The Eastern Dobsonfly is
a ferocious looking creature, both as an adult
(especially the males) and as a larva.
The adult dobsonfly is
about two inches long. It is usually a brownish-gray color,
with long grayish wings which fold down its back.
The male Eastern
Dobsonfly has two long mandibles (jaws) about half the
length of its body. The female has small mandibles. The
male's mandibles cannot hurt you, they are for grasping the
female while mating. The female's bite is
painful.
Department of Entomology
and Nematology, University of Florida. Photographer: James
L. Castner
Here you can see the
difference in the male and female mouthparts.
The Dobsonfly's larvae (picture
above) are called "hellgrammites." They spend most of their lives
underwater in fast-moving parts of streams and rivers. After the
adult dobsonflies mate, the female lays eggs on a branch or on rocks
near a stream. Between 100 and 1,000 eggs are laid in a mass with a
white substance over it. The eggs resemble bird droppings, which may
protect them from predators.
Hellgrammites, after they hatch, will either fall into the stream
from an overhanging branch, or crawl to the water.
This animal spends most
of its life (two to three years) as a larva, living
underwater. Hellgrammites live under rocks to avoid
predators, especially fish. They ambush other animals,
expecially aquatic
insects, such as larvae of dragonflies, damselflies,
stoneflies, and mayflies. Hellgrammites have strong jaws and
can draw blood from a human if not handled carefully. They
use these jaws to take apart their prey. Hellgrammites also
have little hooks on their abdomens
which allow them to grab onto items so that they don't get
swept away in the current. Hellgrammites are not very good
swimmers. They move mostly by crawling.
Copyright, Garold W.
Sneegas
When Hellgrammites get full-sized,
they crawl from the water to pupate
(form a coccoon). They will crawl under a rock or log near the water,
and overwinter
as a pupa. The following summer, the adult Eastern Dobsonfly will
emerge to mate. They do not eat. Dobsonflies will live only a few
days.
Eastern Dobsonflies are often
attracted to lights at night.
Dobsonflies rarely come into
contact with humans directly. Sometimes they are seen on window
screens or near outdor lights at night. Fishermen use Hellgrammites
as bait to catch Largemouth Bass, catfish, and other fishes.
Hellgrammites also help control aquatic insect
populations.
