Varroa Mite Management
Varroa destructor is the single greatest threat to honey bee colonies worldwide, and managing mite levels is the most important thing you can do to keep your hives alive. Untreated colonies in Salem rarely survive more than two years. Mites feed on bee fat bodies, transmit devastating viruses like Deformed Wing Virus and Acute Bee Paralysis Virus, and weaken the bees that your colony depends on to survive winter. Effective mite management requires regular monitoring with a reliable method, knowing your treatment thresholds, and treating promptly when those thresholds are exceeded. This page covers the complete mite management cycle for a Salem, Utah beekeeper running two-deep Langstroth hives.
Important Disclaimer
Always follow the current product label for any mite treatment. Labels specify legal application methods, temperature ranges, honey super restrictions, and safety precautions. Treatment products and recommendations change — consult your local extension service (USU Extension) or the Honey Bee Health Coalition's Varroa management tools for current best practices. Do not rely on anecdotal dosages or unapproved application methods.
Testing Schedule
Mite populations grow exponentially inside brood cells. A colony that tests clean in April can be in crisis by August if left unmonitored. The schedule below shows when to test, what threshold triggers treatment, and Salem-specific timing notes for each testing window. Test every colony individually -- mite levels vary enormously between hives even in the same apiary.
| Month | Test Type | Treatment Threshold | Notes | Salem Timing |
|---|---|---|---|---|
| March | Baseline alcohol wash or sugar roll | 1 mite per 100 bees (1%) — spring threshold is low because mite population will explode with brood rearing | Early spring is a good time to establish a baseline mite count before brood rearing ramps up. Mite levels should be very low coming out of winter. If they are already elevated, the colony entered winter with a high load and needs attention. | In Salem, March inspections depend on weather windows. Wait for a day above 55°F to open the hive. If you cannot get a proper wash sample, at minimum pull a frame of drone brood (if any) and uncap cells to check for mites visually. |
| April | Alcohol wash — first formal test of the season | 2 mites per 100 bees (2%) — treatment threshold for spring | April is the first reliable testing window in Salem. Brood rearing is accelerating and mite populations begin to grow exponentially in brood cells. A wash now gives you a critical baseline. If the count exceeds threshold, treat before adding honey supers to avoid complications with treatment and honey contamination. | Fruit bloom is underway by mid-April in Salem. Test before you add honey supers so that if treatment is needed, you can treat without worrying about honey contamination. Target early-to-mid April for the first wash. |
| May | Alcohol wash — monitor during buildup | 2-3 mites per 100 bees (2-3%) | If you treated in April, test again in May to confirm treatment effectiveness. If April counts were below threshold, test again to track the trajectory. Mite population doubles roughly every month when untreated, so a low April count can become a problem by June. | May is peak swarm season in Salem and you are likely doing weekly inspections anyway. Roll the mite test into your regular inspection routine. Collect your sample from the brood nest, not from a honey super. |
| June | Alcohol wash — mid-season check during honey flow | 3 mites per 100 bees (3%) — summer threshold | June is a critical monitoring point. If honey supers are on, your treatment options are limited. If the count is above threshold with supers on, you need to decide whether to treat with a super-compatible method or accept the risk and plan for aggressive treatment in August when supers come off. Always follow current product label restrictions regarding honey supers. | The main alfalfa and clover flow is on in June in Salem. Test early in the month so you have time to make decisions. If your apiary is near irrigated alfalfa fields, the flow may be strong enough to warrant leaving supers on and deferring treatment to August. |
| July | Alcohol wash — watch for rising mite pressure | 3 mites per 100 bees (3%) | Mite populations are growing rapidly in July as brood nest size peaks. This is the month where unchecked mites begin to cause visible damage (deformed wings, reduced brood viability). If counts are approaching or exceeding threshold, plan your late-summer treatment window carefully. | July in Salem is hot and dry. The flow may be tapering depending on irrigation and drought conditions. If you are planning to pull supers in late July or early August, schedule your mite test for immediately after super removal so you can treat without delay. |
| August | Alcohol wash — CRITICAL late-summer treatment window | 2-3 mites per 100 bees (2-3%) — lower threshold because winter bees are being raised now | August is the most important mite management month of the year. The bees being raised from August through October are the long-lived "winter bees" that must survive until March. If these bees are parasitized by mites and infected with viruses during development, the colony will not survive winter. Treatment in August protects the bees that will carry the colony through to spring. Do not delay. | In Salem, pull honey supers by early-to-mid August. Test immediately. If above threshold, begin treatment the same week. Do not wait for "one more week of flow." Follow product label directions for temperature restrictions — some treatments are less effective or dangerous above certain temperatures. Late August nights in Salem cool down enough for most treatment options. |
| September | Follow-up alcohol wash to verify treatment effectiveness | 1 mite per 100 bees (1%) — very low threshold for fall | After completing your August treatment, test again in September to confirm that mite levels have dropped to safe levels. If the first treatment did not bring counts below threshold, a second treatment with a different method may be necessary. Going into winter with elevated mite levels is the number one cause of winter colony loss. | September in Salem offers good treatment conditions — daytime highs in the 70s-80s and cool nights. Complete all mite treatments by the end of September to give the colony time to raise healthy winter bees before brood rearing shuts down in October. |
| October | Final alcohol wash of the season | 1 mite per 100 bees (1%) — must be low going into winter | This is your last chance to assess mite load before winter. The colony is reducing brood rearing, which means more mites are phoretic (on adult bees) and more visible in a wash. If counts are still elevated after fall treatment, consider an oxalic acid vaporization during the broodless period in December (follow all label directions and safety precautions). Going into winter with more than 1% mite load significantly reduces survival odds. | By mid-October in Salem, brood rearing is winding down. A wash taken now reflects the true mite load on the adult bee population. If treatment is needed, temperature-independent methods are your only option as nights are getting cold. Plan accordingly. |
| December | Oxalic acid vaporization window (broodless period) | N/A — treat if you have reason to believe mite load is elevated | During the broodless period in December, all mites in the colony are phoretic (on adult bees). This is the most effective time for oxalic acid vaporization, which kills phoretic mites with high efficacy. No mites are hidden in capped brood cells, so a single treatment can dramatically reduce the mite population. Always follow label directions, use proper safety equipment (respirator, gloves), and never vaporize with honey supers on. | In Salem, the broodless period typically occurs in December through early January. Confirm broodlessness is likely based on recent cold weather and colony behavior. Vaporize on a day when temps are between 35-55°F and bees are clustered. Do not open the hive — apply through the entrance. |
Baseline alcohol wash or sugar roll
1 mite per 100 bees (1%) — spring threshold is low because mite population will explode with brood rearing
Early spring is a good time to establish a baseline mite count before brood rearing ramps up. Mite levels should be very low coming out of winter. If they are already elevated, the colony entered winter with a high load and needs attention.
In Salem, March inspections depend on weather windows. Wait for a day above 55°F to open the hive. If you cannot get a proper wash sample, at minimum pull a frame of drone brood (if any) and uncap cells to check for mites visually.
Alcohol wash — first formal test of the season
2 mites per 100 bees (2%) — treatment threshold for spring
April is the first reliable testing window in Salem. Brood rearing is accelerating and mite populations begin to grow exponentially in brood cells. A wash now gives you a critical baseline. If the count exceeds threshold, treat before adding honey supers to avoid complications with treatment and honey contamination.
Fruit bloom is underway by mid-April in Salem. Test before you add honey supers so that if treatment is needed, you can treat without worrying about honey contamination. Target early-to-mid April for the first wash.
Alcohol wash — monitor during buildup
2-3 mites per 100 bees (2-3%)
If you treated in April, test again in May to confirm treatment effectiveness. If April counts were below threshold, test again to track the trajectory. Mite population doubles roughly every month when untreated, so a low April count can become a problem by June.
May is peak swarm season in Salem and you are likely doing weekly inspections anyway. Roll the mite test into your regular inspection routine. Collect your sample from the brood nest, not from a honey super.
Alcohol wash — mid-season check during honey flow
3 mites per 100 bees (3%) — summer threshold
June is a critical monitoring point. If honey supers are on, your treatment options are limited. If the count is above threshold with supers on, you need to decide whether to treat with a super-compatible method or accept the risk and plan for aggressive treatment in August when supers come off. Always follow current product label restrictions regarding honey supers.
The main alfalfa and clover flow is on in June in Salem. Test early in the month so you have time to make decisions. If your apiary is near irrigated alfalfa fields, the flow may be strong enough to warrant leaving supers on and deferring treatment to August.
Alcohol wash — watch for rising mite pressure
3 mites per 100 bees (3%)
Mite populations are growing rapidly in July as brood nest size peaks. This is the month where unchecked mites begin to cause visible damage (deformed wings, reduced brood viability). If counts are approaching or exceeding threshold, plan your late-summer treatment window carefully.
July in Salem is hot and dry. The flow may be tapering depending on irrigation and drought conditions. If you are planning to pull supers in late July or early August, schedule your mite test for immediately after super removal so you can treat without delay.
Alcohol wash — CRITICAL late-summer treatment window
2-3 mites per 100 bees (2-3%) — lower threshold because winter bees are being raised now
August is the most important mite management month of the year. The bees being raised from August through October are the long-lived "winter bees" that must survive until March. If these bees are parasitized by mites and infected with viruses during development, the colony will not survive winter. Treatment in August protects the bees that will carry the colony through to spring. Do not delay.
In Salem, pull honey supers by early-to-mid August. Test immediately. If above threshold, begin treatment the same week. Do not wait for "one more week of flow." Follow product label directions for temperature restrictions — some treatments are less effective or dangerous above certain temperatures. Late August nights in Salem cool down enough for most treatment options.
Follow-up alcohol wash to verify treatment effectiveness
1 mite per 100 bees (1%) — very low threshold for fall
After completing your August treatment, test again in September to confirm that mite levels have dropped to safe levels. If the first treatment did not bring counts below threshold, a second treatment with a different method may be necessary. Going into winter with elevated mite levels is the number one cause of winter colony loss.
September in Salem offers good treatment conditions — daytime highs in the 70s-80s and cool nights. Complete all mite treatments by the end of September to give the colony time to raise healthy winter bees before brood rearing shuts down in October.
Final alcohol wash of the season
1 mite per 100 bees (1%) — must be low going into winter
This is your last chance to assess mite load before winter. The colony is reducing brood rearing, which means more mites are phoretic (on adult bees) and more visible in a wash. If counts are still elevated after fall treatment, consider an oxalic acid vaporization during the broodless period in December (follow all label directions and safety precautions). Going into winter with more than 1% mite load significantly reduces survival odds.
By mid-October in Salem, brood rearing is winding down. A wash taken now reflects the true mite load on the adult bee population. If treatment is needed, temperature-independent methods are your only option as nights are getting cold. Plan accordingly.
Oxalic acid vaporization window (broodless period)
N/A — treat if you have reason to believe mite load is elevated
During the broodless period in December, all mites in the colony are phoretic (on adult bees). This is the most effective time for oxalic acid vaporization, which kills phoretic mites with high efficacy. No mites are hidden in capped brood cells, so a single treatment can dramatically reduce the mite population. Always follow label directions, use proper safety equipment (respirator, gloves), and never vaporize with honey supers on.
In Salem, the broodless period typically occurs in December through early January. Confirm broodlessness is likely based on recent cold weather and colony behavior. Vaporize on a day when temps are between 35-55°F and bees are clustered. Do not open the hive — apply through the entrance.
Testing Methods
There are three common methods for monitoring Varroa mite levels. The alcohol wash is the gold standard and the method recommended for making treatment decisions. The sugar roll is a non-lethal alternative with somewhat lower accuracy. Sticky boards are useful for trend monitoring but should not be used as the sole basis for treatment decisions. Learn at least one method well and use it consistently throughout the season.
Alcohol Wash
The gold standard for Varroa monitoring. A half-cup sample of approximately 300 bees is collected from a brood frame and washed in rubbing alcohol (70% isopropyl or 91% isopropyl). The alcohol dislodges mites from the bees, and both bees and mites are strained through a mesh. Mites are counted in the liquid and expressed as mites per 100 bees. This method kills the sampled bees but provides the most accurate count.
Pros
- Most accurate method available to beekeepers
- Consistent and repeatable results
- Simple materials: mason jar with mesh lid, alcohol, collection cup
- Results are immediate — no waiting period
- Widely recommended by researchers and extension services
Cons
- Kills approximately 300 bees per sample (about 1% of a strong colony)
- Requires opening the hive and pulling a brood frame
- Small risk of accidentally collecting the queen — look before you scoop
- Alcohol is flammable — keep away from smoker
Step-by-Step Instructions
- Prepare your wash kit: a mason jar with #8 hardware cloth lid, 70% isopropyl alcohol, a white collection basin or second jar
- Open the hive and pull a frame from the center of the brood nest — this is where mite-carrying nurse bees concentrate
- CRITICAL: Look for the queen on the frame before sampling. Set her aside on another frame if found.
- Hold the jar against the frame and use a sweeping motion to scoop bees into the jar — aim for a half-cup (approximately 300 bees)
- Quickly add enough alcohol to cover the bees completely and seal the jar
- Swirl and shake the jar vigorously for 60 seconds — this dislodges mites from bees
- Strain the contents through the mesh lid into your collection basin — mites pass through, bees stay in the jar
- Rinse the jar and bees a second time to catch any remaining mites
- Count the mites in the basin. Count the bees in the jar (or estimate: a half cup is approximately 300)
- Calculate: (mites counted / bees counted) x 100 = mites per 100 bees
- Record the date, hive, and result in your log
Sugar Roll
A non-lethal alternative to the alcohol wash. A half-cup of bees is collected and rolled in powdered sugar, which dislodges mites. The sugar-coated bees are returned to the hive alive, and mites are counted after shaking the sugar through a mesh screen. While less accurate than an alcohol wash, the sugar roll is preferred by beekeepers who do not want to kill any bees. It works best in warm, dry conditions — humidity reduces sugar effectiveness.
Pros
- Bees are returned to the hive alive — no sample loss
- Psychologically easier for beekeepers who dislike killing bees
- Materials are inexpensive and readily available (powdered sugar, jar, mesh)
- No flammable liquids near the smoker
Cons
- Less accurate than alcohol wash — may miss 20-30% of mites
- Humidity reduces effectiveness significantly — not ideal in wet weather
- Takes slightly longer than an alcohol wash
- Sugar must be pure powdered sugar without cornstarch for best results
- Bees may be stressed and disoriented when returned to the hive
Step-by-Step Instructions
- Prepare: mason jar with #8 hardware cloth lid, 2 tablespoons of powdered sugar, white basin or paper
- Collect a half-cup of bees from a brood frame (check for the queen first)
- Add 2 heaping tablespoons of powdered sugar to the jar
- Seal the jar and roll it gently to coat all bees thoroughly
- Let the jar sit in the shade for 2 minutes — this allows sugar to dislodge mites from bees
- Shake the jar vigorously over the white basin or paper with the mesh lid facing down — sugar and mites fall through
- Continue shaking for 30-60 seconds until no more sugar falls
- Add a splash of water to the sugar in the basin to dissolve it — mites become clearly visible as dark spots
- Count the mites. Divide by the number of bees sampled (approximately 300 for a half-cup)
- Return the sugar-coated bees to the hive by shaking them onto the top bars
- Record the date, hive, and result. Note if conditions were humid, which may affect accuracy
Sticky Board (Natural Mite Drop)
A passive monitoring method where a sticky board (cardboard or plastic coated with grease or petroleum jelly) is placed under a screened bottom board for 24-72 hours. Mites that naturally fall off bees stick to the board and are counted. The result is expressed as daily mite drop (total mites divided by number of days). This method does not require opening the hive and is useful for monitoring trends, but it is the least accurate method for quantifying actual mite infestation levels.
Pros
- Does not require opening the hive or collecting bees
- Can be used in any weather, including winter
- Good for monitoring trends over time when used consistently
- No bees are harmed
- Useful as a supplementary monitoring tool between washes
Cons
- Poor correlation between natural mite drop and actual infestation level
- Results are influenced by colony size, brood amount, temperature, and other factors
- Requires a screened bottom board — solid bottom boards cannot be used
- Boards can collect ants, wax moths, and debris that make counting difficult
- Not recommended as the sole basis for treatment decisions
Step-by-Step Instructions
- Cut a piece of stiff cardboard or corrugated plastic to fit under your screened bottom board
- Coat the board with a thin layer of cooking spray, petroleum jelly, or vegetable shortening
- Slide the board under the screened bottom board — ensure it covers the full area
- Leave the board in place for exactly 24, 48, or 72 hours (record the duration)
- Remove the board carefully without tipping off any mites
- Count all Varroa mites on the board — they are small, oval, reddish-brown dots about 1-2mm
- Calculate daily mite drop: total mites / number of days the board was in place
- General guidelines: fewer than 10 mites per day is low; 10-20 is moderate; over 20 is high (but these are rough estimates)
- Use sticky board results to identify trends — if daily drop is increasing each month, mite population is growing
- Always follow up suspicious sticky board results with an alcohol wash for confirmation
Mite Log
Tracking your mite test results over time is essential for making informed treatment decisions. Use the form below to record each test. Your log is saved in your browser so you can review trends across the season without needing a separate notebook.
Log Mite Test Results
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