Oxalic Acid Discussion

[LazyBkpr]

Yep, I run two Varrox Vaporizors from my cart. 6 hp engine running a 1 wire alternator and a deep cycle battery. I have two buckets int eh cart, one to carry the OA, the vaporizors etc, and the other is for water. Pull the vaporizor out, dip, fill and slide into the next hive..

[CBT]

I found out the hard way not to use your hive tool to flatten your oxalic acid. Forgot to wash it and it took the chrome off.

[Papakeith]

I'm running one Vaporizer.  the varrox unit suggest quenching the tool in between uses in it's instructions. 
I haven't quite made it to the two vaporizer stage yet, but I'm thinking about it.  It would certainly speed up the process.

I do wonder though.  What is the difference between 1,7,21 treatment schedule and 1,7,14?  Why skip the week?

[Perry]

I do wonder though.  What is the difference between 1,7,21 treatment schedule and 1,7,14?  Why skip the week?

Good question, I was wondering the same thing.

[LazyBkpr]

21 days to emergence. If you treat your hive you would think that the open cells would get treated by the vapor, but there is some controversy about how well the oa crystals penetrate below larvae where the varroa would be hiding..
 so to remove all the variables and insure you get as many as possible the skip method is what was recomended..

       IF.. the vapor can penetrate and kill mites under growing larvae it would not be necessary to treat three times.  Taking the nine day variable out you have a week and five days so you could treat twice. One week apart and get them all....

   In treating twice I had greatly variable mite counts.  YES, the number of mites was dramatically reduced, but I could never seem to get a smooth transitional result  five of ten hives would look GOOD, but the other five still showed elevated mite levels.. not bad enough they needed treated as an emergency measure, but I wanted better results..
   I believe that the reasons for the seeming lack of effect were open cells..  Once I started treating the third time the anomaly vanished completely...

   I have not taken the time to figure out WHEN the varroa enter the cell, at what age the bee larvae/pupae is..   Do the Varroa have a specific date/time?  IE they NEVER enter a cell before 7 days.. so a three step treatment every other week might work?
   OR...
   If the varroa start entering cells at 5 days we should stick with the skip method...   
   What I do know is that it has worked spectacularly enough for me to stick to it, even if changes are recommended..   Grandpa always said...   Boy, if it aint broke dont fix it!

[Lburou]

...If the varroa start entering cells at 5 days we should stick with the skip method...   
   What I do know is that it has worked spectacularly enough for me to stick to it, even if changes are recommended..   Grandpa always said...   Boy, if it ain't broke dont fix it!

Lazy, I'd like to know more about this from a scientific point of view.  I've read assertions of phoretic periods lasting 2, 3, 5 and 7 days.  Does anybody really know?  I hope the phoretic interval is closer to seven days than three.  If not, it is best to have bees practicing broodless periods, and treat then. 

[capt44]

I use the oxalic Acid Vapor treatment.
I treat then wait 10 days and treat again.
I've had terrific results using this method.
Here's a note: I've also noticed that when I remove the cloth from the entrance that a few small hive beetle would run out.
They are horrific here this year.

[Lburou]

...Here's a note: I've also noticed that when I remove the cloth from the entrance that a few small hive beetle would run out.
They are horrific here this year.

Noticed that for the first time about a week ago.  Now, I have a hive tool ready. 

[LazyBkpr]

Some of the research I read was looking at the phoretic phase to see if the mites that stayed on the host longer impacted the breeding cycle of the mite or had a larger impact on the bee/host... But I have not seen anything that says there is a specific "time" (3 days, 7 days etc...) of the phoretic cycle.. meaning how long the mite stays on its host...
   Even if it is only three days, the crystals remain in the hive and on the bees for a few days.
 I have read 5 days to 9 days...

   These crystals are deady to mites. In a heavily infested hive you can expect a drop of over 1000 mites in the first 24hr, but the treatment will remain effective for up to a week and you will see a continued but diminishing drop over the next few days.

    So basically treated twice, one week apart the majority of the mites should be DEAD leaving none to enter the cells that are about to be capped, so the third treatment is to catch the mites that emerge as the next cells open (which had mites under larvae but not yet capped during the first treatment).. killing THEM before they go into the cells that are about to be capped.
 If.. that makes sense to anyone...
   So as far as the Phoretic stage.. I am not sure it makes a difference? Or did I miss interpret the question?

[Lburou]

These crystals are deadly to mites. In a heavily infested hive you can expect a drop of over 1000 mites in the first 24hr, but the treatment will remain effective for up to a week and you will see a continued but diminishing drop over the next few days.

That is very interesting Lazy.  I would like to read more about how long OAV crystals are effective in the hive, can you point me toward a source to read about that? 

[LazyBkpr]

  I have quite a list of "snipets" from different sources.. I try to make sure I get the URL but sometimes I dont.. and I do not have that one.. but do have these..


    The literature says this treatment can remove 90% of varroa mites in a colony.  There will be a big mite fall on the first day and they will continue to fall for about two weeks after treatment.
http://www.talkingwithbees.com/beekeeping-how-to-guides/oxalic-acid-beekeeping

   Mites keep on falling down for 4 weeks at a steady rate before I can see a reduction.
http://www.beeman.se/research/oxalic/oxalic-1-nf.htm

  the two links are not universitys or renowned research centers.. but the following page is one from a sloenian university

   Two days after the August 8, 16 and 23 OA treatments, the mite mortality was estimated
at 68.62 ± 12.29%, 65.31 ± 10.61%, and 33.35 ± 13.99 %, respectively. The mite mortality
between the second and fourth day after each of these treatments was estimated at 18.69 ±
7.43%, 22.98 ± 7.69 %, and 14.06 ± 6.75 %), respectively. Between the 2nd and 9th
days after each  OA  application,  a  highly  significant  (p<  0.001)  reduction  in  mite  mortality  was
observed and between the 9th and 11th days after the August 23 application the reduction in
mite  mortality  was  also  significant  (p<  0.05).  After  September  3,  the  mite  mortality  in
colonies with capped broods was constant at 6.25 ± 1.97% during the five weeks leading up
to October 9 (Fig. 2).

https://actavet.vfu.cz/media/pdf/avb_2004073030385.pdf

   I will have to sit down with a rum and coke and see if I can find it Lee.
   

[Lburou]

Thanks Lazy. 

I found something in Randy Oliver's Oxalic Acid presentation coming from a different direction and estimating the number of mites remaining in a hive after treatment with oxalic acid, (Check out slides #61-65).  Still looking for info about the crystals and how long they are effective at killing mites. 

[rober]

this might be easier to use. you'd likely need a respirator

[neillsayers]

Guess you'd have to time it to get dosaging.

[Lburou]

Ran into an EXCELLENT survey article about the biology & control of varroa destructor.  Lazy, this needs to be on your list.  Download   HERE.

This article is quoted as reporting the average length of varroa's phoretic phase at six days.  Haven't found the reference yet, but will eventually.  If the average time a mite spends on the back of a nurse bee is six days, then we have confirmation for a six day cycle for repeated OAV Rx with active brood nests.

[neillsayers]

Lee,

Thanks for sharing this link. I downloaded it to read later. The six day lifespan brings a question to mind. How to they survive the winter/broodless period. It may be answered in the article-I'll be looking for it.

[rober]

how long do most folks leave the wand type vaporizers in the hive? the timing for this should be similar. the advantage would there there'd be no cool down warm up time, just move to the next hive. you could rig up a tube extension so you could set it while applying. a full face respirator might be needed. once you figured it out you could load up enough acid to do all of the hives at any particular location. another plus is that it's self contained. no cords, jumper cables, batteries, generators, etc.

[Nugget Shooter]

Thank you for the article Lee.....

[Lburou]

Rober, I think that vaporizer bears some investigation.  Try it and let us know how it works 

[CBT]

It's only a matter of time before someone makes a good low budget or do it yourself vaporizer. I have some ideas ready for prototype now.