The Secret Weapon Against Varroa Mites: Enforcing a Brood Break with Oxalic Acid
- Laurence Edwards
- May 21
- 4 min read
Updated: Jun 4
Tackling the Varroa Mite Menace
As any experienced beekeeper knows, the varroa mite is one of the most persistent pests in the apiary. These tiny parasites first appeared in the UK in 1992. Since then, beekeepers have been searching for ways to control them effectively. Methods have included chemical treatments like amitraz and formic acid, along with organic remedies like rhubarb leaves and thyme. The battle against varroa is ongoing.
But one organic treatment stands out: oxalic acid. This naturally occurring substance can be mixed with sugar syrup and dribbled onto the bees. Alternatively, it can be sublimated and used to fumigate the hive. The key to maximizing its effectiveness lies in timing the treatment during a natural brood break, making the mites vulnerable.
The Importance of Timing: Enforcing a Brood Break
In the UK, natural brood breaks occur between the middle of November and mid-January, with a duration of 5-10 days. This gap happens when the queen stops laying eggs, and the colony enters dormancy. During this time, beekeepers can treat the colony for varroa. The phoretic mites, living on adult bees, can be effectively targeted with oxalic acid while the reproducing mites in capped brood remain safe.
Yet, the timing of brood breaks can be unpredictable. This is where tools like queen excluders and specialized cages, such as the Scalvini cage, come into play.
The Scalvini Cage: Enforcing a Controlled Brood Break
The Scalvini cage is a shallow, injection-moulded plastic cage that attaches to a brood frame. It allows the queen to continue laying eggs without young nurse bees capping the brood. This ensures that when the colony is treated with oxalic acid, the mites in the open brood are exposed, while the queen remains unharmed.
To implement the Scalvini cage system, follow these steps:
Identify the June Gap: Determine when the June gap, a natural forage break, typically occurs in your area (usually late May or early June).
Introduce the Queen: Four weeks before the expected June gap, place the queen in the Scalvini cage.
Treatment Time: After four weeks (or 26-27 days for full drone brood emergence), remove the honey supers. Treat your colony with oxalic acid, either by dribbling or sublimation.
Release the Queen: Once the treatment is complete, release the queen from the Scalvini cage, allowing the colony to rebuild for the summer honey flow.
Benefits of the Scalvini Cage System
This systemic treatment offers several advantages:
Controlled Brood Break: Ensures the maximum efficacy of oxalic acid treatment against varroa mites.
Prevent Swarming: An additional brood box during the June gap provides bees ample space, reducing swarming and supporting a strong colony.
Feeding: Providing a light 1:1 sugar syrup during the June gap can stimulate rapid colony growth.
Varroa Reduction: The combination of the brood break, oxalic acid treatment, and added brood box can significantly decrease the varroa mite population.
Navigating the Legal Landscape: Oxalic Acid vs. Apibioxal
In the UK, the use of oxalic acid for varroa control is currently not permitted. Beekeepers must instead use Api-bioxal, which is a less effective alternative. Api-bioxal contains glucose and other fillers, making it significantly more expensive and less potent than pure oxalic acid.
For beekeepers who can legally use oxalic acid, this organic treatment can revolutionize the fight against varroa. However, those only able to use Api-bioxal can still utilize the Scalvini cage system for a controlled brood break. This helps maximize the treatment's effectiveness.
Complementing Oxalic Acid with Other Treatments
While the Scalvini cage and oxalic acid treatments are effective, a comprehensive varroa management strategy should include additional measures. Consider a late-season amitraz treatment in mid-August, followed by a second oxalic acid (or Api-bioxal) treatment in late autumn or early winter. This multi-faceted approach helps strengthen the colony's defenses against varroa.
By implementing this strategy, beekeepers can significantly reduce their varroa mite load. This promotes the overall health and vitality of their bees. Ultimately, healthier bees yield more honey and improve the chances of successful overwintering. A thriving apiary is the goal.
Conclusion: Embracing Organic Varroa Control
The fight against varroa mites is challenging for beekeepers. However, using oxalic acid (or Api-bioxal) alongside the Scalvini cage system can provide an effective organic solution. By enforcing a controlled brood break and treating the mites when they're vulnerable, beekeepers can significantly reduce their varroa load. This sets the stage for a productive season.
Whether you are a seasoned beekeeper or just starting, integrating this organic method into your management practices can lead to healthier colonies. To learn more about the Scalvini cage, oxalic acid treatments, and other beekeeping best practices, don't hesitate to explore the resources on the Black Mountain Honey website and join our Discord community.
Remember, healthy bees are the foundation of a thriving apiary. Embracing organic methods like those outlined in this article can help you prepare your colonies for the challenges of the evolving beekeeping landscape.
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