# OAV from top of hive



## johno (Dec 4, 2011)

If you want to build a band heater vaporizer treating from the top is a piece of cake. By drilling a 1/4" hole in the top or second box which you can plug with a small piece of 1/4" dowel you can insert the outlet of the device into this hole and treat in about 30 seconds. You will see the vapor go down and start seeping out of the bottom of the hive entrance. I no longer bother with a veil and gloves when I treat as all my entrances are now reduced to minimum and by working from behind the hives I am not bothered by the bees at all.
Johno


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## Scottsbee (Jan 11, 2017)

Already have the varroa wand. 

Not familiar with the band heater, were you vaporizing from the front before? Are you seeing the same might kill? 

Not sure it matters, as long as the acid is sublimed, doesn't matter what device is used. What I'm wondering is the efficacy of vaporizing from the top most box.


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## dudelt (Mar 18, 2013)

According to other threads in this forum, vaporizing from the top of the hive works just as well as vaporizing from the bottom. You will need to put in a 1 inch shim at the top of the hive to give it some space. I have not tried it my self but it seems to me that you would need to add the shim the day before you vaporize and then later remove it. What I do is replace the entrance reducer with two 1x1 pieces of wood place on each side of the entrance which would give you a reduced opening of about 2-3 inches, just enough to put the vaporizer in. That way you don't need to remove it just before vaporizing and you can quietly put the wand in and cover the hole with the towel.


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## Eikel (Mar 12, 2014)

I've not noticed a difference in efficacy. I mainly use it on nucs as it's easier than removing the robber screens. Try using a piece of T shirt rather than a towel, it's thinner, more flexible and fits on the landing board better.


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## Scottsbee (Jan 11, 2017)

Eikel
Also been going from the top on a Nuc and seems there is a better burn off of the oxalic. The pan just looks cleaner and no cooked bees either. 
Thought about adding a 2 or 3" shim between brood box and bottom board. Not much space now from bottom of frames to bottom of board. Thinking bees are clustered some and hanging out and then I shove a pan into them. Even with a wider opening like dudelt suggests, bees notice the intrusion of the wand and go on alert start attacking the pan and get cooked. Don't they know I'm only trying to help them lol. 

If efficacy is the same either way, I'm leaning towards top down on all hives. 

Thank you for the feedback 
Scott


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## Eikel (Mar 12, 2014)

Realize my efficacy assessment is strictly empirical observation and not something I've sought to quantify. Yeah, some of the frame bottoms have scorch marks and a few bees do get cooked. I keep trying to convince mine I'm a benevolent creature but they keep bringing up my past transgressions, theft and habit of tearing the roof off.

If you're going to use a shim/spacer, I'd go with one tall enough to accommodate a sugar brick or similar emergency winter feed, less specialized equipment is a good thing. I make my own woodware and most of the spacers are from residual scraps but I'll cut a box in half in a pinch.


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## JTGaraas (Jun 7, 2014)

Oxalic acid vaporization from the top is simply done by use of a two (2") inch wooden box with a slot equal to the width of the wand. My box is covered with a clear acrylic sheet so I can watch the burn. After removal of the telescoping cover and inner cover, place a small piece of wood on the frames (so the wand does not touch wood/scorch surface), place box/acrylic cover on top of brood box, insert wand, and perform vaporization. Added benefit - watching the vapors penetrate hive while simultaneously watching the timer on top of the cover, and no commercials!!! Openings are covered as always done for the process, but bee disturbance is equal to any normal cover removal from the back of a hive - a couple of bees may exit.


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## Scottsbee (Jan 11, 2017)

Great idea JT, going to use a medium box that doesn't fit right and put some acrylic on top!! 

The bees don't seem to mind me tearing the roof off. Sure let me know they don't like me poking things in the front door though!! 

Yeah it will be kind of a specialty but maybe worth it to see the vapor action. 

Something that's not talked about much is how much space is needed for storing equipment! 

Thank you 
Scott


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## snl (Nov 20, 2009)

JTGaraas said:


> Oxalic acid vaporization from the top is simply done by use of a two (2") inch wooden box with a slot equal to the width of the wand. My box is covered with a clear acrylic sheet so I can watch the burn. After removal of the telescoping cover and inner cover, place a small piece of wood on the frames (so the wand does not touch wood/scorch surface), place box/acrylic cover on top of brood box, insert wand, and perform vaporization. Added benefit - watching the vapors penetrate hive while simultaneously watching the timer on top of the cover, and no commercials!!! Openings are covered as always done for the process, but bee disturbance is equal to any normal cover removal from the back of a hive - a couple of bees may exit.


Perfect!


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## johno (Dec 4, 2011)

From some tests I have carried out in my yards and my observation hive I have found that the vapor will move more easily into an area if the air can be easily displaced, so when I vaporize from half way up my observation hive which has an entrance in the bottom half the vapor goes down much quicker than up to the top which has no vent. The vapor eventually goes up to the top after about 5 or 6 seconds in the OH which is only 6 frames 3 high so if one is treating a hive of 3 medium boxes from the bottom and there is no top entrance you might not get as much vapor up there as you would like. I have made 1/4" holes between the center frames in my middle boxes and vaporize from there with vapor eventually coming out of both the top and bottom entrances, and yes there is considerable mite falls after treatments and at 30seconds to 1 minute per hive and with no hot body in the hive space get no fried bees so its a winner all around.
Johno


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## jmgi (Jan 15, 2009)

I never liked the idea of sliding the vaporizer in the entrance, too close to the comb for something that gets that hot, besides there are always lots of bees in the way. I built a 3" deep box with the vaporizer built right into it, only a small part of the handle sticks out of a small hole in the box. The vaporizer cup is mounted solidly inside the box on a piece of wood covered with a piece of metal sheeting so it can't move around and keeps the cup about an inch from the top of the top bars. Its a complete unit that goes from hive to hive without messing around with the vaporizer itself, except to put the OA into the cup after I set the 3" box on the top of the open hive. I just throw on an outer cover, plug the entrance with a strip of wood and connect the battery cables to the battery. The smoke will come out of the entrance if there are any small holes, so I know that the vapor gets dispersed very well doing it from the top down.


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## johno (Dec 4, 2011)

This is the easy and quick way to treat from just about any where you want


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## Shuka (Jun 28, 2018)

Hi-
I have been leaving my bottom entrance open (no towel or such). I find that the bees are much more relaxed, as there is no buildup of returning foragers. Also, if I slide the vaporizer in slowly, the bees stay calm. Some vapor escapes from the entrance, but not much more than when I used a towel.


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## LarryBud (Jul 19, 2020)

I'm planning on doing the same thing in a month or so as we get past the fall flow here. I built a two piece hinged box with a slot for the wand to sit in and put threaded rod inside to hold up the end of the shaft. It seems to be a better way than to cook the bottom of the hive. I had posted a video u-tube link from Sweden that was copied from an NJ Beek Association article by a Master Beek (who has successfully used it) a few weeks ago on the procedure where it seems to be a common application but did pickup some static from some on this forum over it. Apparently the criticism was based on a lack of understanding of air density and thermodynamics-even hot dense air falls! I'll have to take some pictures and post them.


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## Jim Braun (Nov 8, 2019)

I use this method on my nucs. I use two shims the size of the nucs with a 1/2" hole drilled between the shims. Put a piece of aluminum flashing on top of the frames to keep from scorching your frames, insert your wand between the shims then turn the outer cover upside down on top of the shims. My nucs don't have a landing board so no towel on them.


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