Green Drake
Ephemera danica — Mayfly, Up-winged fly
The iconic mayfly of British chalk streams — its annual emergence signals the most celebrated fortnight in fly fishing.
Mayflies — Ephemeroptera
Ephemeridae
Body 18–22 mm / Hook size 10–12
Afternoon & evening
Chalk streams, limestone rivers, and alkaline stillwaters with silty beds
Lifecycle
The Green Drake passes through an unusually long nymphal period of one to two years, burrowing deep into the silt and fine gravel of chalk-stream beds. The U-shaped burrow nymph is large and distinctive, with three feathery tails and heavily fringed gills along its abdomen. As it matures it develops dark wing cases visible under its thorax.
Emergence is triggered by water temperature reaching 12–16 °C, typically in late May on southern chalk streams and early June further north. The nymph rises through the water column and the dun bursts through the surface film in a matter of seconds — a vulnerable moment that triggers explosive feeding from trout. The newly-hatched dun (subimago) sits momentarily on the surface to dry its wings before flying to bankside vegetation.
The final moult to the sexually mature spinner (imago) — called the Spent Gnat — typically occurs the following evening. Huge spinner falls at dusk, with wings flat on the surface and body flush in the water, represent the most difficult and rewarding match-the-hatch challenge of the entire season.
Peak months
No hatch commands more reverence in British fly fishing than the Green Drake — locally called "the Mayfly" even though it is just one of many mayfly species. For two to three weeks each spring, chalk streams transform. Wild brown trout that spend most of the year feeding cautiously below the surface throw caution aside, rising freely to drakes throughout the day. Beats that are normally carefully guarded suddenly erupt with activity.
Ephemera danica is the largest upwinged fly on British and European chalk streams. The dun's cream-yellow body, olive-tinged wings, and three long tails make it unmistakable. The spinner — the Spent Gnat — has transparent wings and a gleaming pale abdomen, and lies flush in the surface film after egg-laying.
Historically known as "Duffer's Fortnight" because even inexperienced anglers could catch fish during the hatch, a large spinner fall on a calm evening is in fact one of the most technically demanding situations in dry fly fishing. Trout become locked on the spent spinners lying motionless in the surface, refusing any fly that drags or sits incorrectly.
The species is found across most of Central and Northern Europe on rivers with suitable silty substrates — the English chalk streams (Test, Itchen, Kennet), the limestone rivers of Ireland, Czech Republic, Slovenia, and upland streams in Scandinavia.
Fishing tips
Matching the Dun
During the afternoon dun emergence, fish visibly rising to the large cream-winged adults. A size 10–12 Green Drake dry fly tied on a wide-gape hook, presented drag-free in the fish's feeding lane, is the classic approach. Trout often move upstream to intercept duns, so watch rise form and position carefully before casting. Long, fine tippets (5X) are needed on chalk streams.
The Spinner Fall
The evening spinner fall is technically harder. Use a flat-wing spent pattern (Spent Gnat or CDC Spinner) in size 10–12, presented with absolute precision. The fly must be absolutely flush in the film — no hackle that lifts the body above the surface. Fish sipping spent spinners make small, confident rings: watch the direction of the rise and cast two feet upstream to intercept the drift.
Nymph Before the Hatch
In the hour before hatching begins, trout switch to nymphing on ascending Ephemera nymphs. A large, cream-bodied nymph with tails (size 10) dead-drifted near the bottom, then lifted to the surface as it swims upward, can be devastatingly effective timed correctly.
Fly patterns
Target species
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Other hatches
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MayfliesIron Blue Dun
Nigrobaetis nigerThe fly fisher's dark secret — a small, near-black mayfly that hatches prolifically in cold, blustery conditions when nothing else is on the water.
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CaddisfliesGrannom
Brachycentrus subnubilisThe first major caddis of the year — appearing in huge April swarms, the Grannom kick-starts the surface fly fishing season on chalk streams.