An Eastern Dobsonfly from Southwestern Pennsylvania

BugsInTheNews is a VIEWER-PARTICIPANT WEBSITE. This article by Jerry Cates and Jody Patton, first published on 17 May 2012, was last revised on 8 July 2012. © Bugsinthenews Vol. 13:05(05).


Dobson fly (Corydalis cornuta L.); larva, lateral body: Jody Patton, SW Pa. --- 17 May 2012

Eastern Dobsonfly (Corydalis cornutus L.); larva, lateral body: Jody Patton, SW Pa. --- 17 May 2012

On 13 May 2012 Jody Patton wrote the following:

“My name is Jody Patton & I’m from Southwestern PA. I think I found a Centipede, and will insert a picture or two. I’ve decided to befriend & keep him for a pet.

There’s just a thing or two I need to know: What is he? Is it safe to keep? Can he survive in captivity? Will he bite?

Thank you for your time & expertise,


I replied to Jody that, fortunately for him, this was not a centipede (a venomous animal capable of inflicting a painful, medically significant bite that can take several days to heal) but the harmless larva of an Eastern Dobsonfly (Corydalis cornutus) known — at this stage in its development — as a hellgrammite, a name conferred by an outward appearance that seems more representative of the netherworld than of the here-and-now. Its mandibles are capable of forcefully pinching the skin, and some call the larva “toe-biters” for their propensity to pinch the tootsies of waders who invade their habitats.

My first experience with one of these animals took place in the early 1980’s, in Round Rock, Texas. A mature male Dobson fly had landed on the wall of a nursing facility near Brushy Creek, and Mike Reynolds, on the facility’s maintenance staff, took me to where it reposed — some five feet above the ground on the vertical surface of a building’s exterior — in hopes I would be able to identify what it was. At the time I had no ideas regarding its identity, but a quick perusal of the scientific literature soon yielded much about who and what it was, and its biology.

These insects are fearsome looking, in both the larval and mature stages. The male fly is particularly terrifying in appearance due to its enormous jaws that stretch outward from the face a distance nearly half as long as its body. The mature female’s jaws, by comparison,are relatively short, no longer than the head, though they — like those of the larva but unlike the jaws of the mature male, which are used strictly to hold the female during, as Howard (1914) put it, “the marital caress” — are capable of delivering a severe pinch to a human careless enough to place an appendage within their range of motion. Even then, however, the pinch is of no medical consequence, as it is scarcely capable of tearing human skin and in any case is not supplied with venom.



  • Kingdom Animalia — multicellular, eukaryotic organisms whose body plans become fixed during development, some of which undergo additional processes of metamorphosis later in their lives; most are motile, and thus exhibit spontaneous and independent movements; all animals are heterotrophs that feed by ingesting other organisms or their products. 
  • Phylum Arthropoda (Linnaeus, 1758) — invertebrate animals with external (exo) skeletons, segmented bodies, and jointed appendages; named using the two Greek words ἄρθρον (pron. árthron), meaning “joint” + ποδός (pron. podós), meaning “leg” = “jointed leg”; comprised of insects, arachnids, crustaceans, among others; 
  • Class Insecta (Linnaeus, 1758) — named using the Latin word insectum, a calque of the Greek word ἔντομον (pron. éntomon) = “(that which is) cut into sections”; comprised of arthropods with chitinous external (exo-) skeletons, a three part body composed of a distinct head, thorax, and abdomen, the midmost part having three pairs of jointed legs, and the foremost part having a pair of compound eyes and antennae; 
  • Order Megaloptera (Latrielle, 1802) — named using the two Greek words μέγα (pron. mega) meaning “large” + πτέρυξ (pron. pteryx), meaning “wing” = large wing(s), a reference to the typically 4 inch wings possessed by these animals; 
  • Family Corydalidae — a family of dobsonflies and fishflies, conprised, in North America, of about 7 genera and 19 species: 
  • Genus Corydalis (Linneaus, 1758) — also transcribed Corydalus; named using the Greek word κορυδαλλις (pron. corydallis), meaning a crested lark or the flower, larkspur, apparently related to the Greek word κορυς (pron. corys), meaning a helmet crest, which likely refers to the long mandibles of the adult male, insofar as they either resemble the crest of a lark, or the decorative crests of a helmet. 
  • Species Corydalis cornutus (Linnaeus, 1758) — also transcribed as Corydalus cornutus; named using the Latin word corneus, meaning horn, or horny, a reference to the mandibles of the adult male;


Dobson fly (Corydalis cornuta L.); larva, lateral body: Jody Patton, SW Pa. --- 17 May 2012

Lateral body

Dobson fly (Corydalis cornuta L.); larva, dorsofrontal head: Jody Patton, SW Pa. --- 17 May 2012

Dorsofrontal head

Dobson fly (Corydalis cornuta L.); larva, dorsal head: Jody Patton, SW Pa. --- 17 May 2012

Dorsal head

Anatomy: in process

Behavior: in process

Common Names: dobsons, crawlers, amly, conniption bugs, clipper, water grampus, goggle goy, bogart crock, hell devils, flip-flaps, alligators, Ho Jack, snake-doctor, dragon, and hell-diver.

Distinguishing Characteristics: in process

Distribution: in process

Physiology: in process

Mythology: in process

Similar Families: in process



  • Borror, D. and R. White. 1970. Insects: The Peterson Field Guide Series. Houghton Mifflen Company.
  • Howard, L. 1914. The Insect Book. The New Nature Library,Vol. 7 — Part One. Doubleday, Page & Company.
  • Milne, L., and M. Milne. 1984. The Audubon Society Field Guide to North American Insects and Spiders. Alfred A. Knopf, New York


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