Pale Evening Dun

Ephemerella dorothea

Hook size: #16-18
On the water: May 25 – Jul 10
Peak: Jun 1 – Jun 30
Time of day: Evening

The Sulphur has already finished its rise by the time this one starts. The Pale Evening Dun is its smaller, paler cousin, one that deliberately waits for the last twenty minutes of light before coming off — a window so short you need to be ready before you can no longer see.

Telling it apart

Small: size 16–18, distinctly finer than the Sulphur (14–16).
Very pale yellow body, almost cream, washed out compared to the Sulphur's true sulphur-yellow.
Same genus, Ephemerella, as the Sulphur — same general silhouette, just smaller and paler.
Comes off right at dusk, often in the last twenty minutes of usable light.

Easily confused with

The Sulphur itself, which shares its genus — size and timing settle it: the Sulphur starts around 7 p.m. in a bigger size, the Pale Evening Dun waits for the very end of the day in a smaller one. The small Blue-Winged Olive, active all season, stays greener than yellow.

The Sulphur's small cousin

Ephemerella dorothea and Ephemerella invaria (the Sulphur) share a genus, a general silhouette, and nearly the same river — but the first one consistently comes off later and smaller than the second. On a June evening it's not unusual to watch the Sulphur's rise wind down just as the Pale Evening Dun's is getting started.

That gap isn't accidental: two closely related species exploiting the same kind of water cut down on direct competition by emerging at slightly different points in the same evening window.

Why the very last light

Emerging at dusk rather than in full daylight cuts pressure from visual predators — insect-eating birds especially — without requiring the wait until full dark the way Hexagenia does. It's a compromise window: dark enough to be safer, still light enough for an insect this size to find its way.

The catch is that window barely lasts twenty minutes, and it closes fast once it opens.

Rig up before you can't see

With a window that short, there's no time to change tippet or dig through the fly box once the hatch actually starts. Rig your fine tippet, pick your fly, and read your lie while it's still light — then wait.

Once dusk sets in, trust the sound of the rise and where you know your fly to be more than what you can actually see riding the water.

Fishing it, stage by stage

Nymph / emerger

Late afternoon, in moderate current.

Near bottom, then on a rising drift as dusk approaches.

Tie onPartridge & Orange

Dun

The last twenty minutes of usable light.

A small pale dry, rigged and spotted before the light gives out entirely.

Tie onSulphur Dun

Every other insect worth knowing, month by month: See the full hatch chart