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Sulphur

Also called Sulfur, Sulphur hatch, Sulfur hatch, Ephemerella sulphur

“Sulphur” is a common hatch label for small yellow mayflies, most often in the genus Ephemerella. Anglers use it to match pale yellow duns and their evening spinner falls on many trout rivers.

Group
Mayfly hatches
Category
Entomology & forage
Level
Intermediate
Water
Freshwater

Last updated

What Sulphur means

Look for a light yellow mayfly riding the surface in late afternoon into evening, especially on slower runs and tailouts. In many Eastern and Midwest trout fisheries, anglers call that a “sulphur,” even though several similar species can be involved.

Most sulphur talk centers on two stages. The dun hatch brings pale yellow adults that sit low in the film. Later, the spinner fall can stack fish up in specific lanes, with spent adults lying flat on the surface. Nymphs are typically small and clinger/crawler types, so drifted nymphs and emergers get attention before the first duns show.

Why it matters on the water

“Sulphur” is a reminder to match color and posture, not just a name. A pale yellow parachute may get looks, but a low-riding comparadun or a cripple often fits what trout are actually taking during the hatch.

It also points to timing. Many sulphur events build toward evening, and the spinner fall can be the most selective window. Having a plan for duns, emergers, and spinners keeps the day from turning into random fly changes.

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