Natural Field Biology
April 5, 2014
Hellgrammites make my skin crawl
Fishing and camping was a huge activity of my family when I was a teenager. My father would drag my brother and me to the Conewago Creek with a hoe and a homemade bait catcher fashioned from two bamboo sticks and netting with holes about a quarter-inch square. My brother and I would each hold a stick and my dad using the hoe would lift the rocks in the rapids loosing up anything underneath. I dreaded catching the black worm-like hellgrammites because they were just disgusting to look at and I was certain they would pinch me.
The hellgrammite (also spelled helgramite) is actually a fly, I’ve since learned, and is just as ugly in that cycle of life. It is called a Dobsonfly, is an insect, and its scientific name is Corydalus cornutus, part of the megalopteran family Corydalidae. Figure 1 is an example of an Eastern male and female Dobsonfly, note the size of the pinchers. The Dobsonfly is the largest nerve-winged insect in a family of over 220 species and most closely related to fishflies living in most of Eastern North America, east of the Continental Divide from Canada to Mexico. In the fly state they can grow as long as 5 inches from their pinchers to the tips of their four wings and have multi-segmented antennae emerging from the sides of their creepy heads. They fold their wings along their bodies when not in use. Both sexes have mandibles or pinchers but the males are so big (up to an inch) that they can’t hurt humans because they are unable to get any leverage. They’re not poisonous but they do give off a nasty stink. The female’s pinchers are smaller and like when in the larva stage, they can pinch and break human skin, just as I suspected as a teenager. They eat other insects found in fresh water such as May flies and caddis flies.
Dobsonflies live most of their lives, about 3 years, as larva and grow to about 2 to 3 inches long and are called hellgrammites at that time. (See figure 2) Along the sides of their body, they have two rows of nine breaking holes to breath outside of water and two sets of gills to breathe while in the water. If they aren’t eaten by the aquatic life (frogs, fish, and turtles) or caught as bait, they will crawl onto land around June and at night, sometimes traveling up to 100 feet and burrow into the ground. After about 2 weeks it will shed it black exoskeleton and transform into the dobsonfly, yellow in color with traces of brown. It only lasts for a week in this state in order to mate during the month of July when the weather is hot as insects seem to love. It remains nocturnal during this phase of its life. They lay eggs in a mass between 2,000 and 3,000 in leaves and vines near fresh-running water and when the egg masses dry they look like bird dropping. The eggs will all hatch at the same time and the larvae will crawl out and live for a day or two on dry land before entering the water.
The hellgrammite has been given many nicknames, some going back as far as the original Dutch settlers from New York. Some of the most popular nicknames are Alligator, angle dog, bloomer, hell driver, go-devils, grampus and crawlerbottoms. I personally called them fugly.
Hall, Donald. “Eastern Dobsonfly.” University of Florida Entomology & Nematology. July 2007. Last Updated Apr. 2013. Web. 27 Mar. 2014
“The Helgramite.” Forest and Stream; A journal of Outdoor Life, Travel, Nature Study, Shooting, Fishing, Yachting (1873-1930) Jul 24 1890. 10. ProQuest. Web. 27. Mar. 2014.