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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 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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Ameletus vernalis (Brown Dun) Mayfly Nymph Pictures

I keyed this one out using the Alberta species key from Zloty & Pritchard 1997.

Notes from the ID include:

1. Posterior margin of sternites 6-8 without spines
2. Mesal gill extension "well developed"
3. Basil third of caudal filaments pale
4. Anterior surface of front femora mostly pale
5. Dark band on caudal filaments begins around segment 20
6. Final instars early season

This one keys out pretty cleanly to Ameletus vernalis except the color pattern on the tergites doesn't match. However, two species known in Washington aren't included in the key. Of those two, Ameletus vancouverensis would be too small (adult body length 9 mm), but Ameletus andersoni (currently documented only from a spring in Cowlitz County) has a wide range of sizes and emergence times that could be compatible with this one. So I can't rule that species out, but Ameletus vernalis seems the most likely.

Dorsal view of a Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington
Ventral view of a Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington
Lateral view of a Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington
Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington
Ruler view of a Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington The smallest ruler marks are 1 mm.
Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington
Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington
Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington
Ameletus vernalis (Ameletidae) (Brown Dun) Mayfly Nymph from the Yakima River in Washington

This mayfly was collected from the Yakima River in Washington on April 9th, 2021 and added to Troutnut.com by Troutnut on April 12th, 2021.


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Ameletus vernalis (Brown Dun) Mayfly Nymph Pictures

Collection details
Location: Yakima River, Washington
Date: April 9th, 2021
Added to site: April 12th, 2021
Author: Troutnut
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