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WA Mayfly Description

Taxonomic Name
(Common Name)
Larva (Nymph)Subimago (Dun)
Imago (Spinner)
(Flatheaded Mayfly)
Flattened body; flattened horizontally oriented head; eyes & antennae visible from above; sprawling legs; gills on ab segs 1-7, most with tufts at base; 2 or 3 tails. 2 tails and large hind wings; 2 pairs of cubital intercalary veins present in FWs; 2 tails.

Taxonomic Name
(Common Name)
Larva (Nymph)Subimago (Dun)
Imago (Spinner)
larva (nymph)

Copyright © 2009 Tim Loh

subimago (dun) - male

Copyright © 2005 Bob Newell

imago (spinner) - male

Copyright © 2009 Lynette Schimming

RhithrogenaFlattened body; 1st & 7th gills enlarged, meeting or overlaping beneath abdomen; 3 tails. Stigmatic area of forewing crisscrossed with fine veinlets.
Rhithrogena flavianula  
Rhithrogena hageni
(Greengill; March Brown; Pale Brown Dun; Western Red Quill; Black Quill; Western Black Quill; Dark Tan Spinner; Western March Brown. )
 Body dark reddish brown; length 9 - 10 mm.; 3 tails. Body tannish olive to purplish black; wings mottled medium gray; length 9-11 mm.; 2 tails; emerges Jul - Aug.
Rhithrogena morrisoni  
Rhithrogena robusta  
Rhithrogena undulata  

State of Washington distribution is based on:
Mayflies (Ephemeroptera) of the far western United States (Part I: Washington) by M. D. Meyer & W. P. McCafferty,
and augmented by A DNA Barcode Library for North American Ephemeroptera: etc. by Webb, Jacobus, Funk, et. al.  

Created: 08/16/2013   Last modified: 12/07/2014    www.FlyfishingEntomology.com