Introduction
The Threat of Varroa
A concern across most of the beekeeping world, beekeepers should have a plan for combating the threat of the Varroa destructor mite. First detected in the early 20th Century and subsequently spreading across the globe, the Varroa mite made its way to the United States in 1987.
Left unchecked, this parasitic mite can spread viruses to the bees in your colony and weaken bees by feeding on the underlying fat body tissues of the bees themselves, potentially even causing the colony to completely collapse.
As responsible beekeepers keep in mind that a Varroa outbreak in our colonies can easily be spread to other colonies, well beyond our own bee yard. As such, it’s worth keeping up with Varroa not only for our own benefit, but for the benefit of the bees and for others in the beekeeping community as well.
A Multi-Faceted Approach
Completely eliminating mites within our hives is an unrealistic goal. Provided they are kept below critical levels, bees are very capable of co-existing with Varroa. However, problems occur when mite counts rise above critical levels and our bees are unable to fend off the growing threat. This is when it’s up to us as beekeepers to step in.
Fortunately we have many options at our disposal to fight back against Varroa. These options include the selection of bees that show mite-resistant behaviors, integrated pest management techniques (IPM), and commercially-available Varroa treatment options.
Regular inspections of your colonies, including implementing a regular and effective mite monitoring program, provide actionable information, supporting informed decisions about the application of mite treatments. Additionally, this before-and-after data critically shows a beekeeper the effectiveness of any treatment applied.
Varroa strategy is unique to each beehive and each beekeeper – and due to the ubiquitous nature of Varroa some beekeepers even treat on a set schedule regardless of mite counts as a preventative measure. Others have a keen interest in natural beekeeping and may pursue a treatment-free approach.
Many beekeepers are attracted to the benefits of a natural approach to beekeeping, but only to the extent their bees have a fighting chance of survival. A blind, uninformed adherence to avoiding all treatments is a recipe for disaster, especially for the new beekeeper.
PerfectBee strongly recommends that a treatment-free approach is considered only after building considerable experience as a beekeeper and with a full awareness of the implications, both in and away from the hive.
Whatever your strategy, a full understanding of the Varroa life cycle only helps and – as with all things beekeeping – the more information you have when making decisions, the better. Realistically, however, you can at best expect to help your bees control – but not entirely eliminate – Varroa.
It is also worth mentioning that Varroa have shown a remarkable ability to adapt and build resistance to treatments. It can generally be assumed that a small number of mites will survive a mite treatment. If they do so because they have developed a resistance to a particular treatment, then the offspring of those mites are also likely to be resistant.
Over time, this can result in a Varroa population that is resistant to a treatment. Many beekeepers tackle this by alternating treatments, on the basis that mites that are resistant to one treatment may well be killed by another treatment.
In this article we’ll examine commercially available treatment options, explain how they work and evaluate the pros and cons of each treatment.
Natural Treatments
Apiguard
Available in the PerfectBee Store
Apiguard, which is manufactured by Vita-Europe, is a thymol-based gel that beekeepers purchase in ready-to-go trays. Simply peel off the top and put in the hive on top of brood frames. For larger applications, the product can also be purchased in a more commercially-oriented tub.
How it Works
Thymol, naturally found in the oil of thyme, is very aromatic and has strong antiseptic properties (it is in fact, used in some natural hand sanitizers). With Apiguard, Vita-Europe has taken the natural active ingredient (thymol) and combined it with other ingredients to make a slow-release, thymol gel. When placed in a hive, thymol vapors are released.
Additionally, bees work to remove the foreign substance, subsequently coming into contact with the thymol gel. Through their natural movement they transport it throughout the hive, killing Varroa along the way. How thymol works as a pesticide is not completely understood, but it is thought to bind to various neurological receptors in the mite, resulting in a neurotoxic effect. Apiguard treats phoretic mites (mites attached to adult bees) and does not penetrate cell walls to kill Varroa in capped brood.
Treatment Regimen and Usage
Due to the odiferous nature of thymol, Apiguard should not be used with honey supers on the hive and the manufacturer suggests a summer or fall treatment. Temperatures should be above 60F but below 105F. Apiguard can be used in the spring if desired, but it is not recommended as the product can cause a queen to stop laying for a period of time – typically undesirable during this time of the beekeeping season.
The standard dosage of Apiguard is 50 grams, followed by another 50 gram dose 2 weeks later. However, above 77F 25 gram doses at 1-2 week intervals (up to 4 doses) is suggested. A 25 gram dose can be achieved by using the Apiguard tub, cutting 50 gram trays in half (use the other half for another hive), or by purchasing the product in the 25 gram sachet. As with any mite treatment, read the safety information first, and follow the directions on the label exactly.
Considerations
Apiguard is marketed as a natural treatment. While the active ingredient in Apiguard is natural and the product is approved in the European Union for organic beekeeping (no organic certification currently exists in the United States), Apiguard does contain other synthetic – although food safe – ingredients. At this time, Varroa has not exhibited any known tolerance to thymol. Keep in mind, though, that the product is a bit of a shock to the hive. Some distress and bearding may be observed, particularly in warmer temperatures. Thymol will accumulate in wax, some of which will evaporate over time due to the volatility of the compound.
ApiLifeVar
From the makers of Apivar (detailed later), this is a natural thymol, eucalyptus oil, l-menthol, and camphor oil based product. These natural oils use a porous synthetic tablet as a carrier device.
How it Works
The natural active ingredients in ApiLifeVar work in a similar fashion to Apiguard, and according to literature from the manufacturer, the primary anti-mite action of the product is via its thymol component. When placed in a hive, the vapors of the product fill the hive, and bees additionally come into physical contact with the wafers. Both are mechanisms of action by which the product works against Varroa. ApiLifeVar is a phoretic mite treatment.
Treatment Regimen and Usage
Temperatures must be between 64 and 95 degrees Fahrenheit to use ApiLifeVar, and you can treat up to twice yearly. Application is performed by opening the package and breaking the tablets into 4 pieces (read the directions carefully for guidance on how to do so), and then placing these pieces around the corners of the brood box on top of the frames.
After 7-10 days, you replace these tablets with fresh tablets, wait another 7-10 days and replace again, leaving the last set of tablets in place for 12 days, removing at the end of the treatment period. The product cannot be used when honey supers are in place and must be removed at least 30 days prior to any harvest.
Considerations
As with other thymol-based treatments, bearding may occur and the bees may show a negative reaction to the introduced vapors, which is more apparent in warm or hot weather. As a thymol based product, some wax accumulation can occur with the ApiLifeVar.
Formic Pro
Available in the PerfectBee Store
Formerly offered as Mite-Away-Quick-Strips, or MAQS, Formic Pro is an updated formic acid-based Varroa treatment offered by NOD Apiary Products in Canada. This natural organic acid can be found in ants, and is even naturally found in honey in low amounts.
How it Works
When the Formic Pro strips are placed in a hive, the active ingredient (formic acid) is released over time. These vapors infiltrate the hive, not only killing Varroa mites attached to adult bees, but the vapors also penetrate into capped cells to kill Varroa in capped brood. As such, this treatment is not limited to phoretic mites.
Treatment Regimen and Usage
Formic Pro is applied by way of strips placed on top of brood frames. Daytime high temperatures should be above 50F and below 85F on the first day of treatment, and temperatures above 92F are to be avoided during the first 3 days.
Beekeepers have 2 options for utilizing Formic Pro. Method 1 involves placing two strips in the hive for 14 days. Method 2 involves placing 1 strip in the hive for 10 days, then placing another in the hive for an additional 10 days.
Formic Pro strips contain formic acid in a gel matrix, and this product’s ingredients – active and inactive – are all natural and certified in New Zealand as an organic mite treatment. Formic Pro can be used with honey supers on the hive, and not only kills phoretic mites, but the formic acid vapors will penetrate capped brood cells as well. Varroa is not known to have yet developed any tolerance to formic acid. Formic acid does not accumulate in beeswax.
Considerations
While Formic Pro is intriguing due to its all-natural nature, ability to be used when honey supers are on the hive, and for its ability to penetrate to capped brood, it is very temperature sensitive and can be hard on your bees and queen. Keeping a close eye on the forecast and being absolutely sure the weather will not exceed the appropriate temperature ranges for Formic Pro is critical. A full width bottom entrance is required for ventilation, and placing an empty super on top of the hive is suggested. You must have at least 6 full frames of bees to treat with Formic Pro – so if you’re looking to treat a 5-frame nuc you’ll have to look elsewhere.
HopGuard 3
Now in its 3rd version and marketed as HopGuard 3, this product is manufactured by BetaTec Hop Products (a company focused on the various uses of hops for beekeeping and beyond). HopGuard uses strips impregnated with concentrated compounds from hops.
How it Works
HopGuard is a contact application, working when bees come into contact with the strips containing the hop beta acids and then spread the product throughout the hive. Hopguard does not penetrate into capped cells and thus only treats phoretic mites.
Treatment Regimen and Usage
To use HopGuard 3, you’ll insert the HopGuard strips between brood frames using 2 strips for every 10 frames of brood-chamber bees. Temperatures must be between 52 and 92F, and application is more effective during those times of the year when less brood is present in the hive.
Back-to-back treatments, 14 days apart are suggested by the manufacturer for maximum efficacy, and you can use HopGuard 3 up to 4 times a year. HopGuard 3 can be used with honey supers on, but only treats phoretic mites and the manufacturer suggests an early spring and / or late fall treatment after the honey flow.
Considerations
The active ingredient (hop beta acids) is a natural treatment, while the remaining composition of HopGuard 3 consists of other synthetic components that are all food grade. The treatment has been known to affect bees and cause bearding, especially in hot weather. The manufacturer claims a 70-85% efficacy rate for Varroa reduction. In limited studies, hop beta acids have been shown to accumulate in wax and comb in low amounts, and the label warns to never utilize wax or honey from brood chambers after product application.
Oxalic Acid
Quickly gaining popularity in the beekeeping community, oxalic acid – as with formic – is an organic acid found in nature that is very effective against Varroa when used properly. Oxalic acid is naturally found (in small amounts) in green leafy vegetables like spinach and rhubarb, and can be found in particularly high concentrations in wood sorrels. Available in a crystal formulation from Api-Bioxal, oxalic acid is applied to a hive by utilizing an oxalic acid vaporizer.
How it Works
When oxalic acid is vaporized, the resulting vapor completely fills the hive. The vaporized oxalic acid enters the mite (it is believed via their feet and / or through the mouth of the mite), killing phoretic mites. It is believed by many that oxalic acid vaporization continues to work in the hive with a dwindling residual effect for up to several days. Oxalic acid does not penetrate cell walls and therefore does not reach capped brood.
Treatment Regimen and Usage
To utilize oxalic acid you’ll need to set yourself up with some oxalic acid equipment: the aforementioned vaporizer, an organic acid respirator, other personal protective equipment / PPE, and a power source – beekeepers have used everything from extension cords (if you’re close to the house), to car batteries and portable power stations.
The oxalic acid crystals are heated, turning into a vapor that permeates the hive and has a very high efficacy against phoretic mites. The process is often referred to as “OAV”, standing for oxalic acid vaporization.
Oxalic has no upper temperature limit. On the low side, temperatures warm enough so that the bees are not clustered is suggested. Due to the fact that oxalic is somewhat of a flash treatment and only kills phoretic mites, you will either need to treat when the colony is broodless or treat repeatedly on a fairly strict schedule. In these situations treating 3 times at 5 day intervals is often suggested, but many beekeepers alter this schedule slightly or add a 4th treatment.
Lore varies, but the general idea is to treat over an entire Varroa life cycle, and to treat for those mites that were protected inside sealed brood once they emerge and before they can reproduce.
Oxalic is applied at a rate of 1 gram per brood chamber, and label amendments are currently underway that will permit application with honey supers in place – but this has not yet been finalized.
Considerations
While found in nature, oxalic can be highly toxic to humans, if the vapor is inhaled or consumed in a concentrated form. It should also cause a nasty burn to skin or in the eyes.
Oxalic is known to be easy on your bees and well-tolerated by the hive. Once you have the appropriate equipment, treatments are cost-effective. However, oxalic acid does not work for mites within sealed brood. You’ll also need electric power, additional application equipment, and additional protective gear to utilize OAV. The product is not known to accumulate in wax and comb.
You can read more about the use of Oxalic Acid in our article “A Beekeepers Guide to Using Oxalic Acid“.
Sucrose Octanoate
Included here mostly as a history lesson, sucrose octanoate is not currently a mite treatment method available for purchase, but remains on the EPA registered pesticide product list for Varroa treatments. This product was marketed to beekeepers 15-20 years ago and consisted of sugar esters, created by reacting sugars with fatty acids.
How it Works (or worked)
The product was available as a liquid product that, using a sprayer, was sprayed on every frame…or rather, every bee. When the solution contacted phoretic mites the solution would break down the mite’s exterior cuticle and cause dehydration.
Treatment Regimen and Usage
The time-intensive spraying process had to be repeated weekly, only affected phoretic mites, and was found to only be marginally effective.
Considerations
While Sucrose Octanoate is, at least for the time being, relegated to the history books it remains on the EPA list of approved treatments for the Varroa mite. It is possible that it may reappear in some form in the future, but at this point that seems unlikely. That said, if it ever comes up in a beekeeping trivia event, now you know.
Synthetic Treatments
Apistan
Distributed in the United States by Zoecon, Apistan is a synthetic chemical treatment utilizing tau-fluvalinate, a synthetic miticide.
How it Works
2 strips are inserted into the hive between brood frames at the end of the season for 6 weeks, during which time bees within the colony come into contact with the active ingredient, spreading it throughout the hive. Fluvalinate disrupts the nervous system of mites, causing the paralysis and death of phoretic mites.
Treatment Regimen and Usage
The application rate is 1 strip per 5 combs of brood chamber bees, and daytime high temperatures must exceed 50F. The strips are to be left in place for at least 6 weeks but not more than 8. An early fall, post-honey-flow treatment is suggested. Honey supers cannot be in place during treatment.
Considerations
Fluvalinate is (in the amounts released by the plastic strips), relatively non-toxic to honey bees (the product is more toxic to mites, and very toxic to some aquatic animals). However due to incorrect and / or over-use, the Varroa mite has now developed a resistance to Apistan. If you still choose to utilize this product, it should be utilized only when you know you have an active Varroa problem and only in rotation with other products. Apistan is known to accumulate over time in beeswax.
Apivar
Offered by Veto-pharma, Apivar is a polymer strip containing the synthetic miticide Amitraz.
How it Works
Once placed in the hive, the active ingredient is released over a minimum of a 6 week period. Bees that contact the active ingredient on the strip spread it throughout the hive. Mites exposed to Amitraz are paralyzed, and the process kills phoretic mites throughout the treatment period.
Treatment Regimen and Usage
The product is utilized in a 2 strip per brood-box format (1 strip per 5 frames of bees), that are to be left in the hive for 42 days (not to exceed 56 days), and cannot be used more than twice a year. Honey supers must be removed prior to and during treatment. Treatment can take place in spring or fall, but must be removed 2 weeks prior to the start of the honey flow.
Considerations
The EPA has classified Amitraz as a possible human carcinogen and as with Apistan, it is toxic to aquatic life. Recently, Varroa has also started to demonstrate resistance to Apivar / Amitraz, and if you choose to utilize Apivar in your mite-treatment plan, the manufacturer suggests utilizing the product in a rotation with other mite-treatment products and to follow the directions, exactly. Amitraz is an unstable chemical in the hive and is not known to directly accumulate in beeswax in significant amounts. Rather, it quickly breaks down into other degenerative chemicals that have been shown to accumulate in wax in measurable amounts.
CheckMite+
Manufactured by Bayer, CheckMite+ utilizes coumaphos as the active ingredient, a synthetic organophosphate insecticide first registered as a pesticide in 1958.
How it Works
CheckMite+ is a phoretic treatment. These types of insecticides work by interrupting the nervous system of insects.
Treatment Regimen and Usage
1 strip per 5 frames of bees is again utilized, and this option is most effective when little to no brood is present. You must remove honey supers before starting treatment. The strips are left in the hive for 42 days, not to exceed 45, and you can treat a maximum of twice a year with CheckMite+.
Considerations
These types of pesticides are not known to be carcinogenic to humans, but remain highly toxic (they are one of the most common sources of poisoning worldwide), and can affect the nervous system. Ecologically, coumaphos is particularly toxic to birds and toxic to aquatic life.
In addition to Varroa control, CheckMite+ is also labeled for use in controlling the small hive beetle. Again, Varroa has now developed resistance to the active ingredient in CheckMite+. If you choose to use CheckMite+ you should follow the directions, rotate with other treatments, and monitor Varroa levels to evaluate effectiveness. The product is known to accumulate in comb over time.
Summary
The best option? As with all things beekeeping, there may be no obvious choice. Choosing the right Varroa treatment is a series of compromises depending on your own beekeeping philosophy and approach, your location, and on the unique characteristics of your own bees.
But no matter which direction you choose to go, treating for Varroa – the number one obstacle most beekeepers now face – will go a long way towards maintaining the health of your colonies throughout the year and help colonies make it through those long winters. And hopefully, this article helps you help your bees with those pesky mites.
You can find many of the options we’ve discussed in this article here in the PerfectBee Store.
Have questions related to mites, treatments, or Varroa management strategy? If you are a Colony member we’d love to hear from you. Just head over to the PerfectBee Forum to join other members and our PerfectBee Ambassadors.
Disclaimer: The products discussed in this article must be utilized according to the label directions – it a violation of law to use an EPA-registered pesticide in a manner inconsistent with its labeling. Label directions may vary or change from the information supplied in this article. Read all safety and hazard information on the label and utilize the proper personal protective equipment.
