Eastern dobsonfly adults are large, soft bodied, usually a drab gray, black, or brown, with prominent pincers and long antennae. The wings have conspicuous veins and are usually folded down the length of the body when at rest. The pincers (mandibles) of females are rather stubby and are capable of inflicting a painful bite. The mandibles of males are very long, tusklike, and incapable of hurting people due to lack of leverage.
Larvae, called hellgrammites, are aquatic, somewhat flattened, and usually some shade of black, brown, or tan. Some people think they look like centipedes. The head is equipped with a pair of sharp pincers that can deliver a painful bite. The thorax has 3 pairs of legs. The segmented abdomen has 8 pairs of leglike appendages extending from the sides, each with a cottony or hairy gill tuft at the base. There is a pair of hooked, leglike appendages at the hind tip; these help keep the animal from being swept away in the water current.
Similar species: Fishflies are in the same family and can be large and easily confused with female dobsonflies. Male fishflies, however, don't have the huge tusks, and males of many fishflies have pectinate (comblike or feathery) antennae. Females of the two groups can be distinguished by the more prominent pincers of female dobsonflies, and by their distinctively shaped pronotums (the necklike section just behind the head).
Habitat and Conservation
Adults tend to stay near water and are most often seen in late spring and early summer. They are nocturnal and often attracted to electric lights. As adults, only the females are capable of delivering a painful bite. However, when molested, both sexes will raise their heads and spread their jaws defensively. Dobsonflies are not venomous and the worst they can do is pinch you.
The larvae usually inhabit the swiftest sections of large streams and rivers and usually hide under rocks.
The larvae are predaceous and snatch nearly anything that swims or ambles by, including other aquatic insects, small fish, and so on.
The adults only live a few days or a week. Despite their fierce-looking pincers, adults don't usually eat at this stage, having gained all their nourishment as aquatic larvae. But they can pinch you if you molest them.