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.

Here Oksrukuyik Creek flows away from the Dalton Highway toward the pipeline. It eventually grows into one of the major rivers of the North Slope, and the main drainage to the west of the Sag, but where it crosses the road it's just a small grayling stream.

From Oksrukuyik Creek in Alaska

Stream photos

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Amphizoa Beetle Larva Amphizoa Beetle Larva

Dorsal view of a Amphizoa (Amphizoidae) Beetle Larva from Sears Creek in Washington

This is the first of it's family I've seen, collected from a tiny, fishless stream in the Cascades. The three species of this genus all live in the Northwest and are predators that primarily eat stonefly nymphs Merritt R.W., Cummins, K.W., and Berg, M.B. (2019).

5 Recently Added Photos

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.

diff between march brown &gray fox

This topic is about the Mayfly Species Stenonema vicarium

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.

Example specimens

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Male Stenonema vicarium (March Brown) Mayfly Spinner

Artistic view of a Male Stenonema vicarium (Heptageniidae) (March Brown) Mayfly Spinner from the Teal River in Wisconsin

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Male Stenonema vicarium (March Brown) Mayfly Dun

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."

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Female Stenonema vicarium (March Brown) Mayfly Spinner

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."

Jrcald
Posts: 1

Jrcald on Mar 12, 2007March 12th, 2007, 2:30 am EDT

i know that gray foxs and march browns are classified in the same family but what are the differences ? what is the color differences are both bodies the same color tan ?

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Mar 12, 2007March 12th, 2007, 4:01 am EDT

They're not just in the same family -- they're both the same species, Maccaffertium vicarium. But they are still distinct color variations within that species.

In the specimens I've collected, it seems the "Grey Fox" ones are a little smaller and stockier, and with more gray or amber shades than brown.

The hatching periods and behavior are generally supposed to be the same. Just carry patterns for each variation and try to scoop up a live one on the stream to decide which to use.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

LittleJ
Hollidaysburg Pa

Posts: 251

LittleJ on Mar 12, 2007March 12th, 2007, 8:09 am EDT

I thought "gray fox" were fuscum?.......did they eliminate that species when they went from stenonoma to maccaffertium? just when I think I'm getting the hang of this bug jargon you guys send me another curveball:)
Jeff

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Mar 12, 2007March 12th, 2007, 10:23 am EDT

I thought "gray fox" were fuscum?.......did they eliminate that species when they went from stenonoma to maccaffertium?

Yeah, they eliminated fuscom. I don't think it was in the same paper that bumped all but one of the Stenonema species over to Maccaffertium, but it was probably around the same time.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Konchu