Header image
Enter a name
Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives
Baetis

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

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.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

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.


Start a Discussion of Nymph

Cultus tostonus (Springfly) Stonefly Nymph Pictures

Collection details
Location: Cedar River, Washington
Date: July 2nd, 2021
Added to site: July 4th, 2021
Author: Troutnut
Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy