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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
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 Grammotaulius betteni (Limnephilidae) (Northern Caddisfly) Caddisfly Larva from the Yakima River in Washington
This is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The prosternal horn is present.
- The mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major setae on the ventral edge of the hind femur.
- Chloride epithelia seem to be absent from the dorsal side of any abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on Grammotaulius betteni being the only species of this genus known in Washington state.
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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Stonefly Species Claassenia sabulosa (Golden Stones)

Claassenia sabulosa is the only species in an exclusively western genus. It is also the West's sole representitave in the subfamily Perlinae. Overall, its the least important species among the common western Perlidae . But it is paradoxically the most important at the time of its greatest activity. This is because it is primarily a late Summer/Fall emerger that can be found as late as October in many locations, long after the hatches of its siblings have been relegated to memory.

No other aquatic insect rivals them for size and sheer calorie content during the time of year when they are on the water. The only other truly large aquatic insects that even come close at this time of year are Dicosmoecus caddis, though they usually hatch later. While approaching in wing length, the caddis doesn't come close in body mass. The angler fortunate to come across a major flight of these critters in the fall is apt to have tremendous action as the trout prepare for winter by feeding ravenously.

Where & when

Time of year : Late Summer through Fall

Species Range

Egg-Laying behavior

Time of day: Any time


Besides time of year, the adults of this similarly sized large species can easily be distinguished from the better known western Perlidae by the males having brachypterous (severely shortened) wings and a unique oval hammer on the 9th sternum that is clearly visible without the need for magnification.

Because of its nymphs pronounced anal gills it can be confused with Hesperoperla. They can be sorted easiest by looking at their heads. Claassenia has a large "W" shaped mark in front of the ocelli as opposed to the hour glass shaped vertical marking on Hesperoperla. As a Perlinae, the shape of its head's posterior margin often appears concave (due to the raised transverse occipital ridge). This is opposed to the convex shape of the other large western perlids, giving Claassenia a unique appearance. Their antennae and tails are noticeably much longer also.

Specimens of the Stonefly Species Claassenia sabulosa

1 Male Adult
1 Female Adult
4 Nymphs

Start a Discussion of Claassenia sabulosa


Stonefly Species Claassenia sabulosa (Golden Stones)

Species Range
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