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Dobsonflies, Hellgrammites, Fishflies & Alderflies (Megaloptera)

General information about Dobsonflies, Hellgrammites, Fishflies & Adlerflies (Megaloptera)
Life history Dobsonflies, hellgrammites, fishflies, and alderflies, depending on the species, will spend 1 to 3 years in the water as larvae. When the larval stage is complete, they pupate and usually emerge from the water in late spring to early summer to pupate into adults.
Diversity There are two families in North America.
Distinguishing
characteristics
Long bodies, head and thorax have thick skin, visible mouthparts in front of head, no wing pads, pairs of structures along the sides of the body, and the end of the body has either a pair of prolegs (unjointed legs) with two claws or one single long tapering structure.
Habitat & Feeding Dobsonfly, hellgrammite, fishfly, and alderfly larvae can be found in lakes, streams, spring seeps, ponds, wetlands, bogs, marshes or swamps. They are predators, eating other aquatic insect larvae, worms, crustaceans, and mollusks.
Water quality indicator status Most kinds of dobsonfly and fishfly larvae are found in moderately clean well oxygenated water and are sensitive to pollution. Alderfly larvae are more tolerant of pollution and may be found in areas impacted by pollution.
Fun facts
  • When larvae emerge from the water to pupate into adults, they first excavate a cavity using their jaws and legs.
  • Some larvae can reach 2.5 inches in length!
Image of dobsonfly in the Corydalus sp.
Corydalus sp.
Image of alderfly in the Sailis sp.
Sailis sp.