Sugar Rolls and Sticky Boards: What Varroa Tests Can Tell You

Varroa monitoring methods do not measure exactly the same thing. A powdered-sugar roll estimates mites carried on a sample of adult bees, while a sticky board records mites that fall through the hive floor during a set period. Both can show change, but neither result is meaningful without knowing how the sample was taken. Selecting a method should begin with the management question: colony-level infestation, general trend, or rapid evidence that mites are dropping.

The most useful monitoring program is one that a beekeeper performs consistently and interprets within its limits. An alcohol wash is generally more sensitive for adult-bee infestation, but a well-executed sugar roll can be useful when sacrificing bees is unacceptable. Sticky boards can support observation without opening the brood nest. They should not be converted casually into an exact infestation percentage because brood area, colony population, grooming, weather, and board duration influence natural fall.

Collect approximately one-half cup of nurse bees from brood frames after locating and protecting the queen. Place the sample in a dry screened jar, add the amount of powdered sugar specified for the device, and roll gently until every bee is coated. Allow the jar to rest as directed so bees groom and mites release. Shake the mites and sugar through the screen onto a white surface, then dissolve the sugar with water to make dark mites easier to count.

Return the bees to their colony after the count, recognizing that moisture, clumped sugar, incomplete coating, and short shaking can reduce mite recovery. Powdered sugar should be fresh and fine, and the jar and bees should remain dry. Repeating the shake may recover more mites. The method is less dependable in humid conditions and can underestimate infestation, so use locally published interpretation guidance and avoid comparing a sugar-roll percentage directly with a differently collected sample.

Place a purpose-made adhesive board beneath a screened bottom board where bees cannot walk on it. Leave it for a defined period, often twenty-four to seventy-two hours according to local recommendations, then count mites across the entire grid. Protect the adhesive from ants and debris as much as possible. Divide by the number of days only when your reference threshold is expressed as average daily mite fall and uses the same collection duration.

Sticky boards are particularly helpful for observing whether mite fall changes during certain controls, but an increased drop immediately after treatment may indicate mites are being killed rather than the colony getting worse. Conversely, a low natural drop does not prove that brood cells contain few reproducing mites. Use boards as trend data, not as a stand-alone declaration that a hive is safe. Photographing each board can help verify counts and train new beekeepers.

Every sampling method has noise. A small or entrance-based bee sample can miss the nurse bees most associated with brood and mites. Recent swarming, a brood break, robbing, and drifting can all change results. Testing only the strongest-looking colony can conceal a problem elsewhere in the yard. Sample the same colony locations and life stages when possible, and note unusual conditions so later numbers are not interpreted as if circumstances were identical.

Clinical signs such as scattered brood or deformed wings warrant investigation, but their absence is not a substitute for a mite count. Likewise, seeing no mites on bee backs is reassuring only in the most limited sense; many mites hide between abdominal segments. When a nonlethal test returns a surprisingly low result during a high-risk period, confirm technique or use a more sensitive method. Decisions should reflect evidence, season, and current regional advice.

Set monitoring dates before the season becomes busy: during spring buildup, after the main nectar flow, before winter bees are raised, and after any control action. More frequent checks may be appropriate where brood production is continuous or mite pressure is historically high. Record method, sample size, count, calculated rate, colony strength, and brood status. Using the same method repeatedly makes changes easier to understand than switching methods whenever a result is inconvenient.

If results reach a locally recommended action level, select controls compatible with colony conditions and honey production. Registered miticides must be legal in your jurisdiction and used exactly as their labels require; application windows and honey-super restrictions are not optional. Recheck after the expected control period. Combining accurate monitoring, cultural practices, resistant stock where available, and carefully selected labeled treatments forms an integrated program without relying on a single fragile tactic.