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.

Stream photos

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Perlodidae (Springflies and Yellow Stones) Stonefly Nymph Perlodidae (Springflies and Yellow Stones) Stonefly Nymph

Artistic view of a Perlodidae (Springflies and Yellow Stones) Stonefly Nymph from the Yakima River in Washington

This one seems to lead to Couplet 35 of the Key to Genera of Perlodidae Nymphs and the genus Isoperla, but I'm skeptical that's correct based on the general look. I need to get it under the microscope to review several choices in the key, and it'll probably end up a different Perlodidae.

11 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.

Caddisfly Species Brachycentrus americanus (American Grannoms)

Where & when

Time of year : July and August

This species is most prolific in the West and Midwest, but it may still be of concern to fishermen in the East.

In 80 records from GBIF, adults of this species have mostly been collected during July (31%), August (28%), June (16%), September (13%), and May (9%).

In 109 records from GBIF, this species has been collected at elevations ranging from 3 to 10007 ft, with an average (median) of 6099 ft.

Species Range

source

Map of specific collection sites

Hatching behavior

Time of day : Morning

Special thanks to Lloyd Gonzales, author of the excellent new book Fly-Fishing Pressured Water, for helping to sort out the Brachycentrus species and common names.

Specimens of the Caddisfly Species Brachycentrus americanus

1 Female Adult

Female Brachycentrus americanus (American Grannom) Caddisfly Adult

1 Picture

Female Brachycentrus americanus (Brachycentridae) (American Grannom) Caddisfly Adult from the Fall River in California

Size 11 mm. Prior to this photo the specimen dropped its large egg mass that was a very dark (almost black) olive sphere almost twice the diameter of the abdomen. Notice the abdomen visible through the wings is both thickened and shortened post egg drop.

Collected October 14, 2011 from the Fall River in California

Added by Entoman on October 21, 2011

Collected October 14, 2011 from the Fall River in California and added by Entoman on October 21, 2011

2 Larvae

Brachycentrus americanus (American Grannom) Caddisfly Larva

18 Pictures

Case view of a Brachycentrus americanus (Brachycentridae) (American Grannom) Caddisfly Larva from the Yakima River in Washington

This species of Brachycentrus was extremely common in mid-September kick net samples in the Yakima canyon.

Collected September 11, 2020 from the Yakima River in Washington

Added by Troutnut on September 18, 2020

Collected September 11, 2020 from the Yakima River in Washington and added by Troutnut on September 18, 2020

Brachycentrus americanus (American Grannom) Caddisfly Larva

13 Pictures

Case view of a Brachycentrus americanus (Brachycentridae) (American Grannom) Caddisfly Larva from the Dosewallips River in Washington

Both the genus ID (Merritt & Cummins) and species ID (Flint 1984) are pretty confident for this larva, a nice example of a common western caddisfly. It was by far the most abundant insect in my kicknet sample on this trip, and many of the rocks in the fast riffle where I sampled had dozens of these larvae clinging on.

Collected July 5, 2020 from the Dosewallips River in Washington

Added by Troutnut on July 12, 2020

Collected July 5, 2020 from the Dosewallips River in Washington and added by Troutnut on July 12, 2020

Discussions of Brachycentrus americanus

Brachycentrus americanus on the Lower Sacramento River California

Posted by Troutguide on Oct 29, 2016

Last reply on Oct 29, 2016 by Troutguide

I believe this is the species found in sometimes very large numbers on the Lower Sacramento River in the Redding area. Ten years ago it was present in such large numbers that fishing a fly on the bottom resulted in frequently hooking one of these caddis still in its case. Along with other aquatic insects their numbers have declined to a fraction of once seen. I don't believe the egg Sac dropped by the females to be olive , instread I have seen it to be a bright green. The females seem to oviposit close to the edge of flowing water and not midstream.

Start a Discussion of Brachycentrus americanus

References

Gonzales, Lloyd. 2005. Fly-Fishing Pressured Water. Stackpole Books.
LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.
Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.