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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.

Lateral view of a Clostoeca disjuncta (Limnephilidae) (Northern Caddisfly) Caddisfly Larva from the Yakima River in Washington
This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
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.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Gray Foxes

Like most common names,"Gray Fox" can refer to more than one taxon. They're previewed below, along with 13 specimens. For more detail click through to the scientific names.

Mayfly Species Stenonema vicarium

These are often called Gray Foxes.
In the East and Midwest this is one of the most important hatches of the Spring. They are large flies which emerge sporadically, making for long days of good fishing.

This species contains the two classic Eastern hatches formerly known as Stenonema vicarium and Stenonema fuscum, the "March Brown" and "Gray Fox." Entomologists have discovered that these mayflies belong to the same species, but they still display differences in appearance which the trout notice easily. Anglers should be prepared to imitate both types.
Artistic view of a Male Stenonema vicarium (Heptageniidae) (March Brown) Mayfly Dun from the Namekagon River in Wisconsin
I collected this mayfly on the same trip as a female of the same species. After these photos it molted into a spinner. This is the form of Stenonema vicarium which anglers call the "Gray Fox."
Lateral view of a Female Stenonema vicarium (Heptageniidae) (March Brown) Mayfly Spinner from the Namekagon River in Wisconsin
I collected this mayfly on the same trip as a male of the same species. They are Maccaffertium vicarium mayflies of the type formerly known as Stenonema fuscom, the "Gray Fox."
Dorsal view of a Stenonema vicarium (Heptageniidae) (March Brown) Mayfly Nymph from the Beaverkill River in New York

Mayfly Species Heptagenia solitaria

These are sometimes called Gray Foxes.
Male Heptagenia solitaria (Heptageniidae) (Ginger Quill) Mayfly Spinner from the Flathead River-lower in Montana
This species is common in the Flathead River below Kerr Day. The river here is fairly warm with a cobble and boulder bottom with heavy periphyton at times. This species is not common elsewhere in western Montana.
Heptagenia solitaria (Heptageniidae) (Ginger Quill) Mayfly Nymph from the Flathead River-lower in Montana

Mayfly Genus Stenacron

These are very rarely called Gray Foxes.
The species in this genus were formerly classified in Stenonema. See the genus Maccaffertium for details. Only one species, Stenacron interpunctatum, is important to fly fishermen. See its page for details.
Artistic view of a Male Stenacron (Heptageniidae) (Light Cahill) Mayfly Dun from the Teal River in Wisconsin
Lateral view of a Male Stenacron interpunctatum (Heptageniidae) (Light Cahill) Mayfly Spinner from the Namekagon River in Wisconsin
Stenacron (Heptageniidae) (Light Cahill) Mayfly Nymph from unknown in Wisconsin

Mayfly Species Stenacron interpunctatum

These are very rarely called Gray Foxes.
This is the best of the sporadic summer hatches known to anglers as Light Cahills. It was formerly known as Stenonema canadense and is considered by most angling historians as the model for that classic Catskill pattern.
Lateral view of a Female Stenacron interpunctatum (Heptageniidae) (Light Cahill) Mayfly Dun from the West Branch of Owego Creek in New York
This is a fairly small late-season female Stenacron dun.
Lateral view of a Male Stenacron interpunctatum (Heptageniidae) (Light Cahill) Mayfly Spinner from the Namekagon River in Wisconsin
Dorsal view of a Stenacron interpunctatum (Heptageniidae) (Light Cahill) Mayfly Nymph from the Marengo River in Wisconsin

Mayfly Species Ephemera varia

These are very rarely called Gray Foxes.
This is an excellent hatch of a different character than its Ephemera brethren. Rather than emerging in a flurry of activity within a week, the Ephemera varia hatch may last for more than a month in a single place.
Artistic view of a Female Ephemera varia (Ephemeridae) (Yellow Drake) Mayfly Dun from Aquarium in New York
This yellow drake dun hatched out of my aquarium over a month before her brethren in the wild are slated to emerge. She seems a bit small, and that might be the reason.
Lateral view of a Female Ephemera varia (Ephemeridae) (Yellow Drake) Mayfly Spinner from Cayuta Creek in New York
I found this female spinner ovipositing in a small stream. She came along while I was playing a trout -- every good bug seemed to do that last night! I didn't have my bug net, so I caught the trout in my landing net, released the trout, and caught the mayfly in my landing net. Her wing got a bit messed up from that.
A burrowing mayfly nymph. The juvenile stage of the brown drake, Ephemera simulans

Dorsal view of a Ephemera varia (Ephemeridae) (Yellow Drake) Mayfly Nymph from Fall Creek in New York
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