Dobsonfly

The dobsonfly, Corydalus cornutus, is a two-inch long, dark-colored insect of North and Central America, that spends most of its life in its larval stage. The larvae are called hellgrammites, live under rocks at the bottoms of lakes, and prey on other insect larvae.

Dobsonflies have large, powerful jaws, strong enough even to draw blood from humans. Despite the fact that the males' mandibles are much bigger than the females', they are unable to harm humans. They are used excusively for grasping the females during mating. The female's mandible are smaller but able to inflict painful bites. After a few years of living and growing underwater, they crawl out onto land and pupate. They stay in their coccoons over the winter and emerge only to mate. Upon emerging, they live for only a few days. They do not eat in their adult stage.

External Links/Sources

http://www.fcps.k12.va.us/StratfordLandingES/Ecology/mpages/dobsonfly.htm

http://mbgnet.mobot.org/fresh/slide/dobson.htm

http://insects.tamu.edu/fieldguide/bimg121.html