Oxalic Acid Vaporizers and How to Use Them

Discovering mites in your hive can be a tough pill to swallow, luckily though, it doesn’t mean the end. There are many ways to get rid of mites in a beehive, however, most include pesticides which can be harmful to bees.

There is, however, one way to kill mites without killing your bees—that is by using an oxalic acid vaporizer.

How To Use An Oxalic Acid Vaporizer

What Is Oxalic Acid?

Oxalic acid, also known as oxalate, is actually a natural compound. It’s found in many nuts and vegetables, such as rhubarb, beets, and cocoa.

The human body can even produce oxalic acid on its own. While it’s good to have some amount of oxalic acid in your body, it’s not good to consume excessive amounts of it.

When the oxalic acid enters the body, it binds to minerals found in the body. It will then create compounds such as iron oxalate and calcium oxalate. This usually happens in the colon, the compounds are then disposed of in the stool or urine.

Oxalic acid can also form compounds within parts of the urinary tract or kidneys. This sometimes leads to kidney stones since it becomes difficult for the body to remove.

How Effective Is Oxalic Acid?

Varroa mites are a problem for beekeepers around the globe. They are small, red bloodsucking mites. Some bee experts refer to them as the bedbugs of beehives.

Varroa mites will bite a bee and then hang on to it while feeding on its fat. This weakens the bee as it loses vital fat and blood.

When inspecting your hive, you may notice black, brown, or red spots on the thorax or body of the bees. These are the mites that are feeding on your bees’ blood. If left untreated, varroa mites will cause fatal damage to your colony.

Varroa Mites on a bee

Oxalic acid has been used by European beekeepers for many years now. It has been shown that varroa mites are sensitive to different types of acids, such as lactic and citric.

The organic acid that they are most sensitive to is oxalate. No one knows exactly how it kills the mites—all we know is that it’s effective.

One theory is that it makes the mites unable to feed. Another theory is that it makes them unable to move around.

How to Use an Oxalic Acid Vaporizer

Using an oxalic acid vaporizer is actually quite simple, however, it can take a while. There are a few things you will need, these include:

  • A good oxalic acid vaporizer (here are my favorites)
  • Oxalic acid
  • A car battery
  • Protective gear, preferably gloves, glasses, and a mask
  • A crowbar or hive tool
  • Towel or cloth

Step One: Prepare the Vaporizer

I highly recommend laying out the things you need on a table or surface to make sure you have everything. Open up your oxalic acid, you can buy this at any hardware store or online. It’s important that you buy oxalic acid in powder form, liquid won’t work in the vaporizer.

On the vaporizer, there should be a long metal shaft followed by a small scoop, this is called the acid pan. You need to take about a quarter of a teaspoonful of acid per brood box and pack it into the pan.

If you have two brood boxes, as most beekeepers do, you should use half a teaspoonful. The amount of acid you use has to be accurate, too much could cause issues for the bees.

Step Two: Prepare the Hive

Before you begin to vaporize, it’s important to make sure the hive is ready. If you still haven’t harvested your honey, then it’s best to remove the honey supers before treatment.

This will also make the bees move further down into the hive. It’s essential that the oxalic acid reaches as many bees as possible to get rid of all the mites.

Next, you can use a crowbar or hive tool to lift the hive just enough to fit the vaporizer. You can easily slip a piece of wood in between the bottom board and first super. Remember to look out for any bees that might get crushed.

If you have a sticky board, you may want to slip it in at the bottom. By doing this, you can inspect the infestation once the treatment is over.

A sticky board is an insert that you can use in a Langstroth hive. It’s basically a rectangular piece of cardboard with a sticky side.

You insert it at the bottom of the hive, underneath the screened bottom. The mites will fall through the screen and stick to the insert.

Step Three: Protect Yourself

It’s crucial to wear protective gear when working with oxalic acid. Preferably, you should wear protective gloves and a respiratory mask to limit the fumes you might inhale. Protective eyewear is also important as direct contact could cause corneal damage.

Some beekeepers also like to wear protective gear to avoid stings, however, this may not be necessary. You won’t be handling the bees, and you actually only open the hive enough to fit the vaporizer.

Step Four: Begin the Treatment

All vaporizers should come with two cords—one black and one red. Connect the two to the battery, red to red and black to black. The vaporizer should then begin to heat up.

Insert the vaporizer into the hive entrance. To make sure the treatment is as effective as possible, you can seal the opening using a towel or cloth. Simply pack it in place around the vaporizer so the fumes won’t escape.

How long the treatment takes depends on the device you’re using. Some vaporizers have a digital display to show you the temperature it’s at. With others, you’ll just have to use a timer to know when it’s done.

It’s good to leave it in the hive for about two to three minutes, depending on your vaporizer. You can then take it out and check the acid pan.

If there’s a lot of acid left, you can stick it back in. If it’s empty, the treatment is done and you can move on to the next hive.

What we have explained is a passive vaporizer, but there is another type called an active vaporizer. These aren’t as popular as the passive, but let me explain how it works.

It’s a bigger device that includes a fan that blows the fumes into the hive. You, therefore, won’t have to insert anything into the hive. An active vaporizer is a popular choice for winter treatments.

During the cold months of winter, honeybees cluster to keep warm. They do this by forming a big group, or cluster, of bees. The bees will use their combined body heat to keep the nest warm and toasty.

A passive vaporizer can have a difficult time penetrating the cluster. The active vaporizer will simply blow the oxalic acid into the hive and onto the bees.


Finding mites in your hive is never fun, but by using oxalic acid you can get rid of them safely. Oxalic acid is a natural compound, in fact, there’s a small amount of it already present in beehives. It’s highly effective when treating your hive for mites, however, how it kills them is unknown.

You have to be careful when operating an oxalic acid vaporizer. Not only are you dealing with high volts of electricity, but you’re also dealing with heated acids. Accidents have occurred where the acid has splattered, and therefore, we advise that you wear protective gear.

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