# Does OAV treatment have residual effect?



## JWChesnut (Jul 31, 2013)

Not really any residual. Based on bottom board drop, mite fall peaks by day 3 and quickly returns to a "background" level. I see a shift from dark red to mottled or "clear" mites after treatment indicating that imatures are falling, but this shift quickly returns to a background of all deep red mites.


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## Hedghawg (Apr 25, 2016)

JWChesnut said:


> Not really any residual. Based on bottom board drop, mite fall peaks by day 3 and quickly returns to a "background" level. I see a shift from dark red to mottled or "clear" mites after treatment indicating that imatures are falling, but this shift quickly returns to a background of all deep red mites.


Thanks Chesnut, I'll use this treatment as a learning tool. Once I treat I'll inspect and take photos of the bottom board every 24 hrs for 3 or 4 days and see what I end up with.


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## sjj (Jan 2, 2007)

Hedghawg said:


> ...OAV leaves tiny OA crystals ... say a day or two after treatment, is it ok to go conduct a hive inspection? ....


Put the latex/rubber gloves on for your safety. Do not inhale this 'medicine'.


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## missybee (Sep 6, 2014)

We had our hives get hit hard with mites, even after treating and having low counts in September. 

With the first OAV, the mite drop was horrendous.








We did another treatment 5 days later, the drop was a lot less, forgot to take pictures. 
The 2nd day after treatment, I cleaned my inserts and now the drop is a mite now and then. At this point we are monitoring and if need be will treat again when they are clustered, December or later. 

We did a OAV this year in February and saved two hives that were being hit hard with mites. They were down to a frame of bees coming out of winter. The treatment allowed them to rebound and become one of our best honey producers.


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## texanbelchers (Aug 4, 2014)

When needed I generally inspect before treatment. I found a 5 day interval treatment schedule more effective than 7 days. I suppose this is from some combination of residuals, phoretic time, hive sealing, temperature, humidity, and maybe hours of foraging, etc. In any case, at the 5 day point I couldn't see anything in the hive, but i don't see bacteria either. Other than fewer mites the biggest effect I saw in the hive was burning on the bottom of some frames.


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## missybee (Sep 6, 2014)

texanbelchers said:


> . Other than fewer mites the biggest effect I saw in the hive was burning on the bottom of some frames.


We put our screened bottom board hives on a, either solid bottom board, or my home made solid bottom boards. Opening to the back of the hives. Now when we treat we close the front entrance and place the OAV wand in from the back below the screened bottom board. I changed all after we found scorched framed and melted wax in one of the hives we had treated going in from the front. Now no worries.


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## Hedghawg (Apr 25, 2016)

I've never used the vaporizer and have been worried about scorching, melting or worse. When I looked through my bottom screen I could see the bees clustered down to the screen. My plan is to slide a cinder block under the hive to put the vaporizer on. I've fashioned a square electrical box extension ring to put on top of the block and around the heating element which will enclose the oav in hopes of allowing the vapor to travel up into the hive rather than dissipate some before it gets up in there good. Maybe it wouldn't matter but as I've never done this I thought I'd take extra care.


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## missybee (Sep 6, 2014)

We would take a paint stick to knock off burr comb, move the bees, try to make sure we harmed nothing. 
But even with doing that we would pull out a few dead bees in the pan. After the burn and scorch we totally changed our method. 

You could build a cheap enclosure, a piece of wood or hardiback, a shim (like this one a mann lake https://www.mannlakeltd.com/10-frame-shim-with-entrance-unassembled) Or make a shim, have a opening in the shim to slip the pan in. Place the wood and shim under the hive on a cinder block, or whatever will hold it up for the 2-3 minutes you need to cook the acid. That would send most of the vapor up into the hive.

I have treated a screened bottom board hive just holding the pan under the hive, a lot of vapor escaped. I did get a mite drop. Not as much as the other hives. I forgot to fix this one hives bottom board set up.

Make sure you wear a mask, good one, you will have your face down in the vapors. I bought a 3m 6001 mask with the correct filters to protect from the vapors.


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## John Davis (Apr 29, 2014)

Hedghawg and others
Vaporizing through the screen even if the vaporizer is enclosed as you describe will not give adequate results as Missybee indicated.
The OA sublimates (goes directly from a solid to a vapor) as soon as the temp of the vapor drops the OA recrystalizes, the screen acts as a heat sink and much of the vapor crystallizes on the wire instead of passing into the hive. The shim mentioned above can be used from the top of the hive as well.
The bees remove the crystals, most are gone after the first 3 - 4 days which is why the mite drop decreases after that time. In the first couple days you may get some skin irritation from contact with the OA.


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## johno (Dec 4, 2011)

You guys should look at the band heater vaporizer under equipment and hardware, there are 2 basic types that sublimate the hives from the back. the cheaper version treats a hive in 30 seconds and will treat the next after allowing a minute to reach operating temperature, the more expensive device treats hives as fast as you can move from hive to hive. I have heard of a beekeeper treating 65 hives in 60 minutes. All this with no fried bees and with exact dosages, and cheap to make.
Johno


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## enjambres (Jun 30, 2013)

A simple solution to worries about scorching low-hanging bees and combs is to insert a two-inch high shim between the bottom board and the first box, leaving it there permanently. It has other useful benefits, too, but I hate treating hives without it now.

I do look in with a flashlight before sticking the wand in, and always use a puff of smoke to move any hanging bees up a little bit.

BTW, OAVing below a screen is problematic in cooler temps as the screen acts a condensation surface, cooling and retaining a lot of OA crystals (aka "snow"), reducing the propagation throughout the hive. The acid is also hard, in the long term, on the galvanized screening. I protect the screening, even though I only use the wand above the screen, by inserting a thin piece of aluminum (actually rimless cookie sheets) which I leave in until after I have fully ventilated the hive, post treatment. Replacing screening on SBB is a royal PITA, and those puppies cost $12-15 each.

Nancy


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## texanbelchers (Aug 4, 2014)

johno said:


> You guys should look at the band heater vaporizer under equipment and hardware, there are 2 basic types that sublimate the hives from the back. the cheaper version treats a hive in 30 seconds and will treat the next after allowing a minute to reach operating temperature, the more expensive device treats hives as fast as you can move from hive to hive. I have heard of a beekeeper treating 65 hives in 60 minutes. All this with no fried bees and with exact dosages, and cheap to make.
> Johno


This is what I have gone to. Much faster, easier, and more reliable. I just go through the entrance.


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## baybee (Jan 10, 2016)

Slatted racks, as discussed many times here, in addition to several other benefits, keep the wax well away from the vaporizer wand.


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## snl (Nov 20, 2009)

If you wish you can vaporize from the top down. Just make a shim/rim the size of a hive body but about 2" high. Cut a small slot in the center of shim/rim for the vaporizer rod. 
Remove the top and inner covers. Load the vaporizer with OA and place it on a small piece of 1/4" plywood (maybe 4"x4"... to keep the frames from scorching) in the middle of the hive, directly on the frames. Place the shim /rim then the top cover and vaporize.


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## missybee (Sep 6, 2014)

We have been doing it through the screen for around 2 years now, so far no damage seen to the screened bottom boards. Only saw the "snow" on one hive after a recent OAV. Not that much just a bit. It was a cool morning. The other 18 hives no issue. 

The mite drop was wonderful. 

With the way I made the solid board below the screened board we can really close them down. If the screen gets damaged I will just fix them.


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## Hedghawg (Apr 25, 2016)

I think you guys have convinced me with "shims". I went to the big box hardware store and bought 1 3/4 x 3/4 stock, glued and brad nailed it together for the bottom board, heck I even got a coat of paint on it. I'll install tomorrow while looking for burr comb and a quick check for brood and any critters. Now do you reckon 1 3/4" extra space at the bottom is going to cause other problems if left on all winter, comb build-up, etc.? I noticed the shim link posted above was not that tall. If so maybe I'll do a top vape option as snl suggested.


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## missybee (Sep 6, 2014)

Hedghawg said:


> I noticed the shim link posted above was not that tall. If so maybe I'll do a top vape option as snl suggested.


I just posted the link so you would know what I was talking about. I moderate a different forum (not bees) to used to needing to post examples of everything!

My second bottom board is made with 2x2's which are about 1.5 inches. Mine is below the screen. I have found my bees do burr comb anywhere there is extra space.


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## snl (Nov 20, 2009)

In the winter, I’ve found there is no problem with burr comb building as the bees are not building comb at that time.


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## missybee (Sep 6, 2014)

snl said:


> In the winter, I’ve found there is no problem with burr comb building as the bees are not building comb at that time.


So true! 

The swarm, we just hived from the tree branch, is actually doing some comb. They are a bit confused.


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## Hedghawg (Apr 25, 2016)

The weather isn't cooperating as planned so I didn't go into the hive and install the spacer to vape from the inside. As posted above, the vapor did somewhat recrystallize on the screen. The first two pics are of the brick that was under the vaporizer and of the bottom screen.

I was expecting some since it was mentioned but still disappointed. The second set of pics is where I ran a test on an empty hive and am now less disappointed as I see how much vapor actually did rise through the screen for a good part of the 2 1/2 minutes. I notice though less crystals on the screen and no crystals on the "test brick" than on the actual treated hive. I wonder why that is?


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## beepro (Dec 31, 2012)

It is because the bees will distribute the oa crystals through out the
hive when they started fanning while the oav unit is on. The fanning action is
enough to disperse the oac to cover more bees and hive parts. The testing has no
fanning so no air movement to distribute the crystals to cover it more. If you have you tube 
subscription I can link you to the oav gadget experiment on you tube that you can see the oa vapor 
with fanning bees almost like a cyclone action. Then we can talk about what the bees and oav are
doing in the vid with a timer to track it.


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## missybee (Sep 6, 2014)

bee pro would love to see that! Can you post the link?


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## Hedghawg (Apr 25, 2016)

beepro said:


> It is because the bees will distribute the oa crystals through out the
> hive when they started fanning while the oav unit is on. The fanning action is
> enough to disperse the oac to cover more bees and hive parts. The testing has no
> fanning so no air movement to distribute the crystals to cover it more. If you have you tube
> ...


I would like to see that also, I'm surprised I haven't as I've been power watching beekeeping youtube videos lately.


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## snl (Nov 20, 2009)

Hedghawg said:


> I would like to see that also, I'm surprised I haven't as I've been power watching beekeeping youtube videos lately.


If you do find his video (and it's the one he previously had) you can't see ANYTHING happening.......a joke....


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## johno (Dec 4, 2011)

[video]https://www.facebook.com/groups/136296719714571/?ref=bookmarks[/video]
Take a look at this test guys.
Johno


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## johno (Dec 4, 2011)

Sorry guys that link wont work, if you go to facebook and look for Northern Neck Beekeepers you will find that video on the site.
Johno


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## beepro (Dec 31, 2012)

snl said:


> ....can't see ANYTHING happening.......a joke....


That is because I do night time beekeeping all along. Not a joke. You just see smokes because you don't
understand my invention or what's going on while watching the vid before. Because I have not yet explain it here. At the
minimum I can explain the oav and bees interaction because I was there observing the oav burning until completion. 

Don't worry snl, the bee community is not yet ready for this. I have since step away from
this gadget and have invented a better and more efficient to install unit. Not to mention a lot safer for
the beekeeper too. Thanks you for triggering my inventive side again. Just follow Edison's attitudes when it comes to inventing things. And never give up! Let me see if I can find the vid link again.


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## Mike Gillmore (Feb 25, 2006)

Hedghawg said:


> The first two pics are of the brick that was under the vaporizer and of the bottom screen.


Referring to post #21.
I've always treated my hives successfully from under the screened bottom and sometimes will find a little residue as seen in your 3rd pic, but the amount of crystals left on the brick and screen in the 1st and 2nd pics seems to be much more then unusual. 

Anyone have any ideas?


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## snl (Nov 20, 2009)

Mike Gillmore said:


> Referring to post #21
> 
> Anyone have any ideas?


What was the temperature at the time?


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## Hedghawg (Apr 25, 2016)

The temperature was around 50


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## Kuro (Jun 18, 2015)

Mike Gillmore said:


> Referring to post #21.
> I've always treated my hives successfully from under the screened bottom and sometimes will find a little residue as seen in your 3rd pic, but the amount of crystals left on the brick and screen in the 1st and 2nd pics seems to be much more then unusual.
> 
> Anyone have any ideas?


I cannot remember which thread but somebody mentioned that when OA crystals are too wet, the excess water may boil and spill over.


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## Hedghawg (Apr 25, 2016)

I considered the wet acid thought but my test vape under the same conditions turned out pretty well. In any case the mite count was not impressive (5 or 6 a day) and the only other thing I've done is the paper towel method back in mid September. That either worked real well or, I have a colony that is impervious to mites or, it could be that the ova treatment last week was a flop. I treated again today above the screen with a 2" shim under the brood box, we'll see in the next couple days.....


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