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.