Beekeeping Oxalic Acid Dosing Calculator
Created by: Ethan Brooks
Last updated:
Calculate precise oxalic acid quantities for varroa mite treatment. Get exact measurements for both the dribble method (sugar syrup solution) and vaporization, with step-by-step instructions and safety guidelines.
Oxalic Acid Dosing Calculator
OA DosingCalculate precise oxalic acid quantities for dribble or vaporization treatments
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What is a Beekeeping Oxalic Acid Dosing Calculator?
A beekeeping oxalic acid dosing calculator helps you measure precise quantities of oxalic acid for treating varroa mites in honey bee colonies. Oxalic acid is one of the most effective and economical mite treatments available, but proper dosing is critical for both effectiveness and bee safety.
Our calculator supports both the dribble (trickle) method using sugar syrup and vaporization (sublimation), providing exact measurements based on your number of hives and chosen application method.
Dribble Method vs. Vaporization
Dribble (Trickle) Method
The dribble method involves mixing oxalic acid with sugar syrup and drizzling it directly onto the bees between frames. It's accessible to beginners and requires minimal equipment.
- Mix 35g oxalic acid dihydrate per liter of 1:1 sugar syrup
- Apply 5ml between each seam of bees
- Maximum 50ml per hive (10 seams)
- Single application only — do not repeat within 21 days
Vaporization (Sublimation)
Vaporization heats oxalic acid crystals until they sublimate into a gas that permeates the hive. It's highly effective and can be repeated when brood is present.
- Standard dose: 2g per hive (1g for ProVap-style units)
- Can do 3 treatments, 7 days apart, to catch emerging mites
- Requires specialized equipment and respiratory protection
- More effective than dribble when brood is present
When to Use Oxalic Acid
Oxalic acid only kills mites on adult bees — it cannot penetrate capped brood cells. For maximum effectiveness:
- Broodless period: Single treatment (dribble or vapor) is highly effective (90-95%+ kill rate)
- With brood present: Use vaporization with 3 treatments, 7 days apart
- Temperature: Best applied when temps are 35-55°F (2-13°C)
- Timing: Late fall through early winter in most climates
Oxalic Acid Safety
Oxalic acid is a natural compound found in many plants (rhubarb, spinach) but concentrated forms require careful handling:
- Always wear nitrile gloves when handling
- Wear eye protection for both methods
- Use a full-face respirator with acid gas cartridges for vaporization
- Work outdoors and upwind when vaporizing
- Keep solution off skin — it's corrosive
Frequently Asked Questions
How much oxalic acid per hive for dribble method?
For the dribble method, apply 5ml of oxalic acid solution between each seam of bees, up to a maximum of 50ml per hive (10 seams). The solution is made by dissolving 35g of oxalic acid dihydrate in 1 liter of 1:1 sugar syrup.
How much oxalic acid for vaporization?
Standard vaporizers use 2 grams of oxalic acid dihydrate per hive. Commercial units like ProVap may use only 1 gram per hive. Always follow your vaporizer manufacturer's recommendations.
Can I use oxalic acid when brood is present?
Yes, but effectiveness is reduced since oxalic acid cannot kill mites under capped brood. For colonies with brood, use vaporization with 3 treatments spaced 7 days apart to catch mites emerging with new bees.
How often can I treat with oxalic acid?
The dribble method should only be used once per brood cycle (21 days) as repeated applications can harm bees. Vaporization can be done up to 3 times, 7 days apart. During a broodless period, a single treatment of either method is sufficient.
Is oxalic acid safe for bees?
When used correctly, oxalic acid is safe for adult bees but can be harmful to open brood. The dribble method is slightly harder on bees than vaporization. Always follow dosing guidelines and don't exceed recommended amounts.
What temperature should I apply oxalic acid?
The ideal temperature range is 35-55°F (2-13°C). Bees should be clustered but not too tightly. Avoid treating in very cold weather when bees cannot move to distribute the treatment, or when it's warm enough for bees to be flying actively.
Sources and References
- Randy Oliver, Scientific Beekeeping, "Oxalic Acid Treatment for Varroa" scientificbeekeeping.com
- USDA-ARS Bee Research Laboratory, "Oxalic Acid for Varroa Control"
- Honey Bee Health Coalition, "Tools for Varroa Management Guide"
- University of Minnesota Bee Lab, "Oxalic Acid Application Methods"