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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.

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

Specimens of the Hellgrammite Genus Nigronia

1 Male Adult
4 Larvae

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


Start a Discussion of Nigronia


  • 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.

Hellgrammite Genus Nigronia (Fishflies)

Species in Nigronia: Nigronia serricornis
1 species (Nigronia fasciatus) isn't included.
Genus Range
Common Name
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