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WA Mayfly Description

Taxonomic Name
(Common Name)
Larva (Nymph)Subimago (Dun)
Imago (Spinner)
(Common Burrower Mayfly )
Gills long with a feather-like fringe; tusks curve upward when viewed from side and are smooth (don't have small spines) on the half closest to the head; antannae w/whorls of long setae.Blotches or pigmented cross veins on wings, forewing A1 single, attached to hind margin by 2 or more veinlets; 2 or 3 tails.

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

Copyright © Jason Neuswanger

subimago (dun) - male

Copyright © 2005 Lynette Schimming

subimago (dun) - female

Copyright © 2009 Lynn Avis

imago (spinner) - male

Copyright © 2008 Lynette Schimming

imago (spinner) - female

Copyright © 2010 Eric Matthews
HexageniaHead w/conicical rounded, or truncate frontal process; mandibular tusks upturned when viewed from side, and w/hairs along entire length; gills on ab. seg. 1 very small, otherwise w/large feather-like gills. .
Hexagenia bilineata  
Hexagenia limbata
(Big Yellow May; Giant Mayfly; Great Lead-winged Drake; Burrowing Mayfly; Giant Yellow Mayfly; Fishfly; Giant Michigan Mayfly; Great Olive-winged Drake; Great Pale Yellow Drake; Great Sulphur Drake; Hex; Michigan Caddis; Sandfly; Michigan Spinner. )
 Rounded frontal process dome-shaped; double gills on 1st segment; tusks less than 1 .5x head length; tarsal claws. Body dark brown tergites w/lighter sternites; wings smokey gray w/olive cast, darkly shaded on margin; length 17-40 mm.; 2 tails; emerges May 20 - early Aug.

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