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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

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.


Hellgrammites are the fearsome predatory larvae of the dobsonflies. Unlike mayflies, caddisflies, and stoneflies, their life cycle does not include specific points of vulnerability, but the larvae end up in the drift often enough to be important to trout. (Note: Some would say that technically only larvae of the Corydalus genus are hellgrammites, but anglers widely use the term for all larvae in the family.)

This common name refers to only one family. Click its scientific name to learn more.

Insect Family Corydalidae

These are often called Hellgrammites.
Hellgrammites are the vicious larvae of the Dobsonflies, some of the only trout stream insects which pose a biting threat to the angler. The pincers of the adult are even more frightening that the larva's, and they're aggressive enough to use them once in a while.

This family's life cycle does not create good dry fly opportunities, but the larvae may be eaten by trout year-round. They are a secret told only by stomach samples of well-fed trout.
A fishfly larva. This fishfly (genus Nigonia) is closely related in appearance to Hellgrammites

Artistic view of a Nigronia serricornis (Corydalidae) (Fishfly) Hellgrammite Larva from Salmon Creek in New York


Scientific Name
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