Oxalic Vapor

[cam bishop]

I only have about 50 hives and my flow is not intense enough to warrant lots of supers on at one time. But I still see it as pretty labor intensive. I'm going to try it in one yard [about 10 hives], MAQS in another and the Mitegone pads in another. I'm hopeful that the Mitegone will handle the mites - will be much less work and cheaper. As I continue to expand with no help, labor will become a big factor. I really don't want to go to shop towels and amitraz.

[Allen Dick]

Take a look at Jean-Pierre Chap[leau's solution. http://www.apinovar.com/research.en.html

It is a good solution here in Canada.

The other option is to reduce the mite loads to near zero by spring.

Up here in Alberta, if the loads are under well under 1% in spring, they do not reach serious levels until the next winter unless there are local invasions or the seasons are longer than ours. Even a few months of extra brood rearing may tip the balance, though, as I am finding with the EPS boxes.

That is why I am workingh on trying to reach low, low levels in fall and winter.

[cam bishop]

Thanks very much for the link. I think the cost of the trays would be prohibitive for me. I also note that he does not recommend the flash treatment for nucs or weak colonies. Also, I wonder if his thresholds, particularly in late summer are not too high. I am also wondering if his fall treatment is too late for really healthy winter bees. I'm a little conflicted about it however. I notice that the hive with DWV has recovered pretty well, has a good cluster and continues to survive. I thought it would collapse by now. And I no longer see any DWV. The paper that I found so compelling completely gives the impression that this hive should be dead now. Of course, winter isn't over and this has been one of the mildest winters on record, so maybe I shouldn't put much stock in it. I'm hoping that my tests this summer will give me some direction. I also wonder about being able to leave the Mitegone pads in the hive in the spring? Since they have ok'd the MAQS with supers on, why couldn't one keep the Mitegone pads in also? Since most of the formic goes to the bottom of the hive, it shouldn't impact the honey. Or am I misguided on this? I like the idea of very low to mite free hives in the winter and early spring. It will be interesting how our hives winter this year. Are you having a warm winter too? it was 56°F here [13.3°C] here today and all hives were flying.

[Allen Dick]

> Also, I wonder if his thresholds, particularly in late summer are not too high.

Good question. I think he has done his homework, though.

The joker in the deck is viruses. I think that without whatever came into my outfit last year, my survival should have been much better as the mites were not all that bad, not in every hive.

Mites vector disease, and the more mites, the worse the spread, both between hives and within a hive.

> I am also wondering if his fall treatment is too late for really healthy winter bees.

Many people think so, but his work proves his case, at least in his situation at that time. Add in any unexpected adverse influence, though and they could be twice too high.

> The paper that I found so compelling completely gives the impression that this hive should be dead now.

Don't forget that most studies speak of averages and probabilites. (That's where mine differs). Although the odds might be against that hive, it might just be the exception, come from behind and win the derby.

Look at hives three, four and six in my study. Who'da guessed they would end up where they are?

> I also wonder about being able to leave the Mitegone pads in the hive in the spring?

Ask Bill Ruzicka at Mitegone.

> I like the idea of very low to mite free hives in the winter and early spring.

That is the whole secret. Hit the mites when they are at their weakest and make them start again from nothing.

> Are you having a warm winter too?

Yes, very warm. The weather trends are on my site daily and on this plot:
http://www.honeybeeworld.com/diary/imag ... opTemp.jpg

[cam bishop]

I found a few mites today. Several were quite a light tan and I would not have seen most of the mites if I had not been using glasses and a lighted magnifier.

Wonder if they're starting to raise a little brood in those EPS boxes. I think I have some hives raising brood right now with this mild winter.

[Allen Dick]

They usually get some brood going about now. If there is any brood in late fall, it is usually minimal, but after the winter solstice, the amount increases. That is why wrapping is not too critical until after Christmas.

Once the brood rearing begins, the colonies make maximum effort to maintain the cluster temperature at 95 degrees +/- 0.5 degree in the centre where the brood is located. Both heat and humidity must be controlled witin tight limits for successful brood rearing. With fewer and older bees, any help they get in conserving and managing heat and humidity is beneficial and can make the difference between survival and prospering, and hive death..

For me to see new mites now, brood would have to have been started about 21 days back in time. That is quite possible. I could check cluster temperatures with my infra-red thermometer, I suppose, but I know this without checking for past experience.

I would like to pull a few frames with brood to check for mites in the brood, but I know that would be destructive and potentially lethal to the colony. I have been pretty rough on these colonies for the sake of 'science' if you can call my blundering 'science', but in spite of that, I actually do want them to survive and be splittable in spring.

It is also possible that some hives did not stop brood rearing, but that I knocked back the mites enough that I was not seeing new mites emerging with the young bees. That has been my only indicator of brood emerging: new mites or immatures, and they would not be seen if there are few or no mother mites left to enter cells.

I don't know how many have visied the drop summary page lately since there is so much to look at and it has been changed repeatedly, but now I have added individual charts to the page and am pretty well at the final version.

Here is the link:
http://www.honeybeeworld.com/diary/files/drop.htm

[cam bishop]

It is now two weeks to the day since I did the last mite drop counts.

How are the hives doing otherwise? All still alive?

[Allen Dick]

Can't tell. I just pulled the boards, but have no reason to think otherwise. Nothing has changed.

Report will follow.

[cam bishop]

Read Randy's observations on Bee-L and your response. I think, for those of us who have followed closely, there is no problem reading the charts. I want to reaffirm how helpful this test has been at least to me, since I've felt for a while that OA vapor was a good mite remedy. I still feel that way, but some reservations have cropped up because of this study. It has been very helpful to find that multiple vaporization's don't seem to harm the bees, in your hives and in mine. I had 100% survival this year with multiple treatments. Lost all my production hives last year with one treatment. I don't believe it was the only factor, but it certainly was part of it. Interestingly I had one of the hive tested in the last year batch by Dave Wick and he found no virus issues and the bee inspector remarked what good hives I had in July when he inspected them. But the hive still died. I wonder if OA vapor has other qualities that we don't see for survival. I would have bet that hive 3 in your test would not survive as I thought that my hive with DWV would also not survive. But both did. It's clear that bees can handle certain loads of varroa, particularly without nosema and virus issues. I've read that DWV is in all hives, so maybe it's not the kiss of death I thought it was.

This test and my experience convinced me to use other methods of mite control. I'm going to put a foundationless frame in every hive this year and cut the drone brood out with each visit. I'm also going to try some of Bill's MiteGone pads this year - just got my formic in. I'm wondering if alternating both might make each more effective.

I still have lots of questions - this varroa thing certainly makes beekeeping different than the '70's - but this study has answered many of them and I am in your debt for your thoroughness and diligence in doing it. i hope you'll keep it up through the early summer, since those results will also be relevant IMO.

Thanks again

[Allen Dick]

Thanks. Are there any improvements that might help?

Different hive configuration? More test hives? Other ideas?

I can see problems tracking the hives coming when I have to work the hives, though, since these are colonies I plan to split at least once and hopefully twice.

Also, the stock may move more towards Saskatraz stock (see http://www.saskatraz.com ) since Meijers ordered 2,000 of Albert's queens and we work together a lot.

[cam bishop]

Thanks. Are there any improvements that might help?

Different hive configuration? More test hives? Other ideas?

I wonder how singles will winter with OA vapor as the primary miticide? I wintered doubles this year, chickened out on the singles but judging how my Carni's consumed stores could have done singles. Again, this was not a normal winter. No ice/snow, no below 0°F temps, so not a great test. Maybe a couple of control hives with other treatments? just to compare.

I think it will be impossible to continue the test when you start splitting. Far too many variables. You have proved so many things in this test that I hope you'll continue it next fall/winter.

[cam bishop]

Just finished working my production hives today. I pulled considerable drone brood from each hive. Saw one mature mite and 2 tan mites [which I don't think would have matured]. This out of probably 100+ drone brood. So I'm pretty happy with my OA vapor today.

[Allen Dick]

That is encouraging. We need a reliable method of varroa control which does not involve using chemicals which are not food ingredients. Oxalic acid is found commonly in safe foods ans does not carry a risk to food quality or safety in the amounts beekeepers use.

The main drawback for OA vapour is that the application methods are clumsy at present and also that applications must be repeated if brood is present.

It seems that repetition is not harmful although we have no proof that there are not some adverse effects on bees.

It seems inconceivable that bees walk around and perform (apparently) normally when covered with OA dust, but they do. If that were a mammal covered with the dust, severe burns would occur in the breathing system and anywhere moisture is found on the surface, like eyes and mouth, etc... but it seems bees are dry enough that the acid is not wetted and they OK. What happens if a bee encounters water when coated with OA dust? Don't know, but with drizzle, they are covered with a dilute solution and it seems relatively harmless, but not as harmless as the dry dust.

Our current applicators are extremely crude Rube Goldberg machines. I can see that it should be possible to build a rechargeable OA evaporator the size of a policeman's flashlight and can imagine a number of design formats that are far more convenient, safe, and which administer a dose more reliably and uniformly.

Will I ever prototype one? I have the parts. (Not for the 'flashlight' model, but for several ideas which make application less clumsy).

[cam bishop]

Will I ever prototype one? I have the parts.

Why not? Might help the retirement funds considerably! I'd probably buy a few.

[Allen Dick]

Let's discuss the ideal format here.

Later, though. I have to go for a walk. It is beautiful out there.

* * * *

OK. I'm back again.

I have two fairly easy models in mind.
One is in the form of lightweight lids which have an evaporator built in.
They would be used in sets of five or ten.
Place one on a hive, drop in the acid, press a button, go to the next hive.
Place one on a hive, drop in the acid, press a button, go to the next hive.
Place one on a hive, drop in the acid, press a button, go to the next hive.
...
Go back to the first hive and remove the unit, replace the original hive cover and continue
...

---
The next unit would be shaped like a corn broom and operated from a standing position.
The unit would be adapted fit into a hive entrance and mostly close it off.
Air has to escape somewhere and an open top entrance would help to know when the dust has filled the hive.
Either the unit would hang on the entrance by going inside a little or a prop leg could drop to the ground.
---

I like the first unit best because it can provide even distribution to the cluster when it is in the top box, because no bending is required and because the lids sit on top. The question of residual dust being released on lid removal is something I would have to test.

[cam bishop]

I like the idea of putting it on the top of the hive. Will need a blower of some sort so the fumes would distribute evenly in the hive. What about the bottom box. I have some bees that winter in the bottom box. I also think OA vapor works best if used before brood rearing ceases, so one would need to dust the whole hive to be effective. I'm not concerned with the dust. AFAIK most of it is pretty inert at that point. Fumes are the biggest concern and I've certainly inhaled some with no ill effects except a short cough.

How would it be powered? Self contained batteries - lithium? or external? I find one of the slowdowns is dealing with batteries, particularly when I can't drive to the hives. I've been using a battery pack, but that has it's own issues.

[Allen Dick]

Without going into the ultra compact design, which involves engineering and expense to prototype, there are a number of possibilities for a hivetop applicator.

A blower could be as simple as a smoker bellows, but I prefer a muffin fan. Alternately, a pulse from an air tank and small compressor could be used.

An electric iron has good temperature regulation and heat inertia, but requires 600 to 1000 W of 110 V power, depending on the model selected. The draw is intermittent, but that draw means either a big inverter and some batteries in addition to a vehicle with an alternator -- or a big generator if more than a couple were to be run at once.

The iron would be mounted inverted under a centre hole in a deep lid. The OA is dropped through the hole and then the air stream is applied through the same hole or nearby. The iron surface set on "rayon" should be very stable in temperature and have enough heat in its mass to sublimate the OA with minimal or zero decomposition, unlike some current commercial models which have no regulation and depend on airflow for modulation of the temperature.

My chemistry is rusty, so I have not calculated the actual volume of gas generated by 1 gram of oxalic acid dihydrate, but the interior volume of a hive body is only 1.5 cu ft before the frames and bees are considered and the frames are 0.8 cu ft., leaving about 0.7 cu ft of airspace per box. That is not much air. Current power applicators inject far more.

As for a compact, battery model, electric drills, electric snippers, etc have established systems for charging, and standard spare and replacement batteries available for affordable cost, so that is a start. The evaporator design depends IMO on a number of factors. At present, I do not know the heat of fusion or the heat of evaporation of the OA component. Water properties are well-known. These numbers determine the heat input required to achieve the evaporation and the feasibility of using battery power. Both the heat of fusion and the heat of evaporation for the measured quantity of the dihydrate must be supplied, along with enough energy to overcome any heat leakage or losses over a short time in order to achieve satisfactory and complete sublimation. The sublimated OA must then be distributed quickly.

My understanding is that the vapour phase is transitory since the cooling air will precipitate it very quickly. If achieving a very fine particle is all this elaborate process accomplishes, then I wonder why we need to heat the OA at all. Maybe just grinding it very fine and blowing it into the hive would accomplish the same end result?

[cam bishop]

Maybe just grinding it very fine and blowing it into the hive would accomplish the same end result?

I tried to find a study on doing this and came up empty. Wonder if anyone has tried this? Seems like the Europeans, who use OA a lot would have something on it.

[Allen Dick]

I like the unit that Juanse's friend made.
http://www.youtube.com/watch?v=eYgjVlIfEo8

[cam bishop]

Yes, seems simple enough to build. Major problem would be the melting of the pvc tube. Seems like several could be constructed and run in a chain. Looks like a computer fan on the end. I might try to construct one. I have a machine shop that could make the bowl for me like the Heilysers that I have now. Put a glow plug in it and a fan on the end. Wonder how strong a current we'd need?