Extended Release Oxalic Acid Treatment


The extended-release application method is not yet approved by the EPA.

Randy Oliver:

"Beekeepers worldwide are caught between a mite that has proven able to rapidly develop resistance to synthetic miticides, and the slow pace of development and adoption of mite-resistant bee stock - the eventual solution to varroa.  During the interim, by choice or lack of alternatives, beekeepers are shifting to the use of “natural” treatments.  Oxalic acid (OA) is one of the most promising of those treatments, but its efficacy is limited unless applied during a broodless period. An extended-application method would free it from that limitation.

The problem with oxalic acid is that either of the currently approved application methods (dribble or vaporization) kills mites for only about three days.  So unless applied during a broodless period, or repeated at 4-day intervals, oxalic is not very effective over much of the season, due to a proportion of the mites being protected in the sealed brood.  By creating an extended-release formulation, we may have found a treatment that is “natural,” suitable for organic approval, safe for the applicator, non-contaminating of honey, shows no noticeable adverse effects upon the colony, as well as being inexpensive and highly effective at reducing mite populations."

We will refer Extended-Release Oxalic Acid treatment as OAE.


Please read the following references for more details on this treatment technique.

The following links are from Scientific Beekeeping, a website published by Randy Oliver. Randy Oliver is a world-renowned speaker, educator, bee biologist, leading researcher, commercial beekeeper, and regular contributor to the American Beekeeping Journal. He is one of the premier beekeeping speakers in the U.S. and the owner/author of http://scientificbeekeeping.com.

The following is how I (Jamie Haskell), do it. Please do your research and verify your own method.

Shopping List

OAE is a very inexpensive treatment, but you need some gear to safely and accurately make it. Here's what has worked well for me:





(price as of May 2022)
Induction Cooktop Provides a safe, no-flame way to heat up the solution. The cooktop surface does not get very hot during use, as the heat is induced directly into the pan. One less thing to worry about. Amazon


Digital Kitchen Scale To weigh the Oxalic Acid and Glycerin Amazon


Pan 1/3 6" deep To make a double boiler to heat and mix the OA solution. Amazon


Pan 1/3 4" deep To make a double boiler to heat and mix the OA solution. Amazon


Kitchen Tongs Mixing the solution and bathing the dishcloths. Amazon






(price as of May 2022)
Oxalic Acid The key ingredient. Handle with care - OA is toxic and very acidic. Always wear gloves, eye protection, and a mask. Amazon


Provides 22 40g doses
Cost per 40g: $.68

Vegetable glycerin Used to dissolve the OA and adhere to the pads.

Best measured by weight. 40g is approximately 33ml.



Provides approx. 28 doses
Cost per 40g dose: $.36

Swedish dishcloths. These are soaked in the OAE solution and placed in the hive. Amazon


Provides 10 doses
Cost per dose: $2.00

Startup cost (equipment and one set of supplies): $166
Treatment cost per hive (one saturated Dishcloth, with 40g OA): $3.04

How To Prepare


Per hive:

  • 1   Swedish Dishcloth
  • 40g   Glycerin
  • 40g   Oxalic Acid
Note: Randy Oliver's experiments range from 30g to 50g OA per hive. 


Best do this in a sheltered outdoor area with no wind, or perhaps in the garage. Oxalic Acid is toxic... I would recommend not doing this in the kitchen or indoors. If you are outside, be careful about the OA blowing around. It is a similar consistency to granulated sugar, so a gust of wind would tend to blow it around, making for a hazardous workspace and more involved cleanup.
1. Cut the Swedish Dishcloths in half.
2. Prep your storage container - I use a heavy-duty Ziploc bag, and roll back the top so it stays open for easier insertion of the finished pads.
3. Put on your eye protection, gloves, and mask.
4. Put about an inch of water in the deeper pan, and bring it to a boil.
5. Put the shallower pan on the digital scale, set it grams, and tare it.
6. Slowly pour in the glycerin to the computed weight (40g x number of treatments).
7. Tare the scale.
8. Carefully add the Oxalic Acid to the computed weight (40g x number of treatments).
9. Put the shallow pan in the boiling deep pan. Use the tongs or a spoon to stir the mixture. Stir occasionally and wait until the mixture is clear, and all the OA is dissolved.
10. Turn off the stove.
11. Insert the Swedish Dishcloth halves, and use the tongs to gently move them around until all of the OA mixture has been absorbed by the towels.
12. Place the OA pads into your storage container, seal, and rinse off the outside and your gloves to remove any residual OA.
13. Thoroughly rinse off all your equipment outside.


Place two half pads (one full Swedish Dishcloth) on the top bars of the lower brood chamber in the spring. They can remain in the hive until the fall.

Integrated Pest Management

From Wikipedia:

Integrated pest management (IPM), also known as integrated pest control (IPC) is a broad-based approach that integrates practices for economic control of pests. IPM aims to suppress pest populations below the economic injury level (EIL). The UN's Food and Agriculture Organization defines IPM as "the careful consideration of all available pest control techniques and subsequent integration of appropriate measures that discourage the development of pest populations and keep pesticides and other interventions to levels that are economically justified and reduce or minimize risks to human health and the environment. IPM emphasizes the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms." Entomologists and ecologists have urged the adoption of IPM pest control since the 1970s.[2] IPM allows for safer pest control.

Read More

Oxalic Acid Vaporization

We do not recommend OA vaporization.

  • It is very dangerous to breath. You MUST wear a special chemical respirator.
  • It requires many sequential treatments to be effective.
  • It does not penetrate into capped brood, where much of the Varroa is.
  • It should be applied at dawn or dusk when most bees are in the hive.

The [[Oxalic Acid Dribble]] method is much more effective and does not require multiple, sequential applications.

Oxalic Acid Dribble

From BetterBee:
Oxalic Acid Dribble is a method that uses oxalic acid mixed with sugar syrup. It is applied using a large syringe to squirt the mixture onto the bees clustered between the frames.

The bees are not harmed by physical contact with the oxalic acid-laced syrup but, inevitably, they consume a small amount of the oxalic acid containing-syrup which is mildly harmful. For this reason, oxalic acid dribble is best done in a single treatment, not in a repeated series. This is particularly important in winter when individual bees must stay alive for a much longer time. Fortunately, during the brood pause, a single treatment is usually all that’s needed, so an oxalic acid dribble is a satisfactory option at this time of year. The method works best when there are only two boxes on the hive. It can be used when there are more boxes (such as in a hive made up of three or more medium boxes) but that makes for extra work.

Honey Supers: This treatment is most effective in the winter. Do NOT apply to honey supers. Only apply to brood boxes.
Temperature Range: none
* BetterBee Instructions
* Honey Bee Suite
* Randy Oliver – Oxalic Acid Treatment Table


Hopguard is manufactured by BetaTec. BetaTec research has discovered a natural hop compound that is highly effective in combating Varroa. HopGuard® II and HopGuard 3 are scientifically-proven natural Varroa control systems that provide the beekeeper with a natural, safe, and easy-to-use alternative to traditional harsh chemicals.

Each HopGuard 3 kit contains either 10 or 24 insert strips, ready for use.

Honey Supers: The strong smell may taint your honey.
Temperature Range: daytime temps > 50° F

  • Overview
  • Instructions
  • The daytime temperature should be above 50°F (10°C).
  • Use 2 strips per brood chamber (i.e. one strip per 5 frames of bees; two strips per 10 frames of bees)
  • Strips should be hung between brood frames.
  • Refer to the package label for full instructions.

Formic Pro

FORMIC PRO™ causes mortality to both male and female varroa under the brood cap as well as to the varroa on the adult bees. FORMIC PRO™ is to be used as part of an integrated pest management (IPM) program.

FORMIC PRO is an extended shelf life formulation (24-months) and doesn’t require any temperature-controlled storage.

Honey Supers: OK
Temperature Range: between 50° F – 85° F. Will cause bee mortality if over the specified temperature.
* Treatment Guidelines
* Application Video


  • Apivar is generally regarded as a safe, easy-to-use treatment option for Varroa Mites.
  • Do not use when honey supers are present according to the USDA.
  • The best times are early spring before flowers start to bloom and nectar starts to be plentiful, and in the fall after you’ve harvested your honey supers.
  • The Apivar strips need to be inside your hives for at least 42 days… so if you’re treating in the spring, treat in early spring.

Honey Supers: NO
Temperature Range: none
* Apivar Brochure
* How to Use Apivar Strips


Apiguard is a slow-release gel that ensures the correct dosage of its active ingredient, thymol. Thymol is a naturally occurring substance derived from the plant thyme.

According to the manufacturer:
Apiguard may taint honey in supers, but it is unlikely, especially if the honey stores are sealed. Apiguard may taint the brood wax, and low traces may reach the wax of the supers. Honey collected during Apiguard treatment can be fed back to the bees.

  • Honey Supers: The strong smell may taint your honey.
  • Temperature Range: works best above 60° F
  • Usage

Varroa Treatments


The following videos are highly recommended. Randy Oliver maintains a large apiary in Grass Valley, CA. His climate and conditions are similar to ours, unlike many other videos and resources on the web from beekeepers back east or in Canada. He does good science - he uses controls, data analysis, etc.



Treatments that are OK to apply with honey supers are highlighted green.

March  46 - 66 Apivar, Formic Pro, Hopguard, OA Dribble, OA Pads
April  49 - 71 Apivar, Apiguard, Formic Pro, Hopguard, OA Pads
May 52 - 77 Apivar, Apiguard, Hopguard, OA Pads
June 56 - 83  Apivar, Apiguard, Hopguard, OA Pads
July 58 - 88 Apivar, Apiguard, Hopguard, OA Pads
August 58 - 87 Apivar, Apiguard, Hopguard, OA Pads
September 56 - 84 Apivar, Apiguard, Hopguard, OA Pads
October 53 - 76 Apivar, Apiguard, Formic Pro, Hopguard, OA Dribble, OA Pads
November 46 - 65 Apivar, Apiguard, Formic Pro, Hopguard, OA Dribble, OA Pads
December 42 - 58 Apivar, Formic Pro, Hopguard, OA Dribble, OA Pads
January 42 - 59 Apivar, Formic Pro, Hopguard, OA Dribble, OA Pads
February 44 - 62 Apivar, Formic Pro, Hopguard, OA Dribble, OA Pads


  • Average temperatures are from here.
  • The above table is approximate, based on typical monthly temperatures and conditions. Please check the weather report, especially before using Formic Pro.
  • The Oxalic Acid Dribble can be used when honey supers are present, but it must NOT be used in the supers - it should be applied to the brood boxes only.