Using Oxalic Acid Vaporization in Beehives
Oxalic Acid Vaporization is one of the best tools in the beekeeper’s fight again varroa mites – a major pest of bees. A naturally occurring substance, oxalic acid, is an effort to step away from the use of synthetic chemicals in beehives. Varroa control is essential for successful beekeeping.
When varroa mites arrived in our country, the face of beekeeping was changed forever. These external parasites of honey bees weakened and killed thousands of colonies.
Many large bee companies went out of business and almost all of the feral or wild bee colonies died. Since the mid 1980’s, the fight between varroa mites and beekeepers has raged.
One of the biggest challenges of varroa mite control is this: How do you kill a mite living on a bee? The honey bee and the mite share some common characteristics.
How can we kill the mite and not harm the bee? What about chemical residues left behind in the honey and beeswax? Humans eat products that are harvested from the hive.
What is Oxalic Acid?
Oxalic Acid is an organic compound that occurs naturally in nature. It is a white crystalline solid that is colorless in water. You will find it in such things as: peanuts, sweet potatoes, wheat bran and pecans.
Some oxalic acid is even found in honey. Also, because it is not fat soluble it does not build up in the beeswax comb.
But just because it is a natural organic compound, that does not mean it is not powerful. Oxalic acid is several thousands times stronger than vinegar.
It is bitter to the taste and irritating to the nose and mouth. Beekeepers should use proper protective wear when using this or any other acid.
Oxalic Acid (OA) has been used by European Beekeepers for many years. With reports of 90-99% efficacy in killing mites, they found it be a useful tool in the fight with varroa. It was only approved for use in the US in the last few years.
Products available in stores are labeled for use in beehives. Some beekeepers use generics too.
How Oxalic Acid Helps Control Varroa Mites
We know that oxalic acid kills mites. It is about 70 times more toxic to varroa mites than honey bees.
There is still debate over the exact way mites are killed. Whether it is through inhalation of the vapor or direct contact with spiky dried crystals.
Either way, we do know that it kills varroa mites with minimal dangerous affects on the bees.
There are (at this time) 2 approved methods of using oxalic acid for mite control.
Dribble Method of Using Oxalic Acid
In the dribble method of using oxalic acid, the acid is mixed with warm 1:1 sugar water (equal parts of sugar and water). Then, the mix is sucked up into a syringe and 5 ml is applied between each of the frames in the hive – directly wetting the bees.
Care must be taken to not use more than a total of 50 ml per colony and of course you would adjust for smaller colonies.
Because the dribble method is hard on the cuticle (exoskeleton) of the bees’, it should only be done 2 times a year.
Vaporizing Oxalic Acid With a Heated Wand
Another method is “oxalic acid vaporization“, Oxalic Acid crystals are placed on a special wand. The wand is inserted into the hive and heated to vaporize the crystals.
There are many types of wands available to purchase. Some work great but as expensive, some are more affordable and work okay and others are pieces of kaka.
The wand I currently is called the Varrox from Oxavap. It has held up for many years and is still working great.
When Should Your Treat Your Bees?
It doesn’t matter what time of day you do your treatment. But, I think the hives are less fussy early in the morning.
With vaporization we are not trying to coat the bees, rather we are injected the vapor into the hive. As foragers come and go they will be exposed to the treatment.
Following all safety precautions as set forth on the Oxalic Acid label-proceed with the following steps.
As for time of year, do your mite counts this is the only way to know the level of varroa infestation in your hives. Count again after treatment to make sure you were successful.
How to Use Oxalic Acid Vaporization
This is an overview of one way to use oxalic acid with a vaporizer in your bee yard. Please use appropriate safety gear to protect your skin and lungs. Do NOT inhale the vapor – do not.
Let’s gather our materials and head out to the apiary.
- safety gear – as directed on OA label
- oxalic acid crystals
- oxalic acid vaporizer
- power source for vaporizer
- measuring spoon
- bucket with cool water (if your model allows cooling)
- rags, old towel, etc – to use as temporary plugs
- grid board – if you have screened bottom boards
You should keep most of your oxalic acid vaporization tools together. I use an old plastic cat litter tub. Anything will work.
Oxalic Acid Vaporization Steps
- insert grid board under screened bottom boards
- Remove hive top and loosely plug the hole in the inner cover
- measure the required amount of oxalic acid and place on cold wand
- slowly insert vaporizer wand into the front of the hive
- lay an old towel (or similar) across the front
- connect vaporizer to power source
- set your timer (2.5 – 3 min?) time depends on vaporizer model
- energize the vaporizer and stand upwind from the hive
- at the end of the timer, let the vapor cool a few minutes before removing the wand
- wait an additional 8-10 min before opening all the entrances and ventilation ports
Using Oxalic Acid When Brood is Present
No varroa mite treatment is perfect. Oxalic acid treatments only kill phoretic mites. Those are the foundress mites that are riding around on the adult bees.
Most of the time, the majority of mites in a hive will be inside the capped brood. Oxalic Acid does not kill mites under the cap.
This is why many beekeepers only use Oxalic Acid during times when the colonies are broodless – such as late Fall/Winter.
Killing Varroa Mites With Oxalic Acid When Brood is Present
For many Southern beekeepers, finding a natural treatment to use for mite control is very difficult.
Some of the other “softer mite treatments” are temperature sensitive. At the time of year when I really need to treat my colonies, it’s too hot.
By the time the daily temps cool down, my colony may already be dead or so infested with mites that it has one foot in the grave.
To overcome this challenge, we do 3 vaporization treatments that are 4-6 days apart. In this way, as more mites emerge with new bees -most of the mites will be out of a cell and exposed to one of the treatments.
How many times a year do you need to treat for varroa mites with oxalic acid? It depends on several factors including the genetics of your hives and where you live. Mites are a bigger problem in some regions.
Whenever, you treat your colony be sure to recheck in a couple of weeks to make sure it worked!
Final Thoughts on Using Oxalic Acid In Beehives
For now, there is no perfect way to kill the mites in your colony. All treatments has some negative effect on the bees or the comb and honey inside.
But, doing nothing is not an option as varroa will eventually kill the colony. Oxalic Acid Vaporization is an effective way to manage varroa mite numbers in your beehives.
Use all safety precautions and recheck your colony for effectiveness a couple of weeks later.