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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.

Dorsal view of a Holocentropus (Polycentropodidae) Caddisfly Larva from the Yakima River in Washington
This one seems to tentatively key to Holocentropus, although I can't make out the anal spines in Couplet 7 of the Key to Genera of Polycentropodidae Larvae nor the dark bands in Couplet 4 of the Key to Genera of Polycentropodidae Larvae, making me wonder if I went wrong somewhere in keying it out. I don't see where that could have happened, though. It might also be that it's a very immature larva and doesn't possess all the identifying characteristics in the key yet. If Holocentropus is correct, then Holocentropus flavus and Holocentropus interruptus are the two likely possibilities based on range, but I was not able to find a description of their larvae.
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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Cultus tostonus (Springfly) Stonefly Nymph Pictures

This specimen keys pretty well to Cultus. Key characteristics observed under the microscope but not necessarily apparent on my photo are the lack of submental gills (or any gills at all), the lack of short, stout setae on the occiput or anterolateral prothoracic margins, and the lack of a low knob below the subapical tooth on the lacinia. Species known to be found in Washington are Cultus pilatus and Cultus tostonus. It clearly does not fit the description by Frison (1942) of Diploperla pilata, as Cultus pilatus was first named. I cannot find a detailed description of the nymph of tostonus, but Ricker 1952 describes a defining character of the adults, "Head mostly yellow, the only important dark marking being the bands which join the anterior to the lateral ocelli ; median pronotal stripe, at its middle, about one-fifth of the width of the pronotum." The nymph shows a very dark pattern fitting that description on the head (likely retained into adulthood) and the pronotal stripe is about the right width, too. Given that visual description, the range, and the poor fit to pilatus, I'm calling this Cultus tostonus.

Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington
Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington
Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington
Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington
Ventral view of a Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington
Ruler view of a Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington The smallest ruler marks are 1 mm.
Dorsal view of a Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington
Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington
Mesosternum

Cultus tostonus (Perlodidae) (Springfly) Stonefly Nymph from the Cedar River in Washington

This stonefly was collected from the Cedar River in Washington on July 2nd, 2021 and added to Troutnut.com by Troutnut on July 4th, 2021.


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Cultus tostonus (Springfly) Stonefly Nymph Pictures

Collection details
Location: Cedar River, Washington
Date: July 2nd, 2021
Added to site: July 4th, 2021
Author: Troutnut
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