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Predatory Insects

Eastern Dobsonflies Emerging

7-9-18 male dobsonfly2_U1A0727

Eastern Dobsonfly (Corydalus cornutus) larvae, known as Hellgramites, are the top invertebrate predators in the rocky streams where they occur. In this stage they look like underwater centipedes and consume tadpoles, small fish, and other young aquatic larvae. Adults keep watch over them from a nearby area above the water.

After leaving their stream and pupating on land, the 4”-5 ½”-winged adults, referred to as Eastern Dobsonflies, emerge. Males can easily be distinguished from females by their large, sickled-shaped mandibles which the females lack. (The short, powerful mandibles of the female are capable of giving a painful bite, which the males’ mandibles are not.) Adults are primarily nocturnal and they do not eat. During their short lifespan (about three days for males, eight to ten days for females) they concentrate on reproducing.

The elongated jaws of the male are used both as part of the premating ritual (males place their mandibles on the wings of the females) and as weapons for fighting rival males.   (Thanks to Clyde Jenne for photo op.)

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