# Oxalic vapor



## Michael Palmer (Dec 29, 2006)

bee stung said:


> Will oxalic vapor kill brood? Does it do any thing to the hive beatle?
> Thanks John


No, it doesn't kill brood. I used OA vapor for 3 years. In '06, I vaporized three times, 7 days apart...trying to get some control while colonies still had brood. Before first treatment, I marked frames with brood...both sealed and unsealed. After the 3rd treatment, I re-examined the brood frames. I could find no damage. The unsealed brood was sealed, or emerging, the sealed had hatched, and queen was laying in that comb space.


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## irwin harlton (Jan 7, 2005)

*do you know*

what percentage of varroa you killed


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## Michael Palmer (Dec 29, 2006)

irwin harlton said:


> what percentage of varroa you killed


Not enough. I did alcohol wash on the test colonies, and got % infestation. 25 mites on 250 bees would be 10% infestation, etc. 1 week after third treatment, the % infestation was the same, or just slightly less. 

I've never done sugar dusting to kill phoretic mites. I know it works, but how many weekly treatments are necessary to achieve desired results? I thought that OA vaporization would work the same way. Kill off the phoretic mites. Hatching mites ride on bees for a number of days, before re-entering cells to breed. Either once every 7 days isn't often enough, I didn't treat enough times, or OA vapor didn't kill the phoretic mites.

I read the studies, and I know that it's claimed to work. I didn't have much success. I know OA is supposed to be used when colonies are broodless. I re-Vaporized all my colonies in November of that year. Most should have been broodless by then, or nearly so. Early the following summer I was seeing high mite loads again. For whatever reason, OA wasn't working for me.


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## Dan Williamson (Apr 6, 2004)

Michael... What type of vaporizer were you using?


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## Michael Palmer (Dec 29, 2006)

Dan Williamson said:


> Michael... What type of vaporizer were you using?


Heilyser Technologies, from British Colombia, Canada


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## irwin harlton (Jan 7, 2005)

*you got those oxalic acid resistant mites*

they are originally from Russia, where they used alot of oxalic


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## drobbins (Jun 1, 2005)

irwin,

that's an interesting statement
the general consensus is that mites can't develop resistance to oxalic acid
where did you come up with this piece of information?

Dave


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## tecumseh (Apr 26, 2005)

a couple of questions to michael palmer. at one point you descibe treating three time, what time of years was this application and what was your source of oxalic?


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## MichaelW (Jun 1, 2005)

I don't have the details, but I've heard bee lab reports that they couldn't get OA vapor to work. In the last ABJ I read they discuss how vaporizing OA is bad for your health, not just when you actually vaporize it but also later on if crystals form inside the hive that can later be breathed in when working hives. Add to that the previous reports of kidney trouble in beekeepers that vaporized OA and looks like to me vaporizing OA is not the way to go. The ONLY research I've seen where OA works is the trickling method. Thats supposed to be done a specific way. Check the last few months of the American Bee Journal for more information.

Seems like Beesource is the only place people still recommend vaporizing OA, not that anyone has actually recommended it in this thread.


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## Michael Palmer (Dec 29, 2006)

tecumseh said:


> a couple of questions to michael palmer. at one point you descibe treating three time, what time of years was this application and what was your source of oxalic?


First two weeks of September. I marked frames of brood, did an alcohol wash, and treated the first time. Then treated two more times at 7 day intervals. 7 days later I checked the brood frames I had marked, and did a secong alcohol wash.

This 7 day treatment was recommended by Heinz at Heilyser Technologies...the company that made the vaporizers. I was surprised that the results were so negative. I thought the mite count would be somewhat lower than before treatment. The mite levels my bees had at the time was after two years of OV vaporization in November. There really aren't other beekeepers around me, except an occasional hobbyist with a couple hives. The mites didn't re-infest my colonies, they weren't controlled by the OA.

The Oxalic Acid came from http://www.wintersunchem.com/


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## drobbins (Jun 1, 2005)

This is my 4th spring of keeping bees and my original hive of commercial italians has never been treated with anything but oxalic acid vaporized with the Heilyser unit, I treat each year at Christmas
if it doesn't work then I guess they're thriving without treatment
after breaking them up last year to make some splits they have just come through the winter in a 5 frame medium nuc and they're rockin
I have 8 hives now and most have never had anything but vaporized OA except I did experiment with about half of them last August with some thymol
most are headed toward small cell
mites just don't seem to be a problem at this point
to be honest I must say I've tried to acquire some mite tolerant stock
not recommending anything, just reporting my experience

Dave


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## mobees (Jul 26, 2004)

*Mites*

It seems like the mites are getting harder to kill every year.


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## Kieck (Dec 2, 2005)

> the general consensus is that mites can't develop resistance to oxalic acid -drobbins


I realize it may be a "general" consensus, but that doesn't make it right. I've tried to point out before that such ideas are not based on data, just conjecture that "animals can't avoid mechanical damage."

First, we have no evidence that the "damage" to the mites by OA is "mechanical."

And, secondly, any number of animals have evolved mechanisms to overcome "mechanical" threats.

I've stated it before, and I'll state it again: If the selective pressure is great enough, mites are likely to evolve "resistance" or "tolerance" to oxalic acid.


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## tecumseh (Apr 26, 2005)

thanks for the answers michael... hope you don't mind if I ask a few more???

I am unfamilar with the alcohol wash.... how is this done and what is this suppose to measure?

Why a September treatment? this would seem to be counter intuitive to my way of thinking (but what the heck, I quite typically look at the world up side down and backward anyway).

I suspect (speculate) that given your discription that an untreated control might have provided some important information. Which is to say that the 'untreated' mites could have represent such a significant reservior of mites in the hive that a treatment, at that particular time of year, was doing all it could do to keep the mite numbers level?

Personally I find oxalic vapor (I don't think from what I have read that I would consider oxalic dribbling in the same way) to be one of several tools in combating varroa. at this time I don't wish to randomly toss out any of the few tools that appears to work in some form or fashion.


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## Axtmann (Dec 29, 2002)

*OA resistance*

It’s like someone works on a blast furnace for 40 years, I’m sure he will be resistant to liquid steel (one day). If not maybe his next generation will be.

Rhubarb grows for thousand of years and even today bucks don’t like it because of the high concentration of oxalic acid in there leafs.

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When using OA vapor be sure the hive is totally sealed during treatment and at least for 10 –15 minutes after you removed the vaporizer. 

Check drone brood and see how many Varroa in their cells. With a high amount of mites in closed cells (brood/drone) you can treat with OA 10 times or more and you will still find mites. 
If they’re wild colonies or other beekeepers in you’re 3 km radius bees and drones always bringing mites into the hives.

Treating a hive during summer or fall in an emergency!

As soon as you find bees with deformed wings and/or to many mites in a hive, remove all the brood and treat with OA two times a week apart. 
You can do it even in late August or early September depends on your location. 

In a brood free colony OA vapor kills all Varroa. The Queen starts again and the colony has healthy bees. 
I know you think you must destroy several frames of sealed brood - it is NOT necessary!

Put the brood frames in an empty hive box, brush enough bees from several other colonies in the hive and bring them out of the 3km range. 
As soon as all brood has hatched treat with OA vapor, it kills the mites because they have no place to hide. 

Give this colony a queen cell or if you don’t need more colonies, brush the bees in front of your hives.

I treat my colonies for almost 10 years or even more, with OA as a late fall/winter treatment - end of November or December, when there is no or almost no brood. 

During spring or summer (outside the main honey flow) I used Thymol crystals and now Thymol strips.
I lost no colonies to the mites (Trachea or Varroa) for many years.


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## tecumseh (Apr 26, 2005)

axtmann writes:
Treating a hive during summer or fall in an emergency!

tecumseh ask:
are you suggest this is crisis management at work?

then axtmann writes:
During spring or summer (outside the main honey flow) I used Thymol crystals and now Thymol strips.

tecumseh replies:
isn't the day time temperature requirement for thymol fairly specific and narrow? Could you please add a bit of detail about your use (and history) of using thymol?


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## Michael Palmer (Dec 29, 2006)

tecumseh said:


> thanks for the answers michael... hope you don't mind if I ask a few more???
> 
> I am unfamilar with the alcohol wash.... how is this done and what is this suppose to measure?
> 
> ...


Alcohol wash...From the center of the broodnest, scoop up a third of a cup of bees, and pour them into an empty canning jar. Pour in enough alcohol to cover bees. Cover the jar with cap and lid, and shake...a lot. Phoretic mites will drop off bees, into alcohol. Replace jar lid with one made of 8 mesh screen. Shake out alcohol, through screen, into white bowl. Add more alcohol to jar, re cover with lid, shake, and again shake out through screen. Count the mites. Count the bees. Figure out the % infestation. 10 mites on 100 bees equals 10% infestation.

What does it mean? Depending on the time of year...a low % means your ok, while high might mean treatment is necessary. You would want the spring count to be a very low number. In the fall...say August, you would want to see less than 10%...5% would be better. Alcohol wash is a rough estimate of varroa population in a colony. For reall meaning, you must experiment, and determing your threshold at different times of the year.

I treated in September, because I had high mite load. I wanted to see if 3 weekly treatments would have any effect on the mite population. I fully realize that OA should be administered when the colonies are broodless. I was surprised that there was no effect on the % infestation rate...well not really surprised...maybe dissappointed. I suppose control hives could have yielded some information. And, the fact that the % infestation didn't go up except in a few cases. Perhaps I should have vaporized at 5 day intervals, and for several more times. There's a limit, as you know, to just how much time can be spent per colony. 

I would say this would be like sugar dusting. How many times, and how many days apart, would you have to treat colonies with 10% infestation?


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## tecumseh (Apr 26, 2005)

thanks michael for the detail...

and yep at my age I am very aware of the time/colony limitation.


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