# Oxalic Acic



## Alex Cantacuzene (May 29, 2003)

Hello Axtmann,
I have several questions on the use of Oxalic and you might be able to help. Please contact me.


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## Axtmann (Dec 29, 2002)

I hope I can answer your questions? Im not an expert but Im treating my bees only with oxalic acid for a few years and I still have healthy colonies .and no chemical residues in my honey.
We should do it here on the forum there might be more interested beekeepers.


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## Alex Cantacuzene (May 29, 2003)

Hello Axtmann,
I have looked at http://bwrangler.litarium.com/oxalic-acid-vaporizer/ and also have tried to contact Dennis. I have made the small vaporizer as shown on page 4 of 5. I did make the tubing to the hive about 4" long to keep the heat a little further away from the hive. The vertical tubintg is a little longer than the version with the copper tubing and so I wondered if I fill it to the top there might be more oxalic than needed. I am trying to shoot for about 1.5 grams and still have to find a way to weigh it. 
Here are the questions: 1. From your experience will this set-up work? 2. Should I push vapor in the top and bottom super or only into the top super? 3. The advice that I see on Oxalic is not to treat while there is brood. Will it hurt the brood or is it because the brood is capped and the mites will not be exposed? My motivation in all of this is to stay away from chemicals that could develop residue and resistance to the mites. By the way, I do read and speak German and the reports from Germany and Switzerland in the Internet are encouraging. 
Dennis if you should read this I appreciate your work on this and woul like your input also. 
Thanks, Alex


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## Axtmann (Dec 29, 2002)

As I said before to Dennis, I also played a while with a home made Vaporizer. I had some trouble and spend twice the cost from the original. When I heat up the *** thing the end cup fall off and the boiling acid spilled all over. 
The original has fine thread on all pipes and some have soldering stuff in the thread. The 700 have a big metal on the heating end where the acid is. I printed the picture from the website and went to a machine shop but the guys are crazy, they told me it takes at least two hour or more to machine all the parts. Therefore I could buy at least 3 from Kanada including shipping.
I have no idea how to measure 1.5 or 2 grams; you need a very good scale. I tread each colony with 2 grams and use the cup I got with the 700. 
You can treat your colonies any time the year but it kills only the mites outside the cells. Oxalic acid dos not penetrate in wax and cant reach the mites in closed cells. If youre using the right amount acid the vapor has no harm to brood, bees or the queen.
I started in August and treated my colonies 5 times 7 days apart and killed a lot of the mites. I know there more mites breeding in the cells but I will wait till November when the bees have less or no brood. You can vaporize as long as the temperature above the freezing point.


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## Alex Cantacuzene (May 29, 2003)

Hello Axtmann,
Many thanks for your reply. Now that the temperatures are dropping here I will do some treating. The small vaporizer does not scare me as I have a fairly well equipped shop and I do all of these things myself. I am just not sure if I should treat both deep supers or only the top one and let the stuff drift down. Right now I just have one hive operating and am working on three others for spring. I also have taken some 4" dia scrap pipe and welded together an 18" high stand that is mounted to a concrete pedestal. This is to get the whole thing off the ground. This will allow me to put some sticky stuff on the pipe and keep the ants and other critters out.
Thanks again, Alex


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## BWrangler (Aug 14, 2002)

Hello Everyone,

I would like to add just one note of caution. The oxalic acid fumes don't bother the bees very much. But they are very toxic to the beekeeper. Don't breath them in no matter what! A small volume can contaminate a large area and they are hard to see once diluted in the air.

Be Careful.

Regards
Dennis


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## Alex Cantacuzene (May 29, 2003)

Hi all,
Well I did it early this morning in the hope that the girls would still be asleep. Closed the bottom front, put the vaporizer in the hole of the top super and started heating. Nothing happened for the prescribed time. Did see some white stuff around the joints of the tubing and stayed with it for about four minutes. Shut the burner down and let the rig cool down. After about 15 minutes I opened the hive with about 300 waiting to get in, I think I have early risers, and a whole bunch pushing from the inside to get out. I did notice some from the inside with a very fine dusting of white. The rig still had some hardened Oxalic that I cleaned out. I used about a table spoon of Oxalic and measured with a plastic dipper from one of those fertilizer packages. It did not all dissolve but I hope it was enough for a starter. Will keep monitoring the slidin board under the SBB. Thanks again for your guidance, Dennis and Axtmann.


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## mikeaegina (Dec 28, 2002)

I would like to ask you Axtmann, if oxalic acid has any effect in chalkbrood and if it does in wich form (i mean giving it with syrup of with the vaporizer). I used acetic acid with very good results but it's very hard to find pure chemical acetic acid in Greece.


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## Axtmann (Dec 29, 2002)

Hi mikeaegina

As I know the oxalic acid has not be tested as a treatment against chalk brood. The vaporizer works very good against the Varroa. Chalk brood comes from a fungus Ascosphaera apis and the spores infected laves with the food. Bees or air flow spreading the spores inside the hive and they are very resistant. Spores can survive at least 15 years or longer and they growing the best when the brood temperature is (29ºC) lower than the normal 35º C. This is happen when the proportion from brood and bees are out of balance. For example it is often happen when we have a nice spring with long warm days and suddenly the wetter gets cooler. Lots of brood but not enough bees to keep them warm, it also can be happen when bees are sick from Nosema or Varroa. 
Other possibilities:
Lack of food (Pollen/ Nectar)
Hot days and to cool nights
To much draught
Medicaments with the intestinal flora destroying
Your colonies need a better location

The best to get rid of the chalk brood is feed the bees with a mixture of 3 parts sugar and 2 parts water or feed honey. Normally you can see the next day bees cleaning the hive and lots of chalk brood is in front of the hive. 

Hold the colony crowded in the hive for at least 2  3 weeks before you put a honey supper on top.
Dont use the combs from infected colonies again destroy them and clean your tools before you work on other colonies.


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## John Buckner (Mar 27, 2003)

Hi Folks, 
Has anyone tried soaking shop towels in a solution of Oxalic acid and placing sheets on top of the frames, or mixing the acid with Canola or FGMO ?
I would have to do a lot more research on the subject before I would try it.


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## Alex Cantacuzene (May 29, 2003)

Hello John et al,

I have only used oxalic acid by fogging it with the small homemade brass tubing and fitting rig that Dennis described. I drilled 3/4" holes in an upper corner of the deep supers. The oxalic acid that I used came from the paint department of Lowes and normally is used for bleaching wood. I have also used FGMO with a Burgess fogger and at present prefer it as it is faster and safer for the beekeeper. I have not tried anything else so far. BTW the varroa drop is declining sharply right now, hopefully we are on the right track.


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## Jorge (Sep 24, 2002)

Hello guys,

After my rather unsuccesful attempt at controlling Varroa mites with FGMO I decided to try Oxalic Acid. So, I looked at Dennis' web page for his description of a homa-made vaporizer but was unsure about some details. SO, I decided to bite the bullet and get the canadian 600 model. As it was getting colder and the thing was not arriving I decided to just build one. I spent a grand total of about US$8: one 4" long 3/4 diameter tube with thread on both ends, one 2" long 3/4 diameter tube also with thread on both ends, one cap to screw into one end of the shorter tube (this makes the "magazine" where the OA goes in), and a 90 degree elbow into which the 2 threaded tubes screw in. That's it. The free end of the longer tube srews into a 3/4" hole drilled somewhere on the side of the top box of the hive. After filling the magazine with OA, you can screw it into the elbow that is now attached to the hive ... and BINGO. 
Dennis, you are a genious. This is orders of magnitude more conviniet than the BC600 vaporizer that I payed 50 bucks for: there are virtualy no fumes released to the outside because the whole things screws onto the hive (other than 2 or 3 puffs from the burnig cristals of OA that I spilled over the sides of the magazine when loading it), it is 1/5 the price of the commercial vaporizer and, since it is screwed to the hive, you need no stand or whatever to hold it in place, so you have both ands free to hold the torch and swat flies or the pestering dog away.

I finally vaporized today since the temp has a bit above freezing and by just putting my ear against the hive before and right after vaporizing, the bees went into a amazing buzz (I suppose trying to get rid of this stuff).

I must say, that aside from wearing gloves (which didn't hurt given that the propane cylinder was near freezing), the procedure was a breeze. It takes a little longer than fogging, but it certainly takes A LOT LESS than replacing emulsion cords with far fewer stings. It is cheap! I payed about 8 dollars for the vaporizer (all of whose parts screw in by hand, no tools needed; I didn't even use teflon for the joints since I figure it would burn anyways, and did not see any leaks at the joints), I payed about US$6 for one pound of OA at the corner hardware store (at 2 grams per application per hive, with 4 applications per hive per year (2 in Fall and 2 in Spring) this should last for about 56 hive-years, or one year for 56 hives! Total cost per application per hive is pennies even considering the propane spent.

If FGMO is used over the summer for profilactic mite (Tracheal and Varroa) treatment and a couple of OA applications in the fall and perhaps the Spring, this should do it. We'll see.

I will report on the effectiveness of the treatment in a few days when I count the fallen mites.

Jorge


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## Jorge (Sep 24, 2002)

This is a question for Michel Bush:

Michel, did you do an ether roll test after your first Oxalic acid application as you said you might?
Did you do a second application of OA? If so, what was the v-mite count after that?

JOrge


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## Michael Bush (Aug 2, 2002)

>This is a question for Michel Bush:
Michel, did you do an ether roll test after your first Oxalic acid application as you said you might?

No. The only days warm enough to do anything I treated again.

>Did you do a second application of OA? If so, what was the v-mite count after that?

Yes I did. I did a count a couple of days after but haven't done another since the snow hit. The intial application killed about 200 mites per hive. The subsequent treatment at my last count had killed an average of about 60 per hive bringing the total to 260 per hive. If it kills the same percent each time that's about 70% each time. Maybe I need to find a better way to measure. I think I may not be using enough Oxalic acid.


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## Alex Cantacuzene (May 29, 2003)

Hello all,
Being away from our bees during the winter is painful, we are right now in Florida.A neighbor is keeping an eye on our girls in Kentucky. As described, the homemade OA vaporizer worked well and I will use it again in the spring. The only thing is the measurement of the acid. The usual recommendations are for 1.5 to 2 grams. Well, I don't have such a fine scale so I used the small cup from packaged fertilizer and has a volume of one tablespoon. I don't know what that is in weight and maybe someone with a scale can check it out. I feel confident that measuring with a spoon right in the container or a plastic bag is about the safest way. Happy holidays!


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## BWrangler (Aug 14, 2002)

Hi Jorge and Everyone,

I'm glad the hive top evaporator is useful for you.

I am reminded by your post that maybe I hadn't clearly stated the importance of the threaded adapter on my web page.

The threads on the adapter are ground down on a taper, but enough thread is left on the adapter to bit into the wood when it's inserted into the hole on the hive body.

The bees sometimes enlarge a hole on older equipment. And some larger holes can accumulate a rim of propolis. If the adapter is just seated in the propolis rather than the wood, it will fall out when it gets hot.

That's why the threads are slightly ground down on a taper. If the hole in the hive body is slightly larger than 3/4", the full thread toward the base of the adapter would still bite into the wood.

I like oxalic. It is the most benign(for the bees) mite treatment I've used in a beehive and also one of the most effective. It takes about 4 days for mite drop to become evident and increased mite drop continues for slightly less than two weeks.

The only real drawback is the noxious fumes if breathed in. Very few fumes escape the hive if all goes well. Just make sure the evaporator is seated in wood and not propolis.

To decrease the per hive working time in a beeyard, more than one evaporator could be run at a time. Natural cooling would be used rather than water. And the evaporators could be switched out when they are cold.

Some Thoughts
Dennis


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## Axtmann (Dec 29, 2002)

Michael it is not only a question how much Oxalic Acid you have to bring into the hive. Make sure that you reached every part inside the hive. I worked with a regular Vaporizer before and than I bought a Vaporizer with air connection. The hive must totally fill up with OA fog. I found out vaporizing from top thru a hole works fine but the fog goes down to the lower part of the hive before totally filling up the top.
To make 100% sure that you reached everything, vaporize from the entrance and wait till the fog comes out of the top hole before closing the hole with a plug. 
To find out how efficient the treatment is make a test with Chumaphos or Apistan 10 days after your second OA treatment. 
Everybody here is playing with homemade Vaporizer, some have a very good result, but lots of them have not even 70%, I have no idea why. Its not the Oxalic Acid; its most of the time the tool they use to apply the acid to the bees.


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## Alex Cantacuzene (May 29, 2003)

Hello Dennis et al,
Yes the tapered and ground down (I filed mine) fitting is important. It will fasten nicely in the hole in the box and the taper will make up for wear.


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## Michael Bush (Aug 2, 2002)

I weighed what I was using (on my reloading scale) and it was 2.85 grams (44 grains). 1.5 grams would be 23 grains.


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## mattoleriver (Sep 20, 2003)

Alex Cantacuzene wrote:
>The usual recommendations are for 1.5 to 2 grams. Well, I don't have such a fine scale so I used the small cup from packaged fertilizer and has a volume of one tablespoon. 

Alex, I just measured 1.5 grams of oxalic acid (Bondex wood bleach) and came up with approximately 1/2 level teaspoon. If this is correct your tablespoonful would be a HUGE amount. My measurement may have been affected by the presence of moisture in my OA sample. The OA that I weighed was the last little bit in a very old can and it had the appearance of table salt that has been left uncovered in a damp environment. It would still pour in small clumps but not as individual grains. Maybe somebody with a fresher sample of OA can give you a better estimate of volume. I'll be interested to hear if the quantity that you used has caused any damage to the bees, I hope it hasn't.
George


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## Alex Cantacuzene (May 29, 2003)

Hello Mattoleriver et al,
Thanks for the come-back on the oxalic acid. With the amount that I described the bees did quite well. If you have one of those home-built vaporizers that Dennis described and that I use, the bottom brass cap is about the amount that I used. So far things seem to work well, so says my neighbor who looks at our girls while we spend the winter in Florida. Can't wait for spring and work with them again. Take care.


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## Michael Bush (Aug 2, 2002)

That's what I was using too. The brass cap held 2.85 grams. It seemed to work fine with no ill effects on the bees. I was worried after rereading Bwrangers page and it looked like he was filing the bottom pipe nipple and the cap, so I weighed what was in the cap.


[This message has been edited by Michael Bush (edited January 25, 2004).]


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## BWrangler (Aug 14, 2002)

Hi Guys,

Oxalic acid has been tested with quite a range of dosages. http://www.mellifera.de/engl2.htm 

For the bees, its the most benign mite treatment I have used. Far less disturbance and side effects than even powdered sugar.

Don't forget that the volume of the hive is a factor in determining dosages. A three story deep hive will need more oxalic than a five fram nuc.

Some of the dosages recommended on the web don't tell much about hive size. I have seen 1 1/2 grams per Langstroth super recommended. Most of the websites talk about just 1 to 2 grams per hive.

When setting up the dosage for my vaporizer, I used the instructions and the volume measuring spoon that came with my commercial evaporator. I haven't actually weighted the oxalic.

It interesting to note that in the research linked above, two dosages 1.4g and 2.8g were used in different hive configurations. Little difference was seen in the results. 

It appears that dosage is not as critical with oxalic as it is with formic and other chems. The mites seem very suseptible to oxalic and the bees are very tolerant or people would be killing their bees with the wide dosage range. 

Regards
Dennis

[This message has been edited by BWrangler (edited January 25, 2004).]


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## mattoleriver (Sep 20, 2003)

I'm still a little confused by what I've been reading on this subject. Much of the information is based on non-vaporized applications and seems like the effect is more limited. I have a few questions for those that have used OA vapor: 
1.Are some people treating with OA while honey supers are on the hive?
2.Are OA treatments limited to approximately the same schedule as commercial chemical treatments, or do/can they go on all year?
3.Are the different chemical treatments regulated at the state level or at the federal level? Is any state authorizing use of OA in the hive?
4.Does OA have any measurable effect on tracheal mites?
Thanks
George


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## Michael Bush (Aug 2, 2002)

>1.Are some people treating with OA while honey supers are on the hive?

I am not. I can't speak for others.

>2.Are OA treatments limited to approximately the same schedule as commercial chemical treatments, or do/can they go on all year?

I just used OA once this fall. IF I continue to use it it will be in the spring and fall when no supers are on, but I may discontinue when I get all of my hives finished regressing to small cell.

>3.Are the different chemical treatments regulated at the state level or at the federal level? Is any state authorizing use of OA in the hive?

It's a bit of a gray area, but basically OA is already in the honey. Formic acid is already approved. I don't think OA is approved, but the FDA and EAP seem content if it is already an ingrediant in the food.

>4.Does OA have any measurable effect on tracheal mites?

I have heard that it does. Since I've been using FGMO I haven't had any problems with T mites, so I can't say.


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## Axtmann (Dec 29, 2002)

Im not using OA vapor during honey flow but new tests are made in some bee institutes in Europe and the result is, that OA has no harm to honey and is already an natural ingredient in honey. 
They also find out that Thymol are very toxic and is a high risk for cancer (brands new results). All available Thymol products to treat honeybees carrying this high risk and we will see how long they are available?

If oxalic acid (COOH2) is heated up and vaporized it is instable and falls apart in CO 2, CO und H 2 O (oxygen, carbon monoxide, water) and a few parts of formic acid.

There are Honey test results from untreated and treated colonies. One site is in German the other is a translation into English. Go to page 13.
http://www.apis.admin.ch/english/host/pdf/alternativ/York/OS0109Radetzki.pdf 
Or go to this site. http://www.members.shaw.ca/orioleln/Oxalic_Acid.htm


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## BULLSEYE BILL (Oct 2, 2002)

I found my first mouse infestation this last weekend while checking bottom boards.

Do you think I can kill a mouse with oxalic treatment?


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## Michael Bush (Aug 2, 2002)

Don't know about that, but I bet you can run them out of the hive temporalily.


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## Jorge (Sep 24, 2002)

I have a little rezult to report on oxalic acid treatment:

2 weeks ago I treated with OA during a day when the temperature was in the high 30s. I collected 75 mites under the SBB of one hive and 64 under the other. During the following week I collected 4 and 1 respectively.

So, I conclude the treatment actually worked quite nicely. Today I will repeat and that should do it for the spring. I will also go and help a neighbor treat his since he did not treat his hives last fall at all and his bees will surely infect mine if left like that (he already lost 4/6 hives this winter, surely to the mites).

Jorge


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## mattoleriver (Sep 20, 2003)

Jorge,
I'm just curious, did you do a count after treating with OA in December? How did it look then?
George


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## Jorge (Sep 24, 2002)

Sorry, I had such a mess with mites and was in a terrible rush to do the application before leaving the country for 3 weeks that I just did it without decent stats.

Jorge


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## scsasdsa (Jan 23, 2004)

Hi All
I have been trying to work out an easy way to measure the Oxalic acid. I found a weights and measures site and found that 1 gram is = to 15.342 grains (grains being the unit of measure used when reloading ammunition)so I used my reloading scale (grains) so two grams would be 30.684 grains then using measuring spoons found 2 grams to be about 1/2 teaspoon. so if using 2 grams per deep hive body and assuming 2 deeps 1 tablespoon should be just about right I plan to try this amouth today if the temps get to 40 as predicted. I will post the results as soon as I see what happens.

good beekeeping


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## BWrangler (Aug 14, 2002)

Hi Guys,

The commercial oxalic evaporators use small scoops to measure the oxalic dosage. Theone I bought uses a standard plumbing cap with a small handle attached to it. 

Considering the consistency of my oxalic acid powder and the diameter of the scoops, there is probably lots of variance in the dosage when the scoop is filled.

It seems that a fairly broad range exists for an effective treatment.

Scsasdsa, my dosage measurements are pretty close to yours. I run three story hives so some of the pictures I've posted would show a larger dosage than would be needed on smaller hives.

Regards
Dennis

[This message has been edited by topbarguy (edited February 28, 2004).]


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## Guest (Feb 28, 2004)

Even the cheapest digital kitchen scale
($20 - $25) has a small recessed button
hidden in the base that will make it
read in grams rather than pounds and
ounces. They are more than accruate
enough for measuring oxalic crystals.

If you put the container on the scale,
and press the "tare" button, it will
"zero out" the weight of the container,
and you can dribble in your crystals.

I'd suggest pre-measuring your "doses"
into zip-lock bags or small plastic
vials, so you can have a "pocketful
of shells", as suggested by the song
"Bulls on Parade" by "Rage Against 
The Machine".


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## Jorge (Sep 24, 2002)

About applying the oxalic acid: aside from probably spreading a lot more OA fumes around, is there any good reason NOT to apply the OA through the SBB opening? I have not seen that suggested anywhere (but I may simply not remember well) and seems pretty obvious so that bees are minimally disturbed.

On a different observation: today the temps were >50oF and so I opened my 2 surviving hives (out of 3) and reversed boxes, etc. To my astonishment I found that the bottom (that is the screen of the SBB) was completely covered with dead bees. Now I don't trust any numbers for falled mites measured through the winter with a SBB. Most would have been trapped on the dead bees accumulating on the screen. I will keep counting now that the boards are clean but I suspect that a new oxalic acid application is soon needed.

Jorge


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## Michael Bush (Aug 2, 2002)

>About applying the oxalic acid: aside from probably spreading a lot more OA fumes around, is there any good reason NOT to apply the OA through the SBB opening? I have not seen that suggested anywhere (but I may simply not remember well) and seems pretty obvious so that bees are minimally disturbed.

First under no circumstances do you want to breath the stuff. You will be coughing uncontrolably for the next several hours. and I think that's a problem when trying to do it from an open SBB.

Second, you want a concentration of the stuff in the hive. I would put the trays in, if you have them and do it from the top because the vapor is heavier than air and will fall down through the hive. It does not go up so well (gravity and all that). When people fog from the entrance they have the bottom close and actually fill the entire hive with vapor, which you can't do if it keeps coming back out the bottom.


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## Jorge (Sep 24, 2002)

Yes. I agree, Michael. However, I am applying it with heat by sublimating the cristals with a vaporizer (like the one described by BWrangler). Since the vapor is hot it goes up at least for a while until it cools off again (I don't apply it as cristals on the top).
Of course, I would seal it all and only leave a hole for the applicator. I need to run the appropriate test one of these days.

Jorge


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## Michael Bush (Aug 2, 2002)

I believe Axtman is administering it from the bottom and using enough vapor to fill it. If the bottom is closed off, I would think it could work. But how well can you seal it? I'd hate to have my head down there and fumes leaking out. A lot of administering it is paying attention to the prevailing wind and making sure you're face is up wind.


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## Dave W (Aug 3, 2002)

Measuring Oxalic Acid Crystals

I measured the contents of a new package of Oxalic Acid and found it contained 16 fl oz. The label says, "Net Weight 12 oz". 

If 1 oz avoirdupois = 28.35 grams
My container weighs = 340.2 grams

16 fl oz = 32 tablespoons = 96 teaspoons
So 1/2 level teaspoon should weigh 1.77 grams. (340.2/192)


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## Michael Bush (Aug 2, 2002)

>Measuring Oxalic Acid Crystals I measured the contents of a new package of Oxalic Acid and found it contained 16 fl oz. The label says, "Net Weight 12 oz". 

>If 1 oz avoirdupois = 28.35 grams
It does.

>My container weighs = 340.2 grams
You mean the contents weigh 340.2 grams or 12 oz.

>16 fl oz = 32 tablespoons = 96 teaspoons
Correct.

>So 1/2 level teaspoon should weigh 1.77 >grams. (340.2/192) 
Took me a second, but 192 is the number of half teaspoons in 16 fl oz.

The math sounds valid. This is all good theory. My guess is that this measuring by volume will be more accurate since the oxalic acid crystals seem to be very hydrophillic and I'm guessing the weight per volume increses everytime I open the container. Your figuring the weight based on the weight marked and there is bound to be slightly more weight than marked to make sure it's not less than it's labled. Also the weight will vary by the humidity absorbed by the crystals. So other people weighing it on a scale and then measuring the volume may get different weight per volume beacuse of this.

Sounds close enough for me. In the end the vapor can only fill the hive, which is the intent and after that it will leak out somwhere, so I don't know that it has to be perfect. It is helpful and less wasteful to get pretty close to the right amount and in order to be effective it is necessary to get at least enough to fill the hive with vapor.


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## Axtmann (Dec 29, 2002)

For an oxalic acid Vaporizer you need up to 2 grams oxalic crystals and it is very easy to measure the acid crystals without any scale. 
Take a plastic syringe with a scale from 1 to 10 ml and cut with a razor blade the part of where the thread for the needle is. Now the syringe is full open and you can suck the crystals into the syringe. 1 ml = 1gram oxalic acid, 2 ml = 2 grams oxalic acid and so on.


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## BULLSEYE BILL (Oct 2, 2002)

My main concerns useing the acid are;
1, breathing it, and
2, how do you know when all the acid has been volitized? (vaporized?)

So, I buildt a box from the scrap of a cut down deep when I made it into a medium, and covered one side with plexiglas. I sealed the glas to the wood with Gorilla Glue for good measure, and used screws to attach it.

On one end I drilled a hole and attached the vaporizer as described in Bwrangler/Topbarguy's web site. The vaporizer will stay attached to the box.

When using the box to treat the hive, I can remove the tops and install the treatment box with vaporizer towards the back and stay away from the openings of the hive, and be able to see when the acid is completely used up.

I am confused about the amounts now. I thought that the recomendation was one gram for small hives and up to three grams on large hives. I was using two grams per hive without size of hive considerations.

Is there a 'per brood box' recomendation?


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## Axtmann (Dec 29, 2002)

Bill I checked a web site from Switzerland and they made tests with different amount of acid from 1 to 5 grams. Between 3 and 5 grams is no different in the result on the mite kills, you can kill a mite only once. I think in the area round 5 grams it starts to get danger to the bees. 

When vaporizing the colony you must seal the entrance during the treatment and you also must wait at least 10 mins before you can open the entrance. Otherwise the treatment is not efficient. A treatment with open SBB is totally useless.

The last two years I used my outside vaporizer heated up with a little propane torch and I was sure the oxalic fog is heavy so I blow (on some hives) the fog with a pump in the upper part from the hive through a whole. 
Now I got more colonies so I bought a second vaporizer a JB200, which is much faster but runs on a car battery. The small heat pan filled with the crystals is in 60 seconds totally empty. It says it is possible to connect several vaporizers in a line that mean maybe 5 or 10 hives the same time (in 60 sec) its almost unbelievable.

I made my first test outside and could see that the fog cloud goes up in the air. That told me I was always wrong with my idea that oxalic fog is heavier than air.


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## BULLSEYE BILL (Oct 2, 2002)

>When vaporizing the colony you must seal the entrance during the treatment and you also must wait at least 10 mins before you can open the entrance. Otherwise the treatment is not efficient. A treatment with open SBB is totally useless.

OK, so I should make sure that I have the bottom tray installed in my SBB (is usually is in the winter), and the opening reduced to the smallest size or shut completely. Use up to three grams of acid, wait ten minutes before I remove my acid box and go to the next hive. I will make another acid box and alternate.

Gottcha, thanks Axtmann.

By the way, what is Axtmann? Is that your family name, or does it have another meaning? I have these visions of a German lumberjack...


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## Axtmann (Dec 29, 2002)

Bill I never used more than 2 grams acid to treat my colonies and it works fine. It is very important to check the mite fall the following 4 or 5 days.
By the way the lumberjack is my family name.


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## chemistbert (Mar 4, 2004)

I thought it necessary to respond to the folks that are trying to tie weight to volume. There is no good way to do that with a bulk solid. One can use the bulk density but who has time for that or the equiptment to measure bulk densities. Also bulk density changes with how settled the solid is. The best way to measure for someone who can't get to a lab is an inexpensive reloading scale. A kitchen scale is not the best as it is good (usually) to plus or minus 1g. Now the best question, does it matter. If you are shotting for 2g and the error with volume measurement is at say 50% then you could be 1.5 or 3.5g. I don't know that it is that signifcant. My 2 cents.

Matt


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## BULLSEYE BILL (Oct 2, 2002)

>If you are shotting for 2g and the error with volume measurement is at say 50% then you could be 1.5 or 3.5g. I don't know that it is that signifcant.

I believe that 50% would be a range of 1 to 3 grams if the target is 2 gm.

I used an electronic reloading scale and a little powder scoop to make my measurements. What I do is use one and one half scoops to equal 2 gm. being careful not to compact the acid. I think my plus / minus tolerance should be quite close, cretainly good enough for what I am doing.


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## Jorge (Sep 24, 2002)

Today I did a test: 
I drilled a 5/8" hole in the bottom box of a 2-deep-box dead hive with all of its frames in place. Replaced inner and outer covers with an old widow glass, sealed the entrance (top and bottom) and the rear-hive opening of my SBB (which is closed at the bottom) as I do when treating my live hives (with paper towel smushed into entrances,etc) and proceeded to vaporize ~ 2grams of OA. I made the hole around 1-2" from the bottom edge of the box right in the middle of the back side. After 1-2 minutes of heating up the stuff, the fumes where clearly showing at the top of the hive through the glass. I removed the glass and, again, the fumes were clrarly coming out everywere at the top. I also opened up a little bit the SBB entrance and vapor was also coming out through there.
CONCLUSION of the test: vaporized OA goes up (as we can all see when some cristals are vaporized in the open) and easily reaches the top bars of a normal 2-deep hive. As it rises through the 2 deeps, it also spreads around laterally enough to cover most of the hive. I imagine that with bees inside fannig this stuff around the mixing throughout the entire volume of the hive would be even better.
I am not sure that vaporizing through a hole at the top of th hive as suggested by BWrangler will achive a good mixing throughout the hive as the hot vapors clearly tend to go up rather than down.

Jorge


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## Michael Bush (Aug 2, 2002)

I did mine from the top and you could see that some was coming out all the cracks and out the entrance. I think if you fill the volume with vapor then you filled it whether from the top or bottom. It seems to rise at first when it's hot and fall as it cools. I don't know if the bottom is BETTER or not, it may be, but I think either will work if you have enough vapor to fill the hive.


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## db_land (Aug 29, 2003)

How do the bees react to the oxalic acid vapors? Do they behave the same as when smoked (i.e. fan and stuff themselves with honey)? Thanks


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## Michael Bush (Aug 2, 2002)

Oddly enough they don't seem to react to it much at all. I would think the heat alone, not to mention the caustic vapors, would get them in an uproar but they hardly seem to notice.


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## chemistbert (Mar 4, 2004)

It is not a matter of mixing in a normal relativly sealed hive. The vapors will fill the hive due to displacement. You are adding them much fater than they can escape so little mixing is occuring. The vapors "shove" the normal air out of the way. And diffusion will take care of the rest.


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## Whitey (Jul 7, 2003)

I just built a Oxy crack pipe Al a Bee wranglers pics. It and the Oxacylic Acid cost under $10. I gave each hive a 2 gram puff and will check the mite fall and do it again in a week or so. Real simple.

I do not like the chemical treatment options.


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## BWrangler (Aug 14, 2002)

Yeah, oxalic acid... fuming bees... what will they think of next, say's the g man while sniffing the white powder.

He's in the hospital and well I'm in cuffs awaiting test results :> )))

I should have stuck to just smoking them with them wild weeds growing out on the farm :> ))))

On the serious side, a cautionary note. Any beekeeper using that other stuff should not get the powders or the pipes mixed up. Could get self treated for mites :> ))



[This message has been edited by topbarguy (edited March 15, 2004).]


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## BWrangler (Aug 14, 2002)

Hi,

I thought I would update everyone on a recent test of my oxalic evaporators. The hives were three stories tall with a typical early spring cluster located in the middle box. There wasn't any top ventilation. 

The bees were not tightly cluster. The bees were flying. The temperature was 60 degrees F. They were not actively ventilating the hive.

The bottom board evaporator used with a plugged hive entrance provided the best dispersion under these conditions. Water vapor quickly condensed on the plex as soon as the evaporator was heated. The acid vapors quickly moved upward and were dispersed throughout the three story hive.

The hive top evaporator worked better when the hives were more populus and the bees were actively drawing air from upper ventilation holes down and out the hive entrance.

Regards
topbarguy


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## BWrangler (Aug 14, 2002)

Hi

I've made an interesting modification to Bwranglers bottom board evaporator. The straight piece of copper tubing can be bent. The bent portion can be inserted into the hive entrance and the magazine can be heated to the side of the hive rather than right in front of the entrance. 

If the tubing is also bent downward a little, the magazine will be below the hive entrance ensuring only vapor will be expelled from the tube

regards
topbarguy


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## BULLSEYE BILL (Oct 2, 2002)

Topbarguy, you and Bwrangler should get together...









I made a hive top evaporizer like yours. Three inch box with plexiglas and the vaporizer permaniatly attached. While I was watching the vapor disperse, I noticed that it would start again when I moved the heat to the other side of the magazine.

Do you apply the flame to the bottom or sides of the magazine?


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## BWrangler (Aug 14, 2002)

Hi Bullseye,

I start heating the L and move downward. Then I focus on the lower part of the magazine for the last couple of minutes.

It gets very windy here at times. And the wind can really affect how the evaporators heat up, especially if the propane bottle is getting empty. Also some brands of propane seem to burn hotter than others. Is it my imagination?

I inspect the magazine after every hive to make sure all the oxalic has been vaporized. If any residue remains, I add an extra minute to the process for the next hive.

regards
topbarguy


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## db_land (Aug 29, 2003)

Hey topbarguy, et al
How hot does the tube get? Is it hot enough to kill the bees that touch it? I made a bwrangler style oxalic acid vaporizer, but the tude is only a foot long. I may try it on a hive or two this weekend. Not sure of the best way to get the vapors into the hive - tube through front entrance and all other openings sealed with paper towels? The hives have SBB which will be closed off.


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## Jorge (Sep 24, 2002)

One foot long tube sounds too long. I made an applicator with a 3" long extension that connects to a hole in the body of either the bottom or the top box. Both seem to work. It is my observation that applications with outside temps much below 50oF (~9oC) are pretty useless as the bees are clustered and the vapors don't really make it into the center of it. At the lowest temps that allows the bees to fly is OK. Less than that ... ????

Jorge


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## Axtmann (Dec 29, 2002)

Jorge you can vaporize as soon as the temperatures are a few (4 or 5) degrees over the freezing point. The cluster is always in motion the outside bees must go inside to warm up and they bring the acid to the other bees. 
I vaporize the first time with electric vaporizers and this is much easier and faster. Have no idea whether Bwrangler has this kind on his website? You can see the model on the Vaporizer site it has the number JB200.
No leftover in the pipe and no propane torch no pipe cleaning and two colonies at the same time. The whole process takes just over one minutes. I use a cable approx 10 meters / 30 ft. and connected the vaporizers to the cigarette lighter in my car. 
Its really fun sitting comfortable, plug in waiting a minutes and plug out. Then the same with the next two hives. No problem whit wind or rain. I have to connect a switch to the cable is might be better?


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## BWrangler (Aug 14, 2002)

Hi 

The Canadians are spending $200k to research and get oxalic acid approved as a non-contaiminating mite treatment.

See: http://www.honeybeeworld.com/diary/ 

Could it be that the Canadians are truely concerned about food quality and safety? They recalled contaiminated honey long before the US even recognized it as a problem.

Maybe in the US it's just easier to shovel it in a can and ship it off to the packing man.

regards
topbarguy


[This message has been edited by topbarguy (edited March 20, 2004).]


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## Jorge (Sep 24, 2002)

Hi Axtman,

What you say may be right but I did do measurements and continue to make them. I have made OA applications already a few times when the temps were low, i.e. below 50oF (or 9oC), and the numbers of mites dropped were relatively low, by which I mean that the next time I applied OA the numbers of mite drops were similar to the previous applications. You would expect a significant drop in mite deaths if the OA kills >90% of the mites each time you apply it. Once I applied it when the temps final went above 50oF, I had even larger numbers of dead mites and now, finally, the daily natural drop has come down to about 1 per hive. 
To me the best explanation is that the OA is not reaching all the bees that it could. I hope to do another application today and see how many I really are left alive in there.
Note that all these application were made during the winter time, so the high numbers in subsequent applications can't be explained by mites being protecxted from the acid within sealed cells.

About to the applicator, when you only have 3-6 hives, and your hives are many meters away from the closest you can bring your car, the BWrangler applicator is still the cheapest and an adecuate option.
Jorge


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## Axtmann (Dec 29, 2002)

Jorge your right for a few hives is it ok. We have many beekeeper building there own tool but there must be sometimes a different in efficiency. I heard that some had to vaporize several times before they get most of the mites. When time is not a question those tools might be ok but with more hives you cant play around. Important is always the inspection with a sticky board.


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## Axtmann (Dec 29, 2002)

Jorge when you vaporize from the outside try to warm up the pipe to the hive before you start heating the acid. I find out the acid condensates very fast to cold metal it is possible that you blow more hot water fog than acid into the hive. The hot acid doesnt condensates so fast to a plastic hose thats maybe the reason why my first vaporizer gets connected to a clear plastic hose?


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## Jorge (Sep 24, 2002)

Yes, I always check to see if a lot remained in the tubes of the vaporizer. A tiny little bit always remains at the very end of the tube going into the hive where the tube remains coldest (in the form of long fine cristals that look like sppoke in a bike wheel). The rest is ALL gone and it is really almost nothing.

After an OA application about 35 hrs ago, I just counted 3 dead mites on the (no-so-sticky board) of each of my 2 hives. I will continue counting for a week but this already looks wonderful compared with the 200-300 I got one day after last time i applied OA (2 weeks ago).

Jorge


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## JohnBeeMan (Feb 24, 2004)

Have been reading this thread with interest and have a couple of questions:
1) I noticed someone's comment about getting Oxalic acid at Lowe's since it is used to brighten wood. My son does deck cleaning and stows his material in my shed- so I just went and checked. There are two 25KG bags (at 3 grams per hive I could do a lot of hives)of oxalic acid in my shed. It says 99.5% Min on side of bags. Is this the same stuff to use on the bees?
2) How often do you treat? Is it based on mite count or just fall/spring schedule?
3) Does anyone combine oxalic acid treatments with a FGMO approach?


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## Michael Bush (Aug 2, 2002)

>It says 99.5% Min on side of bags. Is this the same stuff to use on the bees?
That's what I'm using.

>How often do you treat? Is it based on mite count or just fall/spring schedule?

Your choice. I treated twice last fall and onece this spring all on the hives and a followup on the one with a lot of mites. Most only had none or one. But one had about thirty. That's the one I treated twice.

>Does anyone combine oxalic acid treatments with a FGMO approach?

I fogged with FGMO all last year and then did the oxalic to see how well the FGMO did. There were reasonable mite counts in all the hives, I thought. But the oxalic sure finished most of the remaining ones. I posted those counts earlier, but don't remember exactly what they were off the top of my head.


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## John D. Smith (Mar 17, 2003)

I made a vaporizer and generally followed the steps outlined here. When I tested it, I didn't see much "smoke" come out. There were a few white wisps, but I was expecting something like my fogger ie a steady stream of white. I realize that the volume will be less than the fogger, but how long does it last? To me, it didn't seem possible for the OA vapor to fill the hive.


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## Michael Bush (Aug 2, 2002)

I didn't get clouds of it like the fogger when I did it by any means. I don't think you WANT that. A little goes a long ways.


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## Axtmann (Dec 29, 2002)

Its not a cloud like the fogger produce but when I use the vaporizer with air connection the steam from 2 grams (half tee spoon) oxalic acid is enough to fill almost 2 hives. There even more steam with the electric one, it produces a big white cloud. 
Put a glass (old window) on top of one hive and there is fog all over and you can see bees with white powder in their hair. 
Make the test with a glass on top of a hive and if there is not enough fog it might be something wrong with your vaporizer.


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## suttonbeeman (Aug 22, 2003)

We have receintly converted to a all palletized operation. We have screened some pallets while some are still solid bottoms. Anyone have any experience in treating or ideas on how to treat with screened pallets. Since we are migatory we are starting to get resistance to the chemical treatments (we are in the hot seat in Forida of resistance)Since the pallets have clips that keep hives from shifting during transet you about have to screen the bottoms of the pallets. How long does it take to fog? We have just started looking at this. Is it fesiable to treat 500+ colonies? Thanks Rick


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## suttonbeeman (Aug 22, 2003)

Does anyone have any experience when using palletized hives? In the last 2 yrs we have converted to pallets. We have started using screen on our bottons (pallet bottoms are (cut out and screen put in place.)How would we treat with acid using the screen bottom....would have to move colonies off pallets and put in a thin board to close up....we migrate to Fl and are in the hot area of mite resistance there.Is it fesiable to treat 500+ colonies? The pallets have clips to keep hives form shifting during transit.....so hard to use a "special" screen board. Thanks


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## Axtmann (Dec 29, 2002)

Beeman if you like to work with oxalic acid the hive needs to be sealed totally. Maybe you can put plywood with foam under the treated hives or with foam strips like they seal doors and windows?

In my opinion the only way is working with some electric vaporizers. I work with two of them and a treatment takes 60 second and sometime a little bit longer maybe 70 seconds. Depends on the amount of acid or the power of my battery. Lets say you work with 5 vaporizer that mean, 5 hives in approx 1 minute or 300 hives in an hour. 

But I think it takes a while to handle the vaporizer, filling, bringing into the hive, moving out and refilling and in the next 5 hives. Im sure you need a helper and if you treat only 250 colonies in an hour (with 5 vaporizer) thats still a lot. If you have enough helper go for more vaporizer it saves you time.
The best would be to contact the manufacturer.


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## JohnBeeMan (Feb 24, 2004)

I tried my first Oxalic acid treatment yesterday. I used the 'crack pipe' from brass fitting from Lowes and drilled hole about 1/3 from top of upper large brood box (2 box hive) and pipe was loade with 1/2 teaspoon crystals. After about 4 minutes of heating with torch I did notice a few small bits of vapors escaping from under top cover. After about 10 minites I removed paper towels from main enterance and every thing appeared ok. By late afternoon I noticed about 100 bees hanging out around the enterance and a few bees on top and further sides of the hive. This agitation was not expected , is it abnormal?

I only counted 14 mites this morning (I am new at counting them so not real sure I am counting correctly). I was also expecting more. I still have a tray in and plan to count again tomorrow.

I still have two more hives to treat but was planning to wait a couple of days to make sure I had not done something wrong.


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## Axtmann (Dec 29, 2002)

John 14 mites is a lot this time of the year you should monitor the mite fall and treat the colony at least 3 more times approx 5 days apart. With brood in the colony there is only a fraction of mites outside the closed cells. 

When heating the Oxalic Acid the hot vapor goes up so you should treat from the entrance not from the top. I heard from tests in Switzerland that vaporizing from top has a maximal efficiency of 55%  65%, from the entrance the efficiency is up to 99% on the mites outside the closed cells, dont ask me why.
I didnt know this before and made the same mistake for a while last year.

Youre doing nothing wrong, there is no harm to bees or queen when using Oxalic Acid. The good thing is oxalic acid killed the Varroa and your bees need NO cleaning behavior to get rid of them compare to oil fogging every week or so. 

I have also trays in my colonies and monitor the mite fall since mid January. Yesterday I found the first Varroa in one of my hives in almost 3 months; the other hives 0 so far and there is no weekly fogging necessary.


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## Walt McBride (Apr 4, 2004)

Axtman You are a big proponet for oxalic acid, so I thought I would ask you what type of oxalic acid do you vaporize in your electric device, oxalic acid-dehydrate? dihydrate? or anhydrous? there is a difference I understand. Could you elaborate?


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## Axtmann (Dec 29, 2002)

Hello Walt yes Im using oxalic acid for a few years with the best result of all treatments I ever used. No chemical residue in wax or honey and no resistant possible and this is the first season I work with an electric vaporizer. 

I checked my container and it says (500 Gramm Oxalsäure Dihydrat) 500 grams oxalic acid dihydrat. It is a white crystal like coarse salt.
Enough for approx 250 treatments and cost me 5.25 Euro (6.30 US $).
That mean 0.02 cent per treatment.


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## Michael Bush (Aug 2, 2002)

Mine looks like Axtman describes and is in the hardware store as wood bleach.


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