Hi Jeremy, Juanse and all

I apologize for my delay. 
Here it is again how we are prepare and use "cardboard strips soaked into a solution of Oxalic acid and Glycerin" against varroa spp. 

INGREDIENTS for 20 colonies.
80 cardboard strips 1,5 mm stick x 3 cm wide x 35 cm long (gray cardboard like the base of book's cover without varnish)
Glycerine (Food grade - USP) pure: 1000 g
Oxalic acid: 600 g

PREPARATION
Heat the glycerine up to 65ºC and add the Oxalic acid stirring it.
The temperature will fall to near 35ºC then you need to maintain heating and stirring the mixture up to it become crystal around 55ºC-58ºC Do not trespass 65ºC

Soak the strips in this product. The strip needs a night to get all the sollution. It is about 19 to 20 g of solution by strip.

Then allow strips to drain for a day or less until they become dry in the surface.

TREATMENTS
Do tests before anything and 15 to 20 days after the treatment.
Put 4 strips per brood chamber with more than 4 brood combs and 10 frames plenties of bees in Spring. Bees will remove the strips in about 40 to 60 days.

Check what is it happening at the begining of Summer after a honey crop or when you prepare the colonies to be moved. If there are varroa then add strips according your criteria.
At the end of the season, inmediately after de last crop you can add 4 strips to be safe during the autum and winter.

CAUTION
Some friends as Juanse Barros (Chile) and Ricardo Prieto (the main responsable of this method) reported bees looses in winter with this cardboard. Also Randy pointed me some recristalization of acid over the strips.
I don't know why but it could be the following:
With a great difference of temerature outside and inside of the colony during many days without ventilation, the vapor inside the colony condenses in the strips because hygroscopicity of the glycerine. Then the acid moves to water because polarity and finally when the bees suck this condensation they die. Or simply when the bee removes the wet air from the colony this condensation is dried and the acid become into fine cristals.

Before winter if the autum's treatment was done too late and the bee did not remove the strips then it is necessary to remove the strips to leave the beehives without risk.

We published it in "Espacio Apicola" magazine No. 109 (June 2014) ISSN 1850-0757 and the most complete and adusted version in Espacio Apicola #112 (June 2015)

Now an Argentine commercial brand registers a product very similar to this. They do not mention the vehicle of the acid and they are using a solution with less acid.

It is important to point that: 
the active principle is the Oxalic acid,
the vehicle is glicerine (USP)
and the cardboard is a support.

As you can prepare a syrup to feed bees or the syrup with antibiotics to your children... you can prepare this treatment for your bees. Acid and glycerin has better traceability than the water that you are using to prepare any syrup.

Best regards
Fernando


Fernando Esteban
Cordoba, Arg
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+54 (9) 351 4597264
________________________________________
De: Informed Discussion of Beekeeping Issues and Bee Biology [[log in to unmask]] En nombre de Cusick Farms [[log in to unmask]]
Enviado el: jueves, 09 de junio de 2016 10:57 a.m.
Para: [log in to unmask]
Asunto: [BEE-L] Oxalic in glycerin?

I was searching the archives for information on treating with oxalic acid
in glycerine (as strips I think).  I want to say Juanse brought it up but
couldn't find the thread.  If anyone can point me in the right direction
I'd appreciate it.  The way a lot of my hives are set up vaporization would
be a pain so I was thinking about trying to add to my treatment rotation
other ways.

Thanks,
Jeremy
West Michigan
(good early flow this year, black locust seemed to do well couple hives
already have 2 supers full)

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