Wisconsin Fly Fishing for Trout

Wisconsin Mayfly Hatch Chart

There are approximately 157 documented mayfly species in Wisconsin (as of 2014) that live in our lakes and streams. Many of those mayfly species are not found in abundant enough numbers to be important to fly fishermen.

Below are listed the most common Wisconsin mayfly hatches that are important to fly fishermen. The chart was created from my many years studying the aquatic insects found in our northern Wisconsin trout streams. The mayfly hatch chart covers northern Wisconsin and central Wisconsin trout streams, such as the Namekagon, Bois Brule, Prairie, Wolf, Oconto, Peshtigo, Pine, etc.

Note: the mayfly species I have listed below are from my observations over the years. None of the species were documented under a microscope by me. There is entomological documentation done by Wisconsin scientists in the northern part of Wisconsin as to the existence of these mayflies, not always to the specie level. Also, understand this is a generalized listing. There will be northern trout streams where some of these mayfly species do not exist in. There is no "one size fits all" rule when it comes to trout stream ecosystems.

The X's represent individual weeks within a given month and the approximate emergence time for each mayfly specie. The hatch dates will vary from year to year depending on the weather conditions, seasonal climate changes, stream type, floods, etc.

Northern Wisconsin Mayfly Hatches

Common Name Scientific Name / Details Mar Apr May Jun Jul Aug Sep
Blue Wing Olives (BWO)(2) Baetis, Acentrella
size:4-7mm (#18 -#24)
nymphs 3 tails (middle tail shorter)
adults 2 tails
--XX XXXX XXXX XXXX     XXXX
Gray Drake Siphloplecton basale
size: 14-16 mm (#8)
nymphs 3 tails / duns 2 tails
  --X X--        
Hendrickson Ephemerella subvaria
size: 10-12 mm (#12)
nymphs 3 tails / duns 3 tails
  --XX XX--        
Sulphurs Ephemerella invaria
size: 9-10 mm (#14)
nymphs 3 tails / duns 3 tails
    --XX X---      
Sulphur Ephemerella dorothea dorothea
size: 6-7 mm (#18)
nymphs 3 tails / duns 3 tails
    --XX XX---      
Pale Morning Dun (PMD) Ephemerella excrucians
size: 6-7 mm (#18)
nymphs 3 tails / duns 3 tails
    --XX XX---      
Small Blue-Winged Olive Attenella attenuata
size: 6-7 mm (#18) olive body
nymphs 3 tails / duns 3 tails
    --X XX---      
Black Quill Leptophlebia cupida
size: 10-11 mm (#12)
nymphs 3 tails / duns 3 tails
    --XX X---      
Gray Drake Siphlonurus alternatus
size 12 -16 mm (#8)
nymphs 3 tails
duns / spinners 2 tails
    --XX XX---      
Little Mahogany Paraleptophlebia mollis
size: 6-8 mm (#16-#18)
nymphs 3 tails / duns 2 tails
    ---X XX-      
Little Dark Hendrickson Ephemerella needhami
size: 9-10 mm (#14)
nymphs 3 tails / duns 3 tails
    ---X XX-      
Epeorus vitreus (Sulphur) Epeorus vitreus
size 9 - 12 mm
nymphs 2 tails / duns 2 tails
    ---X XX-      
March Brown / Gray Fox Maccaffertium vicarium
(formerly Stenonema)
size 14-16 mm (#10 2x long)
nymphs 3 tails (clingers)
duns 2 tails (speckled wings)
    ---X XXX-      
Armored Speckled-Wing Baetisca laurentina
size 10-12 mm (#12)
nymphs 3 tails (fat body)
duns 2 tails (chubby mottled wing)
    ---X XXX-      
Light Cahill Stenacron / Maccaffertium
(several species)
size 9-1 mm (#12 2x long)
nymphs 3 tails (clingers)
duns 2 tails (speckled wings)
      XXX-      
Darth Vader Teloganopsis deficiens
size: 4-5 mm (#20)
Blackish wings
pale yellow legs
nymphs 3 tails / duns 3 tails
      XXX-      
Brown Drake(1) Ephemera simulans
size 12-15 mm (#10 2x long)
nymphs 3 tails (burrower)
duns 3 tails (brown splotch wing)
      XXX-      
Hex Hatch
Michigan Caddis(1)
Hexagenia limbata & bilineata
size 16-35 mm (#6)
nymphs 3 tails (burrower)
duns 3 tails
      --XX X---    
Mahogany Dun Isonychia bicolor
size 13-16 mm (#8 2x long)
nymphs 3 tails (swimmers)
duns 2 tails
      ---X XXXX XX--  
Tricos Tricorythodes minutus
3 -3 1/2 mm (#22 - #24)
nymphs 3 tails
adults 3 tails
        -XXX    
Large Rusty Spinner(1) Hexagenia atrocaudata
size 16-30 mm (#6)
nymphs 3 tails (burrower)
duns 3 tails
        --XX X---  
Little Yellow Quill Leucrocuta hebe
size 9-12 mm (#12)
duns 2 tails
duns yellow body & orange thorax
        ---X XXX-  
White Mayfly(1) Ephoron leukon
size 10-13 mm (#12)
nymphs 3 tails (burrowers)
duns 2 tails (white body)
          XXX-  
Common Name Scientific Name / Details Mar Apr May Jun Jul Aug Sep

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

(2) - there are several mayfly species that all fall under Blue Wing Olives (BWO) and hatch at different times during the season. Some I see are too sporadic to get the trout's attention.

See also: General Characteristics for Mayfly Species of Northern Wisconsin

Northern Wisconsin Trout Stream Caddisfly Hatches (Sedge)

Below are listed the most common Northen Wisconsin caddisflies that are found in our freestone streams that may have importance to fly fishermen in different stages of their lifecycle.

See also: Lifecycle of Caddisflies for more detailed information.


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