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How to torch your hive with an oxalic acid vaporizer

At first I thought this story was unusual. Debbie, a newer beekeeper who reported the incident to me, explained that she accompanied a seasoned beekeeper to his apiary to learn about applying oxalic acid with a vaporizer.

Here is her story, edited for brevity:

The one hive caught fire. It was hectic trying to get the boxes apart and watering the hive down to stop the flames.  The flames were shooting out everywhere. I don’t know if the bees will be able to recover or not.  He would not permit me to clean up the hive; he just put the hive back together, dead bees and all, and said the bees will fix the hive.

This is not how I do things, and I probably will not go with this person ever again.  It was disturbing to me.  If it was my hive, I would have cleaned it out, checked [to see] if the queen was still alive, etc. [I would] not just shut it up and leave the bees devastated as they were.

What else I didn’t like is…the bees continued to “attack” this poker and thus burn themselves up.…When you take the poker out, there are several bees on the end of the poker burnt to a crisp.

We did 35 hives and all did the same thing.  Some ran out of the hive so fast, it wasn’t even funny. [The bees] actually “attack” the rod [when] it’s hot, touch it, and the end just burns them up. I even asked the guy about why he thought the bees would attack something so hot.

The vapors will knock you out. The one guy I went with got a good whiff, and I had to catch him; he almost fell over.  I think one is supposed to wear a respirator, as breathing in these fumes causes one to cough and gag, and inside it probably does more harm to the lungs.  I tried to watch the way the wind was blowing and then stand on the other side.

Solutions to torching and scorching

Based on Debbie’s comments, I did a web search and learned that torching a hive with a vaporizer is not uncommon. In addition, many who don’t actually ignite the hive manage to scorch the frames and burn some bees. It seems that burr comb hanging down below the frames is the main problem. Such wax is easily lit by the hot metal vaporizer and explodes into flame.

Beekeepers have devised a number of solutions to these problems:

    • Some have found that using a slatted rack below the brood boxes increases the distance from the lower frames and accumulated burr combs, thus reducing the fire hazard.
    • Other beekeepers put a narrow three-inch shim on the top of the hive that contains an opening large enough to accept the vaporizer. This reduces the fire danger because there is no wax comb above the hot plate.
    • Some people wrap the sides and bottom of the vaporizer with aluminum foil, a system that dissipates heat and keeps the hottest parts away from flammable objects.
    • Some simply clear the burr comb away from the insertion area with an extra long hive tool.

My sexist remark for the day is this:  I know that a man—a male human—invented the vaporizer. It is so man-like to want big, powerful, macho equipment to do a wee little job. More power. More complexity. More hazards. Yay! One guy told me, “Some catch fire. So what? It is what it is.”

Whatever happened to the dribble method?

I learned to dribble oxalic acid from Randy Oliver’s website. Before my first application, I stalled around forever, obsessing over how to do it properly. Then I saw the video of Margaret Cowley of Bee Craft Magazine applying an oxalic acid dribble to her bees. She made it so drop-dead simple that all my hesitation disappeared. And it truly is as easy as it looks.

With the dribble method, there is no fire danger, no expensive equipment, no batteries to haul around, and no respirator needed. It is fast, dirt cheap, and it works. The biggest drawback, apparently, is that it doesn’t look very macho.

The vapor method works because the vapor condenses on the bees. The dribble method works because bees communicate and groom by touching each other. They quickly spread the stuff around the hive.

Endless discussion has centered around which is better, which is safer for the bees, which kills more mites, and on and on. You can find research and arguments to support either side. The latest research I read suggests that vapor may be slightly more efficacious. But my opinion is the slight benefit is offset by the many negatives.

Winter application of oxalic acid

One common argument for vapor is that you want to apply oxalic acid when little or no brood is present. That means you need to apply it in the dead of winter when it’s too cold to open the hives. But with a few exceptions for particularly cold places, I don’t see much problem with opening a hive for a couple of minutes in winter.

The main danger with opening a hive in winter is chilling the brood. But the whole point of applying oxalic acid in winter is to use the broodless window to kill the most mites. So with no brood in the hive to start with, a couple minutes of open time will not hurt anything. In addition, those of you with infrared imagers can apply oxalic especially fast because you know where the colony is before you open the hive.

Vaporizers are the current “bee thing”

Oxalic acid is an inexpensive organic acid used for mite control. © Rusty Burlew.

I completely understand that some of you are not concerned with toasting a few bees. I get that. But setting a hive ablaze should be a financial concern, if nothing else. Additionally, using a vaporizer in areas of extreme drought sounds foolhardy at best.

My personal dislike of vaporizers has more to do with the accumulation of stuff. I try to “travel light” and I resist purchasing specialty equipment when I can do the job with the tools I have. But regardless of your personal preference, I offer Debbie’s story as a warning about the things that can go wrong. Bottom line: If you vaporize, do it with care.

More on the dribble method

For more on the dribble method see “How to apply an oxalic acid dribble.” For Margaret Cowley’s video, see “Oxalic acid trickling.” Another good demonstration video can be found on Emily Scott’s blog, “Drizzling oxalic acid on bees.”

Honey Bee Suite



I made a bottom board that is screened and has a gap at the front so I can easily treat a bee free area and the vapors will rise through the screen.



Now that makes sense. Good work.

Tom Nolan

I have done the dribble method and it works fine. I now use the Varrox vaporizer. I use double brood boxes and the bees tend to cluster between the two boxes. When I separate the boxes to do the dribble method I break the cluster and this is why I prefer the vaporizer. I am in Ontario Canada where the temps can be cool in the fall. I do not have to separate the boxes with the vaporizer. I use great care with the Varrox vaporizer (which is not cheap). I also use a mask and gloves. I have seen a lot of homemade vaporizers on the web and I wonder how safe most of them are?
Thanks for another great article. A good reminder to use caution with the vaporizer.

Markus Buchner

Hey there,

I just wanted to answer on Tom Nolan’s comment about the Varrox vaporizer. It has been developed by Mellifera e.V., a German organisation researching and developing methods for organic beekeeping:

Varrox has been tested with over 1500 colonies with great success:

Ironically this method is not approved by German laws, so German beekeepers take their bees regularly onto journeys to Austria and Switzerland.

Because oxalic acid does not affect capped brood, beekeepers treat their bees 3 to 5 times in two weeks, so that one brood cycle is covered completely to catch every mite.

Maybe you find this information useful,

all the best,



I have never used one and I am not an organic beekeeper but I still have trouble getting past something called an “Oxalic Acid Vaporizer”.


This is what happened to me Rusty. Last year I vaporized one of my hives and when I saw the vapor looked a little heavy, open the hives to flames engulfing my hive. Heartbroken, I put it back together in form of a nuc and the next day looked for the queen. Didn’t find her so I went and bought one. The hive still didn’t survive. The actual acid holder container actually was burned off. So I bought a more expensive one and put on a slatted rack. So far, no problems. It seems Rusty with everything there is a risk of killing the queen or the bee’s absconding. But your article is food for thought.

Don Coventry

Some problems and solutions with oxalic acid treatment.
Here in the coastal pacific northwest, bees rarely go brood-less in the winter. The last time was December 2012. My hives had between 2 and 5 seams of brood at the end of last November.
When brood-less, oxalic acid dribble or vaporization appears to give close to a 100% knockdown. Once vaporized oxalic acid immediately condenses into its anhydrous form, and the dust coats everything in the hive. In its dihydrate form, oxalic acid does not damage mites unless ingested by the bees.

I use vaporization because it does not appear to damage bees at all, unlike forcing them to ingest the acid dribble. I also use an external vaporizer and re-circulation system to apply the dust, in order to avoid the heating and fire problem.

My main concern with vaporization is not breathing the vapor (only a mad bee keeper would not wear protection) but the long term effect on the eyes. I see very few people wearing properly fitting goggles when handling acidic vapors.

I am currently experimenting with caging the queen for two weeks and then treating a week later. If it works, it will be an inexpensive and effective late summer treatment. I would love to hear from people who have tried it.

Ashley King

I’d love to know how your experiments went. I’m currently doing the same thing. She’s been caged for 15 days and I plan to release her in 3 days and treat after 6 days.

Ann Chilcott, Scottish Expert Beemaster

Greetings from Scotland,

If you look at the recent work of Prof Francis Ratnieks, et al, you will see that sublimating oxalic acid during broodless (if possible) periods is more efficient than the trickling method and is less harmful to the bees. Also less invasive.

I have been sublimating for several years and place the evaporator under mesh floor on the outside as I have burnt frames in the past myself. Of course the acid is corrosive so I wear an appropriate gas mask. (not cheap, but anyone who is careless with chemicals is bonkers). I hope that this helps. Prof Ratnieks is based at Sussex University, UK and is speaking, alongside your very own Prof Seeley, at our Scottish Convention on Sept 10th in Elgin. There are still places so why not come along and join us for our tartan weekend. See Scottish Beekeepers Association website for details.

Best wishes


Have you ever actually used vapor?


No. As I stated in the article, I use the dribble method largely because I do not want to allocate money or storage space to the vaporizer, battery, and respirator. The expense of other mite control products is the main reason I switched to the oxalic dribble. But I’m repeating myself here.

I should mention I have accompanied others who were vaporizing, which further convinced me to stay with the dribble system.

Peg Davis

Hi Rusty:

I have a method that seems to work for me. All of my hives have screened bottom boards. I take the trays out below the screens. I have made a tray out of a cheap metal cooking pan but any flat aluminum surface or foil will do. I put the tray in below the screen, close off the front entrance, and put the vaporizer on the tray below the screen from the back. I block the sides with rags and then vaporize. As for staying away from the fumes, I have a very long extension cord which I can switch on from the basement or the honey house.

Hopefully this might be helpful for someone else.




A creative idea and a nice way to solve several different problems. Thanks!

Sue Vaughan

I have been trying to find a good option for treating for varroa when using top bar hives. I live in the east of England and the winters lately have been mild enough for the queens to keep on laying, so being brood free at the winter solstice is not guaranteed. I have not convinced myself that breaking open the propolised bars is less harmful than leaving the bees untreated but have been trying to find out more about vaporising the oxalic acid and hence not needing to break open the colony.

How do you treat your top bar colonies, Rusty?

Thank you for your excellent site, I’m delighted to have found it.
How do you treat your top bar hive?



Lately I’ve been using oxalic acid dribbled between the top bars. I have to take out a bar or two from the end, space the bars a little (which requires breaking the propolis seal) and dribbling between the bars. I have never considered breaking propolis seals an issue. Even in the dead of winter they reseal due to heat from the colony.


Don Coventry,

An alternative to your method would be to take two hives and give capped brood to one of them and open brood to the other. Treat the open brood hive and let it be a receiver of all new brood from the capped brood hive for the next couple of weeks.. Eventually all capped brood will emerge and you can treat this hive too. Now take some capped brood from the first treated hive to help equalize the populations. Summer bees die so fast, you really loose quite a bit of hive strength by caging the queen. Thoughts?

David S

Being a particularly non macho individual, I have found vaporising the most effective treatment I’ve used. It’s simple, less intrusive and quick. I’ve watched bees hovering in the vapour issuing from the entrance without any signs of distress. The knockdown effect is remarkable and the system is perfectly safe if the instrument is inserted beneath the ventilated floor, resting on a wooden board or similar. I don’t think machismo has anything to do with it, but then I don’t light my smoker with a blow lamp either.

AJ Simm

You need to be careful when you use this stuff that you are not overheating it. It is suppose to vaporize and not burn. It will react with the oxygen in the air and start burning if you get it too hot. You should do a cold test outside of the hive to see how long your vaporizer takes to finish off a dose w/o burning, and then always use that time or less to do your treatments. All vaporizers perform differently, so it’s important to test your own equipment/battery/setup.



Excellent points. Thank you for sharing good information. I hope everyone tests their equipment before they start. It could save both bees and woodenware.


Does anyone in the states sell those oxalic acid containers with the treatment pre-mixed as shown in the videos?



I haven’t seen them, but you’d think they’d be available somewhere.


Regarding your sexist comment that the OA vaporizer had to be
designed by a man. I couldn’t help but think the same about leaving a burning smoker on a wood table. “Must have been a woman.”


Touché, Chris! This round goes to you! Very funny.


I am a 2nd year beekeeper in canada, an my first year i used the dribbling method with good success. Both of my hives wintered extremely well. My problem with the dribbling method is that, because it can only be done once, one has to wait for the bees to be bloodless. That delays treatment untill very late fall or early winter. Everything i read says we should be treating in mid/ late August. Because the vaporizer can be used consecutively, it allows us to treat much earlier. That makes for stronger bees going into winter, rather than weakening our winter bees.

I hav not used a vaporizer, but have been considering it. Thoughts? Is it that bad to treat winter bees? I did last year and they came through great, but we had an easy winter here.



Like many other beekeepers, I believe the best practice is to alternate treatments. I recommend ApiLife Var (thymol) in August and oxalic acid in winter.



After reading the story I can’t help but think these people did not properly research prior to using the vaporizer and possibly used a homemade version. Based on the description they did not block off the entrances with rag, If that is true then they were not performing the treatment correctly. I just started using sublimination. I bought my kit from mannlake. It came with very clear instructions plus a organic vapor protection mask. To say they had to catch someone falling over due to breathing the vapors and that maybe they need some sort of mask? I have to wonder if they were using 100% oxalic acid and not some other crystals? Unfortunately that story is full of mishapps that could have been avoided with proper instructions.

On the dribble method an earlier poster spoke of forcing the bees to eat the acid in sugar water. This is incorrect according to what I have come to understand. The sugar is to make it sticky so the mixture is drug around by the bees as they walk around the hive. Then when the mites emerge they get the crystals on them and they die. Is that not correct?

I like the vaporizer since it can be used in temps down to 34 degrees according to Dr. Marion Ellis if I am recalling his power point presentation correctly. The original person who had all the issues would benefit from watching the video.

Do you have a write up on the dribble method, how it works and how to do it or do you refer people to Randy Oliver’s site?

I found this blog entry when I searched for “vaporized oxalic acid not working ” this story is the closest I could find to people having issues.

Thanks – love your blog – lots of great info.



I’m a 2nd year beekeeper in the Pacific Northwest. In November, I started the oxalic acid vapor treatment; 3 treatments for 3 hives, once ever 7 days. I am using a self timer vaporizer. I use a 12 vdc car battery with a plastic carrying handle. I go out early, plug up the top brood box entrances with wine corks. I have my bee veil on and wear disposable nitrile gloves. The vaporizer has a very long cord. I hook up the battery. I remove the mouse guard. I have screened bottom boards and the slotted spacer board above it. I place the measured spoon amount of crystals in the vaporizer “cup” and push the rod as far as it goes in, then tuck an old bath towel strip around it to seal the bees entrance. I take another towel strip and plug up the sticky board entrance. I also put in a sticky board when I vaporize. Okay, now I turn the toggle switch to on and go sit in a chair next to the battery, about 10-12′ away. The timer light goes out about in 5 minutes. I wait another 5 minutes, before going back to the hive and removing the vaporizer and towel strips and cork plug before moving on to the next hive. I don’t use respirators which I have, but I am very careful and watchful of the entire process. First mite counts in 24 hours after treatment with 3 hives respectively each week was: 1st 7,8, 32. 2nd 33,72, 74. 3rd 21, 39, 122! I didn’t have any dead bees except for the normal 3 or 4. My problem is wasps, trying to raid the hives. I’m going to vaporize treat again as I don’t like the mite counts at all. Perhaps this is why I had an almost nil honey super production this year.

Richard Caton

We have some nice weather here in Minnesota so I went out to check on the girls and put on some more winter patties. Two hives were dead outs so I brought them in the garage to clean them up and I also wanted to check the frames after using the vaporizer. The wood was charred black on the frames that were over the vaporizer. Time to go online and do some research. These are very good articles, very informative. Last fall was my first time using the vaporizer and it is a learning experience. First I ran a test outside the hive for the 2 1/2 minutes as suggested and it vaporized all the xtls. No problem. However after doing 5 hives the battery starts to lose its punch and the time has to be slightly increased to vaporize all the xtls. I use a screened bottom board on top of a regular bottom board for ventilation and to monitor the hive. The method mentioned here for putting the vaporizer under the screened bottom board is excellent and should prevent fires and still be effective. Thank all of you very much for the help.



I’m glad you found it helpful. I’m also happy to hear you didn’t start a fire!

Braden Bills

I have some apiaries that I want to take care of. I didn’t know that unprofessional application of oxalic acid vaporizer could be such a big problem! I don’t want to risk lighting anything on fire, so I’ll be extra careful with it.


Interesting article but am afraid I cannot agree with using a ‘dribble’ method, I know tooo many people who have lost Qs.
I use a converted roof to vapourise … … you can see if the OA has vapourised and no wax to light up.



I’ve been using the dribble method for several years with no ill effects. If you follow the directions, it works easily and safely.

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