Oxalic acid vaporiser and open mesh floor

is it possible to use an Oxalic acid vaporiser with an open mesh floor? Has anyone any experience of using a vaporiser at all?

ValMc said:

is it possible to use an Oxalic acid vaporiser with an open mesh floor? Has anyone any experience of using a vaporiser at all?

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Yes, you need to seal the hive up as completely as possible for effective treatment, and close off mesh floors.

ValMc said:

is it possible to use an Oxalic acid vaporiser with an open mesh floor? Has anyone any experience of using a vaporiser at all?

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You can download the instructions for the process from the Varrox web site then assess whether it is for you.
http://www.biovet.ch/en/Imkerei/varrox-vaporizer.html

I use it and like the speed and ease of use. Just a couple of warnings. Oxalic acid fumes are dangerous, so use some common sense and protective gear.
The fumes can also condense on the mesh floor if you place the Varrox UNDER the mesh as I do so the bees have less chance of being 'fried'. (I made a 'special' varroa type tray) So you may be better replacing the std varroa floor with stainless steel mash (supplied by the "mesh company") as the acid will not initiate corrosion on stainless as it will on 'zintex' standard mesh.
Hope this makes sense.

Personally, Oxalic acid will never go anywhere near my hives ever again.

I vapourise and find it very good. I also put it under the meshfloor and let the smoke waft its way up into the hive. I seal off the entrance and the back of the hive (under the mesh floor where I slide the vapourizer in) with rags. A simple procedure.

Hachi said:

Personally, Oxalic acid will never go anywhere near my hives ever again.

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@Hachi. Why?

Jimy Dee said:

I vapourise and find it very good.

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Likewise, very quick and effective, gentle on the bees, and costs next to nothing once the necessary equipment is acquired, just have a 6mm hole drilled in the side of the floors for administering the treatment, which takes 25 seconds per colony.

Hivemaker. said:

Likewise, very quick and effective, gentle on the bees, and costs next to nothing once the necessary equipment is acquired, just have a 6mm hole drilled in the side of the floors for administering the treatment, which takes 25 seconds per colony.

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Is that a solid floor, and do you use the Sublimox?

Hawklord said:

Is that a solid floor, and do you use the Sublimox?

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Yes, few mesh floors, but most are solid floors, and yes it is a Sublimox i use.

ValMc said:

is it possible to use an Oxalic acid vaporiser with an open mesh floor? Has anyone any experience of using a vaporiser at all?

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Make sure your open mesh floors are not made of plastic, it melts.
However if a Varox vaporiser is used ( the safest option) it can be placed under a plastic open mesh floor providing a space is left above it, not noticed any sublimation on plastic or metal floors.
I have even used the Varox system on P*&NS poly nucs with the small metal open mesh floors quite successfully.

Plastic mesh floors, an experiment a few years back, when varroa first hit our area ( and we got it first in Torbay!) Who on Earth discovered the effect of OA on varroa?


James

James do you block off your open mess floors before using the vaporiser and if so how do you do it? I emailed one distributor of the product and they said that you should not use it with an open mesh floor at all as the vapour will escape and therefore not be effective.

ValMc said:

James do you block off your open mess floors before using the vaporiser and if so how do you do it? I emailed one distributor of the product and they said that you should not use it with an open mesh floor at all as the vapour will escape and therefore not be effective.

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I am just a humble novice but from what I read here the simple solution could be lifting brood boxes off the OMF onto a solid piece of board, do the 25 second treatment and leave for as long as needed. then move back onto OMF...

thenovice said:

I am just a humble novice but from what I read here the simple solution could be lifting brood boxes off the OMF onto a solid piece of board, do the 25 second treatment and leave for as long as needed. then move back onto OMF...

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Probably simpler still (for dealing with the bees) to bodily lift floor and all and slip in a solid "underfloor" with the vaporiser.
You'd have the effect of vaporising through the mesh, but with a sealed bottom without disturbing the bees by cracking off their floor.

Of course, for those with standardised floors one could make a plywood "inspection tray" (with draught excluder seals) and fasten the vaporiser to it. Then its simply slipping that tray (instead of the naked vaporiser) into each hive.

ValMc said:

James do you block off your open mess floors before using the vaporiser and if so how do you do it?...

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A correx/plastic inspection slide under the open mesh is fine as long as it's in good condition.

The "Varrox" type electrically heats a small cup which is inserted into the hive. The cup reaches over 200C but that's fine sitting on an open galvanised or stainless mesh floor for the two minutes at full heat and ten to cool. The idea is to distribute sublimated oxalic throughout the hive and that relies on convection currents, you should see vapour emerging from minute gaps between boxes and under crown boards. Vaporising directly under the mesh risks interrupting the convection and oxalic condensing on the mesh, reducing the effective dose. It's not the cost that's a problem, it's that you don't know all the oxalic has got through the mesh and is circulating effectively in the hive. As long as the plastic varroa slide has no obvious gaps or tears and isn't touching the mesh that's an obvious way to close the air flow through the base, use gaffer tape or foam strip to block at the back between slide and floor. The stem of the Varrox type can be a little too deep to sit comfortably under the usual gap in a National entrance block, either replace the whole entrance block with a foam strip or be ready to block any gaps that result with damp kitchen roll or similar.

You want minimal disturbance so the bees settle again as quickly as possible. It's probably 5-10C outside if you vaporise in winter, moving the hive just prolongs the time they are disturbed.

alanf said:

~~~~~~~~~~The "Varrox" type electrically heats a small cup which is inserted into the hive. " Vaporising directly under the mesh risks interrupting the convection and oxalic condensing on the mesh, reducing the effective dose.~~~~~~~~~~~~
.

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Prof Ratnieks and his Phd student Hassan said at the last LASI Workshops that the mortality of bees was much higher if the varrox was above the mesh and that there was no difference in Mite kill at 97% if the varrox was put below the mesh, so long as the back and front of the hive were sealed

I am thinking of cutting a board the same shape as the correx board out of hardboard and inserting that in the slots and using foam strips to seal (thats if i can borrow a varrox LOL)

MuswellMetro said:

Prof Ratnieks and his Phd student Hassan said at the last LASI Workshops that the mortality of bees was much higher if the varrox was above the mesh and that there was no difference in Mite kill at 97% if the varrox was put below the mesh, so long as the back and front of the hive were sealed

I am thinking of cutting a board the same shape as the correx board out of hardboard and inserting that in the slots and using foam strips to seal (thats if i can borrow a varrox LOL)

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Agree entirely. Basically if there are 'fumes' seeping out of the hive then it is doing it's job provided you have sealed off the entrance block and 'sealed 'the OMF (I just put a similar board to a varroa board but layered with Aluminium sheet to stand the heat) then stuff anything to 'plug' any obvious holes. (See instructions that come with the Varrox)
It is natural to see small amounts of fumes escaping usually around the 'plug' around the Varrox 'handle'. ( Hence the need for a mask and to keep your distance whilst operating the appliance). This loss due to seepage is of no consequence as the dose will be enough. It therefore also goes for the little that condenses on the mesh floor if you sublimate from under it.

YES
We do seal off the hive, but once the OA fumes are seen to be permeating up and out of the hive lid, then the base cover ( Correx or ply) is replaced.
I generally leave on for a day or so as I like to see the little bugs toes up on the tray.
Then the tray comes out for the winter.

Also very effective on fresh swarms, if you get any up country?



James

MuswellMetro said:

Prof Ratnieks and his Phd student Hassan said at the last LASI Workshops that the mortality of bees was much higher if the varrox was above the mesh and that there was no difference in Mite kill at 97% if the varrox was put below the mesh, so long as the back and front of the hive were sealed

I am thinking of cutting a board the same shape as the correx board out of hardboard and inserting that in the slots and using foam strips to seal (thats if i can borrow a varrox LOL)

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I'd be interested in seeing the numbers. All the Varrox instructions and videos make no mention of anything other than in through the entrance above the floor, similarly the Canadian Heilyser and other makes mentioned around the web. I can't see how passing the vapour through a cold mesh won't affect the amount and distribution in the hive. It could be that a smaller or cooler dose is still effective of course, but should that lead to reducing the total dose rather than giving a partial dose through an obstruction?

alanf said:

I'd be interested in seeing the numbers.

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Likewise... and i actually prefer doing oxalic sublimation into the top of the hive, the vapour appears to permeate/ sink/fall, down through the hive better than it rises up through.

The problems is that it is a Phd student research project so they are very careful not to release too many facts

they have tested a control against three weights of oxalic dihydrate 2g, 3,25g and 4g in balanced hives and sampled varroa on 200 bees before and after, this was compared to oxalic in sugar solution applied by spray and by dribble insimilar balanced hives

the gave the % mite kills, but on worker bee losses and Queen losses!! i cannot remmeber whether they said how these were calculated