Below are listed the most common Wisconsin mayfly hatches created by John Simonson (WiFlyFisher). This is mainly for the northwest Wisconsin and central Wisconsin trout streams, such as: the Namekagon River, Bois Brule, Prairie, Wolf, etc.).
The X's represent individual weeks within a given month and the approximate emergence time for each mayfly. The hatch dates will vary from year to year depending on the weather conditions, seasonal climate changes, type of stream, etc.
See also: General Characteristics for Mayfly Species of Northern Wisconsin
Common Name | Scientific Name / Details | Mar | Apr | May | Jun | Jul | Aug | Sep |
Blue Wing Olives (BWO)(2) | Baetis size:6-7mm (#18 -#22) 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 / rotunda / excrucians 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--- | |||||
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- | |||||
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 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
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.
See also: Lifecycle of Caddisflies for more detailed information.