53. Treating for Varroa mites infestation:
- Kanna Das
- Jul 7, 2025
- 6 min read
Treating for Varroa mite infestation
If there is one challenge that every modern beekeeper must come to terms with, it is the varroa mite. Varroa has changed beekeeping forever. Colonies that once survived on their own now depend on informed, attentive keepers. Understanding varroa mites—what they are, how they harm bees, how to monitor them, and how to manage them economically—empowers a hobby beekeeper to protect both their bees and their enjoyment of the craft.
What Are Varroa Mites?
Varroa destructor is a tiny, reddish-brown parasitic mite about the size of a pinhead. Despite its small size, it is one of the most destructive threats to honeybees worldwide. Varroa mites originally parasitised Asian honeybees, which evolved defences against them. When the mite jumped to European honeybees (Apis mellifera), the bees had no natural resistance, and the consequences were devastating.
Varroa mites live on adult bees and inside brood cells. They feed on the bee’s fat body (not just blood, as once believed), weakening the bee’s immune system and overall health. Even more dangerous, varroa mites act as vectors for deadly viruses, including Deformed Wing Virus (DWV).
Without management, most colonies infested with varroa will collapse within one to three years.
How Varroa Mites Affect Bee Colonies
At first, a colony with varroa may look perfectly normal. This is what makes varroa so dangerous—it is a silent killer.
Effects on Individual Bees
Shortened lifespan
Weakened immune systems
Deformed wings or abdomens
Reduced ability to forage or regulate hive temperature
Bees emerging from mite-infested brood cells often appear smaller, weaker, or visibly deformed. These bees cannot contribute effectively to the colony.
Effects on the Colony
Declining population despite a laying queen
Poor brood patterns
Increased susceptibility to disease
Winter losses due to weakened “winter bees”
By late summer and autumn, unchecked mite populations explode just as the colony is raising bees meant to survive winter. This timing is especially deadly.
For a hobby beekeeper, it can be heartbreaking to open a hive in spring and find it empty—not because of neglect, but because varroa went unnoticed.
How to Check for Varroa Mites
Monitoring is the foundation of varroa management. Treating without checking is guesswork; checking gives you confidence and control.
1. Sugar Shake (or Icing Sugar Roll)
This is one of the most popular methods for hobbyists.
How it works:
Collect about 300 bees (½ cup) from a brood frame
Add icing sugar and gently shake
Sugar dislodges mites, which fall through a mesh lid
Bees are returned alive to the hive
Pros:
Bees survive
Inexpensive
Reliable when done properly
Cons:
Requires careful handling
2. Alcohol Wash
This is considered the most accurate method.
How it works:
Same bee sample size
Bees are washed in alcohol, killing them
Mites are counted accurately
Pros:
Very accurate
Cons:
Bees are sacrificed
Emotionally difficult for beginners
Many hobby beekeepers start with sugar shakes and switch to alcohol washes once they are more comfortable.
3. Sticky Board (Natural Mite Drop)
A sticky sheet is placed under a screened bottom board.
Pros:
Non-invasive
Easy
Cons:
Less accurate
Only shows falling mites, not total infestation
Sticky boards are useful as a trend indicator, not a standalone diagnostic tool.
How Often Should You Check for Varroa?
Varroa monitoring should be routine, not occasional.
A good rule of thumb for hobby beekeepers:
Every 4–6 weeks during the active season
Before and after any treatment
Late summer and early autumn are critical
Many experienced beekeepers say:
“If you don’t check for varroa, you already have a varroa problem.”
Keeping simple notes—dates, counts, actions—helps you spot patterns and improve year after year.
When Is Treatment Necessary?
Treatment thresholds vary by region, but a commonly used guideline is:
2–3% infestation (6–9 mites per 300 bees) during spring/summer
Lower tolerance in autumn, when winter bees are being raised
Your local beekeeping association may provide region-specific thresholds—always worth following.
Most Economical Varroa Remedies for Hobby Beekeepers
Managing varroa does not need to be expensive. Many effective treatments are affordable and practical for small-scale beekeeping.
1. Organic Acids (Highly Popular)
Oxalic acid and formic acid are widely used.
Oxalic Acid
Very inexpensive
Effective when little or no brood is present
Applied via vaporisation or dribbling
Pros:
Low cost
Minimal residue in wax
Cons:
Not effective on mites in capped brood
Formic Acid
Penetrates capped brood
Useful during warmer months
Pros:
Kills mites under caps
Cons:
Temperature-sensitive
Can stress queens if misused
2. Thymol-Based Treatments
Derived from thyme oil.
Pros:
Natural product
Moderate cost
Effective in warm conditions
Cons:
Strong smell
Can affect honey flavour if misused
3. Drone Brood Trapping (Very Economical)
Varroa prefer drone brood.
How it works:
Insert a drone frame
Allow bees to cap it
Remove and freeze the frame
Kill mites along with drone brood
Pros:
Very low cost
Chemical-free
Cons:
Labour-intensive
Not sufficient alone for high infestations
4. Screened Bottom Boards
While not a treatment, they help reduce mite reinfestation by preventing fallen mites from climbing back onto bees.
Integrated Pest Management (IPM): The Best Approach
The most successful hobby beekeepers don’t rely on one method—they combine strategies.
An IPM approach includes:
Regular monitoring
Mechanical controls (screened boards, drone trapping)
Timely treatments based on data
Good nutrition and strong queens
Healthy colonies tolerate mites better than stressed ones.
A Human Perspective: Learning to Live With Varroa
Varroa mites can feel overwhelming at first. Many beginners feel discouraged when they realise bees need intervention to survive. But managing varroa is not a failure—it’s part of modern stewardship. Think of it like gardening. You don’t ignore pests and hope for the best. You observe, learn, and act gently but decisively.
When you open a hive and see strong brood, calm bees, and steady growth, you’ll know your efforts matter. Your bees may never thank you directly—but they will thrive because of your care.
Varroa mites may be relentless, but informed beekeepers are stronger. With knowledge, consistency, and a calm approach, even a small-scale hobby beekeeper can keep healthy, resilient colonies—and continue enjoying one of the most rewarding relationships in nature.
The varroa mite threshold is the infestation level at which action should be taken to protect the colony. It’s not a fixed number worldwide, but most beekeeping authorities agree on practical thresholds that hobby beekeepers can safely use.
Below are widely accepted guidelines based on the percentage of mites per adult bees (usually measured using a 300-bee sample with a sugar shake or alcohol wash).
Standard Varroa Treatment Thresholds
🟢 Spring (build-up period)
Threshold: 2% infestation
What this means:~6 mites per 300 bees
Why: Colonies are growing fast, and early intervention prevents population explosions later.
🟡 Summer (honey flow)
Threshold: 3% infestation
What this means:~9 mites per 300 bees
Why: Mite populations rise rapidly during brood rearing. Treatment may need to be timed around honey supers.
🔴 Late Summer / Early Autumn (critical period)
Threshold: 2% or lower
What this means:~6 mites per 300 bees
Why: This is when winter bees are raised. Even moderate mite levels can shorten their lifespan and cause winter collapse.
❄️ Winter (broodless period)
No threshold—preventative treatment (often oxalic acid) is commonly applied if mites were present earlier.
Simple Rule for Hobby Beekeepers
If you remember just one rule, make it this:
"If mite levels are 2–3% or higher, treat."
Waiting longer almost always leads to bigger problems later.
Why Thresholds Matter
Varroa mites reproduce exponentially, not gradually. A colony that looks healthy today can collapse within weeks if thresholds are exceeded—especially in warm climates or during brood-heavy periods.
Colonies often show no visible signs until it’s too late. That’s why monitoring before symptoms appear is essential.
Practical Tip
Check every 4–6 weeks
Always test before and after treatment
Keep simple records (date, count, action taken)
Final Thought
Varroa management isn’t about perfection—it’s about timely decisions. Treating at the right threshold protects your bees, your investment, and your enjoyment of beekeeping. Healthy bees forgive many mistakes; unchecked varroa does not. Checking for varroa mites - sugar powder method -video https://youtu.be/VTLOdFnPbJ0?si=ndB23fLWmKKRF-Zl
Checking for varroa mites - alcohol wash method -video
Varroa treatment- using strips - video
Varroa treatment- using oxalic acid
Varroa treatment- using oxalic acid -gas vaporiser
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