Oxalic fogging.

[John B]

I have been loath to try new methods of varoa control but conventional treatments are no longer keeping my hives alive so I have been giving fogging a try. I gave the hives four treatments Five days apart in January and three treatments five days apart in March. The first of the March treatments was after recording and only a few days after the new Queens should have been laying. I did a full check on everything today and they looked remarkably healthy and there was only one queenless hive out of 40. I did an alcohol wash on two separate hives which I know isn't much but I hate killing the bees. Zero varoa which is pretty pleasing. I will probably give them another couple of fogs in late April and perhaps one in the middle of winter. I am really interested in what other people are doing with this product and how they are getting on. The treatment is quick to do and extremely cheap but does involve a lot of visits. So far I have not combined other jobs with treatment but I assume it is possible to do so.
Still early days but so far I am really impressed.

 

[tristan]

i read up on it, especially as some people had put good data up on it.
basically it boils down to how much varroa there is and the amount of visits.
the acid doesn't last long in the hive, its all gone by day 4. so it needs a repeat every 4-5 days. i would have to find the paper but someone had to do a huge amount of visits to get high mite levels down. if you do a full main 8 week treatment, thats at least 12 visits.
doing a part treatment mid season you could do less.
it also uses quite a large amount of acid. dry acid is only 1/3 the effectiveness of wet acid.
its best use is during broodless period.

@John B good to see you have done it reasonably well and at least some testing. tho its better to have a before and after test so you know its the treatment thats done the job. i have struck 0 mite hives before.

 

[JohnF]

There's been a bit of research on oxalic (and not just staples):
- one compared vaping oxalic vs trickling and concluded that tricking was superior
https://doi.org/10.1080/00218839.2017.1327937

- another stated that their vaping could not bring down varroa levels below their threshold
Assessing Repeated Oxalic Acid Vaporization in Honey Bee (Hymenoptera: Apidae) Colonies for Control of the Ectoparasitic Mite Varroa destructor

However more recently, Cameron Jack in the USA has been studying the oxalic concentration to use for vaping, suggesting that higher levels than the USA legal limit of 1g are superior (up to 4g per brood box)

https://doi.org/10.1080/00218839.2021.1877447

I agree with Tristan - need to know the levels beforehand. Here in Gisborne my few hives have had remarkably low levels in mid-Feb when treatments went in

 

[southbee]

. I did an alcohol wash on two separate hives which I know isn't much but I hate killing the bees.

We use CO2, this way the bees don't die. It's a bit of set up cost, but cheap to run. Get a co2 bottle and regulator. Then put a cheap plastic hose and a airgun from the hardware store on it, as there's no pressure on it, it's fine. Make yourself a plastic pipe, preferably clear, with a grid 1/3 of the way up, which will hold the bees but varroa will fall through, then a lid on both ends. Drill a little hole in the bigger end of the pipe, then put the bees in there and give them about 10 sec. of co2 with your airgun through the hole. They'll fall asleep quickly, once they are give them a good shake and then return them to the hive. Count the varroa which fell off on the bottom lid. We found it easy and quick to use and very reliable, we did lots of check tests and it seems to be accurate. I can post a pic of our set up if you like.

 

[southbee]

There's been a bit of research on oxalic (and not just staples):
- one compared vaping oxalic vs trickling and concluded that tricking was superior
https://doi.org/10.1080/00218839.2017.1327937

- another stated that their vaping could not bring down varroa levels below their threshold
Assessing Repeated Oxalic Acid Vaporization in Honey Bee (Hymenoptera: Apidae) Colonies for Control of the Ectoparasitic Mite Varroa destructor

However more recently, Cameron Jack in the USA has been studying the oxalic concentration to use for vaping, suggesting that higher levels than the USA legal limit of 1g are superior (up to 4g per brood box)

https://doi.org/10.1080/00218839.2021.1877447

I agree with Tristan - need to know the levels beforehand. Here in Gisborne my few hives have had remarkably low levels in mid-Feb when treatments went in

We've done vapour for a while now as an extra treatment, mainly in the winter. It does seem to work mostly......it keeps the mite numbers down, gets rid of any which escaped the chemical treatment, which is important. It does depend a bit on how it's done and when and the local conditions too, so I think it's best to try in your situation and then work out how to improve it. I also like it for a quick help treatment for any hives with high numbers at any time, it doesn't seem to do any harm to the bees, quite the opposite, they seem to clean out the frames better after a fogging.

 

[tristan]

We use CO2, this way the bees don't die. It's a bit of set up cost, but cheap to run. Get a co2 bottle and regulator. Then put a cheap plastic hose and a airgun from the hardware store on it, as there's no pressure on it, it's fine. Make yourself a plastic pipe, preferably clear, with a grid 1/3 of the way up, which will hold the bees but varroa will fall through, then a lid on both ends. Drill a little hole in the bigger end of the pipe, then put the bees in there and give them about 10 sec. of co2 with your airgun through the hole. They'll fall asleep quickly, once they are give them a good shake and then return them to the hive. Count the varroa which fell off on the bottom lid. We found it easy and quick to use and very reliable, we did lots of check tests and it seems to be accurate. I can post a pic of our set up if you like.

it would be great to see a pic.
i think nz beeswax was trailing a unit that takes disposable co2 cartridges.

but word of caution, make sure its reliable and repeatable. wash out the bees with alcohol to see if any mites where left behind.

 

[southbee]

Will do. I used the cartridges before but they're expensive.....
If you wash out the bees with alcohol they will die again. Do a repeat test on the hive on the same day and see if there's a different result. Like any tool it's got to be used right, i.e. the same amount of bees, from a brood comb.....

 

[tristan]

If you wash out the bees with alcohol they will die again. Do a repeat test on the hive on the same day and see if there's a different result.

not what i meant, tho thats a good way to check for consistency.

the co2 test doesn't get every mite thats on the bee sample. it might only find 50% or 70% depending on how its done (even alcohol wash doesn't get 100%).
if you alcohol wash that sample after the co2 then you see what mites its missed. then you can improve it. otherwise you could be underreporting by a large amount. of course only need to alcohol wash them until you have the test up to a reasonable standard.

 

[southbee]

it would be great to see a pic.
i think nz beeswax was trailing a unit that takes disposable co2 cartridges.

but word of caution, make sure its reliable and repeatable. wash out the bees with alcohol to see if any mites where left behind.

Sorry took a while for the pictures. The co2 bottle set up is home done, the plastic collecting container we got some years back from Swienty, but it would be easy to make one similar. It seems to be very consistent and we find varroa on hives which look ok, no signs of any damage yet.