I use in EasyVap: 1/2 tsp made of 2x 1/4 tsp = ~3g.
It is good enough for me.

 

For best results I do a series of treatments 1 treatment every 4 days for a brood cycle.
After 5 treatments you won't likely find any live mites in your hive.

One treatment just slows down the mites for a moment.

Multiple treatments, gets the mites that emerge from the protection of the cells.

 

And how do you measure one treatment amount of OA?

 

One gram per treatment seems outdated advice. Post #2 by @jtgoral is accurate enough. It has near the same weight as the same volume of water would. More recent recommendations for effective vaporization treatments have been upped compared to original label recommendations.

Maybe someone can link you to threads here on the forum where this has been discussed at length by experienced users.

 

get a small scale
measure the amount you are going to use.
put it in the cap.
fill a few caps and dump them to weight, after 20 or so capp fills you will be fairly close.
if close is not your style, get several caps weight the dose put in the cap next

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GG

 

+/- 0.005 oz means +/- 1.4 g. I think this is not accurate enough when measuring 3-4 grams.

 

I bought a digital scale: 200g x 0.01g from Ebay - ex-China (of course) - and confirmed it's accuracy with a couple of small newly minted coins of known weight. I then made a small measuring 'spoon' from a copper plumbing olive epoxied onto a sliver of wood, which (by sheer coincidence) holds near enough 1.0 gram of OA dihydrate. I've been using that 'spoon' as a guide ever since.

In practice I tend to vary the amount of OA given, according to both box size AND the colony strength - so the amount given is never uber-precise, but having a 1.0 gram 'spoon' enables me to judge the amount given far better than if I didn't have it.
LJ

 

A 20 cc plastic syringe makes a handy measuring and charging tool. Cut the needle end of the body off at the zero mark. I pull it back to the 4 cc mark and plunge it into the OA container and it can then be squirted into the vaporizor cup. A 4 cc volume averages very close to 4 grams and is my usual dose. Your particular container of OA may be quite free running like table salt or clumpy like icing sugar. For this method the bit clumpy is preferred.

 

Thank you all. I’ll use my scale as you have suggested (I have a couple of these)

Amazon.com

Also, I’m going to look into dosage. 1 gm may be insufficient.

i plan to treat
Day 1
Day 7
Day 13

Cheers!
Mike

 

i plan to treat
Day 1
Day 7
Day 13

Once you have paid for the unit and the OA
IMO 4 times 4 days spaced is a better protocol.

GG

 

Yes…1 gram is insufficient, Mike. 2 grams per brood chamber is good. 4 grams for a large colony👍

2 grams = 1/2 tsp

 

While you are rexamining dosage as suggested by Snarge, you might also review more recent thinking about interval between treatments. Efficacy drops of sharply past 2 days after treatment. Too large a window of opportunity for mites to emerge post treatment and re enter cells. If the mite count is high and surrounding beekeepers mite load is high, influx of new mites could leave you treading water if you are not aggressive enough. There is more risk to your bees from undertreating than from overtreating with OA vaporization.

 

I have used johnos vaporizer and the instavap. I either top off the cap with johnos or dunk the plunger for the instavap. When I first started and used the wand I think I used a teaspoon. Never got any more scientific about it than that. Never saw any issues from my method so I'm thinking the measuring doesn't have to be that exact.

 

top off the cap with Johno’s…

An easier way—to avoid using a syringe to fill the blue cap—just invert and dunk it like you do the InstantVap plunger…for a 4 gram dose, that is. Saves a utensil😻

 

Works great,even with gloves.

 

This is exactly what I use, even with the EasyVap cups. Just makes it easy to put it in without getting it all over.

 

Thanks Jack! One picture is worth a thousand words! Yes it works great.

 

That has to be THE best method yet for dosing accurately ... nice one.
LJ

 

Exactly, the caps hold 4 grams loose filled. It's close enough to fill to half for a 2 gram and somewhere in-between for 3 grams. Dose dependent on hive size. The key is to use enough and a bit more will not hurt. It's when you under dose you'll have problems.

 

But not everyone uses those caps. Personally, I want to adjust dosing in a far more reliable way, especially when dosing nucs. That modified syringe idea is near-enough perfect, imo. Would work with everything - even the Varrox kit.
LJ

 

But not everyone uses those caps.

But of course! One could use maid_marian’s thimble…once the quantity has been previously verified💕😂

Jk…the syringe is great for anything…even a cap.

 

... I have a oxalic package that is 35 grams total. How do I measure the 1 gram ...

In general discussions, "oxalic acid" typically implies the dihydrate form unless otherwise specified.When someone mentions "oxalic acid" without specifying the form, they usually have the dihydrate form in mind. This form is the most stable and most commonly used.

Oxalic acid is typically measured by weight using precise scales. The measurement is in grams (g) or kilograms (kg).

Measuring by volume is typically done for solutions, in milliliters (mL) or liters (L), denoting the volume of the solution containing a certain concentration of oxalic acid. When measuring the concentration of oxalic acid in a solution, it typically refers to the concentration of the anhydrous oxalic acid. Grams of anhydrous oxalic acid per milliliter or liter of solution, (w/v).

 

Well, that may be the point that you guys were making, but it wasn't the point that I was making ...

Snarge said: An easier way — to avoid using a syringe to fill the blue cap

BonafideVermont said: Exactly, the caps hold 4 grams loose filled.

The point being made in those two posts as I read them was that they were solely concerned with the loading of vapourisers that only employ blue caps and not with any other design.

In contrast, the modified syringe method can be employed with every form of vapouriser, as well as providing some degree of precision of measurement of smaller quantities which the blue caps do not provide (bearing in mind sjj's point that volume and weight (more correctly 'mass') - especially of a compressible substance - are not interchangeable).

Your technique of guessing smaller quantities of OA crystals appears to be one of adopting a somewhat cavalier approach towards the dosing of colonies with Vapourised Oxalic Acid, and this in a country which - unlike Britain - has fairly strict rules about such procedures.

Whether you consider your laws to be sensible or not really isn't of importance: they are the existing laws in your country which either need to obeyed, or not obeyed - and face the consequences - or they require amendment. When laws state doses of 1, 2, 4 grammes or whatever, they mean just that - not to just heap the stuff in using guesswork. Fortunately in Britain, our legislation - in practice - presents as having a rather more tolerant approach where insects are concerned, when compared with your own EPA.

I think it's worth pointing out that the killing of mites itself really isn't an issue - it's easy enough to achieve especially if treatments are repeated. The problem which needs dealing with is that of re-infestation, which is one reason why I (in an area with few beekeepers and thus little re-infestation) find that maintenance dosing with amounts around 1g per box to be perfectly adequate, whereas the same dose has been shown to have next to zero effect within southern areas of the US.
'best,
LJ

 

Again, another reason to use the cut-off syringe. It's easy to use and it makes exact dosing that much easier, for treating nucs or other odd-sized colonies.

 

EPA label of Apibioxal states "1 gram per brood box".
I overwinter in 4 medium brood boxes. These are not honey supers.
So that's a 4 g application.

Multiple weighings on a relatively accurate kitchen scale gives me a weight of 4g for a 5 ml dose measured with a cut off syringe.

Inserting the syringe into a container with a slight twisting motion gives me more or less consistant density and volume.

Any one who has watched a cooking show on tv knows that to get a consistant measurement with a measuring spoon,one must strike off the excess with a straight edge.

In a short discussion with Jen Berry a few years ago at a bee conference,she agreed that my dosing met the "intent" of the label law since box size is not mentioned and "brood box" is difficult to define when no brood is present.

 

While using ml for solid granular material is painful to me, 1 ml = 1 cc. 5 ml is 1 tsp...

Striking off the top of the spoon is necessary, but tedious, especially using a 1/4 tsp measure...

I like your method. I will probably adopt it.

With regard to the LABEL, since they do not specify the measurement method or required accuracy the amount specified is pretty meaningless. If it is 1 +/- 0.5, that is one thing. If it is 1 +1 /- 0 tharmt is another.

I think you are free to follow the Rotisserie Chicken Rule.

Sam's Club rotisserie chickens are all labeled as 3 pounds. At $4.98 that is a great deal. However, chickens come in all sizes. All of their chickens are at least 3 pounds. But some are noticeably larger. So much so that some customers spend considerable time looking for the larger ones.

On one occasion I bought a chicken that was so big I just had to weigh it. It scaled in at 4 pounds 10 ounces. A "three pound" chicken. Just like the label. At least 3 pounds.

So as long as you follow the Rotisserie Chicken Rule, you should be OK.

 

You can buy 1/4 and 1/2 teaspoon measures anywhere you look. I scoop, drag the top off and dose. To make it easy you can put the OA in a jar with a top similar to the top of a can of baking powder. Scoop, scrape and go....in one motion.

I'm not going to over think this.

 

Thanks all. I only have two colonies. I will use my small scale (which is accurate to 0.1 gram) and establish the volume that way. I have to admit some of you had wonderful posts here with good and practical knowledge. Thank you.

Big Mike

 

I've used a digital scale to check multiple times, and I marked where 1 or 2 grams is on the syringe.

Set the syringe, thump it down into the OA a couple of times to make sure it's tight and push the plunger. Perfect amount every time, and it's WAY faster and easier than playing with measuring spoons. I have seen nothing easier, faster or more accurate.

That being said, if anyone has anything better, I'd be interested to see it.

 

Looks like beating a dead horse now....

The French flag next to Registered on the left is wrong. I am in Chicagoland, back from Rome and Paris. Time for holidays at home with the family.