You cannot fight an enemy you cannot measure. And Varroa mites, tiny and tucked between bee abdominal segments or hidden inside capped brood cells, are maddeningly easy to underestimate. A hive can look perfectly healthy — bustling with activity, frames full of brood, supers filling with honey — while carrying a mite load that will kill it by winter.
This is why testing is non-negotiable. Not once a year. Not "when you notice a problem." At least three times per year — spring, mid-summer, and late summer/early fall — using a method accurate enough to guide treatment decisions.
The two most reliable methods for backyard beekeepers are the alcohol wash and the sugar shake. Both involve sampling adult bees and counting the mites that fall off when the bees are agitated. Let's learn how to do this correctly.
Mite levels vary by season. In early spring, after a broodless winter (when mites can only survive on adult bees), counts are typically low. By mid-summer, with continuous brood-rearing, mite populations explode. By fall, an untreated hive can have mite levels 10-20 times higher than it had in April.
The threshold for concern is 3% — meaning 3 mites per 100 bees, or roughly 9 mites in a sample of 300 bees. Above 3%, the colony is at serious risk. Treatment is strongly recommended. Above 5%, treatment is urgent.
But here's the catch: visual inspection alone won't tell you if you're at 3%. You might see a few mites on bees and think, "Oh, just a few, no big deal." Meanwhile, thousands of mites are reproducing inside capped brood cells, invisible to you. By the time mites are obvious (bees with deformed wings, mites crawling on frames), your infestation is catastrophic.
Test. Don't guess.
Minimum Schedule (3x per year):
More frequent testing (monthly) is better if you can manage it. It lets you catch problems early and fine-tune your treatment timing.
The alcohol wash kills the sampled bees, which is unfortunate but necessary for accuracy. The alcohol dislodges mites completely, giving you a true count.
What You Need:
Step 1: Collect 300 Bees
Open the hive and locate a frame of brood — ideally one with a mix of open brood and emerging bees. Avoid frames with only honey (foragers) or only capped brood (too few adult bees).
Use your ½-cup measuring scoop (or a wide-mouth jar) to scoop about 300 bees off the frame. A half-cup of bees = roughly 300 bees. Don't obsess over precision. Aim for "around 300."
Critical: Do NOT accidentally scoop the queen. Check the frame first. If you see her, pick a different frame. Losing your queen during a mite test is a tragedy.
Step 2: Add Alcohol
Pour the bees into your jar. Immediately add enough alcohol to cover them — about 1 cup. Put the screened lid on tightly.
The bees will die within seconds. This is the necessary cost of an accurate test. Mourn them briefly, then proceed.
Step 3: Shake Vigorously
Shake the jar hard for 60 seconds. Not a gentle swirl. A violent shake, like you're making a protein shake. The goal is to dislodge every mite from every bee.
The alcohol breaks down the bees' waxy coating and loosens the mites' grip. After a minute of shaking, every mite that was on those bees is now floating free in the alcohol.
Step 4: Strain and Count
Pour the contents of the jar through the screened lid into your white tray. The bees stay in the jar (held back by the screen). The alcohol and mites pour out.
Let the alcohol settle for a moment. The mites will sink to the bottom or float on the surface (they're reddish-brown and about the size of a pinhead — you can't miss them).
Count the mites. Write it down.
Step 5: Calculate the Percentage
If you sampled ~300 bees and found:
The math: (Number of mites ÷ 300 bees) × 100 = percentage.
Example: 12 mites in 300 bees = (12 ÷ 300) × 100 = 4% infestation. Time to treat.
The sugar shake is a non-lethal alternative. It's less accurate than the alcohol wash (you might miss 10-30% of mites), but it allows you to release the bees after testing.
What You Need:
Step 1: Collect 300 Bees
Same as alcohol wash. Scoop ~300 bees from a brood frame into your jar. Avoid the queen.
Step 2: Add Powdered Sugar
Through the screened lid, sprinkle about 2 tablespoons of powdered sugar over the bees. Put the lid on and shake gently to coat them.
Step 3: Let It Sit
Let the jar sit for 2 minutes. The sugar makes the bees groom themselves, which dislodges mites. It also makes mites' feet slippery so they lose their grip.
Step 4: Shake and Release Mites
Hold the jar upside-down over your white tray. Shake hard for 30-60 seconds. The mites and sugar will fall through the screen onto the tray. The bees stay in the jar.
Step 5: Release the Bees
Open the jar near the hive entrance and dump the bees out. They'll be covered in sugar, slightly disoriented, but alive. They'll clean themselves off and rejoin the colony.
Step 6: Count the Mites
Examine the pile of sugar on your tray. Look for reddish-brown specks (the mites). Count them. Use the same 3% threshold as the alcohol wash.
Note: Because the sugar shake is less aggressive than the alcohol wash, it may miss some mites. If you get a borderline result (e.g., 6-8 mites), consider treating anyway — the true count might be higher.
This is a supplementary method, not a replacement for alcohol wash or sugar shake. It gives you a qualitative sense of infestation severity but doesn't provide an exact percentage.
How It Works:
Install a frame of drone foundation (larger cells) in the brood nest. Bees will draw it out and the queen will lay drone eggs. Wait until the drone brood is capped (about 10 days after laying). Remove the frame and uncap 50-100 drone cells using a capping fork or hive tool.
Inspect the white pupae inside. Mites are highly visible on the white background — dark reddish-brown specks on or near the pupae.
What You're Looking For:
After inspecting, you can either destroy the frame (killing the mites with it — a crude but effective form of mite control) or return it to the hive.
Why 3%? Why not 5%, or 1%?
Research shows that colonies with mite levels above 3% in late summer/fall have significantly higher winter mortality rates. At 3%, the mites are reproducing fast enough that by winter, the colony will be overwhelmed. Virus transmission accelerates. Winter bees emerge weak and short-lived.
Treating at 3% or below gives you a buffer. You catch the infestation before it cascades into disaster.
Some beekeepers aim for even lower thresholds (1-2%) as a precaution. This is especially wise in areas with short treatment windows or harsh winters.
You fly blind. You assume your bees are fine because they look fine. Then, in September, you notice a few bees with crumpled wings. By October, half your bees are dead. By November, the hive is silent.
Testing takes 20 minutes. It costs you 300 bees (which the colony replaces in hours) and a cup of rubbing alcohol. The information it provides — treat now or monitor and retest — is literally life or death for your colony.
"A beekeeper who treats without testing wastes money and risks resistance. A beekeeper who refuses to test is courting disaster. Test, then treat. In that order."
— Integrated Pest Management for Beekeepers, 2018