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Hatches › Mayfly
Ephemerella excrucians · species
A dependable mayfly match when trout key on pale nymphs, emergers, duns, and spent spinners.
Category
Mayfly
Category
The insect or forage category for this profile.
Size
Typically imitated in moderate mayfly sizes, often around #14–18 depending on water and hatch.
Size
Typical size range anglers imitate on the water.
Key stages
Eggs, Nymph, Emerger, Dun, Spinner, Egg Laying Spinner, Spent Spinner
Key stages
Life stages most relevant to fly fishing this hatch or forage.
Water types
Rivers, Streams, Riffle-to-run sections
Water types
Water types where this bug or forage is commonly found.
Pale Morning Dun refers here to Ephemerella excrucians, a spiny crawler mayfly in the family Ephemerellidae. It is found across Canada and the continental United States, making it a familiar hatch for Idaho anglers.
Also known as: PMD
Female mayflies lay hundreds to thousands of eggs either in or near the water. These eggs eventually sink to the stream bottom, where they will develop.
Nymphs spend the majority of their lives on the stream bottom. They feed and grow, undergoing several molts as they mature.
As the nymph matures, it rises to the water's surface. At this point, the adult form begins to hatch from its nymphal shuck.
The newly emerged adult, known as a dun, rests on or just above the water's surface. It allows its wings to dry and harden before further transformation.
Mated adult mayflies, now in their spinner stage, ascend into the air. This aerial phase is primarily for mating and reproduction.
After mating, the female spinner returns to the water's surface. She carefully deposits her eggs to ensure the continuation of the species.
Following egg-laying, adult mayflies die. Their spent bodies often float on the water's surface, becoming an easy meal for fish.
Nymph
Loon Outdoors
Materials
Emerger
Loon Outdoors
Materials
Dun
tightlinevideo
Materials
Egg Laying Spinner
Traditional Flies and Dries
Materials
Spent Spinner
Caddis Fly Angling Shop
Materials
Pale Morning Dun
One species, multiple rivers.
Episode 101 · Aug 13, 2019
