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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.

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.
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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Female Siphlonurus autumnalis (Gray Drake) Mayfly Spinner Pictures

I found this specimen and saw a few more of its kind during midday on a small, steep, rocky creek fairly high in the Cascades, different from the previously reported habitats of its species.

Appears to be Siphlonurus autumnalis

Female Siphlonurus autumnalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from Mystery Creek #249 in Washington
Female Siphlonurus autumnalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from Mystery Creek #249 in Washington
Lateral view of a Female Siphlonurus autumnalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from Mystery Creek #249 in Washington
Dorsal view of a Female Siphlonurus autumnalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from Mystery Creek #249 in Washington
Female Siphlonurus autumnalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from Mystery Creek #249 in Washington
Female Siphlonurus autumnalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from Mystery Creek #249 in Washington
Ventral view of a Female Siphlonurus autumnalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from Mystery Creek #249 in Washington
Ruler view of a Female Siphlonurus autumnalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from Mystery Creek #249 in Washington The smallest ruler marks are 1 mm.

This mayfly was collected from Mystery Creek #249 in Washington on September 29th, 2020 and added to Troutnut.com by Troutnut on November 10th, 2020.


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Female Siphlonurus autumnalis (Gray Drake) Mayfly Spinner Pictures

Collection details
Location: Mystery Creek #249, Washington
Date: September 29th, 2020
Added to site: November 10th, 2020
Author: Troutnut
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