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

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.

• Little Black Caddis
• Little Short-Horn Sedge (Glossosoma sp.)
• American Grannom (Brachycentrus sp.)
• 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.