Minnesota Alderflies, Dobsonflies, and Fishflies


Order Megaloptera

Megaloptera is the order of alderflies, dobsonflies, and fishflies. Until recently they were included in the order Neuroptera, along with snakeflies and lacewings, which they closely resemble. Adults are terrestrial and are found near ponds or streams. Larvae are aquatic. They occur in streams usually under stones. They take 1 to 5 years to complete metamorposis.

There are about 300 known species of Megaloptera worldwide, 43 species in 8 genera in North America north of Mexico, and at least 7 species in Minnesota.

Megaloptera are large, soft-bodied insects distinguished by the following:

  • four delicate, membranous wings with numerous veins, including many cross veins near the leading edge (costal margin);
  • forewing a little wider at the base than the hindwing;
  • wings held roof-like over the body when at rest;
  • hindwing with a pleated region allowing the wing to be folded over the abdomen;
  • mouthparts adapted for chewing, though some adults do not feed;
  • large compound eyes;
  • long antennae with many segments; and
  • last part of the leg (tarsus) with 5 segments.

  spring fishfly  


Recent Additions

Spring fishfly

Spring fishfly (Chauliodes rastricornis) is a large, short-lived, primitive-looking, winged insect. It occurs in the United States and southern Canada east of the Great Plains. It is common in Minnesota. Larvae are found in a variety of aquatic habitats, including ponds, swamps, marshes, and springs. They take one to five years to reach maturity. They feed on both algae and small invertebrates, including crustaceans, clams, worms, and other insects. Adults are found from late May to early July near larval habitats. They live only a few days to a week. They are active at dusk but remain hidden during the day. It is thought that they do not feed, though they have been collected in moth traps.

spring fishfly





This list includes only alderflies, dobsonflies, and fishflies that have been recorded in Minnesota, but not all of the alderflies, dobsonflies, and fishflies found in Minnesota.


Profile Photo Video      

alderfly (Sialis itasca)

spring fishfly


alderfly (Sialis mohri)


alderfly (Sialis velata)


eastern dobsonfly (Corydalus cornutus)


saw-combed fishfly (Nigronia serricornis)

Profile Photo    

spring fishfly (Chauliodes rastricornis)

Chauliodes rastricornis (spring fishfly)

Corydalus cornutus (eastern dobsonfly)

Nigronia serricornis (saw-combed fishfly)

Sialis itasca (alderfly)

Sialis mohri (alderfly)

Sialis velata (alderfly)

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