Header image
Enter a name
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 Kogotus (Perlodidae) Stonefly Nymph from Mystery Creek #199 in Washington
This one pretty clearly keys to Kogotus, but it also looks fairly different from specimens I caught in the same creek about a month later in the year. With only one species of the genus known in Washington, I'm not sure about the answer to this ID.
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.

Male Rhithrogena virilis Mayfly Spinner Pictures

I'm fairly sure this is a specimen of Rhithrogena virilis based on closeup examination of the reproductive anatomy under the microscope (not shown in photos). The other other species of Rhithrogena this large is Rhithrogena flavianula, but the key in Needham's Biology of Mayflies mentions annulation in the abdomen (visible in some images on bugguide.net) more distinct than that on this specimen.

The body and front wing were both about 15.5 mm long, while the cerci were 40 mm long.

There's a pale amber tinge to the anterior areas of the wings, which doesn't show up all that well against the blue background.

Lateral view of a Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Dorsal view of a Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Tick marks are 1/16". The body and front wing were both about 15.5 mm long.

Ruler view of a Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington The smallest ruler marks are 1/16".
Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington
Ventral view of a Male Rhithrogena virilis (Heptageniidae) Mayfly Spinner from the South Fork Sauk River in Washington

This mayfly was collected from the South Fork Sauk River in Washington on July 5th, 2017 and added to Troutnut.com by Troutnut on July 6th, 2017.


Start a Discussion of Spinner

Male Rhithrogena virilis Mayfly Spinner Pictures

Collection details
Location: South Fork Sauk River, Washington
Date: July 5th, 2017
Added to site: July 6th, 2017
Author: Troutnut
Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy