Wisconsin Fly Fishing for Trout

General Characteristics for Mayfly Species of Northern Wisconsin

Back to Wisconsin Mayfly Hatch Chart

At a much younger age while studying the various mayflies that hatched on my favorite northern Wisconsin trout streams I put together chart in a notebook to help me remember some of the important characteristics for the most common mayflies that I frequently saw hatching. Below I have reproduced the chart in an HTML table and updated the genus and species names to their current names, as of 2012. Hopefully, you will find this mayfly chart beneficial in your pursuit to be more knowledgeable about the mayflies trout feed on in northern Wisconsin.

Nymph Habitat - the common water and stream bottom type the various nymphs prefer in a stream. The densest hatches are usually found where the nymphs ideal habitat is found. For example: Hexagenia limbata are burrowing nymphs that live in the silt and mucky areas of a stream and that is where the best hatches will occur during a Hexagenia emergence.
Most Common Hatch Time - this is generally what I have observed but this can vary a lot depending on water and air temperatures, cloud cover, etc.
Spinner Fall - the most common time of day or evening when a spinner fall will occur, there are always exceptions.
*** Sporadic indicates a mayfly that hatches off and on all during the day, not a dense hatch at one given time of day.

Common Name Scientific Name / Details Nymph Type Nymph Habitat Most Common Hatch Times Spinner fall
Slow
Current
Silt &
Mucky
Medium
Current
Gravel
Fast
Current
Rocky
Morning Afternoon Evening Sporadic Morning Afternoon Evening
Blue Wing Olives (BWO)(2) Baetis
size: 6-7 mm (#18 - #22)
nymphs 3 tails (middle shorter)
duns 2 tails
Swimmer   X   (?) X X       X
Gray Drake Siphloplecton basale
size: 14-16 mm (#8)
nymphs 3 tails / duns 2 tails
Swimmer   X X   X         X
Hendrickson Ephemerella subvaria
size: 10-12 mm (#12)
nymphs 3 tails / duns 3 tails
Crawler   X   (?) X     (?)   X
Sulphurs Ephemerella invaria / rotunda / excrucians
size: 9-10 mm (#14)
nymphs 3 tails / duns 3 tails
Crawler   X     X X       X
Sulphurs Ephemerella dorothea
size: 6-7 mm (#18)
nymphs 3 tails / duns 3 tails
Crawler   X       X       X
Gray Drake Siphlonurus alternatus
size 12 -16 mm (#8)
nymphs 3 tails
duns / spinners 2 tails
Swimmer     X       X     X
Little Dark Hendrickson Ephemerella needhami
size: 9-10 mm (#14)
nymphs 3 tails / duns 3 tails
Crawler   X       X       X
Sulphur Epeorus vitreus
size 9 - 12 mm
nymphs 2 tails / duns 2 tails
Clinger   X X     X       X
March Brown / Gray Fox Maccaffertium vicarium
(formerly Stenonema)
size 14-16 mm (#10 2x long)
nymphs 3 tails (clingers)
duns 2 tails (speckled wings)

 

Clinger
 

X


X
   

 

 

X
   

 

X
Armored Speckled-Wing Baetisca laurentina
size 10-12 mm (#12)
nymphs 3 tails (very fat body)
duns 2 tails (chubby mottled wing)

Crawler
 

X


X
   

X
     

X
Common Name Scientific Name / Details Nymph Type Nymph Habitat Most Common Hatch Times Spinner fall
Slow
Current
Silt &
Mucky
Medium
Current
Gravel
Fast
Current
Rocky
Morning Afternoon Evening Sporadic Morning Afternoon Evening
Light Cahill Stenacron / Maccaffertium
(several species)
size 9-1 mm (#12 2x long)
nymphs 3 tails (clingers)
duns 2 tails (speckled wings)
Clinger   X X       X     X
Darth Vader Serratella deficiens
size: 4-5 mm (#20)
Blackish wings
pale yellow legs
nymphs 3 tails / duns 3 tails
Crawler   X       X       X
Brown Drake(1) Ephemera simulans
size 12-15 mm (#10 2x long)
nymphs 3 tails (burrower)
duns 3 tails (brown splotch wing)
Burrower X         X       X
Hex Hatch
Michigan Caddis(1)
Hexagenia limbata
size 16-35 mm (#6)
nymphs 3 tails (burrower)
duns 3 tails
Burrower X         Dark        
Mahogany Dun Isonychia bicolor
size 13-16 mm (#8 2x long)
nymphs 3 tails (swimmers)
duns 2 tails
Swimmer   X X       X     X
Tricos Tricorythodes minutus
3 -3 1/2 mm (#22)
nymphs 3 tails
duns 3 tails (blackish body)
Crawler X X   X       X    
Large Rusty Spinner(1) Hexagenia atrocaudata
size 16-30 mm (#6)
nymphs 3 tails (burrower)
duns 3 tails
Burrower X         X       X
Little Yellow Quill Leucrocuta hebe
size 9-12 mm (#12)
duns 2 tails
duns yellow body & orange thorax
Crawler   X               X
White Fly(1) Ephoron leukon
size 10-13 mm (#12)
nymphs 3 tails (burrowers)
duns 2 tails (white body)
Burrower X         X       X
Common Name Scientific Name / Details Nymph Type Slow
Current
Silt &
Mucky
Medium
Creent
Gravel
Fast
Current
Rocky
Morning Afternoon Evening Sporadic Morning Afternoon Evening
Nymph Habitat Most Common Hatch Times Spinner fall

Notes:
(1) - indicates mayfly nymphs that burrow in sand, silt and muck. The densest hatches for these insects will occur in those stretches of the stream.

(2) - there are several mayflies species (Baetis, Plauditus, etc.) that all fall under Blue Wing Olives (BWO) and hatch at different times during the season. Some I see are too sparse to really get the trout's attention.

   Copyright © 2016 WiFlyFisher.com. All Rights Reserved.