Oxalic acid Powerpoint presentation

Updated 15 January 2016 Updated oxalic acid ppt presentation

Since the EPA registered oxalic acid for the use in beehives (as far as I know, Brushy Mountain has the only registered product to date), I’ve been flooded with questions about using it (since I’ve used it steadily in my operation for over a decade).

Therefore, I’m making a Powerpoint presentation on using oxalic acid available. You may use this presentation at your local bee club meetings. Most of the slides are self explanatory, plus I’ve added notes to those needing more explanation. The presentation consists of 84 slides: oxalic view

If you use this presentation, I’d appreciate a donation to ScientificBeekeeping.com to help offset my time in preparation.

The Powerpoint presentation can be downloaded at: 2016 Oxalic acid

For those without Powerpoint, a pdf version is at: Oxalic pdf with comments Thanks to beekeeper Dan Lindamood III for taking the time to add my comments as sticky notes (they do not show fully in Chrome–you may need to open in another pdf viewer).

Update 29 Dec 2015: An email from a recreational beekeeper:

“Hey Randy, first let me thank you for all your good work and your ability to transfer information and making it palatable to newbies such it myself. Just want to drop you a quick line about Oxalic acid. This is not scientific–just a practical application advice. I’ve been using it for about a year and a half. Started out with the dribble method and had excellent results. My mite count is practically nil. I recently purchased the vaporizer and would like to make a couple of quick non-scientific observations. First being a backyard beekeeper I have to pull the battery out of my car and drag it out to the backyard hive locations. Treat my five hives and then return the battery to my vehicle and hope that it still has a charge to start my car up. No little task for an auto neophyte. Next if you’re using the vaporizer you can kiss your screen bottom board goodbye. It will most likely eat right through the screen and the heavy Styrofoam type removable bottom used in most commercial screen bottom boards. Next if you’re using plastic frames there an excellent chance that the intense heat will melt them. At least any in the immediate location of the heating element. Last but not least as you mentioned in your articles the fumes of the acid is intense and dangerous but with the added odor of any Bees that may have been cooked in the heating element the smell is pretty bad. Just my two cents of a couple of problems which I don’t ever recall being mentioned or spoken about.”

There are pros and cons to every treatment method, and the decision to dribble or sublimate OA is no exception. I’ve listed the pros and cons in the ppt presentation.

6 Jan update:

A team at the University of Sussex published an excellent paper (not yet published) comparing three methods of oxalic application: spraying each frame of bees individually, dribbling the “seams” of bees, or sublimation with a Varrox M3080 vaporizer. They tested the three methods at different doses of oxalic acid.

A brief take-home on their findings:

Spraying was effective, but tough on the bees, invasive, and time consuming, so I will discuss it no further.

Dribbling and sublimation were fairly comparable, with some notable differences.

At the 2.25 g dose (medium strength dribble, or typical sublimation dose), the efficacy at mite kill (in colonies completely lacking brood) was exactly the same. However, sublimation appeared to be somewhat more “gentle” to the colony, as evidenced by less bee mortality, and more brood in spring. Indeed, colonies appeared to tolerate a 4.5 g dose by sublimation

remarkably well.

Of particular note is that following January treatment, in early May sublimated colonies tended to have more brood (4.9 frames, compared to 3.9) than dribbled colonies. This suggests that sublimation has less of a lasting negative effect upon the colony than does dribbling (likely of greater impact in cold-winter areas with an extended period of dormancy).

Unfortunately, they did not compare a higher-dose dribble to the high dose vaporization. Nor did they take nosema samples, in order to determine the comparative effect upon nosema by treatment method.

Two other practical aspects are operator safety and the amount of time involved in application. The researchers wore vaporizers, but found that if they loaded the hot vaporizer with OA immediately before shoving it into the hive entrance, and then sealed the entrance with foam, that they were exposed to little escaping vapor. Unfortunately, this entails dropping oxalic crystals onto the hot vaporizer at each hive (a safety consideration).

As far as the amount of time involved in application, it took them 3 minutes per hive for sublimation, 2.5 minutes for dribbling. I do not know why it took so long for them to dribble since it takes me only 10 seconds to dribble a 10-frame colony (I apply at the calibrated rate of 1 second per seam of bees).

My take on their excellent studies is that dribbling or sublimation are both practical methods, each with advantages and disadvantages:

*Dribble is safer to the applicator (and quicker), but a bit harder on the bees. It may be the preferred method in climates with late fall and a short winter, due to its safety to the operator, quickness, and the colonies being able to rapidly recover.

*Sublimation may be the preferred method where winters are colder and longer, and the cluster is broodless for a longer period.

I have no experience with sublimation myself, following my initial test of the effect of inhaling a little oxalic vapor (resulting in gut-wrenching coughing). There are a number of simple vaporizers on the market (several available at http://oxavap.com/). However, when testing in Canada during cold weather, Dr. Medhat Nasr found that such vaporizers may overheat and degrade the oxalic acid (resulting in reduction of efficacy) or not adequately penetrate the winter cluster. He found through experimentation that the addition of a blower would help the vapors to penetrate the cluster. At this point, I make no recommendation for any particular vaporizer.

Category: Treatments For Varroa