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Insect Family Corydalidae (Hellgrammites)

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Megaloptera (Hellgrammites, Dobsonflies, and Alderflies)

» Family Corydalidae (Hellgrammites)

Genus in Corydalidae
CorydalusDobsonflies	0	0
NigroniaFishflies	0	0

5 genera aren't included.

Common Name

Match	Common Name
	Hellgrammites

Pictures Below ↓

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.

Hatching Behavior

The larvae exit the stream to pupate in burrows in the ground, so their emergence is completely unimportant to trout.

Egg-Laying Behavior

Egg-laying dobsonfly adults are never, in my experience, common enough on trout streams to cause any sort of rise, but they are the sort of huge meaty insect that trout are unlikely ot pass up.

Juvenile Biology

I do not know how hellgrammites become available to trout, exactly -- perhaps by accident and perhaps they undergo behavioral drift (Behavioral drift: The nymphs and larvae of many aquatic insects sometimes release their grip on the bottom and drift downstream for a while with synchronized timing. This phenomenon increases their vulnerability to trout just like emergence, but it is invisible to the angler above the surface. In many species it occurs daily, most often just after dusk or just before dawn.). They are such large insects and they show up in trout diets often enough that imitations make good searching patterns (Searching pattern: Any artificial fly pattern used when trout that aren't feeding selectively on anything in particular. A searching pattern may be an attractor or an imitation of something specific that the fish might favor even though it's not currently hatching.). In fact, the infamous wooly bugger and wooly worm fly patterns probably owe some of their success to their similarity to hellgrammites.

Pictures of 8 Hellgrammite Specimens:

Specimen Page:12

Corydalus (Dobsonflies) Hellgrammite Larva

View 27 Pictures

Collected May 29, 2007 from Paradise Creek in Pennsylvania
Added to Troutnut.com by Troutnut on June 4, 2007

Nigronia serricornis (Fishfly) Hellgrammite Larva

View 12 Pictures

Collected March 29, 2006 from Salmon Creek in New York
Added to Troutnut.com by Troutnut on April 7, 2006

Nigronia serricornis (Fishfly) Hellgrammite Larva

View 13 Pictures

Collected April 24, 2007 from Factory Brook in New York
Added to Troutnut.com by Troutnut on April 24, 2007

Specimen Page:12

Recent Discussions of Corydalidae

Best time of year to harvest hellgramites 13 Replies »

Posted by Rblouser on Jun 27, 2008

Last reply on Jun 11, 2019 by Sapperstyle

I have just recently started fishing with hellgies and need some info on the best time of year for catching, bait. Any insight will be greatly appreciated

Reply Dobson Fly 26 Replies »

Posted by Jesse on Jun 24, 2011 in the genus Corydalus

Last reply on Sep 12, 2013 by PaulRoberts

What can anyone tell me about the Dobson Fly?

(General now guys, we don't have to go all scientific with it ha)!

Reply Anyone have hellgrammite experiences to share? 56 Replies »

Posted by Troutnut on Nov 18, 2006

Last reply on Aug 23, 2013 by Trout_House

I'm working on a magazine article about hellgrammites, which I think are a generally underrated food source and an extremely cool group of insects.

I'm going to do a lot of research and combine it with my own experiences, but many of you have been fly fishing longer than I've been alive, so I'd like to see if any of you have stories about them -- catching big trout with stomachs full of them, finding trout rising to the dobsonfly adults, getting bit by these bugs, or anything else.

Reply Fishfly is not a hellgramite 5 Replies »

Posted by Ofieldstrea on Jun 24, 2007 in the genus Nigronia

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

Reply trying to figure out 1 Reply »

Posted by Buggy on Apr 19, 2009

Last reply on Apr 19, 2009 by GONZO

I am from ontario canada and i pick hellgrammites for a local bait shop owner i was just wondering when is the earliest i could start picking...last year i started in june but i hear you can start sooner when is the earliest i can do this??? thanks for your help

serious picker

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Jargon Defined:

Behavioral drift: The nymphs and larvae of many aquatic insects sometimes release their grip on the bottom and drift downstream for a while with synchronized timing. This phenomenon increases their vulnerability to trout just like emergence, but it is invisible to the angler above the surface. In many species it occurs daily, most often just after dusk or just before dawn.

Emergence: The transformation of a nymph or pupa into the adult winged stage of an insect. The term may refer to the emergence of an individual, or the daily or yearly event in which all individuals of a species emerge.

Larvae: Many classes of aquatic insects, such as caddisflies, midges, craneflies, dobsonflies, alderflies, and many more, are known as "larvae" rather than "nymphs" in their juvenile stages. They have mostly soft bodies rather than hard exoskeletons. These insects also advance through a "pupa" stage before reaching adulthood.

Searching patterns: Any artificial fly pattern used when trout that aren't feeding selectively on anything in particular. A searching pattern may be an attractor or an imitation of something specific that the fish might favor even though it's not currently hatching.

Useful References:

Brigham, W.U., A.K. Brigham, and A. Gnilke. 1982. Aquatic Insects and Oligochaetes of North and South Carolina. Midwest Aquatic Entomologist.

McCafferty, W.P. 1983. Aquatic Entomology: The Fishermen's Guide and Ecologists' Illustrated Guide to Insects and Their Relatives. Jones and Bartlett Publishers.

Merritt R.W., and K.W. Cummins. 1996. An Introduction to the Aquatic Insects of North America (Third Edition). Kendall/Hunt Publishing Company.

Peckarsky, Barbara. 1990. Freshwater Macroinvertebrates of Northeastern North America. Comstock Publishing.

Schwiebert, Ernest G. 1955. Matching the Hatch. MacMillan Publishing Company.

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.