep 22, 2009)

What is Oxalic Acid? How does it kill mites, and is there any affect on the bees? Thanks Steve


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## Mike Gillmore (Feb 25, 2006)

Randy Oliver has written most of what you will need to know at his site below. Good place to start.

http://scientificbeekeeping.com/oxalic-acid-questions-answers-and-more-questions-part-1-of-2-parts/


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## Tim B (Apr 16, 2009)

*A further update*

Just wanted to offer an update after doing mite counts after treating 25 hives with oxalic acid trickle. Most of the hives had no brood or very little brood. Pre treatment mite counts via sugar shake test of 200 bees yielded mite counts between 5 and 30 mites. Post treatment I am finding counts in most hives of 0-2. I have a couple of hives that are showing counts of 7 and 9 per 200 bees. I'm not sure what is happening in the hives showing the higher counts after oa treatments. 

Since August I have tried several treatments on my hives and here's what I am seeing.

Apistan on two hives: (no follow up count)
Coumaphos: 4 hives: worthless
Hopguard on 5 hives: worthless
60% formic acid fumigator with honeybhealthy on 20 hives in August with large populations and brood nest with mite loads of 10-30 per 200: major knockdown to 2-4 mites per 200 bees, lost three queens
Oxalic Acid trickle: Tried a formula on 4 nucs and was not effective, mixed again with the formula mentioned above but with 19 or 20 grams of oa on 20 hives with zero brood or less than a six inch patch of brood and mite loads of 5-30 mites per 200: 3/4 show 0-2 mites, other 1/4 had 7-9 mites.

I will have to find a way to knock down mite loads that the oa didn't knock out. I'll probably use apistan. 

Conclusion: There are no silver bullets. Formic fumigator is effective but is rough on queens. Probably needs to be used in late may or early june when I rob to knock back the spring buildup of mites while leaving opportunity to requeen if there is queen loss. Oxalic is good to clean up bees for winter but sometimes you can't wait until they are broodless to get rid of mites. I probably should look at thymol for a september application and use oxalic acid trickle for late nov/dec. Formic and Oxalic Acid are only pennies per hive. If I have to purchase a thymol based product such as apiguard or apilife var will add an additional $2.00 per hive.


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## danno (Dec 17, 2007)

*Re: A further update*

something I found out this year is a ml is the same as a cc. if you cant find a ml syringe smaller cc are readly available they just have to filled a few times to hit your 30 - 50 ML dose


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## Luterra (Sep 7, 2011)

*Re: A further update*

Thymol (Apiguard) worked well for me in three out of four treated hives. There appeared to be a correlation between removal of the gel from the tray and effectiveness of treatment. The fourth hive still has loads of mites, so I will be trying a "cleanup" treatment with OA in a couple of weeks.

Mark


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## themrbee (Oct 20, 2006)

So how do you figure the % . What would the concentration of this be ? 
oa 292 g. sugar 4000 g. h2o 4000ml


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## Mike Gillmore (Feb 25, 2006)

This thread caused me to go back and check my math. Looks like I need to make a correction in the calculation. I have not been including the weight of the OA in the total weight of all ingredients combined. 

themrbee
292 / 8292 = .0352 or 3.52%

Correction on the others above. 
19.2 / 619.2 = .0310 or 3.10%
21.0 / 621.0 = .0338 or 3.38%

22.0 / 622 = .0354 or 3.54%

I'm surprised my original formula has been working for me at such a low percentage.


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## sjj (Jan 2, 2007)

themrbee said:


> So how do you figure the % .
> 
> What would the concentration of this be ? oa 292 g. sugar 4000 g. h2o 4000ml



I use mass concentration % [Mass/Volume].


Example 2

ΔV = 292 [g] x 0.605 [mL/g] = 176.66 [mL]

V1:1 = 4000 [g] x 1.63 [mL/g] = 6520 [mL]

volume of the mixture V = V1:1 + ΔV = 6520 + 176.66 = 6696.66 [mL]

mass concentration of OA dih. = 292 [g] / 6696.66 [mL] x 100 % = 4.36 % OA dih.



Example 1

mi = 17,5 [g] OA dih.

ΔVi = 17.5 [g] x 0.605 [mL/g] =10.5875 [mL]

V1:1 = 300.15 [g] x 1.63 [mL/g] = 489.2445 [mL]

volume of the mixture V = V1:1 + ΔV = 499.832 [mL] ~ 500 [mL]

mass concentration of OA dih. = 17.5 [g] / 500 [mL] x 100 % = 3.5 % OA dih.


Johann


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## themrbee (Oct 20, 2006)

Thank You !


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## Mike Gillmore (Feb 25, 2006)

Johann,

Thank you for your post. According to your calculations it appears my original formula would be correct in order to achieve a 3.5% solution, using the Mass/Vol calculations. I don't remember where I originally found the formula but it has been working fine for me.

The Europeans have been using Oxalic Acid treatments for mite control for some time now and I trust their methods. I have a question for you. 
Is the "Mass/Vol" calculation you described the common process used in Europe for OA trickle formulas? 
If so, it appears that those who use the "weight" calculations are making a rather hot mixture with a much higher OA percentage than they realize. I would like to know if the "Mass/Vol" calculations are the accepted standard in Europe. 

Thank you for your post and for your contribution to the discussion.


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## Saltybee (Feb 9, 2012)

If I followed Randy Oliver correctly you need to adjust European formulas for pure acid compared to wood bleach.
A weak mix of sugar may make a batch ineffective as well per Randy.


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## Mike Gillmore (Feb 25, 2006)

Wood Bleach is usually 95%+ Oxalic Acid. The difference between 95% and "pure" OA has little impact in the overall formula. I think the major difference lies in whether you use "volume" calculations of mixed sugar solution vs. "weight".


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## Saltybee (Feb 9, 2012)

I should have been clearer; When looking at other formulas the term oxalic acid is used loosely;

From the British Beekeepers Association:

dihydrate must not be confused with dehydrate(anhydrous).

dihydrate is a compound with 2 molecules of H2o(water) in crytalisation in our case 71.4% concentration.

dehydrate is a compound with almost all H2O removed so is near to 100% in concentration.

My wood bleach is dihydrate , looked up it's MSDS.


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## sjj (Jan 2, 2007)

Saltybee said:


> I should have been clearer; When looking at other formulas the term oxalic acid is used loosely;
> 
> From the British Beekeepers Association:
> 
> ...



Yes, multiply by 0.714 to get OA anh.

0.714 x 3.5% OA dih. = 2.5% OA anh.

Johann


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## Luterra (Sep 7, 2011)

Treated two booming, angry, mite-heavy hives today at 55 degrees - probably our warmest December day. 

100 ml distilled water
100 g sugar
7.5 g oxalic acid dihydrate (lab grade 99.9% pure)

Both hives had 10 frames of bees in the bottom box and ~7 frames in the top. Both probably had a small amount of brood as well, though I didn't pull frames to check. I applied 5 ml to the center seams and 2-4 ml to seams with fewer bees, for a total of around 75 ml per hive. My defensive hive was quite displeased with being pulled apart in winter. Strong smell of bananas, would have had 30+ stings without veil and gloves.

To me it seems like both of these hives have about twice as many bees as they should going into winter. Maybe it's an Italian thing... Still plenty of stores but will have to watch going into spring.


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