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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.

Case view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
It's only barely visible in one of my pictures, but I confirmed under the microscope that this one has a prosternal horn and the antennae are mid-way between the eyes and front of the head capsule.

I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.

The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.

Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
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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Mayfly Genus Attenella

This genus is represented by several important species across the country. In the East, Attenella attenuata (Little Blue-winged Olive) has garnered much attention as an important hatch in past angling texts. However, possible confusion with more abundant Drunella species of Blue-winged Olives has perhaps led to overstatement regarding its importance.

The species Attenella margarita (Little Western Blue-winged Olive) is disributed nationally. Though its eastern presence is relatively minor, in the West this mayfly can produce exceptional hatches.

Two other western species, Attenella delantala and to a lesser extent Attenella soquele often show up quite prominently in stream samples taken in the coastal states. The dramatically marked delantala nymph cannot be easily confused with any other western ephemerellid. Information regarding their winged appearance seems to be unavailable for now. Why they have gone unreported in angling texts is a mystery perhaps due to emergence behavior or misidentification by anglers of the dun and spinner stages. There is much to learn about these species that can be fairly abundant in some locales.

Where & when

In 18 records from GBIF, adults of this genus have been collected during July (56%), June (17%), August (17%), May (6%), and April (6%).

In 6 records from GBIF, this genus has been collected at elevations ranging from 194 to 8350 ft, with an average (median) of 5420 ft.

Genus Range

Hatching behavior

A significant difference between this genus and other ephemerellids is it's reported propensity to emerge from its nymphal shuck from the stream bottom in heptagenid fashion. While other ephemerellids can and do emerge underwater, this usually takes place within a foot at most from the surface. Attenella's availability as a submerged dun in the entire water column means use of the winged wetfly or soft hackles fished deeply can be an important tactic.

Specimens of the Mayfly Genus Attenella

1 Male Dun
3 Female Duns
3 Nymphs

Start a Discussion of Attenella

References

Mayfly Genus Attenella

Genus Range
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