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Excerpts from Jim Conrad's
Naturalist Newsletter
from the March 24, 2007 Newsletter issued from Sierra Gorda Biosphere Reserve, QUERÉTARO, MÉXICO
DOBSONFLY ON A WALL
A little after dawn one morning this week, on the outside stucco wall of one of the office buildings, I noticed the 2.9-inch (7.4 cm) insect shown below:
It was a female Dobsonfly, probably CORYDALUS LUTEUS. I know she's a female because her "pincers" are so SMALL. Male Dobsonflies of this species possess much longer, curved mandibles that extend over a third of the length of their bodies. You can see such a long- mandibled species atop the page at http://tolweb.org/Corydalus.
Down the page at the above address you can also read about the Dobsonfly's natural history. It says, for example, that members of the genus Corydalus are nocturnal and secretive, thus seldom seen. During the day they hide under leaves. Also, Corydalus adults, especially females like ours, are attracted to lights. Probably that's why I found this one beneath a light bulb that had been on all night.
You can imagine the stories country people tell about how dangerous, even deadly, dobsonflies are. However, they're not venomous, and only the female can inflict an unpleasant but not debilitating pinch. The male's gigantic, sickle-shaped "tweezers" are used for holding the female during copulation, and aren't much good for anything else.
Dobsonflies are like cicadas in that they spend by far the greatest part of their lives in their immature or larval stage. When they metamorphose into adults their brief lives are almost entirely focused on finding a mate, reproducing, then dying. The dobsonfly's immature larval stage is aquatic, living 3-5 years in non-polluted, fast-running, well oxygenated rivers before metamorphosing. It's thought that the adults don't even eat, though they may drink a bit.
About 200 species of the dobsonfly genus Corydalus are known, and several extend into North America. They belong to the same insect order, the Neuroptera, as antlions, owlflies and lacewings. My Neuroptera page at www.backyardnature.net/neuropte.htm shows the similarities.
The etymology for the word dobsonfly is a mystery.