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Mayfly Species Rhithrogena impersonata (Dark Red Quill)

Pictures Below
This intriguing species has two distinct colors of nymphs, which were once considered to be different species. Most nymphs are a dark olive gray, but some are a surprisingly bright reddish brown. The red ones were once classified as Rhithrogena sanguinea. There is no apparent difference between the adults of the two varieties.  

Where & When


Regions: East, Midwest

Time Of Year (?): Late May through early July

I have not found any discussion of fishable hatches of this species, but I have sampled two small streams where the nymph population is so dense that there must be good fishing to the adults unless they have the worst of emergence characteristics.

Hatching Behavior


Habitat: Fast water


Spinner Behavior


Time Of Day: Dusk

The Leonards write in Mayflies of Michigan Trout Streams that the spinners gather in great swarms high above the river as the sun sets. They do not say whether this activity culminates in a fishable spinner fall.

Nymph Biology


Current Speed: Fast

Substrate: Gravel



Pictures of 3 Mayfly Specimens in the Species Rhithrogena impersonata:

Rhithrogena impersonata (Dark Red Quill) Mayfly NymphRhithrogena impersonata (Dark Red Quill) Mayfly Nymph View 6 PicturesThis was the only Rhithrogena specimen in a large sample of nymphs from a small Catskill stream. It looks virtually identical to Rhithrogena impersonata specimens collected in the Midwest, but I didn't get to check the distinguishing features under a microscope.
Collected April 19, 2006 from Mongaup Creek in New York
Added to Troutnut.com by Troutnut on April 21, 2006
Rhithrogena impersonata (Dark Red Quill) Mayfly NymphRhithrogena impersonata (Dark Red Quill) Mayfly Nymph View 8 PicturesThis specimen shows one of two distinct color types of Rhithrogena impersonata nymphs. This type is very reddish, especially in the gills, and it was formerly in its own species called Rhithrogena sanguinea.
Collected June 5, 2005 from the Long Lake Branch of the White River in Wisconsin
Added to Troutnut.com by Troutnut on May 24, 2006

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