Northern Wisconsin Trout Stream Mayfly Hatch Chart
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
Northern Wisconsin Mayfly Hatches
| 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- | |||||
| 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 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.
by John Simonson
Reviewed By: Joe Hawkins
Page Rating: 5.0
Review Date: 16 May 2012
Page Review:
This is great mayfly hatch chart!! Thank you WiFlyfisher!
Reviewed By: B Towle
Page Rating: 5.0
Review Date: 3 January 2014
Page Review:
This is extremely helpful. I'm hoping to get started on fly fishing for trout in NW WI and this will help greatly.
Reviewed By: Matt
Page Rating: 5.0
Review Date: 15 February 2014
Page Review:
Overall a very nice presentation of the Wisconsin mayflies. BTW the East Branch of the Delaware has a very intense emergence of simulans in early June for about two weeks. Huge rafts of duns come down river. In the beginning the big browns are gluttons but soon become wise to patterns that don't look very good or have drag in the cast.
Reviewed By: Jim S
Page Rating: 5.0
Review Date: 29 December 2015
Page Review:
Great hatch chart. Appreciate it.
Reviewed By: Bob B
Page Rating: 5.0
Review Date: 27 March 2019
Page Review:
Great website, very informative.