As we have seen in the previous article, and as detailed by recent scientific research (at Toufailia et al. 2015), the sublimation (vaporization) of oxalic acid is one of the best methods to control the infestation of the Varroa Destructor.
In this guide, Oxalika expert technicians explain the treatment process with oxalic acid vapors in detail. What is needed, how to prepare, when to perform treatments, and other important information for beekeepers.
How to carry out oxalic acid vaporization treatment?
Detailed information on how to carry out the treatment with oxalic acid vaporization depends mainly on the type of vaporizer used. It is crucial to strictly follow the instructions given in the respective user manuals to obtain maximum efficiency without endangering the health of the bees and the operator himself.
In this article, we will give you essential tips by comparing different types of vaporizers so that it is easier to choose the model that best suits your needs taking into account the specific methods of use.
Carrying out the treatment
The execution of the oxalic acid treatment and the necessary material depends on the vaporizer model and the type of oxalic acid-based drug used.
For example, you will need a battery if you use a 12-volt model. If, on the other hand, the model works at 110 or 230 Volts, it will be necessary to have a generator capable of supplying the required voltage. It is essential to have an adequate feeding system for the vaporizer.
The type of respiratory protection devices also depends on the vaporizer model and the number of hives treated.
With some vaporizer models, e.g., OXALIKA START and OXALIKA BASIC, oxalic acid is put in the cup when the vaporizer is cold. Connect the vaporizer to the battery only after inserting it in the hive and sealing it. This procedure allows the beekeeper to move away and arrange himself so that the wind drives away any vapors that could escape from the hive. In this case, an anti-particulate mask and, therefore, of the N95/FFP2 type is acceptable to protect the respiratory tract.
Note
If the vaporizer requires the operator’s presence even during the vaporization phase, it is evident that the protection for the respiratory tract must be higher. You will need a mask with filters suitable for organic acid vapors, such as ABE.
If the number of hives to be treated is limited, you can opt for a semi-mask to protect the respiratory tract and opaque glasses to protect the eyes. This solution is unsuitable if you have many hives to treat because, after some minutes, the glasses will tend to fog up. If You have many hives, the best choice is to use an entire mask equipped with an anti-fog system.
Some are cordless and run on 18-volt Li-Ion batteries, some sublimators run on 12 volts, and some run on 110 or 230 volts. How do I choose one suitable for me?
18 Volt vaporizers (no cable) with Lithium Ion battery
These are the newest models and are the best in terms of user convenience. The OXALIKA PRO CORDLESS model is available with different adapters for the batteries of the most common 18-volt power tools (Bosch, De Walt, Makita, Einhell, etc.) and comes with 3 differently spout to suit the most demanding beekeepers. For example, by configuring it with the curved spout facing downwards, you can also treat bees in nuc boxes with sublimated oxalic acid by making a hole in the lid of the nuc box or using the hole for the feeder. If the nuc box is made of polystyrene you must place a thin wooden board between the nuc box lid and the vaporizer. The wooden board must have a hole to allow the spout to pass through.
There are also additional spouts for both treatment from the back of the hive and the bottom entrance.
12 Volt Vaporizers
Usually, cup vaporizers work on 12 volts. The OXALIKA PRO professional vaporizers are available at 12 volts, 110 volts, as well as 230 volts. You must choose based on your needs and the type of apiaries you will operate.
Fundamental to keep in mind: you can’t extend the power cable of 12 Volt vaporizers. Increasing the power line length would be like powering the vaporizer with an almost empty battery.
Considering this: with a 12-volt vaporizer, it is necessary to have the battery with you. No problem if the apiary is in a flat field and you can use perhaps a tiny trolley, even though very uncomfortably if the apiary is in an unstable environment, and you have to carry the battery by hand.
High voltage Vaporizers (110-230 Volt)
With vaporizers operating at the main voltage (110 or 230 volts), it is possible to use cord extensions. You can get main voltage power in three different ways:
- By connecting directly to a power outlet. If you are lucky enough to have the apiary nearby, you can use an extension cable to reach the hives;
- Utilizing an engine generator positioned near the apiary and an extension to get the hives;
- Using a battery set near the apiary and an inverter capable of transforming the 12 Volt voltage into 110 or 230 Volt mains voltage. After that, you can connect the extension cable to the inverter socket. With this solution, a part of the battery charge will be absorbed by the inverter; therefore, the number of treatments that you can carry out with one full charge will be less.
What if I have already purchased a 12 Volt vaporizer and find it inconvenient to carry the battery with me?
No problem! In this case, you can use a power supply device to transform the mains voltage (110 or 230 Volts) into 12 volts. It is much lighter than the battery and more comfortable to carry with you.
For example:
How Do I Choose the Right Type of Oxalic Acid?
Remember that the law of the country in which you operate must permit the use of oxalic acid-based drugs. For example, the only oxalic acid-based drug allowed for vaporization in Italy is API-BIOXAL. Different medicines or even pure oxalic acid may be permitted in other countries.
How do I choose the vaporizer considering the type of oxalic acid?
Some types of oxalic acid-based drugs can leave encrustations in the vaporizer. Suppose you use a kind of acid that leaves residues. In that case, you must purchase a vaporizer explicitly designed to facilitate the removal of these stains, for example, the OXALIKA PREMIUM model or the OXALIKA PRO EASY model.
The acid’s impurities or the excipients in oxalic acid-based drugs cause fouling and stains.
The oxalic acid found on the market is never 100% pure. However, some types have a high purity rate, higher than 99.6%. This guide uses the term pure to refer to acids with a purity greater than 99.6%.
Choose your vaporizer
When choosing your vaporizer, you should keep in mind that the impurities present in the acid could leave residues in the cup in the form of encrustations. You must remove these encrustations before they harden and become thick enough to prevent the vaporizer from functioning correctly.
You can use a specially designed tiny brush with stainless steel bristles for cleaning your vaporizer.
It is imperative to consider that oxalic acid tends to absorb moisture. Oxalic acid that has absorbed water tends to make significant, consistent bubbles during vaporization and stick to surfaces (for example, the walls of the jar containing it). This feature can interfere with the correct functioning of the OXALIKA PRO FAST model, as moist oxalic acid tends to jam the dosing mechanism.
A simple trick for proper cleaning after the last treatment: after disconnecting the power supply, with the cup still hot, drop small quantities of distilled water into the cup. The rapid boiling will cause the detachment of residues without leaving limescale deposits.
How much oxalic acid should I put in the vaporizer?
It depends on the size of the hive to treat, and other factors described extensively in a previous article.
How long does the vaporization process take?
Below are the values for the OXALIKA oxalic acid vaporizers:
- Oxalika Basic – Oxalika Start
- It takes 3 minutes to evaporate 2 grams of oxalic acid. Cool the cup in water before proceeding with subsequent treatment. The total time between one treatment and another is approximately 5 minutes. These are vaporizers suitable for those with few hives (5-10)
- Oxalika Premium
It takes 1 minute and 30 seconds to evaporate 2 grams of oxalic acid. Thanks to its temperature control, there is no need for cooling between treatments. It is suitable for beekeepers who have up to 100 hives. - Oxalika Pro Cordless 18 Volt (no cords)
The most convenient and versatile. 15 seconds for 1 gram 30-35 seconds for 2 grams. - Oxalika Pro Easy
Fast treatment without interruption.
Ten seconds for 1 gram and 20-25 seconds for 2 grams. - Oxalika Pro Smart
With quick-loading valve.
The easiest and fastest to use. - Oxalika Pro Fast for Tablets
A professional vaporizer equipped with a dispenser for oxalic acid tablets. t allows the choice of the dose in multiples of 1 gram between one treatment and the next. 10 seconds for 1 gram.
How does oxalic acid work on mites?
The process by which oxalic acid kills Varroa mites is still not fully understood. The most common scientific opinion is that Varroa absorbs oxalic acid vapors through the soft tissues and appendages (legs). From here, oxalic acid enters the bloodstream of the mite, poisoning it. Other research indicates that oxalic acid can also damage the mite’s mouth. In any case, oxalic acid kills Varroa effectively.
Should I close the hive during the treatment?
Even if a good “watertight” closure is unnecessary, it is advisable to close the hive. Our advice is to seal the hive’s entrance with a damp cloth during the vaporization process and keep it plugged for about 10 minutes after the end of the treatment to maximize the effect.
One way to reduce oxalic acid leakage without sealing the flight opening is to treat from the back of the hive by making a hole for the inlet of the vaporizer spout on the side wall of the inner cover. It would be best if you turned the inner cover upside down. This will also be the most comfortable solution for the operators as they can operate without arching their backs with each treatment.
In case of dispersion of oxalic acid outside the hive, it is advisable to increase the dose slightly.
What is the ideal environmental temperature for treatment?
The environmental temperature for oxalic acid vaporization should not be less than 3ºC. There is no maximum temperature. The minimum temperature of 3ºC is necessary only during treatment and the first 2 hours following.
(Source: https://www.dadant.com/)
What is the best time to perform the treatment?
Since the Varroa reproduces more in spring and summer, in the presence of a brood, the best time to carry out the treatments is autumn-winter. During this period, when there’s an almost total absence of brood, about 80% of Varroa is in a so-called “phoretic” state, i.e., the mites are on the body of adult bees. For this reason, Varroa is more exposed and, therefore, much more sensitive to treatments with oxalic acid.
These are the most suitable times for treatment:
- At the beginning of winter, between the end of November and the Christmas period (northern hemisphere);
- Early in the morning or in the evening, when most of the bees are in the hive;
- When you buy a new swarm of bees;
- In all those cases in which there are no capped brood cells, for example, a few days after swarming, after a block of natural or artificial brood, on the swarms.
Use oxalic acid in the summer.
As we have seen, there is no maximum temperature for the sublimation of oxalic acid. We must consider that brood presence is usually inside the colonies during summer. Therefore, most of the mites will be hiding inside the brood cells. In this sense, performing sublimation treatments with oxalic acid during the summer can be helpful as a containment and prevention measure.
How to use the vaporization procedure to count phoretic mites
You can also perform oxalic acid vaporization as an alternative to counting with powdered sugar or washing with alcohol. Perform the vaporization treatment, inserting a special adhesive sheet on the bottom of the hive. After two days, the sheet will have collected about 95% of the phoretic mites. This way, you can approximate the number of mites in the hive, considering that the brood cells can contain 80-85% of the mites. You can then make an informed decision about when and how often to perform a new treatment.
How often can I carry out the vaporization treatment with oxalic acid?
Although oxalic acid is a natural substance, an excessive dose can cause damage to your bees. For this reason, it is essential to follow the indications of the drug manufacturer and refer to the guidelines of local associations for the mode of treatment.
An effective strategy to maximize the result can be to make an artificial brood break. This way, all mites will move to the body of adult bees and, therefore, will be exposed to treatment with oxalic acid.
You can consult our in-depth article for more information on oxalic acid treatments.
Is oxalic acid toxic to bees?
A 2017 scientific research showed that oxalic acid administered with an aqueous solution (drip method) could represent a health hazard for bees. On the contrary, the researchers have shown that bees tolerate, without obvious health problems, the administration of sublimated (vaporized) oxalic acid at a concentration equal to 175 µg of oxalic acid per bee.
(Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620704/)
Precautions and advice
Oxalic acid is naturally present in honey in tiny quantities. The percentage of oxalic acid in honey increases considerably for a few days after anti-Varroa treatments.
Oxalic acid ingested by bees in high concentrations can cause behavioral damage and shorten the life of your bees. This danger is especially true of treatment methods such as drip, in which oxalic acid is mixed in a solution of water and sugar. Nevertheless, the possibility of ingestion also exists with vaporization. For this reason, we advise you to stick to the quantities and timing indicated above without exaggerating.
Can I use oxalic acid with mounted supers?
No. Oxalic acid, even when vaporized, can leave residues and contaminate honey. We recommend removing the supers before treatment with oxalic acid and waiting 1-2 days before reassembling them. The pause eliminates any residual oxalic acid from the hive and avoids contamination of the honey.
What is the difference between oxalic acid and other treatments?
The first big difference is that although oxalic acid has been used for more than 20 years in Europe (and since 2015 in the US), Varroa does not appear to have developed resistance to oxalic acid. The second significant difference is the cost of the treatment. With alternative drug treatments, the annual cost can quickly go up to 10 times what you would spend on oxalic acid. This also includes the price of the vaporizer.
Conclusions
Oxalic acid is an effective natural acaricide. Although harmful to humans and, in high quantities, also to bees, by following the instructions in this article, you will be able to work safely and obtain the maximum effectiveness of the treatment.
Oxalic acid acts against Varroa through contact with soft tissues and the mouth. Vaporizing remains one of the best methods for treating hives with oxalic acid. Vaporization allows an easy, effective, and fast anti-Varroa treatment.