Learning Objectives
- Perform an alcohol wash correctly and calculate mites per hundred bees.
- Read a mite count against monthly thresholds instead of guessing from bee behaviour.
- Rotate formic, thymol, oxalic and amitraz by mode of action and temperature window, not by brand loyalty.
- Apply treatments in compliance with Health Canada label directions, including honey-super restrictions.
- Use drone brood removal and screened bottom boards as mechanical assists, not replacements for chemical IPM.
- Select and propagate colonies that hold low mite counts without help.
Field infographic
Alcohol-wash thresholds
Mites per 100 bees from a half-cup (≈300 bee) sample of open-brood nurse bees.
Spring (Apr–May)
1%
Treat above 1%. Early mites become August mites multiplied.
Summer (Jun–Jul)
2%
Watch weekly. Rising counts during the flow mean an August problem.
Pre-winter-bee (Aug)
3%
Hard ceiling. Above this, winter bees are damaged before they are born.
Autumn (Sep–Oct)
1%
Go into winter as close to zero as your treatment allows.
Collapse territory
>5%
Expect DWV, robbing, and a dead-out with stores still in the box.
Sample the same three hives every month. A trend line beats a single heroic count.
Diagram
Development times by caste
The clock behind grafting calendars, mite trapping and queenless triage. Click any band for stage detail.
Queen
16 days
Graft day 0 → capped day 5 → move cells day 10 → emerge day 12 → mating flights from day 17 → laying day 21–24.
Worker
21 days
Varroa prefer the 12-day capped stage; the 24-hour graft window and the 9-day post-capping mite cycle both key off it.
Drone
24 days
Longest capped stage means highest mite preference — the basis of drone-brood trapping and of drone saturation in a closed mating population.
Adult worker task progression
Day 1–3
Cell cleaning; hypopharyngeal glands not yet active.
Day 3–12
Nurse bee — glands at peak, feeds larvae and the queen.
Day 12–18
Wax production and comb building; receives and ripens nectar.
Day 18–21
Guard duty; Koschevnikov alarm pheromone response peaks.
Day 21–42
Forager — flight muscle and behaviour shifted by juvenile hormone.
Winter bees
Task progression suspended; high vitellogenin, 4–6 month lifespan.
Count backwards from what you see: eggs mean the queen laid within 3 days; capped worker brood means she was laying at least 9 days ago.
Read these first
This chapter assumes the ground covered below. If any of it is unfamiliar, take the detour — the sequence exists so nothing here has to be taken on faith.
Reading mode
You cannot manage what you have not counted. A colony that looks strong in July with an unmeasured mite load is the classic Similkameen dead-out in February — bees gone, stores full, a story that repeats every year in yards that never picked up an alcohol wash jar. Varroa destructor is not an occasional pest here; it is a permanent resident of every colony in this valley, and the only question worth asking is how many are riding on your bees today, this month, this apiary.
I have watched more colonies die from mite-vectored viruses than from starvation, cold, or every other cause combined. Deformed wing virus, acute bee paralysis virus, and a dozen other RNA viruses use the mite as a hypodermic needle, injecting virus straight into the fat body and hemolymph every time a mite feeds. By the time you see visibly deformed wings on adult bees, the colony has already crossed a viral threshold that no autumn treatment will reverse in time. Counting mites in July is how you buy back the fix.
Why an alcohol wash and not a visual guess
Beekeepers have tried nearly everything to avoid killing three hundred bees to answer this question — sticky boards, natural mite drop counts, sugar shakes, even simply watching bees on the landing board for signs of stress. None of them come close to the accuracy of an alcohol wash, and in an operation of any size the half-cup of bees you sacrifice is cheaper than the colony you lose to an unmeasured load. This is not a hobby-versus-commercial distinction. It is a discipline distinction.
Student chapter
The rest of this chapter is behind the hive gate.
You are reading the open preview of "Varroa by the Numbers: Testing Before Treating". The full chapter — about 10 minutes of it, the beginner and advanced sidebars, the printable field cards and the paired Guelph video work all sit behind a Hive Key.
What a Hive Key opens
- Every chapter in full, both reading tracks
- Printable field cards — mite thresholds, feed schedule, queenright
- The Guelph HBRC video library, paired chapter by chapter
- The Princeton season dashboard, twice a month
How to get one
Hive Keys are issued to Hive Awakening students. Book a seat at the Princeton apiaries and your key comes with the confirmation — Tier 1 for the Beginner Masterclass, Tier 2 for the Master's Apiary.
See the 2027 workshops →Track your way through the curriculum
Students with a Hive Key get completion ticks, percent-through-track and a resume button across every chapter.
Open the student desk →From Section IV — Peak Flow, Summer Management & Varroa