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Oxalic Acid Treatment Table




Be sure to read “Oxalic Acid – Questions and Answers” and “The Learning Curve – Part 3”  before using oxalic acid. It is critical to apply it correctly, or you risk seriously harming your bees!”

Important Note:  the following proportions refer to common oxalic acid dihydrate (wood bleach).  If you manage to get your hands on pure laboratory oxalic acid, you must reduce the amount of acid to only 7/10ths of that of the dihydrate !!!!

Also note that if you use hard water, some of the oxalic acid will precipitate out as calcium oxalate, and thus reduce the efficacy (you’ll easily see the white precipitate if this is the case.

Oxalic strength →

“Hot” 4.2% w:v

“Medium” 3.2% w:v

“Weak” 2.5% w:v

Notes

OA Crystals

1

0.75

0.6

Oxalic crystals must be measured by weight. Sugar and water are about the same by weight or volume (1 pint of either granulated sugar or water weight 1 lb)

Sucrose

10

10

10

Dist. Water

10

10

10


OA Crystals

60g

45g

35g

Makes 1 liter;
Treats about 20 colonies

Sucrose

600g

600g

600g

Dist. Water

600ml

600ml

600ml


OA Crystals

100g

75g

60g

Makes 1620ml;
Treats about 33 colonies

Sucrose

1 kg

1 kg

1 kg

Dist. Water

1 liter

1 liter

1 liter


OA Crystals

232g

174g

139g

Makes 1+ gallon;
Treats about 75 colonies

Sucrose

5 lb

5 lb

5 lb

Dist. Water

2.5 qt 2.5 qt 2.5 qt

OA Crystals

1112g (2 lb 7 oz) 834g (1 lb 13.4 oz) 667g (1 lb 7.5 oz) Makes 5 gallons;
Treats about 375 colonies

Sucrose

25 lb 25 lb 25 lb

Dist. Water

3 gal 3 gal 3 gal

Feedback from Jeanne Hansen, Madison, WI:

The reason I am writing to you is to remark that, as a hobby beekeeper with a single hive to treat with oxalic acid, I had some trouble with the recipes on your web site.  I don’t have a balance delicate enough to weigh 6g of oxalic acid, and besides I only wanted to make half a dose, using 3g.  My only metric measuring container is in my kitchen, marked in Cups, with a few little metric amounts on it.  It’s not very accurate.  To solve my problem, I visited my friend’s lab, and found out how much oxalic acid (wood bleach from the hardware store) fits in a standard teaspoon. 

I know you like raw data, so here it is: 

Aluminum teaspoon             Plastic teaspoon

4.6g                                                                                             3.6

3.8                                                                                                3.6

3.7                                                                                                3.8

3.8                                                                                                3.6

3.8                                                                                                3.7 

Discarding the outlier (spoon was probably not leveled off) the average value is 3.7g oxalic acid per teaspoon.

Thanks, Jeanne!  I also tried measuring oxalic crystals in teaspoons, but found much greater variability, so I hesitate to publish this.  However, here goes:

If you absolutely don’t want to use a postal scale, or a cheap digital scale (plenty on the web for under $10), then an approximate dilution would be 3 tsp oxalic crystals to 5 fl. oz each of water and granulated sugar.  This will give you a bit over a cup of treated syrup, or enough to treat about 4 colonies (or 3 really strong ones).  Don’t try to mix any less, just discard the excess!

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