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.

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Stonefly Species Pteronarcys dorsata (Salmonfly)

This is the largest common eastern stonefly. It's quite abundant in places, but not to the extent of its western counterparts, and since most of its activity is at night it is generally less important. Nevertheless, nymph imitations produce some very large trout, and lucky or very locally knowledgable anglers may find good fishing to the egg-laying adults.

Where & when

Time of year : Late April through late June

Hatching behavior

Time of day : Overnight; some dawn/dusk overflow

Egg-Laying behavior

Time of day: Overnight; some dawn/dusk overflow

Habitat: Riffles

I have watched Pteronarcys dorsata adults gather at treetop level above the riffles a hundred yards upstream from a slow stretch of water that held a tremendous swarm of Hexagenia limbata spinners thirty minutes later. I never saw more than one or two on the water, and the egg-laying supposedly happens well after dark.

Specimens of the Stonefly Species Pteronarcys dorsata

3 Nymphs

Pteronarcys dorsata (Salmonfly) Stonefly Nymph

8 Pictures

Collected February 7, 2004 from the Namekagon River in Wisconsin

Added by Troutnut on January 25, 2006

Pteronarcys dorsata (Salmonfly) Stonefly Nymph

7 Pictures

Collected January 13, 2004 from the Namekagon River in Wisconsin

Added by Troutnut on January 25, 2006

Pteronarcys dorsata (Salmonfly) Stonefly Nymph

3 Pictures

Pteronarcys nymphs live for two years before maturing. This small one is in its first year.

Collected March 10, 2004 from unknown in Wisconsin

Added by Troutnut on January 19, 2006

1 Streamside Picture of Pteronarcys dorsata Stoneflies:

View Fullsize

Large stonefly nymphs sometimes crawl quite far from the water before emerging. This empty case is from a nymph that hatched about 5 feet up in a tree 10 feet from the river.

In this picture: Stonefly Species Pteronarcys dorsata (Salmonfly).

Taken June 11, 2005

Added by Troutnut on January 25, 2006

1 Video of Pteronarcys dorsata Stoneflies:

Pteronarcys

Featuring: Pteronarcys dorsata Stonefly Nymph

Shot on Feb 7, 2004

Added by Troutnut on Mar 31, 2006

Recent Discussions of Pteronarcys dorsata

Question

7 replies

Posted by Max29 on Jan 29, 2008

Last reply on Jan 30, 2008 by Taxon

Are stoneflies and salmonflies the same thing or are they just related because here in the mid west we have the stonfly hatch and if they are related the stonfly could be called the salmonfly and the salmonfly hatch is only in the west because I have trouble because I want to become a better insect identifier when it comes to fishing because i went to other sites that so a stonefly is a stonefly and a salmonfly is a salmon fly but yet you say stonefly nymph but in parenteseses you have american salmonfly so is there really no such thing as a salmonfly but it is rather called a stonefly.