Oxalic Acid Dribble Dose Calculator for Varroa Treatment
The correct oxalic acid dribble dose depends on how many frames of bees you have in your colony. The standard is approximately 5ml of OA solution per frame covered with bees, with a maximum of 50ml total per colony.
Use this guide to calculate your dose before treatment.
TL;DR
- Oxalic acid (Api-Bioxal) is approved for dribble and vaporization methods; both kill only phoretic mites on adult bees
- Vaporization is more effective than dribble when brood is present because bees can contact vaporized acid across the colony
- The extended vaporization protocol (every 5 days for 3 applications) compensates for mites in capped brood
- Oxalic acid has no PHI restriction for honey supers when used according to the Api-Bioxal label
- Efficacy during true broodless periods can reach 95%; with brood present, efficacy drops to 50-70%
- Always wear a respirator and eye protection during vaporization; oxalic acid vapor causes lung damage
The Dribble Dose Formula
Dose per frame: 5ml of Api-Bioxal solution (prepared per label instructions)
Maximum per colony: 50ml total (10 frames covered with bees)
| Frames Covered With Bees | OA Solution to Apply |
|--------------------------|---------------------|
| 1-2 frames | 10ml |
| 3-4 frames | 15-20ml |
| 5-6 frames | 25-30ml |
| 7-8 frames | 35-40ml |
| 9-10 frames | 45-50ml |
| 10+ frames | 50ml (maximum) |
How to Prepare the Solution
Use only FDA-approved Api-Bioxal. The label specifies the preparation ratio, typically dissolving Api-Bioxal in warm 50% sugar syrup. Follow label instructions exactly.
Prepare fresh solution before each treatment session. Discard unused solution at the end of the day.
Application Method
- Prepare your dribble solution
- Load into a 50ml syringe
- Find each frame covered with bees in the cluster
- Dribble the measured amount down the seams between frames over the bees
- Apply evenly across all frames covered, don't pour it all in one spot
- Close the hive
Apply on a mild winter day (above 40°F). Bees should be clustered enough to not scatter from the application.
Important Constraints
Once per year: The Api-Bioxal label limits dribble application to once per colony per year. This is a legal constraint, not just a recommendation.
Broodless only: OA dribble is only effective and appropriate during the broodless period. If brood is present, OA harms larvae. Vaporization is the alternative for treating during active brood season.
Not a repeat treatment: Unlike vaporization, dribble can't be repeated if efficacy was low. For maximum efficacy flexibility, vaporization is preferred for operations that treat more than once per year.
Tracking Your Dribble Treatment
Record your treatment date, number of frames treated, total volume applied, and product lot number. This forms your treatment compliance record.
VarroaVault stores all treatment records, product, dose, date, and application notes, alongside your mite count data so you have a complete history for compliance reporting or personal reference.
FAQ
How much oxalic acid dribble per hive?
The standard is 5ml of prepared OA solution per frame of bees covered, up to a maximum of 50ml per colony. For most winter colonies covering 4-6 frames, that's 20-30ml. Never exceed 50ml regardless of colony size.
Can I do OA dribble twice a year?
The Api-Bioxal label limits OA dribble to once per colony per year. If you want to treat more than once, use OA vaporization, the vaporization protocol allows multiple treatments as part of an extended protocol. Follow label guidance for current application limits.
When is OA dribble better than vaporization?
OA dribble is simpler and requires no equipment, just a syringe. For hobbyists with a few hives and no vaporizer, dribble is the accessible broodless-period treatment option. Vaporization is faster, can be applied without opening the hive, and allows extended protocols. For 5+ hives, a vaporizer investment pays off quickly in speed and flexibility.
How many oxalic acid vaporizations can I do per year?
The Api-Bioxal label allows up to three vaporization treatments per year per hive. Under the extended protocol for colonies with brood present, three applications spaced 5 days apart count as one treatment event. Always follow current label instructions as registration requirements can be updated.
Can I use oxalic acid from the grocery store instead of Api-Bioxal?
No. In the United States, only EPA-registered Api-Bioxal is legal for treating honey bees. Industrial or food-grade oxalic acid is not registered for bee use and cannot be used legally. Using unregistered products violates federal pesticide law and may affect honey marketability. Api-Bioxal is widely available from beekeeping suppliers.
Is oxalic acid safe to use on brood?
Oxalic acid in dribble form is damaging to brood when applied directly; the label specifies use on broodless colonies for dribble application. Vaporized oxalic acid is less directly damaging to brood than dribble and is approved for use with brood present, though efficacy on mites in capped brood is limited. Always follow the label for the application method you are using.
Sources
- American Beekeeping Federation (ABF)
- USDA ARS Bee Research Laboratory
- Honey Bee Health Coalition
- Penn State Extension Apiculture Program
- Project Apis m.
Use the Right Dose, Every Time
Oxalic acid dribble is effective when applied correctly at the right dose during the broodless period. VarroaVault helps you track treatment dates and post-treatment counts to verify efficacy. Learn more about winter treatment timing.
Get Started with VarroaVault
Oxalic acid is one of the most effective and accessible varroa treatments available, but timing and application method determine whether you get 95% efficacy or 50%. VarroaVault tracks your broodless window, application method, and pre/post mite counts so you can see what's actually working in your operation. Start your free trial at varroavault.com.