A census of the night-fliers · MMXXV
Seven of Britain’s most remarkable moths, pinned to the page in pure geometry — keyed by family, habitat and hour. Narrow the drawer, open the plates, read by lamplight.
01 · Prologue
Eleven o’clock is the official hour of the actinicLight rich in near-ultraviolet — invisible to us, glaring to most nocturnal insects, which is why traps favour mercury-vapour and UV LEDs. lamp. The mercury bulb warms to its blue-violet hush, the white sheet is rigged behind it, and the recorder settles in with a notebook and a kettle. This is the light-trap, oldest instrument of the moth census: the one at Rothamsted has run almost continuously since the 1930s, nine decades of nights tallied in glass tubes.
Set beside the butterflies, moths are a scarcely inventoried empire. Britain keeps roughly two and a half thousand species against some sixty butterflies, and any garden lamp, run year on year, still turns up surprises. Every imagoThe final, winged adult stage of an insect’s life cycle — the stage that comes to the lamp. that reaches the sheet is a vote in a very long election, about climate, about hedgerows, about what the dark is still allowed to be.
A light-trap is a question asked of the dark. The moths are the answer.Field notebook, June
Lately the answers have been worrying. Two-thirds of British moth species have declined within living memory — a loss that runs quietly because it happens at night, to animals few people ever see. Yet moths shoulder whole economies: they pollinate the flowers that close by day, and they feed the bats, the owls, the dawn chorus. Empty the sheet, and something upstream goes silent.
This atlas pages seven species chosen for character rather than completeness. Use the facets to narrow the drawer; open a plate to see a moth drawn large; consult the almanac for when the lamp earns its keep. Nothing here runs on script — the census is kept, as it always has been, by attention.
02 · The Census
Open the drawer. Narrow it by family, habitat, or the hour it flies — the census and the almanac keep pace. Open any figure for its plate.
Night-flying
Open plate I: elephant hawk-mothDeilephila elpenor
The caterpillar owns the name: when alarmed it rears up and inflates two false eyespots behind its real head, startling birds into a bluff. The adult, rose and olive and too bright for daylight, is a whirring regular at garden lamps from June onward.
Day-flying
Open plate II: hummingbird hawk-mothMacroglossum stellatarum
Broad daylight is its hour. It hovers at valerian and geranium with a tongue longer than its body, refuelling flower to flower without ever landing. A migrant from the south; some years it arrives in force. Hear the faint hum before you see it.
Night-flying
Open plate III: poplar hawk-mothLaothoe populi
Among our largest moths, and one of the few that never feeds: the adult has no mouthparts and lives a fortnight on reserves banked as a caterpillar. Disturbed at rest, it flashes the crimson bases of its hindwings — a sudden startle, then stillness again.
Night-flying
Open plate IV: peppered mothBiston betularia
The most famous moth in science. On soot-blackened Victorian trees a dark form, carbonaria, out-survived the speckled type until it outnumbered it around Manchester; clean air has since reversed the tally. Evolution observed, not inferred.
Day-flying
Open plate V: cinnabarTyria jacobaeae
It advertises what it already knows: the caterpillar feeds on ragwort and banks its alkaloids, making moth and all poisonous. Scarlet and black is a sentence every bird learns young. Look for it skimming hot sunshine over heath and down.
Day-flying
Open plate VI: garden tigerArctia caja
A tiger in miniature, and disappearing. The woolly-bear caterpillar is folklore; the adult — white forewings marbled like a fingerprint, scarlet hindwings flashed only in flight — has declined sharply across Britain since the 1960s. Count it when you see it.
Day-flying males
Open plate VII: emperor mothSaturnia pavonia
Our only truly imperial species. The males fly in full afternoon sun, steering by scent along heather ridges, while the larger females fly at night. Every wing carries its eyespot — four painted stares for the price of one moth.
This browser predates :has(), so the facets retire themselves; the full census is shown. Everything else on the page still works.
03 · Flight Almanac
Flight periods across the census: a bar marks the months each species is on the wing. Facets above narrow these rows too.
04 · Colophon
Every behaviour on this page is native element state met by a selector. There is no JavaScript anywhere in the document — no script tags, no handlers, no javascript: URLs. If you view source, the source is the whole story.
:has(), counting via CSS counters:target overlays with focusable closeprefers-color-schemescroll() & view() timelines<details> buttons, anchor positioningWith nothing modern supported this page is still a readable catalogue: the OS picks the theme, details open natively, plates open by fragment, anchors jump. Facets and the manual override hide themselves without :has(); without scroll timelines the page simply stays still. View transitions and a true focus trap need script, and both were declined.
Set in Fraunces for display, Source Serif 4 for reading, and IBM Plex Mono for specimen labels. All plates are drawn in SVG geometry; no moth was pinned for this atlas.