Pteronarcys is a small genus of large insects known as giant stoneflies or salmonflies. It occurs in North America and Asia. There are 10 Pteronarcys species worldwide, 8 species in North America north of Mexico, and just 2 species in Minnesota. It is found throughout most of the United States, but it is absent from the Great Basin and the desert southwest, and mostly absent from the Great Plains and the deep south. It is common in Minnesota.

Pteronarcys species are usually referred to as giant stoneflies in the east and as salmonflies in the west. The term salmonflies is derived from the color of the belly of aquatic salmonfly nymphs.

giant stonefly or salmonfly (Pteronarcys sp.)

Photo by Ann Hokanson

Adults appear in the spring and early summer, mostly from April to June. They are usually found near streams. They are active during the night and will come to lights. They do not feed. The young (nymphs) are aquatic. They live in cool, small to medium-sized, fast moving streams. They feed on large particles of plant matter and other organic material that has collected behind any obstruction in a stream.

Description

Adults are 1½″ to 2½″ (38 to 64 mm) in length, and they are usually brown or gray. The body is soft, elongate, and flattened.

The jaws (mandibles) are well developed. The antennae are long and thread-like.

The wings are held flat over the abdomen when at rest. The forewings are long and narrow, and they have many veins. The anal area has 2 or more rows of cross veins. The hindwing is shorter. It has a large anal lobe that is folded like a fan when not in use.

The last part of each leg (tarsus), corresponding to the foot, has three segments.


Distribution
		4, 7, 24, 29, 30, 82, 83. Stoneflies of the United States; U.S. Geological Survey (archived)
7/4/2024


Taxonomy
Order	Plecoptera (stoneflies)
Suborder	Arctoperlaria
Infraorder	Systellognatha
Superfamily	Pteronarcyoidea
Family	Pteronarcyidae (giant stoneflies)
Subfamily	Perlodinae
Tribe	Perlodini

Subordinate Taxa
American salmonfly (Pteronarcys dorsata) Appalachian salmonfly (Pteronarcys proteus) California giant salmonfly (Pteronarcys californica) Carolina salmonfly (Pteronarcys scotti) ebony salmonfly (Pteronarcys princeps) knobbed salmonfly (Pteronarcys biloba) midwestern salmonfly (Pteronarcys pictetii) salmonfly (Pteronarcys reticulata) salmonfly (Pteronarcys sachalina) spiny salmonfly (Pteronarcys comstocki)

Synonyms
Allonarcys Kollaria Pteronareys

Common Names
giant stoneflies salmonflies

Glossary

Tarsus

On insects, the last two to five subdivisions of the leg, attached to the tibia; the foot. On spiders, the last segment of the leg. Plural: tarsi.


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Ann Hokanson

2.5 inches. Potted plant near stone edging 15 yards from a storm water retention area


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Giant Stonefly (Pteronarcys spp.)
Andree Reno Sanborn

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Other Videos

Giant Stone fly! Pteronarcys What is the story of this "monster" fly?
Nature at Your Door Frank Taylor

About

May 29, 2020

This is the largest Stonefly species (Pteronarcidae) in North America. A feast for a trout. Trout fisherman try to tie and match flies to both adults and larva. In this video the life history of stonefly (Plecoptera) adults and aquatic stream-loving nymphs is revealed. The adult is in the genus Pteronarcys while the nymphs of both genera Acroneuria and Peltoperla are investigated.

Families Perlidae and Peltoperlidae.

Pteronarcys
Nicholas Macelko

About

Mar 29, 2021

Camcorder


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