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Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin
Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

Mystery Creek # 199 in Washington

Stream photos

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Onocosmoecus (Great Late-Summer Sedge) Caddisfly LarvaOnocosmoecus (Great Late-Summer Sedge) Caddisfly Larva
Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington
This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.
9 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.
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  1. Trout Streams
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  2. Idaho
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  3. The East Fork Big Lost River

  1. Trout Streams
    2. ›
  2. Idaho
    3. ›
  3. The East Fork Big Lost River

Landscape & scenery photos from the East Fork Big Lost River

The East Fork Big Lost River in Idaho
The East Fork Big Lost River in Idaho
The East Fork Big Lost River in Idaho
The East Fork Big Lost River in Idaho
The East Fork Big Lost River in Idaho
The East Fork Big Lost River in Idaho
The East Fork Big Lost River in Idaho
This was my first Snake River Fine-Spotted Cutthroat. It's probably a stocker, and no trout are native to this river drainage (which disappeared into aquifers in the desert, even before irrigation took the water), but it's still fun to add another subspecies to my list. From the East Fork Big Lost River in Idaho
The East Fork Big Lost River in Idaho
The East Fork Big Lost River in Idaho

Closeup insects by Troutnut from the East Fork Big Lost River in Idaho

6
Female Ephemerella tibialis (Little Western Dark Hendrickson) Mayfly Dun
Lateral view of a Female Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Dun from the East Fork Big Lost River in Idaho
I'm fairly confident calling this dun Ephemerella tibialis because it emerged from one of several similar nymphs in my bucket, which I was able to ID with quite a bit of certainty. However, it looks very different from the other duns I currently have listed, which makes me rethink their IDs.
9
Dolophilodes (Medium Evening Sedge) Caddisfly Larva
Dorsal view of a Dolophilodes (Philopotamidae) (Medium Evening Sedge) Caddisfly Larva from the East Fork Big Lost River in Idaho
I think this larva best fits Dolophilodes, in which the anterior margin of the frontoclypeus is supposed to be "slightly asymmetrical." I can't confidently make out the asymmetry, but the other genera are supposed to have either greater asymmetry or a symmetrical, but convex, shape, whereas this one is clearly concave. Based on distribution records, the species should be either aequalis, dorcus, or pallidipes, but I can't find any source to distinguish between them.
14
Arctopsyche grandis (Great Gray Spotted Sedge) Caddisfly Larva
Lateral view of a Arctopsyche grandis (Hydropsychidae) (Great Gray Spotted Sedge) Caddisfly Larva from the East Fork Big Lost River in Idaho
At first I had trouble believing this giant Hydropsychidae larva was actually a member of its family, because of the size. I had never seen such a thing. It turned out to be a member of this exceptionally large species with a fitting name, grandis.
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Ephemerella tibialis (Little Western Dark Hendrickson) Mayfly Nymph
Lateral view of a Ephemerella tibialis (Ephemerellidae) (Little Western Dark Hendrickson) Mayfly Nymph from the East Fork Big Lost River in Idaho
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Hesperoperla pacifica (Golden Stone) Stonefly Nymph
Dorsal view of a Hesperoperla pacifica (Perlidae) (Golden Stone) Stonefly Nymph from the East Fork Big Lost River in Idaho
ID notes from the microscope: The occiput has a sinuate, irregularly spaced spinule row.
5
Baetis flavistriga (BWO) Mayfly Nymph
Dorsal view of a Baetis flavistriga (Baetidae) (BWO) Mayfly Nymph from the East Fork Big Lost River in Idaho
This specimen keys to the Baetis flavistriga complex, which could be either flavistriga or Baetis phoebus.
7
Attenella margarita (Little Western Blue-Winged Olive) Mayfly Nymph
Dorsal view of a Attenella margarita (Ephemerellidae) (Little Western Blue-Winged Olive) Mayfly Nymph from the East Fork Big Lost River in Idaho
Notes from the microscope on the ID: Maxillary palp is present, distinctly 2-segmented, but very small. Gills on segment 4-7. This specimen has some unfortunate damage to the abdomen, but it's the only one I found in my sample.
12
Female Ephemerella excrucians (Pale Morning Dun) Mayfly Dun
Lateral view of a Female Ephemerella excrucians (Ephemerellidae) (Pale Morning Dun) Mayfly Dun from the Big Lost River in Idaho
This "specimen" is actually two different duns, one missing the middle front and back left legs, the other missing the terminal filament i.e. middle tail. I added them together by accident, but since they're the same species, stage, and gender, I might as well leave them together.
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