Off-Season Varroa Monitoring: What to Do Between October and March

Zone 5 beekeepers who do a January mid-winter count on mild days detect post-treatment reinfestation before spring buildup begins. That early detection gives them several weeks of advantage -- time to plan an early-spring treatment before the mite population has built to a level that affects the spring brood cycle.

Off-season monitoring is not the same as in-season monitoring. The methods, frequency, and interpretation change in winter. But the principle is the same: you can't manage what you don't measure, and mite dynamics don't stop in November.

TL;DR

• Varroa monitoring should happen at minimum once per month during active season (every 3-4 weeks)
• Sticky board counts are the least accurate method; alcohol wash is the gold standard
• The 2% threshold in spring/summer and 1% in fall are widely recommended action points
• Monitoring before and after every treatment allows efficacy calculation and resistance detection
• A count from the outer frames or entrance produces lower, less accurate results than brood nest samples
• VarroaVault stores every count with date, method, and result to build a trend dataset over multiple seasons

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Why Off-Season Monitoring Matters

Three things continue happening to your mite population between October and March that you can't see without counting:

Reinfestation from failing neighboring colonies. Colonies in your area that were at 5%+ mite load in October often fail in January or February. When they fail, surviving bees from the collapsing colony drift and rob to neighboring hives, carrying mites with them. A colony that was at 0.5% in October can be at 2-3% by February purely from reinfestation, with no treatment failure involved.

Residual brood cycles through November-December. In zones 6-7, colonies often continue raising brood through November and even into December. During this period, mite reproduction continues in capped brood cells. A late-season count in November can be meaningfully higher than your October count because of this residual brood rearing.

Overwintering mite dynamics. In fully clustered colonies (zones 4-5), mite reproduction slows but doesn't stop completely. Mite populations in winter clusters are predominantly phoretic (on adult bees), but even phoretic mite populations can grow slowly as new mites emerge from any remaining capped brood and the winter bee population gradually decreases.

Zone-Specific Off-Season Monitoring Guide

Zones 4-5: Cold Winters, Full Cluster

October-November: This is your most important off-season monitoring period. Before the colony goes into full cluster:

• Conduct a standard alcohol wash on every hive
• Any colony above 1% is a candidate for an OA dribble broodless treatment
• Confirm broodless status before dribbling (no capped worker brood)
• Log the broodless dribble and calculate PHI (0 days for OA)

December-January: Full cluster. Standard alcohol wash is impractical and disruptive. Two alternatives:

• Sticky board count: Insert a sticky board for 24-72 hours. Count natural mite drop. A rate above 0.5 mites per day per hive suggests elevated winter load worth following up in spring.
• Wait for a mild day: In some winters, zones 4-5 experience mild spells above 50°F. On a day like this, you can collect a small sample (100-150 bees from the cluster edge) for a small-sample alcohol wash. VarroaVault's small sample calculator adjusts for the reduced sample size.

February: As temperatures begin to moderate and the queen resumes laying, a late-February count establishes your early-spring baseline. This is the count that tells you whether you're starting the season in good shape or with elevated loads from winter reinfestation.

Zones 6-7: Moderate Winters, Partial Cluster

October-November: Same priority as zones 4-5 for the broodless period check. The broodless window may arrive later (November or December) and may be briefer.

• Monitor monthly through November
• When broodless confirmed: OA dribble if count is above 1%

December-January: Colonies in zones 6-7 often have some brood activity even in winter. Monthly monitoring continues:

• Standard alcohol wash on mild days (above 50°F)
• Interpret results in the context of the current brood status
• A colony with active winter brood at 1% in December is different from a broodless colony at 1% -- the brood-present colony will continue accumulating mites

February-March: Increase monitoring frequency to every 2-3 weeks as spring buildup begins. The rapid brood expansion of early spring drives mite population growth at a rate that can cross the 2% threshold faster than a monthly monitoring cadence catches.

Zones 8-10: Mild Winters, Continuous Brood

In zones 8-10, there is no off-season for varroa management. Colonies continue raising brood year-round, and mite populations continue growing. Monthly monitoring continues through all 12 months.

Winter-specific considerations for mild climates:

• The "winter months" (December-February) represent a period of lower colony activity but not cessation
• Treatment timing in mild climates requires more attention to PHI and super status because the honey flow calendar is different
• OA vaporization extended protocol is the most practical year-round treatment option because it works regardless of brood status

The varroa winter monitoring guide covers mild-climate monitoring approaches in more detail.

Off-Season Monitoring Methods

Sticky Board Count

A sticky board (also called a bottom board insert) is a white or yellow sticky surface placed in a tray beneath the hive. It catches mites that fall off bees naturally (natural mite drop) over a defined period.

How to use it:

1. Insert the sticky board beneath the lower hive body entrance
2. Leave for 24-72 hours
3. Count the mites on the board
4. Divide by the number of days to get daily mite drop rate

Interpretation: Daily mite drop rate is not directly comparable to alcohol wash percentage. General guidance:

• Under 0.5 mites/day: Low winter load, likely fine
• 0.5-1 mites/day: Moderate load, worth a spring follow-up count
• Above 1 mite/day: Elevated load, consider early spring treatment when temperature allows

Sticky board counts are less accurate than alcohol washes because mite drop rate is affected by colony behavior, temperature, and brood status. Use them as directional indicators rather than precise measurements.

Small-Sample Alcohol Wash

On mild winter days when the colony is loosely clustered (above 50-55°F), you can collect a smaller sample from the cluster edge for a modified alcohol wash.

Adapted method for winter:

1. Carefully remove one frame from the cluster edge -- avoid the cluster core where the queen is likely to be
2. Gently brush 100-150 bees into your wash container (do not shake the frame)
3. Complete the standard alcohol wash procedure
4. Log the count in VarroaVault with the actual sample size
5. VarroaVault calculates the adjusted percentage and confidence interval for the small sample

A 100-bee winter sample has lower statistical confidence than a 300-bee in-season sample. VarroaVault's small sample calculator shows the confidence interval for your sample size so you know how much weight to give the result.

Brood Nest Visual Check

Not a quantitative method, but useful supplemental information: when you open a hive for a winter check on a mild day, observe the cluster size relative to the frames it occupies. A cluster that's smaller than you'd expect given the colony's fall population suggests higher-than-normal winter bee mortality -- which can be a mite-damage signal.

Recording Off-Season Counts

Log off-season counts the same way you log in-season counts. Note the method (sticky board versus alcohol wash), the sample size (especially for small winter samples), and any relevant observations about cluster size or behavior.

Off-season monitoring frequency by zone is set automatically in VarroaVault: monthly for zones 7-10, quarterly (with mild-day conditional) for zones 4-6. The varroa monitoring frequency by season guide covers in-season frequency. The varroa winter survival guide covers the full winter preparation protocol.

Frequently Asked Questions

Should I monitor for varroa in November and December?

Yes, in all climate zones -- though the method and frequency adapt to conditions. In zones 6-10, full monthly alcohol wash monitoring continues through November and December because colonies continue raising brood and mite populations continue growing. In zones 4-5, the November broodless period check is critical for identifying OA dribble candidates. December monitoring in cold zones can use sticky board counts rather than alcohol washes when cluster disturbance is a concern.

What counts are worth doing in winter?

Three winter counts are worth doing: the October-November broodless period check (standard alcohol wash or small sample); a December-January sticky board count (3-day average mite drop rate); and a late-February small-sample alcohol wash on a mild day to establish your early-spring baseline. Together, these three counts cover the critical off-season monitoring events without requiring you to open hives during the coldest, most disruption-sensitive cluster period.

Does VarroaVault recommend off-season monitoring for my climate zone?

Yes. VarroaVault's monitoring calendar adjusts by climate zone: monthly reminder cadence continues through all 12 months for zones 7-10. For zones 4-6, the November broodless period check fires as a full monitoring event; December-January shifts to a "monitor when conditions allow" reminder with sticky board guidance; and February fires as a spring baseline count reminder. The calendar never goes to zero -- it adjusts frequency by zone while maintaining the monitoring continuity that prevents off-season surprises.

How do I know if my varroa treatment is working?

Run a mite count 2-4 weeks after the treatment ends and compare it to your pre-treatment count. The efficacy formula is: ((pre-count - post-count) / pre-count) x 100. A result above 90% indicates effective treatment. Results below 80% should trigger investigation for possible resistance, application error, or reinfestation. Log both counts in VarroaVault to track efficacy trends across treatment cycles.

How often should I check mite levels in my hives?

At minimum, once per month (every 3-4 weeks) during the active season. Increase to every 2 weeks when counts are near threshold or after a treatment to verify it worked. In fall, monitoring frequency matters most because the window to treat before winter bees are raised is narrow. VarroaVault's monitoring reminders can be set to your preferred interval for each apiary.

What records should I keep for varroa management?

Each record should include: date of count or treatment, hive identifier, monitoring method used, number of bees sampled, mites counted, infestation percentage, treatment product name and EPA registration number, dose applied, treatment start and end dates, and PHI end date. State apiarists typically expect this level of detail during inspections. VarroaVault captures all of these fields in a single log entry.

Sources

• American Beekeeping Federation (ABF)
• USDA ARS Bee Research Laboratory
• Honey Bee Health Coalition
• Penn State Extension Apiculture Program
• Project Apis m.

Get Started with VarroaVault

The information in this guide is most useful when you have your own mite count data to apply it to. VarroaVault stores every count, flags threshold crossings automatically, and builds the treatment history you need for state inspections and effective management decisions. Start your free trial at varroavault.com.