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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 Setvena wahkeena (Perlodidae) (Wahkeena Springfly) Stonefly Nymph from Mystery Creek #199 in Washington
As far as I can tell, this species has only previously been reported from one site in Oregon along the Columbia gorge. However, the key characteristics are fairly unmistakable in all except for one minor detail:
— 4 small yellow spots on frons visible in photos
— Narrow occipital spinule row curves forward (but doesn’t quite meet on stem of ecdysial suture, as it's supposed to in this species)
— Short spinules on anterior margin of front legs
— Short rposterior row of blunt spinules on abdominal tergae, rather than elongated spinules dorsally
I caught several of these mature nymphs in the fishless, tiny headwaters of a creek high in the Wenatchee Mountains.
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.

Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva Pictures

See the forum discussion for discussion with a caddis expert (Dave Ruiter / Creno) about the identification of this specimen. I'm a bit perplexed because some gills seem to have more than 4 branches, which would lead in a different direction at Couplet 18 of the Key to Genera of Limnephilidae Larvae, but Dave knew his stuff a lot better than I did. He was convinced this is Onocosmoecus. The current range maps would put this in Onocosmoecus unicolor as the only option, but he believed there are probably multiple not-yet-distinguished species under that umbrella and suggested keeping this one's ID at the genus level for that reason.

Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Case view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Ruler view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska The smallest ruler marks are 1 mm.
Ventral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Dorsal view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska
Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Chena River in Alaska

This caddisfly was collected from the Chena River in Alaska on May 10th, 2008 and added to Troutnut.com by Troutnut on April 20th, 2011.

Discussions of this Larva

one of the dicosmoecins
3 replies
Posted by Creno on Apr 26, 2011
Last reply on Apr 28, 2011 by Troutnut
Most likely Onocosmoecus but I want to look at a couple critters.
I like the new site look. It will take awhile to look around.
creno

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Onocosmoecus (Great Late-Summer Sedge) Caddisfly Larva Pictures

Collection details
Location: Chena River, Alaska
Date: May 10th, 2008
Added to site: April 20th, 2011
Author: Troutnut
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