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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Dorsal view of a Sweltsa (Chloroperlidae) (Sallfly) Stonefly Nymph from the Yakima River in Washington
This species was fairly abundant in a February sample of the upper Yakima.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Little Maryatts

Like most common names,"Little Maryatt" can refer to more than one taxon. They're previewed below, along with 8 specimens. For more detail click through to the scientific names.

Mayfly Genus Epeorus

These are often called Little Maryatts.
There is remarkable variety of form and color within this prolific genus of fast-water mayflies. Different species are found across the country, and several cause good hatches. Fly anglers are likely to encounter the lesser species on occasion, too.

The best Epeorus hatch in the East is Epeorus pleuralis, the famous Quill Gordon, the first abundant large mayfly hatch of the year. Epeorus vitreus comes a little later and is important in both the East and Midwest.

In the West, Epeorus longimanus dominates in fast, high-altitude streams, while Epeorus albertae inhabits slower and lower waters.
Artistic view of a Male Epeorus deceptivus (Heptageniidae) Mayfly Dun from the South Fork Sauk River in Washington
The lack of a darkened humeral crossvein rules out Epeorus albertae and Epeorus dulciana. The lack of a dark macula on the forefemora rules out Epeorus longimanus. The small size rules out Epeorus grandis and Epeorus permagnus. That leaves as the only possibility known in Washington state Epeorus deceptivus. It is a small species, although not reportedly quite as small as this specimen. I couldn't find anything in the species description in Traver (1935) to definitively confirm or rule out the species ID, given that I don't have the preserved specimen to check under a microscope, but it has to be either deceptivus or something not yet reported in Washington.

It was collected at the same time as a similar-sized female dun.
Epeorus vitreus (Heptageniidae) (Sulphur) Mayfly Nymph from unknown in Wisconsin

Mayfly Species Ephemerella dorothea dorothea

These are sometimes called Little Maryatts.
Ephemerella dorothea consists of two subspecies, which both produce excellent action. Ephemerella dorothea dorothea is a small species of Sulphur in the East, and Ephemerella dorothea infrequens (formerly Ephemerella infrequens) is one of the two main Pale Morning Dun hatches of the West. The remainder of this page focuses on the dorothea dorothea subspecies, and Ephemerella dorothea infrequens is discussed separately on its own page.

This is one of the most challenging mayfly hatches on Eastern waters. On many streams, it follows or overlaps hatches of the larger, lingering Ephemerella invaria.
Dorsal view of a Ephemerella dorothea dorothea (Ephemerellidae) (Pale Evening Dun) Mayfly Nymph from Paradise Creek in Pennsylvania
I keyed this nymph carefully under a microscope to check that it's Ephemerella dorothea.

Mayfly Species Ephemerella invaria

These are very rarely called Little Maryatts.
This species, the primary "Sulphur" hatch, stirs many feelings in the angler. There is nostalgia for days when everything clicked and large, selective trout were brought to hand. There is the bewildering memory of towering clouds of spinners which promise great fishing and then vanish back into the aspens as night falls. There is frustration from the maddening selectivity with which trout approach the emerging duns--a vexing challenge that, for some of us, is the source of our excitement when Sulphur time rolls around.

Ephemerella invaria is one of the two species frequently known as Sulphurs (the other is Ephemerella dorothea). There used to be a third, Ephemerella rotunda, but entomologists recently discovered that invaria and rotunda are a single species with an incredible range of individual variation. This variation and the similarity to the also variable dorothea make telling them apart exceptionally tricky.

As the combination of two already prolific species, this has become the most abundant of all mayfly species in Eastern and Midwestern trout streams.
Lateral view of a Male Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Dun from Penn's Creek in Pennsylvania
Lateral view of a Male Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Spinner from the Teal River in Wisconsin
Dorsal view of a Ephemerella invaria (Ephemerellidae) (Sulphur) Mayfly Nymph from the Beaverkill River in New York
This small Ephemerella invaria nymph was at least a month away from emergence.

Little Maryatts

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