# oxalic acid treated hives with high mite counts



## Nabber86 (Apr 15, 2009)

Works really well for me and never had any problems. I highly recommend it.


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## JRG13 (May 11, 2012)

What was your rate per hive or should I say per box.


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## dnichols (May 28, 2012)

What was your mite counts before the treatments?


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## Andrew Dewey (Aug 23, 2005)

What method did you arrive at your counts with? The usual way of determining the efficacy of a treatment is to test before and after applying the treatment.

If you had high mite infestation to begin with then Oxalic might not have been your best choice for treating as it requires multiple treatments to get at mites emerging from brood cells. The infestation rate of the hive would fall over time.


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## Oldtimer (Jul 4, 2010)

I have improved results by going to 4 treatments 5 days apart.


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## shinbone (Jul 5, 2011)

OAV works really well. If it is not killing mites, then there is a problem with your method of application.


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## shinbone (Jul 5, 2011)

Oldtimer said:


> I have improved results by going to 4 treatments 5 days apart.


i was thinking about doing the same thing. How much of an improvement did you get?


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## Oldtimer (Jul 4, 2010)

Now there's the question!!

I don't count mites so cannot give a definitive answer to that. What I can say is that where I am we have brood all year, no brood break at all to expose all the mites to an easy quick kill. So I started out using the standard 3 weekly treatments, but found it worked well with a lot of hives but some not good enough. So went 4 x's 5 days apart and have found a smaller number of hives needing remedial action later. But it's all rather subjective unfortunately, not really able to quantify it much better than that.

It's clear from reading the experiences of various folks on Beesource, that for some folks OA works really well and there could be many factors that influence that. For me, I have to work a little harder to get the needed results.


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## CircleBee (Mar 3, 2012)

I don't want to take over this thread, but I have one quick question, if I may to those doing multiple vapor treatments. Are you treating with the standard OA dose per frame of bees/deep each time you vaporize? And have you seen any adverse effects? (sorry that was two quick questions). My belief that multiple OA vapor treatments was Ok was recently called into question by another member when I suggested doing just that. This member stated that the directions that came with their vaporizer said one treatment during the brood less period, that "No one suggests multiple vapor treatments", and Implied that this was dangerous advice. I've been doubting myself ever since.


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## Bees of SC (Apr 12, 2013)

GOOD QUESTION, I have been thanking the same thing.


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## johno (Dec 4, 2011)

Treatment consisted of two heaped scoops of OA per hive. Hives were one deep and two mediums or three mediums bottoms closed off and closed off after inserting the vapouriser , three minutes to vapourise then the heiliser removed the hive then closed for a total of ten minutes. The hole in my inner covers has I/8 screen stapled over it and I have lifted the outer cover to see if the vapour comes to the top and it does. I am starting to get the feeling that these mites are tougher than we think, after mite checking I took a mite and put it onto a microscope slide and put a drop of alcohol on it to stop it walking around the slide 10 minutes later I let some folks who came by to see how mite counts were done look at the mite. well he was once again walking around the slide so put another drop of alcohol on him, a half hour later the mite was gone from the slide.
Johno


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## WWW (Feb 6, 2011)

CB
For a number of years now I have been applying OAV one treatment per week for four weeks in August and have seen no ill affects to my hives. One applications per week for three weeks is the standard treatment with OAV, I give my hives a fourth application and have seen only healthy bees in my hives. The dose is 1 gram per deep box and is not per frame, OA dribble is applied per seem of bees.

I have found that people often confuse OAV with the OA dribble method, when using OA dribble one must use one application only in the Fall during broodless period, if more dribbles are done the bees life is severely shortened because the OA/syrup mixture is consumed by the bees and this severely effects the gut of the bee causing it to die earlier during the winter.

As far as the following quote below from the other member, I don't know of any vaporizers that would come with instruction like this. One treatment only per year could be done during the early winter broodless period but the damage from Varroa mites will have already been done by then. There are members here who do three vaporization's in September and then one additional application during the broodless periods between Thanksgiving and Christmas and this also works well but this timing is determined by your geographical location.



CircleBee said:


> This member stated that the directions that came with their vaporizer said one treatment during the brood less period, that "No one suggests multiple vapor treatments", and Implied that this was dangerous advice. I've been doubting myself ever since.


A quick read through Randy Oliver's notes on Oxalic Acid treatment would be helpful to explain the different parts of this treatment which concerns you. http://scientificbeekeeping.com/varroa-management/treatments-for-varroa/


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## lazy shooter (Jun 3, 2011)

johno said:


> Treatment consisted of two heaped scoops of OA per hive. Hives were one deep and two mediums or three mediums bottoms closed off and closed off after inserting the vapouriser , three minutes to vapourise then the heiliser removed the hive then closed for a total of ten minutes. The hole in my inner covers has I/8 screen stapled over it and I have lifted the outer cover to see if the vapour comes to the top and it does. I am starting to get the feeling that these mites are tougher than we think, after mite checking I took a mite and put it onto a microscope slide and put a drop of alcohol on it to stop it walking around the slide 10 minutes later I let some folks who came by to see how mite counts were done look at the mite. well he was once again walking around the slide so put another drop of alcohol on him, a half hour later the mite was gone from the slide.
> Johno


And the next Science Ficition movie will be: "MacroMite, The Varroa That Couldn't be Killed"


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## CircleBee (Mar 3, 2012)

Thank you Bill! Yes, your description was exactly how I understood it. And in fact I had used both the dribble method and the vaporizer (using a home made pipe 3x at weekly intervals), and pointed out that he was confusing the two. That's when he gave me the following link to the instructions for his vaporizer: http://www.biovet.ch/en/Imkerei/varrox-vaporizer.html
When I read those I was kind of shocked, had never heard of using the vaporizing method during the winter cluster. Anyway, thank you for the information and I will from now on continue to use OA as you have described, appreciate it!


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## squarepeg (Jul 9, 2010)

i've no experience, and i assume that the three weeks apart treatments are aimed at getting to the mites that are in capped brood, but if your colonies have been brooding in earnest that may explain the mites that the oa didn't get.


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## cg3 (Jan 16, 2011)

I've been using OAV at 7-10 day intervals, 4x. I've been pleased with the results. Oldtimer suggests 4x at 5 day intervals. Can someone familiar with the mite life cycle comment on most effective treatment interval?


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## johno (Dec 4, 2011)

I do not think the mite life cycle matters, it is the bees brood cycle that counts. As the OAV only gets the phoretic mites, all the mites in the capped brood are safe, so the 7 day or 5 day cycle is aimed at getting the mites that have emerged as I believe the young mites have to be on bees for a certain period of time before going back to breed 
Johno


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## knute (Mar 10, 2013)

The phoretic stage of the mite lifecycle is 5-7 days, so it's possible with a 7 day OA treatment interval that a mite can emerge and make it back into another capped larvae before the next OA treatment. I have been looking for (but haven't found) good data on how many days after treatment the OA is still killing mites. I've seen drop rates, but these don't distinguish between mites that took a few days to die after being exposed as opposed to a mite that mite have emerged a day or more after the treatment and was exposed to lingering OA. Oxalic acid is very hygroscopic, so humidity in the hive will quickly convert the tiny crystals to a reactive solution, and my bet is the OA dissipates very quickly as it "bleaches the woodwork".

I have treated at 3-4 times at 5 day and at 7 day intervals, and anecdotally the 5 day treatment was more effective, but I need to do more controlled testing to be sure. With brood in the hive, OA is definitely not as effective as it is when the hive is broodless. My last round of several treatments at 7 day intervals in July only reduced the mite counts by approximately 50%. (Measured using the powdered sugar shake method, shaking for a solid minute to ensure reasonable accuracy of the count) I'm leaning towards either doing more frequent OA treatments during summer, or switching to MAQS for summer and OA for winter when the mite counts indicate it's time to treat (>2 mites per hundred bees sampled).

For what it's worth, I have seen nearly zero negative effects from using OA (Heilyser JB200). The bees perk up nicely when the mite counts drop.

-Knute



cg3 said:


> I've been using OAV at 7-10 day intervals, 4x. I've been pleased with the results. Oldtimer suggests 4x at 5 day intervals. Can someone familiar with the mite life cycle comment on most effective treatment interval?


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## cg3 (Jan 16, 2011)

knute said:


> The phoretic stage of the mite lifecycle is 5-7 days, ... anecdotally the 5 day treatment was more effective,


Thanks, that was what I was looking for. Anyone else?


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## Stephenpbird (May 22, 2011)

One thing I would suggest for those trying this for the first time, Do a dummy run before treating any hives. You can time how long it takes to vaporize the OA and you can see if all the OA gets vaporized. It may make a difference depending on what size battery you use.
I went for a small battery for convenience sake but regretted it afterwards as I could only treat a few hives properly.


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## GLOCK (Dec 29, 2009)

I treated with OAV last fall and it was the best thing I could of did for my bees.
My hives had 1000s of VARROA the drop's where just crazy .
I had been treating all year long with fogging with FGMO and by JULY I had hives full of mites. so I treated 4 times by OCT. And the drop's looked like this.

I use my truck battery I made the mistake of using a small {lawn tractor} battery and it would run out with by ten hives.
Ya have to make sure you vaporize well and make sure it 's coming out the top of the hive.{60 sec.}

I tested most my hives in mid. JULY with alcohol wash's and did not have one mite out of 20 hives 
I plan on testing again in SEPT. 
I know it sounds to good to be true but it is what it is.
I plan on sticking with OAV it works great and is cheap


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## adgjoan (Oct 19, 2008)

Does the time of day you do the treatment make a difference?


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## GLOCK (Dec 29, 2009)

adgjoan said:


> Does the time of day you do the treatment make a difference?


I'd do it when all the bee's are in the hive.


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## rwurster (Oct 30, 2010)

I use an old radio flyer wagon to carry two car batteries wired in parallel to each other which in turn is wired to a 100 watt solar panel (charge controller) and vaporizer(s). Mobility was my biggest issue and this set up easily gases 24 hives quickly. A commercial guy was interested in my setup/start up cost/cost per hive, so I invited him for a look-see. Pretty sure he's running similar set ups in his yards this year with 2 smaller panels, but using heavier wagons with pneumatic tires.

No one is forgetting their respirator I hope.


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## Stephenpbird (May 22, 2011)

"I bought a tractor battery, I was wondering just how long it would last..."

OA is cheap enough, so sit up wind and try it out


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## crofter (May 5, 2011)

Mite drop after vaporization is supposed to peak about third day. I dont know how long the effects of OA remain but I suspect since it is a thin layer of acidic dust/moisture it may start to taper off around five days. If this is in fact the case then mites emerging in the next several days could escape back under cappings before a scheduled 7 day treatment was repeated. If I had a high mite level I would certainly go with the extra number of treatments on the five day schedule. Since I have seen no mortality or disruption of laying I do not see a negative. 

I got my mite levels down initially with formic acid (and some hopguard) and since then one treatment of Oxalic vapor late fall and another early in spring has been sufficient to control mites. I just pulled supers a few days ago and will start mite testing tomorrow. I place a screened bottom and sticky board on a hive and will do an untreated mite drop count then a sugar shake / alcohol wash before I do a vaporization treatment. I will see what I come up with for mite counts but since I have not found a single mite on large culling of drone brood I think it may be pretty low.

I sure dont expect to see anything like what showed up on Glock's sticky board but as far as I know I am totally isolated from other bees.


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## cristianNiculae (Jul 2, 2013)

Oldtimer said:


> Now there's the question!!
> 
> I don't count mites so cannot give a definitive answer to that.
> ...


Oldtimer, can you please get into more detail about methods you are using in evaluating a colony regarding mites?

I am tired of counting mites too  So far I only know these symptoms: DWV, crawling bees, small bees, bees without wings. I also know people say that when you see that is already too late... OK but in what amount? If I only see singular cases does it mean it's too late? Some more details about this would really help many of us.

So far I have seen some cases of K wings(tracheal mite), no DWV and some crawling bees, not many. I did 2 samples yesterday and found 5% infestation - a slight increase during the last 2 weeks. I still wait for broodless period for applying the OA dribble. It will happen probably at the end of September. However the brood has reduced a lot as bees are backfilling: have some brood on the lower part of the frames on most of my hives... in rest uncapped and capped honey... thank Gog I don't need to feed. I did some flash FA but the results are poor due most probably to the low dose and leaking hives .

Thanks.


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## Oldtimer (Jul 4, 2010)

cristianNiculae said:


> Oldtimer, can you please get into more detail about methods you are using in evaluating a colony regarding mites?


Nothing very scientific I'm afraid. Counting mites is actually a good idea but it's time consuming and once you have more hives it just doesn't work from a time perspective.
All I do is have a look, for the things you said, ie condition of the bees, brood, and general "vibe" of the hive, bees act a certain way when they are getting harassed by mites.

The damage mites do to hives is not only about mite numbers but associated viruses and the bees tolerance to all that so looking at the actual condition of the bees can give a better idea if the hive should be treated than just a straight mite count, and also which hives should be bred from or not bred from. So over a few years you get an idea of if you see a certain amount of signs of mites at a certain time of year you know if that will have to be dealt with or not to avoid greater cost (financially) later.


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## cristianNiculae (Jul 2, 2013)

Thanks. Very interesting and useful reply.


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## snl (Nov 20, 2009)

Stephenpbird said:


> One thing I would suggest for those trying this for the first time, Do a dummy run before treating any hives. You can time how long it takes to vaporize the OA and you can see if all the OA gets vaporized. It may make a difference depending on what size battery you use.


Not all will vaporize in the pan. Impurities in the OA will remain. You should scrape them out with a stick or ??? between uses.


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## robinh (Jun 19, 2014)

I used the OAV the 9th of Aug. and then the 2nd treatment on the 16th.The 1st treatment with 50 mites on the sticky board after 24hrs.and 25 on the 2nd treatment after 24hrs.One is supposed to skip a week and do the 3rd treatment on the next 7th day.After reading this thread i think I will follow the 5 day - 4 treatments,so i will treat again ( 3rd treatment on the 21st) and do a 4th on the 26th . Any comments on this ? This is my 1st time trying the QAV


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## snl (Nov 20, 2009)

robinh said:


> One is supposed to skip a week and do the 3rd treatment on the next 7th day.After reading this thread i think I will follow the 5 day - 4 treatments,... QAV


Robin, 3 treatments 5 days apart is sufficient at this time. Then another right around Thanksgiving (when the hive is basically broodless) will carry you thru winter.......


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## robinh (Jun 19, 2014)

:thumbsup: Thanks SNL


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## Oldtimer (Jul 4, 2010)

Edit - SNL already answered.


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## johno (Dec 4, 2011)

Tried 4 five day treatments on 1 of four hives, remember that hive had just been treated with 3 treatments of OAV and had a mite count of 11 mites. well after the next 4 treatments had a mite count of 6 mites per half cup of bees so seem to be winning there but o so slowly. Another hive after the 3 OAV treatments had a mite count of 9 mites did 4 treatments of mineral oil plus some wintergreen oil fog and ended up with a count of 9 mites again. A 3rd hive I did a 50%formic acid treatment on an absorbent pad about 3 weeks ago this one started with a count of 19 mites and now has a count of 32 mites not good. A 4th hive had a 50% FA treatment at the same time as hive #3 using a Amrine and Noel fume board starting with a count of 11 mites and finishing with a count of 8 mites. Anyone want to draw some conclusions from this little exercise
Johno


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## adgjoan (Oct 19, 2008)

Are there any bee hives within flying distance of your hives? If the other hives have not been treated your bees could be robbing the other hives and bringing the mites home with them.

Are all these hives in the same yard? I would use only one produce to treat the whole yard.


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## wdale (Jun 27, 2014)

Johno
I would try a little higher strength of formic acid 60-65% BUT NOT over 65% and use 20ml per 20 frames of brood ( what I have used is 60 65% formic with mite pads I use 2 types of pads meat absorbent pads from the meat market and plant support blocks cut up into 1/4" strips 4 " wide and 6" long wrapped in perforated plastic and use 60ml syringe for the measured amount 20ml of formic acid I place the 4 meat pad or the two plant pads in the top brood chamber spread on the outer frames or on the frame ends.
I see your mite is going down from what you started with
So hang in there you are winning


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## MissouriMule (Jun 6, 2011)

What time of day do you find is the best to do the treatment?

I recently purchased a Varrocleaner and plan on treating several of my colonies this coming weekend or possible in the afternoon after work it that works OK.


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## snl (Nov 20, 2009)

MissouriMule said:


> What time of day do you find is the best to do the treatment?
> 
> I recently purchased a Varrocleaner and plan on treating several of my colonies this coming weekend ........


It's best (this time of year) to treat early morning or later evenings when most of the bees are in the hive. Treating on a drizzly day (anytime) works great also as they are all mostly in the hive....


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## MissouriMule (Jun 6, 2011)

Makes sense, thanks for the info.


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## snl (Nov 20, 2009)

robinh said:


> This is my 1st time trying the QAV


So robinh, what is your take on OAV?


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## johno (Dec 4, 2011)

Wdale,
I have been using the 50% FA solution at 30mls per 8 frame box for a total of 90 mls per hive originally I left the fume boards on for 24 hours, the last treatment was for 12 hours. I have just treated the hive with a count of 32 mites but will leave the fume board on for 24 hours, there has been a heavy mite drop from this hive after 12 hours. I have read that many beekeepers are using pads and flash treating for 12 hours so I thought that I would try that against the fume board and the fume board seems to do better as I only have 2 fume boards treatment of my 38 hives takes some time. Last season I did a FA treatment in early spring and again in August but this year only in August with OAV and thought that this would suffice but it is not working out that way. When the hives are broodless in December I will do some more OAV and do the same in early spring and see where we stand at that time. adgjoan, The only bees in my area are my bees so I can not put this down to robbing, there is so much brood in my strong hives I tend to think I am not getting the mites from the emerging brood.
Johno


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## Stephenpbird (May 22, 2011)

For FA to work well you need a temp over 20 deg.C but not above 30 deg.C. At the moment we don't have that and are not likely to get it,so we have been recommended to double up on our pads or sponges etc but use the same amount of FA. This seems to be working.


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## johno (Dec 4, 2011)

Stephenbird, the pads I used lay on the frames of the top box and left only about 12mm/ 1/2 an inch gap around the top of the box and the temps were in the 27-28degree range. With the fume board the rising heat from the cluster is trapped by the hollow of the fume board and allows the FA to vaporize quicker so goes the theory it seems to work better than just an absorbent pad.
Johno


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## Stephenpbird (May 22, 2011)

Sound like perfect conditions for a FA treatment. It is puzzling that you don't seem to get an efficiency in the high 90% range.


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## johno (Dec 4, 2011)

I had a very good mite fall from 24 hours with the fume board, I think that FA does very well with phoretic mites but I am not so sure of the efficacy of FA on the capped mites. I plan to alter my treatment plan for the next season to include early spring OAV treatments  then August and September FA treatments and again in the winter OAV when they are broodless and see how that works out.
Johno


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## johno (Dec 4, 2011)

I had a very good mite fall from 24 hours with the fume board, I think that FA does very well with phoretic mites but I am not so sure of the efficacy of FA on the capped mites. I plan to alter my treatment plan for the next season to include early spring OAV treatments then August and September FA treatments and again in the winter OAV when they are broodless and see how that works out.
Johno


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## cristianNiculae (Jul 2, 2013)

Stephenpbird said:


> Sound like perfect conditions for a FA treatment. It is puzzling that you don't seem to get an efficiency in the high 90% range.


Nice thread. I've been doing flash FA(on pads - swiss receipt) myself and noticed lots of mites on the bottom boards afterward. I did it during the day with temps btw. 15 and 20 C. I haven't used it on weaker nucs... those are left untreated and wait an oxalic bath later.


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## Daniel Y (Sep 12, 2011)

CircleBee said:


> This member stated that the directions that came with their vaporizer said one treatment during the brood less period, that "No one suggests multiple vapor treatments", and Implied that this was dangerous advice.


They are certainly free to claim anything they like. it does not make it accurate. a quick search of comments on this group alone would indicate how many people this manufacturer considers nobodies. 
I have never seen one treatment suggested before.


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## WWW (Feb 6, 2011)

Daniel, I think the confusion is based in the Varrox instructions which CircleBee provided in the link, this vaporizer did state that it is "to be used in the broodless time in November-December", which was then further confused with the OA drench method by another member giving skewed advice at some earlier point. http://www.biovet.ch/en/Imkerei/varrox-vaporizer.html


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## knute (Mar 10, 2013)

Since 2/3 of the mites in the hive are under the brood cappings, one treatment during a broodless period is ideal, because then ALL the mites on the hive are exposed to the treatment. When you treat with OAV when the hive has brood, you are only smacking the 1/3 of the mites that are phoretic on the adult bees, hence the need for several treatments to produce a meaningful reduction.


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## robinh (Jun 19, 2014)

snl said:


> So robinh, what is your take on OAV?


After the treatments (4) I think I ended up with around 250 mites total counted on the sticky board , each count was done after 24 hrs. of treatment.The treatment was fairly simple , and my bees tolerated it very well.I plan to treat again ( a single treatment ) around Thanksgiving.


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