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Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Stonefly Genus Isoperla (Stripetails and Yellow Stones)

This is a very common trout stream stonefly genus. It is also huge, with sixty species scattered over the entire continent. Though anglers usually call them Little Yellow Stones or Yellow Sallies, the scientific common name for this genus is Stripetail. The latter is probably better to use as not all of them are necessarily little or yellow.

Specimens of the Stonefly Genus Isoperla

4 Adults
3 Male Adults
1 Female Adult
Female Isoperla fusca (Yellow Sally) Stonefly Adult
The family ID on this one was a little bit tricky. Just going by the size, shape, and color, it looks like Chloroperlidae. However, the second anal vein of the forewing is does not appear to be forked, and the apical maxillary palpal segment is close to the length of the penultimate segment, both of which rule out that family. The position of the cubitoanal crossvein relative to the anal cell in the forewing -- touching it in this case -- indicates Perlidae (and it really doesn't have the "look" of Perlidae at all), but other characteristics, such as the metathorastic sternacostal sutures and lack of gill remnants, point to Perlodidae. That's the right answer. Moving on to Perlodidae, the key characteristics in Merritt & Cummins lead straightforwarly to Isoperla, and the species key in Jewett 1959 (The Stoneflies of the Pacific Northwest) leads to Isoperla fusca.

There is one caveat: That source does suggest a May-July emergence, whereas this one was collected in mid-September.
7 Nymphs

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References

Taxonomy
» Genus Isoperla (Stripetails and Yellow Stones)
Species in Isoperla
Isoperla bilineataYellow Sally00
Isoperla fulvaYellow Sally522
Isoperla fuscaYellow Sally337
Isoperla quinquepunctataLittle Yellow Stonefly25
Isoperla signataYellow Sally00
55 species (Isoperla acula, Isoperla adunca, Isoperla baumanni, Isoperla bellona, Isoperla bifurcata, Isoperla burksi, Isoperla conspicua, Isoperla cotta, Isoperla coushatta, Isoperla davisi, Isoperla decepta, Isoperla decolorata, Isoperla denningi, Isoperla dicala, Isoperla distincta, Isoperla emarginata, Isoperla extensa, Isoperla francesca, Isoperla frisoni, Isoperla gibbsae, Isoperla grammatica, Isoperla gravitans, Isoperla holochlora, Isoperla irregularis, Isoperla jewetti, Isoperla katmaiensis, Isoperla lata, Isoperla longiseta, Isoperla major, Isoperla marlynia, Isoperla marmorata, Isoperla maxana, Isoperla miwok, Isoperla mohri, Isoperla montana, Isoperla mormona, Isoperla namata, Isoperla nana, Isoperla orata, Isoperla ouachita, Isoperla petersoni, Isoperla phalerata, Isoperla pinta, Isoperla punctata, Isoperla rainiera, Isoperla richardsoni, Isoperla roguensis, Isoperla sagittata, Isoperla sibria, Isoperla similis, Isoperla slossonae, Isoperla sordida, Isoperla szczytkoi, Isoperla tilasqua, and Isoperla transmarina) aren't included.
Genus Range
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