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.

I like this one. Glacial river, taiga, tundra, and the perpetual ice cover of a massive high ridge dozens of miles away in the Wrangell Mountains.

From the Copper River in Alaska

Stream photos

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Epeorus albertae (Pink Lady) Mayfly Nymph Epeorus albertae (Pink Lady) Mayfly Nymph

Dorsal view of a Epeorus albertae (Heptageniidae) (Pink Lady) Mayfly Nymph from the East Fork Issaquah Creek in Washington

This specimen keys to the Epeorus albertae group of species. Of the five species in that group, the two known in Washington state are Epeorus albertae and Epeorus dulciana. Of the two, albertae has been collected in vastly more locations in Washington than dulciana, suggesting it is far more common. On that basis alone I'm tentatively putting this nymph in albertae, with the large caveat that there's no real information to rule out dulciana.

5 Recently Added Photos

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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Mayfly Species Rhithrogena undulata (Small Western Red Quills)

This is one of the two most common species of Rhithrogena.

Where & when

Time of year : Mid-June through August

In 5 records from GBIF, adults of this species have been collected during June (20%), September (20%), April (20%), May (20%), and July (20%).

In 1 record from GBIF, this species has been collected at elevation of 5066 ft.

Species Range

source

Map of specific collection sites

Hatching behavior

Rhithrogena undulata duns escape their nymphal shucks underwater, but instead of emerging on the stream bed like most Rhithrogena species, they wait until they are within inches of the surface.

Swisher and Richards in Selective Trout say the duns are unimportant.

Spinner behavior

Time of day: Dusk

Knopp and Cormier call the spinner falls of Rhithrogena undulata "spectacular," and others mention that they are fishable.

Nymph biology

Current speed: Slow to medium

These nymphs prefer slower water than the others in their genus.

Physical description

Most physical descriptions on Troutnut are direct or slightly edited quotes from the original scientific sources describing or updating the species, although there may be errors in copying them to this website. Such descriptions aren't always definitive, because species often turn out to be more variable than the original describers observed. In some cases, only a single specimen was described! However, they are useful starting points.

Male Spinner

Described in Needham et al (1935)

Body length: 7.5 mm
Wing length: 9 mm

A species of the jejuna-undulata group, having no basal lateral spines on penes; tips of penes broad, distinctly outcurved.

Head and thorax dark brown; several yellow spots on pleura. Fore legs brownish; apex of tibia darker. Middle and hind legs pale; dark streaks on femora. Wings hyaline; venation brown. Stigmatic area tinged with smoky; cross veins in this region mostly simple. Abdominal tergites dark brown; lateral margins very narrowly pale. Sternites very pale. Forceps dark brown, tails paler brown. Apices of penes broad, distinctly outcurved; no basal lateral spine, nor small spines near apex (see fig. 102).

Allied to Rhithrogena jejuna and Rhithrogena impersonata. Tips of penes outcurved as in R. jejuna, but not narrowed as in that species; no small apical spines such as occur in R. impersonata.

Specimens of the Mayfly Species Rhithrogena undulata

1 Male Spinner

Male Rhithrogena undulata (Small Western Red Quill) Mayfly Spinner

13 Pictures

Male Rhithrogena undulata (Heptageniidae) (Small Western Red Quill) Mayfly Spinner from the Madison River in Montana

This male was collected at the same time as this female and is likely the same species.

It keys pretty clearly to Rhithrogena undulata using the key in Traver 1935, although the size is larger than expected for that species in that source.

Collected June 30, 2019 from the Madison River in Montana

Added by Troutnut on July 17, 2019

Collected June 30, 2019 from the Madison River in Montana and added by Troutnut on July 17, 2019

1 Female Spinner

Female Rhithrogena undulata (Small Western Red Quill) Mayfly Spinner

5 Pictures

Lateral view of a Female Rhithrogena undulata (Heptageniidae) (Small Western Red Quill) Mayfly Spinner from the Madison River in Montana

This one was collected at the same time as this male and is likely the same species.

Collected June 30, 2019 from the Madison River in Montana

Added by Troutnut on July 17, 2019

Collected June 30, 2019 from the Madison River in Montana and added by Troutnut on July 17, 2019

Start a Discussion of Rhithrogena undulata

References

Arbona, Fred Jr. 1989. Mayflies, the Angler, and the Trout. Nick Lyons Books.
Caucci, Al and Nastasi, Bob. 2004. Hatches II. The Lyons Press.
Knopp, Malcolm and Robert Cormier. 1997. Mayflies: An Angler's Study of Trout Water Ephemeroptera . The Lyons Press.
Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.
Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.