Tracking Varroa Treatment Efficacy: Pre/Post Mite Counts, Wash-Out Periods, and Record Keeping

A Varroa treatment is only as good as your ability to confirm it worked. Beekeepers who treat without measuring pre and post-treatment mite counts are flying blind. They may believe a treatment was effective when it was not, delay necessary follow-up treatment, or continue using a resistant-suspect product for years. Pre and post-count tracking is the foundation of effective Varroa management.

Pre-Treatment Baseline Count

Perform an alcohol wash within 7 days of starting any treatment. Record the date, the colony ID, the count method, and the result in mites per 100 bees. This baseline count serves two purposes: it confirms treatment was warranted (you should be at or above the treatment threshold), and it provides the comparison point for your post-treatment count.

If you have multiple hives, count at least a sample of them before treatment. Mite loads vary significantly between colonies in the same apiary, and treating all hives based on the count from one or two is less informative than sampling a representative portion of your operation.

Post-Treatment Counts and Efficacy Calculation

Conduct your post-treatment wash 2 to 4 weeks after the treatment is complete, not during it. For Apivar (8-week treatment), count at 8 to 10 weeks after insertion. For MAQS or OAV, count 2 to 4 weeks after the treatment ends.

Efficacy is calculated as: (pre-treatment count minus post-treatment count) divided by pre-treatment count, times 100. A pre-treatment count of 4 percent and a post-treatment count of 0.3 percent represents an efficacy of (4 minus 0.3) divided by 4, times 100 equals 92.5 percent. A well-chosen treatment applied correctly should achieve at least 80 to 90 percent efficacy. Below 80 percent, investigate user error or resistance as possible causes.

Wash-Out Periods

Some treatments require a wash-out period before honey supers are installed or before the colony can be treated with a different product. Apivar strips must be removed before a nectar flow and should not be present when honey supers are on. Formic acid (MAQS) can be used with honey supers on under specific temperature conditions but has a risk of flavor impact if used during active ripening. Read current label instructions for each product, as these requirements can change when EPA approvals are updated.

What Records to Keep

Every mite monitoring event should generate a record with: date, colony identifier, monitoring method (alcohol wash or sugar roll), number of bees sampled, mite count, calculated percentage, and any notes on colony condition. Every treatment should record: start date, product name and lot number, dose applied, end date, and the post-treatment count result. Over multiple seasons, these records reveal which colonies are chronically difficult to treat, whether a specific product is losing efficacy in your apiary, and which colonies may warrant requeening for mite-resistant traits. VarroaVault stores all of this data in a searchable format across your entire operation.