[cristianNiculae]

I've done some OAV last week on a hive that had 3% mite infestation and I'm not impressed by the number of mites that fell onto the paper I put on the bottom board: the first 2 days I found 10 each day then only 3. Could it be that the mites are carried away or it's just the failure of the treatment. Normally I should get some hundreds dead.
I'm not that eager to treat anyway. I will do a jar sampling in a week or so again. If this OAV is not that efficient I will use the dribble method on the first brood break. I have formic acid also but I'm afraid to use it after all the work I've done regarding queen rearing.
So far OAV is the only form of treatment I've used but I never had huge mite counts on it.
Who knows... probably I am treatment free and I don't even realize it

 

[shinbone]

Not sure why you wouldn't see large mite drops with OAV. I've always had huge mite drops whenever I use OAV. Are you sure you are using OAV correctly?

 

[cristianNiculae]

Pretty sure on the way I apply it... maybe not that sure on the quality of the acid - that one I cannot verify.

I use a water heater coiled around a small dish. I've done dry tests to determine the timing on AC input to avoid over boiling the acid. I wanted to know if regular paper also works in verifying the treatment results and probably it does. I wouldn't imagine hundreds of mites vanishing in a few hours.

 

[shinbone]

Maybe coat the paper with Vaseline to ensure any mites that fall on it aren't blown away by the wind or otherwise fall off before you can count them?

If you don't see large mite numbers after that, I would double check your application method and OA purity.

 

[cristianNiculae]

Maybe coat the paper with Vaseline to ensure any mites that fall on it aren't blown away by the wind or otherwise fall off before you can count them?

Vaseline is not harmful to the bees? Probably not. OK I will try that. Thanks.

 

[Scpossum]

Use under a screen board. Bees will stick to the vasoline as well if they can get to it. At least that is what I was told last night by a presenter.

 

[cristianNiculae]

I was just planning to build one SBB for these kind of purpose.

 

[shinbone]

Use under a screen board. Bees will stick to the vasoline as well if they can get to it.

Scpossum is correct and I should have been more complete in my answer. As he said, the bees will stick to the Vaseline if you don't run a screened bottom board of some sort. Also, for the nonabsorbent material I use ("Coroplast," which is corrugated plastic sheet), I spray with olive oil to make the mites stick - easier to apply and clean up than Vaseline.

As to your question about the accuracy of a mite drop, the problem with mite drops to monitor mite population is that a sticky board doesn't take into account bee population. Thus, if you see 50 mites on your sticky board in 24 hours, you still don't know the percent infestation because you don't know bee numbers. Doing a sugar or alcohol roll with a 1/2 cup of bees (which equates to about 300 bees) gives you precent infestation because you know the number of bees that produced the observed number of mites. I use the sticky board method because it is easier and gives me results good enough for my purposes.

I used OAV on my 12 hives for the first time last Fall, and each application produced a mite drop similar to the two I posted above. The mite fall would peak about 24 hrs after vaporizing, and taper off over the next few days, with the mite fall going to about 0 by the 5th day.

I did 4 treatments, 7 days apart. It wasn't until the 4th treatment that I noticed the mite fall was less than for the first treatment. I think this makes sense because the general wisdom on OAV timing is that since the OAV doesn't penetrate into capped brood, three applications spaced 7 days apart are needed to cover one complete cycle of emerging bees and hence get most of the mites.

Regardless, the OAV hits the mite population really hard while the bees hardly seem to notice it. There was much less disruption to the hive with OAV than with the Apiguard I had used the previous year (which only caused some increased buzzing when I used it).

This Fall, I am thinking about doing the OAV treatments 5 days apart.

 

[JWChesnut]

The powdered OA needs to sublimate, and this is tricky. OA in the "wood bleach" form is dihydrate (has H20 bound to the molecule). When heated it liquifies into a pool and bubbles. You don't get therapeutic effect until the OA dries to powder and gasses off (as the vapor before then is simple water steam). The bubbling pool vanishes into vapor. The containing cup/pipe end needs to be dry at finish.

 

[cristianNiculae]

Thanks guys for the valuable information.

 

[cristianNiculae]

Well guys... the treatment seems to have worked. I've just did a sugar shake jar sampling again and got only one mite so well under 1%.
I haven't monitored the mite count on the paper since I've last posted, in fact I throw it away.

So it's either:

1. All the mites were on the other frames except the one I've sampled(from the core of the brood nest)
2. Somebody stole my mites from the paper
3. All the mites died after a longer period of time

All after one treatment alone. However last year I also had a low infestation - max. 3% at the end of August.

My conclusion so far is that varroa is not that much of a problem but I'll keep an eye on it. For the next year I'm planning to leave a colony with all the brood through the summer to see the percentages of infestation.

This year I did 30 nucs: cutdown splits before the main flow and again other splits. I'm sure that some of the low rates are due to this fact but I also don't think varroa is a big problem in my area. Time will tell.

Regards,
Cristian

 

[JRG13]

I don't trust drop boards. If the one you didn't use wasn't sticky, I wouldn't put any trust in it either. Dead mites blow around very easily, probably just fell off or got removed from the hive if you just had it on a solid bottom.

 

[GLOCK]

Are getting a good vapor going through the hive like this?

Seems strange I treated last fall and my drops where like this.

Just saying seems strange .
How do you know the hive is 3% infected? And I don't think 3% is that bad to bee treating .
I have tested two of my hives this summer so far and I have no mites going to test most this coming week it is that time again.

 

[cristianNiculae]

How do you know the hive is 3% infected?

I've sampled 300 bees or maybe more in a jar, added powder sugar, shake them above a water dish then count the mites. On the first round 2 weeks ago there were 7 mites. On the last one I had only 2. However, as you said 3% can be left untreated.
In my case I had brood breaks as I made nucs and if I remember correctly Michael Palmer said he doesn't treat his nucs in the first year. Now I can understand why.

I hope I can skip treatments if that's possible or at least do just one acid dribble in the Autumn. I should have a brood break in September, at least I had one last year.

 

[Nabber86]

I've sampled 300 bees or maybe more in a jar, added powder sugar, shake them above a water dish then count the mites. On the first round 2 weeks ago there were 7 mites. On the last one I had only 2. However, as you said 3% can be left untreated.

Are you talking about mites per bee? If so 7/300 = 2.3%. I am not sure how you would compare that to a mite count on a sticky board. If you had a 2 to 3 % infestation rate and 30,000 bees in a hive, I guess that you should see 600 to 900 mites on the sticky board. Anyway, I use a sticky board after OVA treatment as a qualitative assessment; lots of mite means the treatment worked well.

I heard somewhere on Beesource to lightly coat the board with cooking spray. That has to be easier and cleaner than working with vasoline.