oxalic acid treatment

[b.lambert]

Hi
want to give my bees the trickle treatment I have two hives one on a double brood the other single can anyone give me a formulae to treat both. I have the crystals and was told 10g oxalic acid 50g sugar 250ml hot water. Is this okay and will it treat the hives in question?

[Jon]

The correct ratio is 7.5g oxalic with 100g sugar and 100ml water assuming you are using the oxalic dihydrate crystals supplied by the likes of Thorne.
It's late for oxalic treatment as bees probably have some brood by now and most of the mites will be safely tucked away.

I did a blog entry on the oxalic treatment in December here (http://www.sbai.org.uk/sbai_forum/entry.php?98-Oxalic-Acid).

The standard treatment is 5ml per seam irrespective if it is a double or single brood colony.
It is not necessary to separate the two boxes in a double brood colony. Just trickle 5ml into each seam between the frames in the top box.

[gavin]

Just like to agree with Jon, although some do use a more dilute solution (and some use stronger!). That's the one I recommend, 7.5g +100g +100mls. It makes about 160ml, enough for about 5 colonies.

The lower-sugar one must be an old recipe as there is good evidence that higher sugar oxalic mixes are tolerated better.

Is it too late? No, it will do some good, but it is past the ideal time to catch all the mites in broodless colonies.

cheers

Gavin

[Rosie]

Perhaps the low sugar one was used in the days when oxalic acid was sprayed all over the bees. That was abandoned quite early in the development of oxalic acid delivery. I think it was replaced by sublimation and that, in turn, was replaced by the current safest and effective method of trickling.

Rosie

[Eric McArthur]

Rosie wrote:
Perhaps the low sugar one was used in the days when oxalic acid was sprayed all over the bees. That was abandoned quite early in the development of oxalic acid delivery. I think it was replaced by sublimation and that, in turn, was replaced by the current safest and effective method of trickling.
.................................................. ....
The definitive research on the use of oxalic acid as a trickle treatment was carried out by Charriere et al in Switzerland and reported in the Schweizerische Bienen Zeitung in October 1999. The report titled “New Recommendations for the Oxalic Acid Trickle Treatment” was reported for the first time in the English language Bee Press in the November 2000 issue, page 266, of the Scottish Beekeeper magazine.
The results of the oxalic acid trickle treatment were discussed at the International Zollikofen Congress in June 2000 and the consensus from this Congress was that an aqueous solution of 35g oxalic dihydrate dissolved a litre of 1 : 1 sugar syrup was the most suitable for the Central Europe.
The original application of oxalic acid as a spray treatment was employed in Russia by Ivanov and Sotnikov in 1988. The original oxalic acid treatment concept was pioneered in Japan byTakeuichi in 1983.
The spray treatment was perfected by Radetzki in Germany 1994. However it was very labour intensive and was quickly superseded by the Trickle Method. The Fumigation Method came later and is the most flexible if not the most popular.
I myself started using the trickle method in winter 1999 as a prophylactic and to prove to myself that the bees could survive the substance, which of course they can. I used the fumigation treatment for the first time in October 2003. That first treatment knocked down the first “fly in” Varroa incursion and using a constant monitoring system of one Varroa floor per five colonies, I have been able to keep on top of the mite from that very first incursion. Again, ask Peter Stromberg.
I moved over to the 60% formic acid treatment in 2006 and still use it today in conjunction with the trickle - as and when necessary!

Eric

[Jon]

The definitive research on the use of oxalic acid as a trickle treatment was carried out by Charriere et al in Switzerland and reported in the Schweizerische Bienen Zeitung in October 1999.
The results of the oxalic acid trickle treatment were discussed at the International Zollikofen Congress in June 2000 and the consensus from this Congress was that an aqueous solution of 35g oxalic dihydrate dissolved a litre of 1 : 1 sugar syrup was the most suitable for the Central Europe.

I think quite a lot of water has flowed under the bridge since then.

Here is another reference (http://www.culturaapicola.com.ar/apuntes/sanidad/08_san_oxalico_concentracion.pdf).

This states that 3.2% is a good strength for your average colony which is what you get with the ratio I quoted in the post above, 7.5, 100g, 100g

Nanetti seems to be the main authority on Oxalic if anyone wants to google the name.

[Eric McArthur]

Hi Gavin /Jon
Just the odd correction to the above prose:
Jon wrote:
The standard treatment is 5ml per seam irrespective if it is a double or single brood colony.
It is not necessary to separate the two boxes in a double brood colony. Just trickle 5ml into each seam between the frames in the top box.
.................................................. .........................
Eric wrote;
I would be extremely interested in your source for the information stated above:
In a strong colony covering 10 frames (I have had many such colonies!) entering the winter on a single brood box, the bee filled frame spaces will require to be “trickled”. A total of 50 mls will be needed for the job.
Consider a strong colony on double brood boxes with bees covering 6/7 frames in both top and bottom boxes (refer to Ian Craig who reduces his frame complement in his double brood system to eight frames in each box!) Using your wisdom Jon the colony goes into winter grossly under treated having only received some 30+ mls of treatment. Think again!
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Gavin wrote:
The lower-sugar one must be an old recipe as there is good evidence that higher sugar oxalic mixes are tolerated better.
Just like to agree with Jon, although some do use a more dilute solution (and some use stronger!). That's the one I recommend, 7.5g +100g +100mls. It makes about 160ml, enough for about 5 colonies.
..................................................
Eric wrote:
Arithmetic never was my strongest suit! However, you are two hives short, Gavin. Sorry!
I would refer you back to Apiacta, issue 38, (2003) 81 – 87. Relative to the sugar recipes. Three acid solutions are compared and the Swiss procedure reported in the Scottish Beekeeper magazine in the November 2000, issue of the Scottish Beekeeper compares well with the higher 4.2% figure AND the over wintering bees appear to tolerate this better than the 4.2 solution. This Apiacta paper was actually the report back from the “European Group for Integrated Varroa Control” seminar, which took place in Merlebeke, Belgium, which I attended with Jane Chard. A report of the proceedings was printed in the Scottish Beekeeper in the early 2000s.
Oxalic acid fumigation is a much more flexible treatment method since it can be applied several times within a six week period. Using formic acid, if carried out correctly eliminates much of the need for the oxalic treatment
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Jon wrote:
This states that 3.2% is a good strength for your average colony which is what you get with the ratio I quoted in the post above, 7.5, 100g, 100g.
Nanetti seems to be the main authority on Oxalic if anyone wants to google the name.
...................................
Eric wrote;
Is it really? What about the water content of the oxalic dihydrate crystal? I am happy to have a math lesson without rancour!

Nanetti was the man who discovered that oxalic acid solutions worked systemically.

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Eric

[Eric McArthur]

Hi Jon
Just for the record!
Eric
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John wrote:
There are far too many beekeepers who either ignore, or are unaware of current best practice with regard to Oxalic acid strengths and dosages.
My practice (and calculations) follow all the published guidelines for mixing and applying Oxalic acid.
I prefer published research to personal calculations as the dosages have been trialled for years over many colonies Preparation:- Mix 1 litre water with 1k sugar. Add 75g oxalic acid dihydrate (which contains 71.4% oxalic acid). The resulting solution will provide 3.2% oxalic acid.
.................................................. ..............
Using the above data the acid solution strength is:- 100 x 71.4/2003.6 = 3.564%.

Eric

[gavin]

No it isn't.

75g oxalic acid dihydrate plus 1 kg sugar plus 1 litre water gives a volume of around 1600mls. I have a more accurate figure somewhere, but I'm short of time right now.

Those ratios give you:

4.5% oxalic acid dihydrate (w/v) in 1:1 syrup.

Which some folk prefer to express as the anhydrous equivalent of:

3.2% oxalic acid (w/v) in 1:1 syrup.

Both figures have been used in the literature, both are valid as long as you state the full details. Not 3.5%. The recipe above is the standard one. Some people deliberately reduce the concentration, some think that they are but they aren't, and people on forums everywhere argue that some other figure applies, but it doesn't.

all the best

Gavin

[Jon]

From Alan Byham, Regional Bee Inspector in a document on the bbka site. ( states 50ml maximum per colony)
http://www.britishbee.org.uk/files/oxalic_acid.pdf

[Eric McArthur]

No it isn't.

75g oxalic acid dihydrate plus 1 kg sugar plus 1 litre water gives a volume of around 1600mls. I have a more accurate figure somewhere, but I'm short of time right now.

Those ratios give you:

4.5% oxalic acid dihydrate (w/v) in 1:1 syrup.

Which some folk prefer to express as the anhydrous equivalent of:

3.2% oxalic acid (w/v) in 1:1 syrup.

Both figures have been used in the literature, both are valid as long as you state the full details. Not 3.5%. The recipe above is the standard one. Some people deliberately reduce the concentration, some think that they are but they aren't, and people on forums everywhere argue that some other figure applies, but it doesn't.

all the best

Gavin

Hi Gavin
Do the calculation by weight!

Eric

[Rosie]

Eric

Like you I think the percentage should be expressed in weight/weight but for some reason the scientists insist on quoting the bastard proportions of w/v, which to me is both unscientific and idiotic. However, we are stuck with it and when I did the sums some years ago I came up with figures that were similar to Gavin's. Having said that, I also found other sugar concentrations (60%) can be used and concentrations as low as 2.4% w/v anhydrous oxalic acid can also be used almost as effectively. Hence I err on the lower side, especially as I believe that we will never find a bee that can cope with varroa if we continue to blast them all to kingdom come with powerful acids. Lower concentrations must also be better for the poor bees.

I am not trying to persuade others to switch to my methods but my experience does show that the concentrations are not critical.

Rosie

[Calum]

the german recipe is 3,5%
200g sugar
35g oxalic acid dihydrate
,75l water
mixed till disolved, top up to 1 liter
apply luke warm 30ml for a weak colony to 50ml for a strong one (or 5ml per bead)

[gavin]

Hi Gavin
Do the calculation by weight!

Eric

It is certainly possible to do the calculation by weight - and I think that chemists may prefer that way - but the solutions were produced up by biologists and biologists are happy with (w/v) concentrations. So that is how the oxalic concentrations have been presented.

all the best

Gavin

[Eric McArthur]

Hi All
]
Good discussion!

These are my thoughts!

Gavin wrote:
75g (71.4 g dry weight) oxalic acid dihydrate plus 1 kg sugar plus 1 litre water gives a volume of around 1600mls. I have a more accurate figure somewhere,
Those ratios give you:

4.5% oxalic acid dihydrate (w/v) in 1:1 syrup.

Which some folk prefer to express as the anhydrous equivalent of:

3.2% oxalic acid (w/v) in 1:1 syrup.
‘’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’ ’’
The old adage of wood and trees seems to be relevant here! The amount of active ingredient is the critical – how the percentages are arrived at is purely speculative and seemingly irrelevant. See below!
In order to bring perspective to the discussion; let’s look at the big picture. We are dealing with a fixed quantity of crystal (71.4g); a fixed quantity of water ( 1000mls) and sugar(1000g). The water and sugar results in a solution of circa 1600mls, in which is dissolve 71.4 g of crystal oxalic acid dihydrate (active ingredient!).
Jon kindly did the sums and calculated that the 1600 mls would produce 32 - 50 ml treatments Each of these 50 ml treatments will contain, 71.4/32g of oxalic acid dihydrate = 2.23 g (active ingredient!).
Thus a strong colony in a single brood box covering 10 frames will receive a total of 2.23g in 10 x 5 ml trickles.
Consider the Ian Craig, 16 - frame double brood box example mooted earlier and the “accepted wisdom” of only trickling the top box in a double brood set up:
Consider 7, “between frame” spaces occupied by bees; each space received 5mls of solution; a total of 35 mls of solution is delivered. A quick calculation of the amount of active ingredient delivered indicates that only 2.23/50 x 35 = 1.56 g of active ingredient is delivered. This is quite a short fall.
Treating with the organic acids is, as experienced beekeepers know, not an exact science, and to blindly adhere to dogma in the face of novel situations can be unwise.

In any double brood box scenario there is a real danger of under -dosing if only the top box cluster is considered.

Eric

[Jon]

Eric. the maximum recommended dose is 50ml irrespective if there is one brood box or two and irrespective of whether there are 10 frames covered with bees or 15.
If you say more is needed, you are using your own guesstimates again rather than following published research.
I know which I prefer.
If you read some of the references posted in this thread, some of which you posted yourself, you will see that the most critical factor is having the Oxalic solution at a high enough concentration, strong enough to kill mites but not too strong as to damage the bees. ie concentration is more critical than volume.
It doesn't matter if you just trickle into the top brood box in a double system as the bees work the Oxalic right through the colony as they clean it off each other.
The other point to note is that if a cluster is divided between the top box and the lower box, splitting it in December would be a disaster.
Who in their right mind would want to split a cluster of bees in mid winter?
Applying Oxalic is an invasive process in itself but splitting a cluster is not a good idea.


Treating with the organic acids is, as experienced beekeepers know, not an exact science, and to blindly adhere to dogma in the face of novel situations can be unwise.
The problem is those who blindly adhere to novel solutions, the beekeeping tinkermen.

[Calum]

Hi Jon,
I do not like doing it myself, but alot of beekeepers here split the box to apply the oxalic solution to make sure they get it on the cluster.
- If the cluster is between boxes they just carry on and apply the solution to the lower box half of the cluster.. The risk is crushing the queen when closing the box but they all assure me she does not hang about in the open.

It is very invasive but it is done in under a minute.

[Jon]

Hi Calum
It's academic for me anyway as I keep Amm type bees and they never need more than a single brood box to overwinter.
I have heard beekeepers claim that it is unnecessary to split the two boxes as the bees work the oxalic right through the cluster during the cleaning process.
Carnica, Buckfast and Ligustica may well need a second box as they are much more prolific.
In December when I did the oxalic treatment the average colony size was about 6-7 seams of bees although one cluster was over 10.

[Calum]

Hi Jon,
all my productive colonies overwinter on two brood boxes (carnica).
The half of my nucs ran out of space in August so they also got another brood box that they filled up with balsamine..
There are various pros and cons for me on the two brood box front.
I like that they have plenty of space to keep plenty of stores in.
Also they are usually in the upper brood box completely by mid march so I can remove the now empty lower one and sort out the old comb and replace it with 50/50 fresher drawn out comb from the honey room and foundation. That way I have a good flow of wax in the colonies to prevent possible build ups of foul brood spores/ nosema / pesticides in the cold comb.

[EmsE]

I would have thought it was irrelevant whether they were in a double brood system or not as the size of the cluster would be the same, it's just that they've munched their way up the stores in the frame quite quickly (or not had enough).

I'm on a double brood and when applying the oxalic acid all the bees were in the lower box. If I hadn't provided adequate stores, the bees had moved up and the cluster happened to be spanning the 2 boxes, that couldn't justify doubling their medication, surely, as the cluster would still be of the same size.

[Jon]

Some of mine need double brood from May - July but they always overwinter in a single box.
One colony of mine had 20 frames of brood in mid May last year.
I thought it might be hybridised but it was 85% amm according to wing morphometry.
I used it as my main queenright queen rearing colony and got a load of queens from introduced grafts.

I treat any spare comb or comb taken from dead colonies with 80% acetic acid fumes for a week.
I spent a few hours this afternoon cleaning nucs and apideas with Virkon.
I think Virkon kills amost everything apart from AFB spores.
It costs next to nothing to clean up old comb and equipment like this. Better safe than sorry.
Of course Oxalic acid is officially used as a general hive and equipment cleaner!

[EmsE]

I have to confess that I use a double brood in winter not because the bees need it, but because it makes me feel better.

[Jon]

I find mine do not need the extra stores. A typical colony of mine overwinters with about 30lbs of stores which is about 6 full deep frames of honey.
the extra space is actually a big disadvantage in Spring as the bees have a bigger volume to heat and brood build up will be slower.
If brood rearing starts in the top box, this should be less of a problem as the heat will be at the top.

[EmsE]

I like to know that the bees have the option of moving further up if it's too cold for the colony to move sidewards. The previous Autumn I did feed too much and was left with loads of brood frames full of sealed stores in the spring. I cut back this year but still stuck with the double brood box (albeit one hive is a brood & 1/2 due to bad planning)

[Eric McArthur]

Hi Jon
Jon wrote:
The other point to note is that if a cluster is divided between the top box and the lower box, splitting it in December would be a disaster.
Who in their right mind would want to split a cluster of bees in mid winter?
Applying Oxalic is an invasive process in itself but splitting a cluster is not a good idea.
.................................................. ...........................................
In the period prior to the trickle method, the colonies were actually split apart in late November/December and both sides of the occupied combs were SPRAYED with 3 – 4 mls of oxalic acid solution, which they tolerated better than the trickle. I have the original paper (in German) describing the Fischermühle, German 5 year trials. As a matter of fact Ian Ferguson, Kelvin Valley BKA has practised this method for many years and still does!
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Calum wrote:
Hi Jon,
I do not like doing it myself, but a lot of beekeepers here split the box to apply the oxalic solution to make sure they get it on the cluster.
- If the cluster is between boxes they just carry on and apply the solution to the lower box half of the cluster.. The risk is crushing the queen when closing the box but they all assure me she does not hang about in the open.

It is very invasive but it is done in under a minute.!
...........................................
Thanks for that Calum!
Eric

[Eric McArthur]

Hi EmsE
Eric wrote:
Consider 7, “between frame” spaces occupied by bees; each space received 5mls of solution; a total of 35 mls of solution is delivered. A quick calculation of the amount of active ingredient delivered indicates that only 2.23/50 x 35 = 1.56 g of active ingredient is delivered. This is quite a short fall.
Take note of what Calum has written - and use what I wrote and his experience wisely -as and when! Talk to Ian Craig!
In the case mooted the colony will be under dosed, regardless! Look at the weight of active ingredient relative to the volume, 2.32 g is the 10 comb dosage!

Eric

[gavin]

The method which seems to be most popular in the UK is the one described by Wally Shaw:

http://www.dave-cushman.net/bee/wallyshaw.html

and is one of the alternatives tested by Charriere and Imdorf:

http://www.culturaapicola.com.ar/apuntes/sanidad/varroa/acido_oxalico_tratamientos..pdf

A key feature is the use of 5 ml *per seam* of bees. The solution is the 4.5% oxalic acid dihydrate in 1:1 syrup (aka 3.2% oxalic acid) as also recommended by Thornes, although weaker solutions are recommended too in the Swiss paper.

I don't know why you are adding this confusion about the amount dosed to the colony Eric, the instructions are clear: 5 ml per seam of bees not a certain weight of oxalic acid per colony.

Anyway, hasn't the time passed for the annual oxalic acid arguments?! It is usually a November/December debate.

[Calum]

I find mine do not need the extra stores. A typical colony of mine overwinters with about 30lbs of stores which is about 6 full deep frames of honey.
the extra space is actually a big disadvantage in Spring as the bees have a bigger volume to heat and brood build up will be slower.
If brood rearing starts in the top box, this should be less of a problem as the heat will be at the top.

Hi Jon,
the bees normally move from the bottom brood box to the top one as they get through their stores.
A weaker colony will stay in the bottom, but they are usually the ones that couldnt fill a second brood box with stores in the previous autumn so shouldnt be on a second one in the first place.

I have been told that a really strong colony on one box can gather so much stores that the fill every frame full. When it gets cold they can have severe problems due to the stores acting like insulation and so preventing them from being able to keep the cluster warm.

As said I remove the lower box to refresh the comb so if they are not packed in then I leave them on one box till they need the space.

Never heard of Virkon is it water soluble of fat soluble? I only use oxalic or citric acid and vinager to clean my wax when it si molten.
The guy that does my foundation heats it at 120°C for 8 hours which kills a fair bit too...

[Jon]

Hi Calum. It's a water based product.
You dissolve one tablet in 500ml of water.
I use acetic acid for the comb and this stuff for boxes, dummy boards, dividers, apideas etc.

This is the stuff:

http://en.wikipedia.org/wiki/Virkon

http://www.hyperdrug.co.uk/prodinfo.asp?number=VIRKTABS&Variation=

[Calum]

[QUOTE=Jon;4180]Hi Calum. It's a water based product.
You dissolve one tablet in 500ml of water.
I use acetic acid for the comb and this stuff for boxes, dummy boards, dividers, apideas etc.
[QUOTE]

still not quite clear on what you are doing.. you use the acetic acid on the melted wax?
Old comb gets too small for the brood after heavy usage (+pesticide buildup cannont be cleaned out).. When it is no longer possible to see light through it, it is recommended that it should be removed from the hive (at least here in Germany). Many beekeepers only use this for candles, most novices cannot do this as they dont have enough wax and so have to reuse it for foundation.

[Jon]

The acetic acid is to kill nosema spores on comb I want to reuse.
The virkon is a general disinfectant which gets rid of bacteria and virus in general beekeeping equipment.

I just get rid of very old black comb. Not much wax to be had from it anyway. You get more from the cappings.


Old comb gets too small for the brood after heavy usage
Not sure about that. I know the entrance to the cells gets smaller and more rounded but I don't think the actual cell gets much smaller.
There were some studies about this. I'll have a look later.

EDIT
Here's something from Dave Cushman's site.

http://www.dave-cushman.net/bee/smalboldcomb.html

[Calum]

Hi Jon,
fair enough on the link but pesticide accumulation can still be an issue.

If you use steamer you will get quite a bit of lovely golden wax out of old combs.
I fill a brood box or two with old comb place that over a queen excluder and place a binbag in a brood box underneath to catch the water and wax.
I use a wallpaper stripper to generate the steam (just stuff the pipe in under the lid).
http://www.mietguide.de/vermietung_vermieten_mieten/Image/Rent/Mietguide/PMI_2168.jpg

[EmsE]

Hi EmsE
Eric wrote:
Consider 7, “between frame” spaces occupied by bees; each space received 5mls of solution; a total of 35 mls of solution is delivered. A quick calculation of the amount of active ingredient delivered indicates that only 2.23/50 x 35 = 1.56 g of active ingredient is delivered. This is quite a short fall.
Take note of what Calum has written - and use what I wrote and his experience wisely -as and when! Talk to Ian Craig!
In the case mooted the colony will be under dosed, regardless! Look at the weight of active ingredient relative to the volume, 2.32 g is the 10 comb dosage!

Eric
Hi Eric,
What I'm trying to say it that if my 10,000 winter bees occupy 7 seams in 1 brood chamber then I would apply 1 x 5ml to each seam.

However, if I didn't feed enough and my 10,000 bees are spanning the 2 brood chambers (still occupying the same seams) at mid December, then I would still only be wanting to apply the same amount over these 10,000 bees?

If we were discussing a summer treatment where some colonies do truly occupy 2 brood boxes where others just occupy the 1, then I can understand that the treatment is increased proportionally to account for this.

[Eric McArthur]

Hi EmsE
Consider Ian Craig’s method where he has very populous colonies, which he reduces to being over-wintered on 16 frame. According to conversations with Ian the colonies occupy 14 bee spaces even in December. Trickling the recommended 5 mls per occupied space the bees only receive 35 mls (1.56g active ingredient).
Approach the exercise from another direction and all becomes clear. Consider Ian’s procedure of reducing each brood box to 8 frames. After the bees have sorted themselves out the two boxes are separated and the queenless box is given a floor, crown board, roof and a new queen and moved from the apiary (for obvious reasons!). What would he do by way of treatment?
As an aside Ian no longer uses the trickle method. He has move on to using my “short pipe” oxalic acid fumigation method, which is much more flexible than the trickle and can be used multiple times if necessary if the monitoring insert indicates that there is a heavier mite fall of more than one mite every 2 days at a particular interval after a treatment cycle!
Eric

[Eric McArthur]

Hi All
Sadly Dave died yesterday!

I am sure that all his friends will be sad to hear. He had been ill for some time.

Eric