# 035 — Mite Reservoir

## The real problem situation

A beekeeper's standard diagnostic for varroa mite infestation is the
alcohol wash or sugar roll: scoop ~300 adult bees, wash them, count the
mites that come off. The result is reported as "mites per 100 bees."

The problem is that during the brood season (roughly April through
October), only 15–40% of the colony's mites are riding on adult bees at
any given moment. The rest — 60–85% during peak brood — are sealed
inside capped worker cells, reproducing. The wash cannot reach them.
Neither can most chemical treatments. Oxalic acid vaporization, the most
popular single-treatment, has 0% efficacy on mites inside capped cells.

This produces a systematic failure pattern. The beekeeper samples,
reads "1.5%, below threshold," decides not to treat. The true
population is 3–5× higher and compounding. By September the colony is
collapsing. By the time the wash finally crosses the action threshold,
the reservoir has already produced winter-bee damage that cannot be
undone.

The beekeeping literature and most hive-management apps report mite
loads as a single number. They do not render the hidden reservoir. The
beekeeper has to hold the reservoir in their head.

## What was built

A **hidden-reservoir instrument**: a colony-year timeline (Jan 1 to
Dec 31) rendering three curves at once:

1. **The solid black line** — true mite population (phoretic + sealed)
2. **The grey dome below it** — sealed mites hiding in capped brood
3. **The orange line** — what the alcohol wash reads, in mites per 100 bees

Five treatment strategies are available as presets: untreated, spring
strip-treat only, mid-summer oxalic acid at peak brood, late-summer
formic (MAQS), and brood break + late-fall oxalic. Each renders the full
year with the chosen intervention applied, and each surfaces a single
honest readout:

> "The alcohol wash read X%. True population was Y mites, of which Z%
> were sealed. The treatment killed W mites — P% of the true load. R
> remained."

The model is a daily discrete simulation with a 12-day worker sealed
cycle, seasonal capped-brood curve, per-treatment phoretic and sealed
kill coefficients drawn from published field trials, and density-
dependent colony collapse at high mite-to-bee ratios.

## Why this form was chosen

The problem is fundamentally about a hidden reservoir that the visible
measurement systematically under-counts. Any form that did not render
the reservoir alongside the visible measurement would miss the point.

Rejected alternatives:
- a calculator (a number does not make the topology legible)
- a seasonal calendar (does not show the reservoir)
- a phoretic-only chart (is the problem being critiqued)
- a split-screen form + chart (CRUD collapse)

The chosen form — two curves in the same frame, with the treatment
interventions placed as vertical markers and the brood-break window as
a shaded region — makes it impossible to ignore that the wash curve
sits well below the true-population curve all summer, that treatments
during brood season only dip the total line slightly, and that the only
intervention which collapses both curves to near zero is the brood
break + late-OA protocol.

## What is actually interesting

The instrument reveals that *the same oxalic acid applied at different
times has dramatically different kill rates*. In mid-summer: ~31% of
true load killed. After a brood break: ~99% of true load killed. Same
drug, same dose. The difference is whether the reservoir was exposed to
the drug at the moment of treatment.

This is a varroa analogue of John Snow's cholera map — once the hidden
reservoir is visible beside the visible wash reading, the alternative
(treating by calendar, trusting the wash alone) looks naive.

The "at the moment of treatment" card contrasts what the wash told the
beekeeper with what was actually there. That contrast is the part that
lives only in the beekeeper's head today. Making it explicit is the
move.

## Iterations made

- v1.0: First pass had runaway exponential growth (peak >60,000 mites).
  Added density-dependent mortality when mite/bee ratio exceeds 2%.
  Peak-under-pressure now caps around 2500–3000, matching published
  untreated-colony data.
- v1.1: Tuned invasion rate (0.18 daily, ~90% phoretic-to-sealed per
  cycle) to produce ~57% hidden fraction at peak brood, matching
  literature. Offspring coefficient reduced to 0.7 net (accounting for
  invasion loss and foundress mortality).

## Next step

v2.0: editable wash reading and calibration. Let the user enter their
own wash reading from this morning and have the instrument back-solve
for the likely true population given the calendar date. That moves the
instrument from diagnostic to decision support. Adjacent next move:
let the user drop their own treatment dates onto the timeline and
compare side-by-side with a canonical strategy.

## Art direction

Default Night Lab direction: editorial monochrome, Geist for body, mono
for labels and tabular numbers, thin borders, no gradients. Single
restrained accent color (oxidized orange, `#c77700`) for the alcohol
wash curve — justified because it must read as "the one channel the
beekeeper sees" and must be immediately distinguishable from the
grey/black truth curves. The blue queen-cage band is similarly
restrained, only used for the brood-break overlay.

## Promotion read

Maybe — leaning toward strong. The form-to-problem fit is genuinely
native: a hidden reservoir that must be shown alongside the visible
measurement. The "same drug, different timing, very different kill"
insight is a real revelation, not just a visualization. The instrument
passes the north-star "new legibility" test cleanly. What holds it at
"maybe" rather than "strong" is that v1.0 is preset-only; adding custom
wash-reading input and user-placed treatments would move it from
diagnostic to decision instrument. Beekeeping is a fresh domain for
Night Lab.

## Lineage

- New instrument class for Night Lab: **hidden-reservoir instrument**.
  Distinct from threshold-crossing (031), window-positioning (032),
  max-function (033), multi-object spatial collision (034),
  accumulation-toward-threshold (027), path-accumulation (029),
  bandwidth (026), parameter-space (017/021/025/028 family),
  deformation (028), radial (030), translation (031)
- The storytelling device is the *ratio between visible measurement and
  true state*, rendered across a full cycle, with timed interventions
  showing how the ratio governs kill efficacy
- Domain: first Night Lab build in apiculture/entomology

## Promotion candidate read

Strong candidate to revisit for v2.0. The instrument has a clear center
and a generative structure. The "hidden reservoir vs visible
measurement" template could be reused for any domain where the
diagnostic systematically under-counts the real state: glaucoma
(intraocular pressure spikes outside clinic visits), kidney function
(creatinine lags GFR), battery health (voltage lies about capacity),
soil microbiome, atmospheric methane leak point sources.
