The Pros and Cons of Different Autumn Varroa Treatments for Beekeepers
As the temperatures start to drop and the days grow shorter, beekeepers know that autumn is a crucial time to prepare hives for winter survival. One of the most important tasks is managing Varroa destructor, the parasitic mite that poses a significant threat to honeybee colonies. There are a wide range of different treatments that can be used which boil down to 4 active ingredients
Varroa mites weaken bees, spread diseases, and, if left unchecked, can lead to the collapse of a colony. Autumn is an ideal time for Varroa treatment because it’s after the honey harvest, and you want to ensure that your bees go into winter healthy and strong. There are several treatment options available, each with its own pros and cons. In this post, we’ll explore the most common autumn Varroa treatments to help you decide which might be the best fit for your hive.
Of course not all beekeepers decide to use chemical treatment, so use methods like shock swarms to create brood breaks but in this blog post we will focus on Treatments.
1. Oxalic Acid (Trickle or Vaporization)
Oxalic acid is one of the most popular treatments for Varroa mites due to its effectiveness, especially when applied during the broodless period in late autumn or early winter. In the UK Apibioxal is approved for use with bees as an Oxalic Acid treatment.
Pros:
Highly Effective on Phoretic Mites: Oxalic acid is particularly effective at killing mites that are attached to adult bees (phoretic mites). It can achieve high mite drop rates when there is little to no brood in the hive.
Cost-Effective: It's relatively inexpensive and widely available, making it an affordable option for many beekeepers.
No Resistance Issues: Mites have not shown resistance to oxalic acid, unlike some chemical treatments.
Cons:
Ineffective in the Presence of Brood: If your hive still has significant amounts of brood, oxalic acid won’t be able to reach mites hiding inside capped cells, limiting its effectiveness.
Requires Special Equipment (Vaporization): If you opt for vaporization, you’ll need an oxalic acid vaporizer, which can be a bit expensive upfront.
Temperature Sensitivity: Trickle applications can stress bees if done in very cold weather, and vaporization requires the right temperatures for the bees to efficiently disperse the vapor.
2. Formic Acid (MAQS or Formic Pro)
Formic acid is another organic option commonly used in autumn. It comes in the form of strips (like MAQS, Formic Pro) that are placed directly in the hive.
Pros:
Effective in the Presence of Brood: Formic acid can penetrate capped brood cells, making it effective against mites in both the phoretic and reproductive stages.
Quick Knockdown: It acts quickly, usually showing results within a week to 10 days.
Supers: In the case of MAQS it can be used with supers (but this is not the case with Formic Pro in the UK).
Cons:
Temperature Sensitivity: Formic acid can be harmful to bees if temperatures are too high or too low. It’s most effective between 10°C (50°F) and 29°C (85°F), which may limit its use in colder autumn weather.
Queen Loss: In some cases, formic acid can lead to queen losses or cause the colony to reject their queen.
Potential for Hive Disruption: Formic acid can be harsh on bees, potentially causing colony stress or disruption during the treatment period.
3. Amitraz (Apivar)
Apivar is a synthetic treatment containing amitraz, which is widely used due to its effectiveness at controlling Varroa mites.
Pros:
Highly Effective: Apivar has a strong track record for reducing Varroa mite populations significantly when used correctly.
Works Well with Brood: Since amitraz remains active for an extended period, it can kill mites as new bees emerge from capped brood cells.
Less Weather Dependent: Unlike some organic treatments, Apivar is not sensitive to temperature, making it a viable option even as the weather cools.
Cons:
Synthetic Chemical: For beekeepers who prefer organic methods, Apivar may not align with their practices.
Mite Resistance Risk: Varroa mites can develop resistance to amitraz over time, particularly in areas where it has been heavily used.
Long Treatment Period: Apivar requires a 42-56 day treatment period, so it needs to be planned well in advance of winter.
Thymol (Apiguard)
Apiguard is a gel-based treatment containing thymol, an essential oil derived from thyme, that is applied to the hive over several weeks.
Pros:
Organic Option: Like oxalic and formic acids, thymol is a natural treatment that aligns with organic beekeeping methods.
Effective on Mites: Apiguard can significantly reduce mite populations, particularly during the autumn months when mite numbers tend to spike.
Less Harmful to Bees: Thymol is relatively mild on bees compared to some harsher chemical treatments.
Cons:
Temperature Sensitivity: Apiguard is most effective at temperatures between 15°C (60°F) and 30°C (85°F). If the weather is too cool, the gel may not evaporate properly, reducing its effectiveness.
Long Application Period: Apiguard requires multiple applications (usually two treatments spaced apart), which means you need to plan for a month or more to complete the treatment.
Potential Disruption to Bee Behavior: Some beekeepers report that bees can become agitated during treatment, reducing colony activity or causing bees to temporarily avoid treated areas.
Conclusion
Each Varroa treatment has its pros and cons, and the right choice for your apiary depends on factors like the level of infestation, the presence of brood, temperature conditions, and whether you prefer organic methods. Oxalic acid is a great choice for broodless periods, while formic acid and Apivar work well when there’s brood present. Apiguard offers more natural options but require careful application to ensure effectiveness.
In our hives we use a mix of Formic Pro and Apivar Strips, followed by an Oxalic acid vaporisation in late December.
As always, monitoring mite levels before and after treatment is crucial to ensure the health of your bees. No matter which method you choose, keeping Varroa under control during autumn is one of the best ways to ensure your colony’s survival through the winter months.
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