I wanted to share these papers by Rusty Berlew with you all. (Nothing like a little Holiday Reading on treatment efficacy)
Pages 45-47 especially pertinent about mite treatments, but a full read recommended
And also: Controlling mites with Essential Oils and Organic Acids
Much as I love Rustyâs thoughts and writing, I am going to have to check the reference for this statement:
In both 3-day old and 5-day old larvae, cell death occurred in 25% of the mid-gut epithelial cells after five hours of treatment with oxalic acid
Five hours of treatment? Wow. The approved vaporizing method has never taken more than 5 minutes in my hands. I canât imagine topping up the iron, or rotating several through the hive for 5 hours! That must put hundreds of grams of the stuff into the hive.
OK, I just read the article. They made a 6.5% solution of OA, and sprayed it directly onto the larvae. They say each larva was given 0.121mg of solution, but it looks like they actually meant 0.121 mg of OA in the solution. That would be about 2 microlitres of the solution they made up. If they mean solution and not OA, that would be about 0.006mg of OA. I donât know how they could put that little solution accurately onto the larvae. Even 2 microlitres is tough to handle! 
If I put 1 gram of OA into my vaporizer, and put that into a single brood box with 8 full frames, it is vaporized over 8 x 7,000 comb cells = 56,000 cells. Assuming it distributes evenly, which is a little unlikely, but I try, each cell would get a dose of 0.018mg. That is only 15% or a little more than one seventh of the amount that the researchers found to be toxic.
I agree we need to be aware, but open-minded too. I routinely visit my hives the day after treatment, and I have never seen bees throwing out young, dead larvae. Maybe there is a difference in exposure to dissolved versus vaporized OA. My guess is that they were trying to reproduce the kind of dosing that would come from an OA trickle.
As far as formic acid toxicity goes, I totally accept that. I have heard numerous accounts of hives doing poorly and queens dying, particularly when it was used on a hot day.
I am still going to treat with OA vapor though. Either that, or my bees will die from DWV - they get symptoms every year. 
While we are on this topic, The Bee Informed Partnership sent me a funky behavioral research survey, if anyone wants to do it. It is anonymous, so you can be honest. Odd questions, and some are hard to answer accurately, but I guess that is the nature of behavioral studies:
Dear beekeeper,
Thanks for participating in past BIP surveys.
In past survey efforts you let us know if we could contact you if we had other surveys. Well we do!
_We would like to encourage you to complete a short survey developed by collaborators from University of Liege in Belgium. The objective of their study is to better understand beekeepersâ perception of risk regarding Varroa, pesticides, and other factors. The survey also strives to understand how beekeepers make decisions when it comes to adopting or not adopting certain management practices. _
The results will help BIP as it will help us encourage best management practices adoption in US. By taking this survey, you would also support a young scientistâs PhD project!
If you are willing to participate in this survey, please follow this link: http://limesurvey.aesa-epid.be/index.php/677317?lang=en
The survey is composed on 19 questions and takes approximately 15 minutes to fill.
Please donât hesitate to share this email invitation with other beekeepers.
Thank you for your contribution to research and bee health!
_ Happy New Year, from all of us at the very merry team of BIP_
Hi Dawn,
Iâm glad you are reading with a critical eye, as I wondered about some of her results as well-though I do not have have any fumigation experience to compare, in accordance with our natural Beekeeping practices (and lack of mites).
A few years ago, we were given a small swarm of bees with DWV and we euthanized the whole lot of them, rather than leaving them to suffer and infect our bees and any others in the vincinty 
I do agree with Rustyâs final thought:
I am happy to try as many different weapons as possible, within reason. I am in such an urban area though, with many colonies around me infested with Varroa, I canât ever imagine being able to go treatment-free in this region. I agree with what @Dee said in the past; she admires those who do it right, and destroy colonies which will infest others, but that is a tiny minority of beekeepers. I do have VSH bees. They get heavy varroa and show significant signs of DWV if I try not to treat. I have tried leaving the SBB open, but ants and SHB are a constant worry here. My comb is not mostly not natural (either Flow frames or foundation), and I am not using small cell. I might try those one day, but I donât believe that will keep my colonies free of DWV signs in this environment, unfortunately.
I am just doing the best I can in the environment I inhabit, and I will keep an open mind as new options become available. 
MY JB700 OA blower treats a hive in 20 seconds, not 5 hours.
Drinking too much water can be harmful as well: https://en.wikipedia.org/wiki/Water_intoxication
I understand that only uses 0.5g of OA for a double brood box, too. Where did you get it, @Anon?
I donât see it for sale anymore but I got it from Heilyser Technology.
That was why I asked. 
I wondered if they had sold the design to somebody else. It would be interesting to know why they went back to a standard vaporizer concept.
I have one of these
20 seconds is about right. Brilliant machine.
Mine is a Varrox. Takes 5 mins for 2 grams to vaporize in a 2 deep hive. But it works with a jump starter, and I donât have access to 240V easily in the US. 
It drains the jump starter by 8-10% per dose, which works out fine for me. 
I suppose this would be the US equivalent, but I canât get mains power to one of my hives, so I will stick with what I have:
I use an inverter as I donât have power at the apiary.
Leisure battery and inverter and Iâm good to go.
Whatâs US voltage?
110V and 60Hz, which doesnât matter for this, but it does matter for record players
Ah I see.
I seemed to remember it was something different when I was in New York. Some time ago.
I fancy another visit across the pond but not USA. Iâm Looking at Apimondia in Montreal as a jumping off point for some whale watching. 
that will be 2019 though.
The US has always used 110V for normal mains power. It is because Americans canât be trusted with higher voltages for normal plug-in appliances. 
The problem with that is that that power cables need to be much thicker than they are for British 240V appliances in order to carry adequate current. Copper must be sold in large quantities in the US! 
Ovens and washing machines/tumble dryers mostly use 230V, and my Tesla uses 40 Amps at 230V for fast charging or 80 Amps for super fast. 
We had to have an electrical upgrade and a special outlet (socket) installed in the garage at huge cost ($3,000).
I can understand that Dee. How about Philly?
Also about your vaporizer- Iâm assuming this circled part is the vapor end, that sticks into the entrance?
Yes it is. It comes with a handy 2g measured so you tip your oxalic into the white plastic container and holding it upside down you snap it onto the vaporiser. When your ready you tip it the right way up and the oxalic plops into the hot crucible. The vapour comes gushing out.
This is a mate of mine doing his hives. Excuse the musicđ https://m.youtube.com/watch?v=zNVbLYYXP9I
I thought the reasoning behind VHS bees (and Minnesota hygienic) was to not treat, but allow them to evolve greater resistance? Iâve heard that itâs hard to keep resistance due to uncontrollable mating.
Would you ever consider trying a foundationless hive, in combination with a VHS queen? And if you could get some pseudo scorpions to move in too = 
ď¸:ok_hand:t4:
My bees are VSH (Varroa Sensitive Hygiene trait), not VHS (Video Home System)
I think the great hope was to make them less likely to need treatment. However, once you see visible effects of DWV on the bees, the chances of losing the colony if you do not treat is very high. My local mentor says that he has to treat 50% of his VSH colonies every year. I treat mine if the mite count goes above 5 per 100 bees, or I see visible DWV effects. If using their VSH genetics, they can keep the mites below that, or they donât get DWV, I donât treat. It is up to the bees. But I canât afford to keep buying nuclei if I lose a colony, so I am not going to let them die out from lack of treatment.
Thatâs the idea but there are VSH bees and VSH bees. In this country you canât sell VSH bees until they have been proven to be so. If you are selling queens they will therefore have headed a colony for a season so will be a year old. You can sell open mated queens from VSH stock but you canât advertise them as VSH. Thus how many of those sold in the USA are really as described. @Dawn_SD has hit the nail on the head. VSH is a tool. You still need to monitor for mites and treat as appropriate. If you buy VSH bees donât treat, lose them then buy some more what does that tell you ?
