# OAV - A discussion



## Barhopper (Mar 5, 2015)

I’ve had good results with 4 treatments 6 days apart. I start on a Sunday, the on the next Saturday, then the next Friday, and finally on the next Thursday. Work constraints keep me from doing it in less days. Where I live I don’t ever get to a broodless state unless I have a queen problem.


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## viesest (Jul 13, 2016)

snl said:


> 2. How often to treat?


5 to 7 treatments from 9. 15. to 11. 15 and 2-4 treatments from 11. 15. to 1. 15.


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## Tweeter (Apr 19, 2017)

Any adverse conditions seen with the bees and queens using multiple treatments as stated in the above posts?


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## johno (Dec 4, 2011)

After a lot of talk about how OAV adversely affects bees especially queens, the latest one from the ABJ class room is that it damages the queens eyes I must say that I have seen no ill effects from this treatment and I treat often as many as 12 times a year. I have also observed the treatment on an observation hive and see a disruption of the colony for about 5 minutes and then the colony returns to normal. The only problem I found was the time taken to perform the treatments but since the use of the newer types of vaporizer has come about and hives are treated in about 30 seconds I am considering treating some of my hives every time I inspect them. Over the last 4 or 5 years I have used OAV and at times treated a little with 50% formic and have had no ill effects on colonies. My winter losses year after year have been 5 to 10% max mostly to an occasional queen loss and bad beekeeping allowing colonies to starve.
Johno


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## wildbranch2007 (Dec 3, 2008)

I'm in a cooler climate, have you done, or has anyone done any work using a hive with see through sides to see how the vapor disperses in different temps? seems to me when they have brood and it's warm the bees fanning might disrupt the application, and when cool, the vapor dispersal may be different. I remember Lauri doing a video using the pro-vap with and empty hive in cold weather and the OA hit about half the hive pretty good, but not the whole hive, so this could also cause some hit and misses.


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## snl (Nov 20, 2009)

I have gone "round and round" with Jerry about his articles in ABJ regarding OAV and it harm to bees, queens etc........ This is the answer I get back from him regarding his sources for how OAV harms......

" All of my sources have anecdotal information or unpublished material!"

Take Care. Jerry

I've lost faith in Jerry regarding anything he has to say about OAV harming bees.


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## snl (Nov 20, 2009)

wildbranch2007 said:


> I'm in a cooler climate, have you done, or has anyone done any work using a hive with see through sides to see how the vapor disperses in different temps? seems to me when they have brood and it's warm the bees fanning might disrupt the application, and when cool, the vapor dispersal may be different. I remember Lauri doing a video using the pro-vap with and empty hive in cold weather and the OA hit about half the hive pretty good, but not the whole hive, so this could also cause some hit and misses.


If you look, Ian Steppler has shown OAV being applied in Canada. While not a see through hive, the vapor dispersal is very apparent.


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## Mike Gillmore (Feb 25, 2006)

I've been using OAV exclusively since about 2006. If there does happen to be any measurable harm to the bees or queens I've never noticed it slowing them down a bit. After all those years I still see no signs of resistance or diminished results with the treatments.

Every region has their own unique climate cycles to work around and you have to figure out the best treatment regimen for your area. In warmer climates where brooding never really shuts down in the winter months a combination of different treatments is probably the best route to take. 

What has been working well for me in Ohio is 3 or 4 treatments a week apart, starting in late August and into September. This cleans up most of the mites when they are at their peak numbers, before the colony starts to raise their winter bees. Then one more treatment on a warm day between Thanksgiving and Christmas when they are broodless. That's it. They build up very nicely in the spring and outbreed the mites, so no additional treatments are needed again until August, after I've pulled my supers.


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## GarrickG (Nov 29, 2014)

OAV is my only treatment. I treat once in January and many (6 or 7) rounds in the spring and August. I use a 24 hour mite drop on 5 hives in each yard to judge whether I need another round for all the hives in that yard. I don't believe 3 or 4 rounds would ever be enough... Time is the limiting factor. Using a wand was too time consuming. I much prefer my band heater vaporizer. Even if OAV damages bees/queens, I see it as the lessor evil when compared to sickly hives struggling to winter... I also requeen almost all my hives each year...


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## Ian (Jan 16, 2003)

snl said:


> If you look, Ian Steppler has shown OAV being applied in Canada. While not a see through hive, the vapor dispersal is very apparent.


As long as those vapours are penetrating that cluster, the OA dispersal should be uniform.

https://youtu.be/M5ypDMwqAKQ

https://youtu.be/1RKcWVvqWIE


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## Spur9 (Sep 13, 2016)

GarrickG said:


> I use a 24 hour mite drop on 5 hives in each yard to judge whether I need another round for all the hives in that yard.
> View attachment 36516


What is your 24 hour mite count baseline to initiate another round?


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## mgolden (Oct 26, 2011)

Some observations

Ian is using 2 grams on a single 10 frame deep. There is some vapor escaping out the entrance reducer but likely a heavier dose than suggested 1 gram per deep. However, excellent mite control and no or minimal harm to bees. 

OAV applied to a single deep, there is good penetration of the cluster. I did some double deep five and six frame NUCs with 2 grams with Varrox in bottom entrance and there was not a lot of vapor emanating from hole in inner cover.

I have applied 2.5 gram doses to a double deep hive for 8 weeks, 7 days apart, starting in early Sept. I could see no harm to the bees. I suspect some brood was going on and kept seeing significant 3 day mite drops, 450 mites. Hives had been treated with Apivar in early spring. Mite drop seemed high to me so kept treating until drop was less than 50. The weekly treatment seemed to maintain the mite load but didn't lower it. Towards the end of the eight weeks period, there was minimal brooding and mite load was being reduced.


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## Kuro (Jun 18, 2015)

While OAV works really well in my hands in winter, it was not effective August-early November, no matter how I did it (from the top, from the bottom, every 3,4,5 days). To be fair, my goal was to bring mites down to very low levels (post 48hr OAV mite drop <20, undetectable by sugar roll in 0.5 cup bees), which may not have been necessary. I do not doubt one can keep his apiary running by treating with OAV, nothing else. But I only keep 2 hives and desperately want 100% winter survival, so I prefer to rely on commercial products like Apivar and MAQS during summer-fall.


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## dudelt (Mar 18, 2013)

For me, the key is the December treatment. That treatment gets the mite count really low and I do not have to worry about anything until August. In early August, I do 4 treatments 5 days apart. This knocks back the mite load enough to get to December. This year however, I picked up a free package in April that a friend could not use and forgot to treat it immediately. It made it to August, got treated but was dead 1 month later, due to PMS. I did a mite wash after the August treatment but that hive was not in the 50% sample of hives. I did another round of 4 treatments on the rest of the hives in early October in case all the mite covered bees moved to my other hives. My annual losses before OAV was about 90% even though I used MAQS or Apivar those first 3 years. OAV really changed my success rate.


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## johno (Dec 4, 2011)

There is a short video of a single box being treated with OAV on the facebook page of the Northern Neck Beekeepers. The fact that sublimation might not reach all parts of a hive and therefore not be totally successful in getting all of their phoretic mites has troubled me to some extent and by treating a 3 level observation hive I have determined that the vapor does tend to go down more than up and have now made a practice of treating through a 1/4" hole higher up the stack, in the middle of a 2 med hive or through the top of the second in a 3 box hive and have then found the vapor leaking from the top and bottom. The reason I treat more than most is that I am also worried about the movement of mites from hive to hive.
Johno


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## Spur9 (Sep 13, 2016)

Given a OAV that is well dispersed in the hive, do the mites already in the uncapped cells with their breather tubes sticking out get killed? I've been wondering about that.


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## GarrickG (Nov 29, 2014)

Spur9 said:


> What is your 24 hour mite count baseline to initiate another round?


It's pretty subjective. I compare subsequent drops to the previous drops. when it seems like the numbers drop significantly, I give one last round and stop. Often a few of the hives I check have 0, 1, 2 or 3 mites and others have 10 when I stop. That's on the board not with a wash. I use a 0-4 rubric in my mind and write the number on the lid. 0's and 1's are good. 3's and 4's I keep treating. Very subjective but it works for me.


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## Cjj (Dec 12, 2015)

GarrickG i use the same method except i use the 1,2,3, method on my lids after each treatment i mark each lid 1 is good ,2 is need another treatment , 3 is its bad , it works for me


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## wildbranch2007 (Dec 3, 2008)

johno said:


> The fact that sublimation might not reach all parts of a hive and therefore not be totally successful in getting all of their phoretic mites has troubled me to some extent and by treating a 3 level observation hive I have determined that the vapor does tend to go down more than up and have now made a practice of treating through a 1/4" hole higher up the stack, in the middle of a 2 med hive or through the top of the second in a 3 box hive and have then found the vapor leaking from the top and bottom.
> Johno


pretty much exactly what I have determined also, now to see if it reaches the front and sides of the hives, which it may not because it is dropping down towards the bottom. I may experiment with using a scope, drill some holes in the front of the hive and put the scope in, except then you have changed the dynamics of the air flow.


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## grozzie2 (Jun 3, 2011)

johno said:


> The fact that sublimation might not reach all parts of a hive and therefore not be totally successful in getting all of their phoretic mites has troubled me to some extent and by treating a 3 level observation hive I have determined that the vapor does tend to go down more than up


What method are you using to apply the OAV ? I'm using a blower that pushes it in thru the entrance and disperses it everywhere in the hive. Of this I am confident based on seeing it come out all of the cracks when we apply it.


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## johno (Dec 4, 2011)

I am using a band heater type of vaporizer where the vapors are quickly forced out of the hot chamber through pressure generated from the boiling of the OA, what I have found is that if you are vaporizing into a blind area at the top of the hive the air needs to be displaced or the air sort of creates a cushion unless the pressure has an outlet at the top. the cooling vapor will fall down and displace the air through the gaps around the sticky board and also out of the reduced entrance. I have also found that to get a good vapor treatment it is better to have a larger dose than a smaller dose or in other words 3 grams against 2 hell the OA is cheap enough and I see no ill effect anecdotally or practically.
Johno


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## dudelt (Mar 18, 2013)

I have noticed the same problem when treating hives. Not much OA would seep out of the top compared with what was coming out of the bottom. It was very noticeable in a top bar hive I treated last year too. The top bar hive I treated by mistake was a dead out but the OA residue was clearly visible a month later when I opened it up. The residue only went about 5 bars from the vaporization site. This left roughly 2/3's of the hive untouched. This year I switched over to a Provap 110 and am vaporizing from the tops of the Langstroth hives and am treating the top bar hive with a split dose in 2 different spots in the hives. It appears to be working better.


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## Fivej (Apr 4, 2016)

For those noticing that the vapors are not reaching the top of the hive: Has anyone experimented with adding a shim with holes drilled in all 4 sides to the top of the stack? I am wondering if it would create a chimney effect and pull the OAV up through the hive. Also, if the vapor drops, perhaps make a shim and do it from the top of the stack like some do. I see the vapor leaking out of my hives at the top. Perhaps this is a good reason not to seal every crack like some do? Personally, I don't bother. J


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## Scottsbee (Jan 11, 2017)

Anyone see this before? Doesn't seem normal.


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## Cloverdale (Mar 26, 2012)

Ian not to get off topic but is that bubble wrap you are using for insulation/inner cover?


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## snl (Nov 20, 2009)

SB,
What was the temperature at the time? I’ve seen that before with low temperatures and/or an undercharged battery. Try hooking it up to a running car/truck battery and tell us the results.


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## Grins (May 24, 2016)

Scottsbee said:


> Anyone see this before? Doesn't seem normal.


What is the consistency of the material around the cup? If it feels like ash the OA sublimated and precipitated there, if it feels like the powdered OA it didn't sublimate. If it is precipitate it seems like the flow was too restricted above the vaporizer.


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## Ian (Jan 16, 2003)

Looks like spatter residue of the element


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## Scottsbee (Jan 11, 2017)

Temp was upper 50s F, ash like consistency and the battery just came off the charger. Battery is old, will check output. 
Maybe our OA absorbed some moisture?? 

OA was applied from top of hive under a spacer. 1 Inch of space from pan to top of spacer. 

Seemed to be getting hot enough, OA seemed to boil, turn to liquid, then boil over the pan.


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## dudelt (Mar 18, 2013)

OA liquefies at 101-102 C, just above the boiling point of water. What you saw was the water in the OA come to a boil and then the OA liquefied. The reason for the residue outside of the pan is that the water boiled and it takes some of the OA out of the vaporizing pan. The OA in the original container will absorb water from the air. Keep the container well sealed to keep the moisture out of it.


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## psm1212 (Feb 9, 2016)

dudelt said:


> OA liquefies at 101-102 C, just above the boiling point of water. What you saw was the water in the OA come to a boil and then the OA liquefied. The reason for the residue outside of the pan is that the water boiled and it takes some of the OA out of the vaporizing pan. The OA in the original container will absorb water from the air. Keep the container well sealed to keep the moisture out of it.


Is the treatment still effective with that type of result?


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## dudelt (Mar 18, 2013)

I have never seen any scientific tests to prove it one way or another but I would guess that yes, the treatment would be effective but maybe not as effective as if the entire dosage had been vaporized. When I used a pan type vaporizer, I never followed the directions exactly. Usually, once I saw the OA vapor coming out of the hive cracks, I would disconnect from the battery and let the residual heat vaporize what ever might be left in the pan. I figured there was no reason to keep heating a vaporizer that had already vaporized all or most of the OA. A few times I found that a lot of the OA in the pan had not been vaporized and I did not retreat the hives when I found this. I never noticed a spike in hive losses or varroa populations in those hives.


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## snl (Nov 20, 2009)

dudelt said:


> .....A few times I found that a lot of the OA in the pan had not been vaporized and I did not retreat the hives when I found this. I never noticed a spike in hive losses or varroa populations in those hives.


With that much OA not vaporized, I’d treat again as if that treatment never happened. I’d also get some fresh OA that does not have as much moisture. If you get Savogran wood bleach, empty it into old plastic mayo or ?? jar with a tight fitting lid. Those Savogran containers are a pain in the butt to open and close.


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## billabell (Apr 19, 2010)

I treated from the bottom rear of 3 box mediums. To aid with dispersal I just laid a little battery fan under the screened bottom board near the front entrance on low and it seems to aid dispersal, but I really dont think it is needed. I will do 4-5 treatments in December and then again in Feb/March and then again in August/Sept. I see no harm to the bees.


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## Lauri (Feb 1, 2012)

Here is a video of *OAV treatment done with the Provap in a large Observation type hive.

https://youtu.be/_1zHjIniES4

Treatment done a few days ago, 11-29-17. Western Washington State, about 46 degrees F. 

This big OB hive has a total interior volume of about 4 deeps (Occupied bee volume of about 2 1/2 deeps) so the Provap takes a few seconds to come back up to temp. after that much OA dumps into the bowl. About 47 seconds into video, you see the Provap getting back up to temp and vaporizing the rest of the OA with more forceful puffs of vapor. Remainder of video is lengthy, but recorded for you to see how long the vapor cloud remains. The reduced Top and bottom entrances were not sealed for this treatment. This hive has bees, but they are sucked up a little higher into the comb above, due to temp starting to drop at the end of the day.
The majority of the standard Lang hives treated that day were done between 49 & 51 degrees F with loose clusters and little light flying
I prefer to treat my taller hives from the top so vapor will settle _down through_ the cluster and seams of bees between the frames and not try to get it to _rise _in cool temps, which it difficult to do without a larger dose.

I have a lot of taller hives (due to using some 8 frame equipment) and vapor settles far faster that it will rise in dense interior situations. (Filled frames of Honey and semi clustered bees) I *believe top application *Results in the use of less OA to get proper dosages.*

Under dosing with any mite treatment is not only marginally effective, but can result in a false sense of security for the beekeeper.*
Proper distribution is important. Allowing / adjusting dosage for *leakage due to open entrances and imperfections in the hive is necessary so you don't over or under dose.
Understanding how the vapor moves and distributes within the hive is important.
I though you might like to see this to help you visualize the OAV process.*

I am not an OAV expert of course, these are just my observations from my own yards.

















Here is how that OB hive looked early July about the height of it's population.

















I have never seen any negative impacts of the queens, bees, brood etc from OAV. While I and am careful not to overdose, I do apply thoroughly.


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## Lauri (Feb 1, 2012)

Duplicate post.

Also I have no idea what all those ** are. Please disregard them.


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## Lauri (Feb 1, 2012)

Duplicate


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## Lauri (Feb 1, 2012)

Ian said:


> As long as those vapours are penetrating that cluster, the OA dispersal should be uniform.
> 
> https://youtu.be/1RKcWVvqWIE


The end of this video _really_ show the vapor distribution


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## Bee Arthur (Mar 21, 2015)

Spur9 said:


> What is your 24 hour mite count baseline to initiate another round?


I built an online calculator that tries to answer this very question, Spur9. Check it out and let me know what you think.


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## Bee Arthur (Mar 21, 2015)

snl said:


> I have gone "round and round" with Jerry about his articles in ABJ regarding OAV and it harm to bees, queens etc........ This is the answer I get back from him regarding his sources for how OAV harms......
> 
> " All of my sources have anecdotal information or unpublished material!"
> 
> ...


Couldn't agree with you more, snl. He recites a lot of the same speculation I hear at local bee clubs. It's frustrating. Trust me, if OAV is hurting bees, I want to know about it. But I've yet to see real evidence it does any harm.


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## allniter (Aug 22, 2011)

JERRY was our quest speaker at our HARVEST DINNER in NOV.--- FORT WAYNE IN, ---HE said the same OAV burn the bees eyes --after meeting I talked to JERRY I told him I treated once a month when the temp was above 40+ degree up until APRIL--after I treated the hive 4 times in SEPT,-I only lost one hive out of 40+ hives --he said well keep up doing the same


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## fatshark (Jun 17, 2009)

snl said:


> If you look, Ian Steppler has shown OAV being applied in Canada. While not a see through hive, the vapor dispersal is very apparent.


Many of my colonies have perspex crownboards. I use a Sublimox 'active' vaporiser through a hole in the sidewall of the floor. The vapour rapidly (<20 seconds) spreads throughout the hive, whatever the temperature. I've not treated below zero centigrade.

However, I prefer to treat when the winter cluster is a bit more open - for example at 7-10 C after a protracted cold period. 

Anecdotal evidence ... (!) ... but I think the vapour permeates the cluster better and gives better results.


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