Header image
Enter a name
Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin
Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

Lateral view of a Psychodidae True Fly Larva from Mystery Creek #308 in Washington
This wild-looking little thing completely puzzled me. At first I was thinking beetle or month larva, until I got a look at the pictures on the computer screen. I made a couple of incorrect guesses before entomologist Greg Courtney pointed me in the right direction with Psychodidae. He suggested a possible genus of Thornburghiella, but could not rule out some other members of the tribe Pericomini.
27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Taxonomic Keys for Aquatic Invertebrate Identification

Taxonomic Keys for Aquatic Invertebrate Identification

The taxonomic keys on this website are adapted from a variety of books and scientific papers, and they represent the combined hard work of hundreds of entomologists over many decades. I claim no credit for creating them in most cases, only arranging them in a more user-friendly format and adding some illustrations. These keys only cover North American taxa. If you're new to keys, see my Introduction to Taxonomic Keys.

High-level keys

Mayfly keys

Mayfly family keys to genus

This list includes keys to genus for all North American mayfly families.

Adult stage (male spinners)
Nymph stage

Mayfly genus keys to species

Only a small number of keys all the way to species are online yet, but that's an ongoing project.

Adult stage (male spinners)
Nymph stage

Caddisfly keys

Caddisfly family keys to genus

This list includes keys to genus for all North American caddisfly families.

Adult stage
Larval stage

Stonefly keys

Stonefly family keys to genus

This list includes keys to genus for all North American mayfly families.

Adult stage
Nymph stage

Stonefly genus keys to species

Only a small number of keys all the way to species are online yet, but that's an ongoing project.

Adult stage
Nymph stage

True fly keys (midges, etc.)

Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy