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.

Stream photos

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Tricorythodes (Trico) Mayfly Nymph Tricorythodes (Trico) Mayfly Nymph

Dorsal view of a Tricorythodes (Leptohyphidae) (Trico) Mayfly Nymph from Mystery Creek #308 in Washington

9 Recently Added Photos

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.

Hellgrammite Genus Nigronia (Fishflies)

This seems to be the most common trout stream dobsonfly genus.

Where & when

In 98 records from GBIF, adults of this genus have mostly been collected during June (32%), May (30%), July (20%), and April (13%).

In 26 records from GBIF, this genus has been collected at elevations ranging from 295 to 5279 ft, with an average (median) of 1926 ft.

Genus Range

source

Map of specific collection sites

Specimens of the Hellgrammite Genus Nigronia

1 Male Adult

Male Nigronia serricornis (Fishfly) Hellgrammite Adult

10 Pictures

Lateral view of a Male Nigronia serricornis (Corydalidae) (Fishfly) Hellgrammite Adult from Brodhead Creek in Pennsylvania

Collected May 28, 2007 from Brodhead Creek in Pennsylvania

Added by Troutnut on June 4, 2007

Collected May 28, 2007 from Brodhead Creek in Pennsylvania and added by Troutnut on June 4, 2007

4 Larvae

Nigronia serricornis (Fishfly) Hellgrammite Larva

12 Pictures

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

Collected March 28, 2006 from Salmon Creek in New York

Added by Troutnut on April 7, 2006

Collected March 28, 2006 from Salmon Creek in New York and added by Troutnut on April 7, 2006

Nigronia serricornis (Fishfly) Hellgrammite Larva

13 Pictures

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

I unfortunately lost some of the originals of this specimen, so I was only able to re-process about half the pictures in the 2023 update.

Collected April 23, 2007 from Factory Brook in New York

Added by Troutnut on April 24, 2007

Collected April 23, 2007 from Factory Brook in New York and added by Troutnut on April 24, 2007

Nigronia serricornis (Fishfly) Hellgrammite Larva

5 Pictures

Dorsal view of a Nigronia serricornis (Corydalidae) (Fishfly) Hellgrammite Larva from unknown in Wisconsin

Collected January 13, 2004 from unknown in Wisconsin

Added by Troutnut on January 25, 2006

Collected January 13, 2004 from unknown in Wisconsin and added by Troutnut on January 25, 2006

Nigronia serricornis (Fishfly) Hellgrammite Larva

4 Pictures

Dorsal view of a Nigronia serricornis (Corydalidae) (Fishfly) Hellgrammite Larva from the Namekagon River in Wisconsin

Collected January 12, 2004 from the Namekagon River in Wisconsin

Added by Troutnut on January 25, 2006

Collected January 12, 2004 from the Namekagon River in Wisconsin and added by Troutnut on January 25, 2006

Discussions of Nigronia

Fishfly is not a hellgramite

5 replies

Posted by Ofieldstrea on Jun 24, 2007

Last reply on Jun 28, 2011 by PaulRoberts

Troutnut ... the term "hellgramite" is reserved for the Dobsonfly (Corydalinae). Though the Fishfly (Chauliodinae) and the dobsonfly are from the same Megaloptera family, at first glance appear similar, and have similar stages of development, they are from different subfamily with differing subspecies and have very different morphology and biology.

The dobsonfly inhabit the more oxygenated waters of riffles and possess only tuffed gills for respiration. The fishfly inhabit the quiter waters of pools and still water. Fishflies have a primative gills called lateral filaments, while some species of fishfly utilize breathing tubes, located posterior, to accomodate the use of atmospheric oxygen for breathing in low dissolved oxygen envirions while remaining submerged.

So .. it is incorrect to use the term 'hellgramite' when talking about the fishfly larvae. They are simply, 'fishfly larvae'. You really should change your reference.

---- Reference -----
McCafferty, W. Patrick, 1981. Aquatic Entomology; Chpt. 11, Fishflies, Dobsonflies and Alderflies (order Megaloptera), p. 189-196

--------------------------
O'fieldstream

Start a Discussion of Nigronia

References

Brigham, W.U., A.K. Brigham, and A. Gnilke. 1982. Aquatic Insects and Oligochaetes of North and South Carolina. Midwest Aquatic Entomologist.
Knight, Allen W. and C.A. Siegfried. 1977. The Distribution of Corydalus cornutus (Linnaeus) and Nigronia serricornis (Say) (Megaloptera: Corydalidae) in Michigan. Great Lakes Entomologist 10(2): 39-46.
Neunzig, H.H. 1966. Larvae of the Genus Nigronia Banks. Proceedings of the Entomological Society of Washington 68(1): 11-16.
Stehr, Frederick W. 1998. Immature Insects. Kendall/Hunt Publishing Company.
Usinger, R.L. 1956. Aquatic Insects California, with keys to North American Genera and California species. University of California Press.