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WA Mayfly Description

Taxonomic Name
(Common Name)
Larva (Nymph)Subimago (Dun)
Imago (Spinner)
(Spiny Crawler Mayfly )
Diverse shapes and sizes, but usually robust, sometimes flattened, often with tubercles or spines; always with 3 tails; wholly dorsal gills (never on Ab2) which slightly overlap and undute sequentially. 3 tails; pronounced angle on fore margin of hind wings; short unattached intercalary veins on outer margin of FW.

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

Copyright © 2011 Kurt Schirmer

subimago (dun) - male

Copyright © 2010

imago (spinner) - male

Copyright © 2010 Colin M

imago (spinner) - female

Copyright © 2010 Colin M
EphemerellaFinger-like max. palps well developed; femora & tails all similar; gills on ab. seg. 3; no disk of hairs on u/s of ab.; sides of ab. seg. 9 don't extended to the tails; tails approx. equal in length; last 2/3 of tails w/bristles extending laterally. .
Ephemerella alleni  
Ephemerella aurivillii  
 Top hind edge of (at least) abdominal segments 3-7 w/small to medium tubercles; hind corners of abdominal segment 3 w/points similar to following segments; front of head smooth (no tubercles). .
Ephemerella dorothea infrequens
(Pale Morning Dun; Rusty Spinner; Pale Morning Spinner; PMD. )
 Body uniform brown color, abdomen w/weak, light markings; no abdominal tubercles; points on the sides of segment 4 and 5 are relatively long compared to those of inermis; small oval gills on segs 3-7. Body cream w/olive cast; wings light gray; length 5.5-7 mm.; 3 tails; emerges May-mid Jul.
Ephemerella excrucians  
Ephemerella tibialis
(Red Quill; Whitegloved Howdy; Small Dark Hendrickson; Small Western Dark Hendrickson. )
 Abdominal segments 2-8 w/small, sharply pointed tubercles on hind edge; rear edges of middle abdominal segments straight, often w/dorsal stripe down middle of abdomen; dark/light banding on legs. Body dark reddish brown; wings pale to dark gray; length 7-9 mm.; 3 tails; emerges Aug 1 - Sep 15.
Ephemerella velmae  
Ephemerella verruca  

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