Wisconsin Fly Fishing for Trout

Northern Wisconsin Mayfly Hatch Chart

There is 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 the 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 actually documented under a microscope by me. There is entomological documentation done by scientists in the northern part of Wisconsin as to the existence of these mayfly species.

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 chmayflies I anges, type of stream, 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---      
Sulphurs Ephemerella 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 Serratella 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 sand, silt and muck. The densest hatches for these insects will occur in those stretches of the stream.

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

See also: General Characteristics for Mayfly Species of Northern Wisconsin

Northern Wisconsin Trout Stream Caddisfly Hatches (Sedge)

Below is a listing of 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.

  • Little Black Caddis
  • Little Short-Horn Sedge
  • American Grannom
  • Spotted Sedge
  • Green Sedge (Green Rock Worm / Apple Caddis)
  • Little Sister Sedge
  • Long-Horned Sedge
  • Little Plain Brown Sedge
  • Zebra Caddis
  • White Miller
  • Giant Rusty Sedge
  • Great Brown Autumn Sedge (large stick cases)
  • Little Dot-Winged Sedge

See also: Lifecycle of Caddisflies for more detailed information.


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