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  • oxalic acid

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General Q&A, Bee chat and only Bee chat please
 #9502  by Liam
 18 Nov 2020, 12:44
So. An update to this for some extra advice if someone can.

Vaporised 4th November, roughly 200 mites dropped from each hive.
Today (18th nov) my numbers are at 20 drop per day. Not sure how long they drop from treatment. P.s the 20 a day is more than I started with lol I presume still dropping from treatment?.

Vape again? Leave until later in the year, maybe around Christmas?. Thoughts? Maybe check again for a week and count drops?.
 #9504  by NigelP
 18 Nov 2020, 13:54
Hi Liam, what many do if vaping when brood is present is to space 3 or 4 vapes at intervals. Mites inside sealed brood cells are not harmed by the vapour, so by vaping at intervals you will hit them after they have emerged. Cells are sealed for around 12 days so spacing at 5 days should (note emphasis on should) get most of them.
I'd definitely vape again ASAP and see what happens.
 #9505  by thewoodgatherer
 18 Nov 2020, 20:27
Well my association has agreed for me to do a video showing a vaping treatment using full PPE and highlighting the safety requirements and risks etc. Also following Api- bioxal instructions( only one vaping allowed per 12 months). I must admit I was not aware of this limitation which is clearly written in the 2018 edition of the instructions. Has anyone noticed a reduction in the queens longevity following multiple treatments.
 #9506  by victor meldrew
 18 Nov 2020, 20:47
I would leave the next treatment until the turn of the year . This abnormal weather has encouraged the Queens to lay and the foragers to forage!
Reports of hives being on the lite side . Keep hefting !
Cheers .
 #9507  by Justabeekeeper
 18 Nov 2020, 22:35
If you vapourise OA 3 times 5 days apart when brood is present you'll have around 70% efficacy. Sounds low but it's comparable to apiguard in field tests.
Depending what method you use to vapourise the OA will effect the efficacy during late winter.
Because the bees are tightly clustered a passive method like the varrox won't penetrate the cluster so most of the varroa won't be exposed to the treatment. A more powerful applicator like the sublimox can disturb the cluster not as much as pulling the frames and removing the brood as some recommended though.
What I have done for years is treat in autumn normally in september when there is a natural brood break and then again in early spring when the temperature is a little warmer and the bees less tightly clustered. There is generally brood present but it does give you an idea of the mite load.
I tend to treat from above using a clear crownboard and eke with a hole in, the dispersal seems to be much better that way than through the entrance.
Any mite that is in a cell is immune to OA vapour, upto 18 hours before the cell is sealed the varroa can hide in the pool of food in the cell.
Ignore the ill informed, leave them to tip tepid acid syrup on their bees in the middle of winter.
 #9508  by AdamD
 19 Nov 2020, 09:14
thewoodgatherer wrote:
18 Nov 2020, 20:27
Well my association has agreed for me to do a video showing a vaping treatment using full PPE and highlighting the safety requirements and risks etc. Also following Api- bioxal instructions( only one vaping allowed per 12 months). I must admit I was not aware of this limitation which is clearly written in the 2018 edition of the instructions. Has anyone noticed a reduction in the queens longevity following multiple treatments.
I was under the impression that dribbling oxalic acid should only be done once (so it must be done with little sealed brood in the hive to be effective) whereas vaporization can be done several times without harm. This seems to be at odds to the leaflet that thewoodgatherer has mentioned.
 #9509  by thewoodgatherer
 19 Nov 2020, 16:30
AdamD wrote:[quote=thewoodgatherer post_id=9505 time=<a href="tel:1605731276" data-original-title="" title="">1605731276</a> user_id=100]
Well my association has agreed for me to do a video showing a vaping treatment using full PPE and highlighting the safety requirements and risks etc. Also following Api- bioxal instructions( only one vaping allowed per 12 months). I must admit I was not aware of this limitation which is clearly written in the 2018 edition of the instructions. Has anyone noticed a reduction in the queens longevity following multiple treatments.
I was under the impression that dribbling oxalic acid should only be done once (so it must be done with little sealed brood in the hive to be effective) whereas vaporization can be done several times without harm. This seems to be at odds to the leaflet that thewoodgatherer has mentioned.[/quote]

Exactly my understanding and I made this known at a zoom meeting only to be shot down in flames and then have the instruction leaflet posted on Facebook to prove me wrong, with the section clearly stating to be used only once per year when vaporising highlighted. I would post a copy here but I don’t know how to.
Like I say I would be interested if anyone has noticed increased queen mortality. I have certainly not noticed increased worker mortality even having vaped 6 or 7 times, but I did have some early supercedures this year of young queens too.
 #9510  by Spike
 19 Nov 2020, 20:02
The impression I have is that vaping is pretty safe for bees better than dribbling..
 #9511  by Patrick
 19 Nov 2020, 22:20
Just to reassure those intending to trickle treat who are concerned they might be doing their bees an unintended disservice, I have used trickled OA for many years without any queen or colony loss clearly attributable to it. Combined with a rotated summer treatment, varroa is pretty much a non-issue year on year.

Is OA vaping “better” in percentage kills in published research studies? Apparently. Are those research results always replicable in hobbyist practical experience ? Apparently not. Well, I’ll go the foot of our stairs..

I am sure to try vaping at some point and will ask advice from others on here when I do. But trickling seems to work okay as well.
 #9527  by nealh
 24 Nov 2020, 19:33
The api-bioxal recs for one treatment only is based on the dribbling technique, bees will ingest some of the sugar solution and so the Queen may also ingest. The effect could kill her as it may do her work force.
One could simply use Oxalic as a hive/wood cleanser for which it is meant for.