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Stoneflies - Plecoptera: Pteronarcyidae

Pteronarcys californica
Salmonfly, Giant Salmonfly, Willowfly, Giant Stonefly

Newport 1848
Updated 18 Mar 2021
TSN 102473


These big, prehistoric looking nymphs are common in medium-sized rivers below 7500ft, usually in trash piles and leaf packs or under large stones in eddies near shore. Enormous numbers of adults emerging over a few weeks in the Black Canyon and many other western streams are quite the spectacle and a favorite of the trout and flyfishermen alike. There have been attempts to reintroduce them in the Gunnison River above the dams in the Aspinall unit.

Life History

Richardson and Gaufin noted this species eats detritus. All of the specimens they examined had sand in their guts. No sand was found in the hind gut so they assume the nymphs regurgitate the sand as required. Algae was found in many specimens. Traces of animal matter were found in some guts. Laboratory observations of feeding habits on leaf packs led to the observation that P. californica is occasionally cannibalistic. Usually nymphs lie hidden with antennae protruding and waving side to side. When food contacts their antennae the nymphs rush out and seize the food with their maxillae. While searching for food, P. californica nymphs move slowly with their antennae continuously moving back and forth.

Locations Collected

Gunnison River at Soap Creek and McCabe Lane, Black Canyon, Lake Fork of the Gunnison.

Good Links

Species details from plecoptera.species.file

Photo - Nymph from Michael Wigle Photography.

Photo of adult - from the Tree of Life

Another Photo of adult - from the Tree of Life

Hatch chart for East, Taylor, and the Gunnison River through Black Canyon. http://www.dragonflyanglers.com/page.cfm?pageid=2119

Hatch Chart for the Gunnison Gorge & Black Canyon from Cimarron Creek Guides in Montrose http://www.cimarroncreek.com/flyfishing/hatchchart.cfm

Photos, Map, Museum specimens, DNA - Barcodinglife.org


Armold,MT; Blomquist,GJ and Jackson,LL 1969 Cuticular lipids of insects-III. The surface lipids of the aquatic and terrestrial life forms of the big stonefly, Pteronarcys californica Newport. Comparative Biochemistry and Physiology 31(5)685-692.
1. 1. Surface lipid composition of the adult and naiad big stonefly differ in that a larger percentage of hydrocarbons, wax esters, free fatty acids and sterols are found on the adult, while the naiad surface lipid has more triglyceride.
2. 2. Major qualitative differences between adult and naiad surface lipids exist in the hydrocarbon fraction. Significant quantitative differences were found in all fractions except the sterol fractions.
3. 3. Results of this investigation show that the aquatic naiad form and the terrestrial adult form of the big stonefly have different surface lipid compositions. It appears that this insect's surface lipid composition varies with life stage depending upon the needed water conservation mechanism.

Béthoux,O 2005 Wing venation pattern of Plecoptera (Insecta: Neoptera). Illiesia, 1(9):52-81. PDF

Birrell,JH; Meek,JB and Nelson,CR 2019 Decline of the giant salmonfly Pteronarcys californica Newport, 1848 (Plecoptera: Pteronarcidae) in the Provo river, Utah, USA Illiesia, 15(5)53-97. PDF
     Abstract: "Anthropogenic disturbances are causing many aquatic insect species, including those in Plecoptera, to lose geographic range, and, in some cases, succumb to extinction. One species, Pteronarcys californica Newport, 1848, has declined in several rivers in the western United States during the past century. It has been extirpated from the Arkansas River of Colorado and the Logan River of northern Utah and is now in decline in the Provo River of central Utah. We sampled the Provo River for two years (20162017) to determine the abundance and distribution of P. californica and other stonefly species. In over 300 samples, we found only 17 P. californica individuals. Our study demonstrates that their abundance and distribution have declined dramatically when compared to baseline values obtained from museum records, unpublished data and publications from the past century. Total stonefly species abundance and richness may also be lower compared to historical data. Because Plecoptera are bioindicators of water quality, this decline indicates that the health of the Provo River is deteriorating, especially in the lower reaches where few stoneflies were found. These findings suggest that active steps should be taken to protect the Provo River and its aquatic biodiversity."

Branham,JM and Hathaway,RR 1975 Sexual differences in the growth of Pteronarcys californica Newport and Pteronarcella badia (Hagen) (Plecoptera). Canadian Journal of Zoology, 1975, 53:(5) 501-506.

Clubb,RW; Lords,JL and Gaufin,AR 1975 Isolation and characterization of a glycoprotein from the stonefly, Pteronarcys californica, which binds cadmium. Journal of Insect Physiology 21 (1)53-60.
     Abstract: The present study reports the isolation and characterization of a cadmium-containing glycoprotein from the water-soluble fraction of an aquatic insect. The isolated glycoprotein contained 067% cadmium, 621% carbohydrate, and 372% protein. The glycoprotein appears to be involved in the detoxification of cadmium, because species insensitive to cadmium contain five times the amount of the glycoprotein as do species sensitive to cadmium.

Colburn,T 1986 The use of the stonefly Pteronarcys californica Newport as a measure of biologically available cadmium in a high altitude river system Colorado, USA. Water Quality Bulletin 11, 141-147.
     Concerned about the heavy metal Cadmium in water often used for human consumption in Gunnison County, Colorado, the author exposed P. californica in cages to the water and accompanying sediments in various rivers in the upper Gunnison Basin. She found Cadmium concentrations lowest in the highest elevation cages. An interesting result was that sometimes the stoneflies had higher concentrations of Cadmium that the water samples might indicate. She said this showed that stoneflies indicate the cadmium present in the sediments. She suggests P. californica metal concentrations may be a better way to monitor stream levels of Cadmium than water samples.

Cui, Y; Béthoux, O; Kondratieff,B; Shih,C and Ren,D 2016 The first fossil salmonfly (Insecta: Plecoptera: Pteronarcyidae), back to the Middle Jurassic. BMC evolutionary biology, 16(1) 217 HTML

Freilich, JE 1991 Movement patterns and ecology of Pteronarcys nymphs (Plecoptera). Freshwater Biology, 25(2) 379-394.
     " SUMMARY. 1. Individually tagged Pteronarcys californica (Newport) nymphs were caught and recaptured over a 3-month period to determine their movement patterns and home range size. Sex/age structure, population density, and food habits (from gut contents) were also recorded. More than 1000 nymphs were tagged of which 256 (25%) were recaptured at least once. Tagged insects were confined to contiguous fast water, cobble riffles. Low velocity, silt-bottomed pools acted as barriers.
2. This stonefly has a 3-year life cycle although only the two oldest nymphet size-classes were tagged. Females were larger than males at all ages. The population sex ratio was skewed 60:40 towards females. Densities averaged 1.7 m-2±0.17 SE (range 0-19 m-2).
3. Most movements were short, indicating that a majority of the stoneflies stayed within a few meters of their first capture point (mean 1.8 m downstream ±0.51 SE, range 44 m downstream to 40 m upstream). Significant patch size is a stream reach 24 m long that would contain 85% of the average individual's movements. Time between captures averaged 16 d ±0.734 SE (maximum 81 d). Eight individuals were notable for extremely rapid upstream movements ranging from 6 to 22 m d-1.
4. Frequency of movements up and downstream differed significantly between the sexes. Pteronarcys distribution was clumped with certain quadrate representing 'zones of attraction.' The stoneflies moved rapidly between zones, then stayed many days in those areas. Movements differed significantly from random walk models.
5. Guts contained 75% diatoms, 15% vascular plant material, and 8% animal remains. Females ate significantly more diatoms than males on a volumetric basis."

Gaufin,AR; Clubb,R and Newell,R 1974 Studies on the tolerance of aquatic insects to low oxygen concentrations. Great Basin Naturalist 34:45-59. PDF
      The authors studied the acute short term tolerance of aquatic insects to low oxygen. They used the 96 hour Median Tolerance Limit. The TLm96 for P. californica was 3.2-3.9mg/l and 34% oxygen saturation which was the highest tolerance for low oxygen among the stoneflies tested except for Skwala americana.

Gaufin,AR and Hern,S 1971 Laboratory studies on tolerance of aquatic insects to heated waters. Journal of the Kansas Entomological Society 44:240-245. PDF
     Abstract: "The mature larvae of fifteen species of aquatic insects (Diptera, Ephemeroptera, Plecoptera, and Trichoptera) and the scud (Amphipoda) were tested to determine their relative sensitivity to heated waters under laboratory conditions. The temperature at which 50% died after 96 hours (TLm96) was recorded as the lethal temperature. This ranged from 11.7 C for the torrential stream mayfly, Cinygmula par Baton, to 32.6 C for the snipefly, Atherix variegata Walker. "       The TLm96 for P. californica was 27.0°C.

Goodyear,KL and McNeill,S 1999 Bioaccumulation of heavy metals by aquatic macro-invertebrates of different feeding guilds: a review. Science of the Total Environment, 229(1) 1-19. PDF

Gregory,JS; Beesley,SS and Van Kirk,RW 2000 Effect of springtime water temperature on the time of emergence and size of Pteronarcys californica in the Henry's Fork catchment, Idaho, U.S.A. Freshwater Biology 45(1) 75

Hornig,CE and Brusven,MA 1986 Effects of suspended sediment on leaf processing by Hesperophylax occidentalis (Trichoptera: Limnephilidae) and Pteronarcys californica (Plecoptera: Pteronarcidae). Western North American Naturalist 46 (1) 33-38 PDF
     Abstract: "The effects of suspended sediments on stream invertebrate detrital processing were investigated under replicated conditions in light and temperature-controlled chambers in the laboratory. The leaf-shredding insects Pteronarcys californica and Hesperophylax occidentalis were studied. Mean daily ingestion rates were lower among insects subjected to suspended sediments (1.5 and 3.0 g/l) than insects held in suspended sediment-free environments for seven of the eight trials. In five of the eight trials, mean ingestion rates were suppressed by ?41% when compared to insects held in suspended sediment-free environments. Feeding inhibition was typically greater at the end of the feeding trials (14 days) than at the beginning (0-4 days). The effects of suspended sediments on ingestion were apparently related to the feeding status of the insects at the time of a trial. Insects in an active feeding mode were less influenced by suspended sediment than those in an inactive feeding mode. We conclude that, depending on the season and the duration of impact, suspended sediment can suppress processing of coarse particulate organic matter and thus adversely influence important nutrient and energy pathways in low-order streams. "

Illinois Natural History Survey (INHS) accessed 15 Jan 2010 http://www.inhs.uiuc.edu/
Cat. # Species Stream Location County State Country Date
5805 Pteronarcys californica Gunnison River Gunnison [Gunnison] Colorado United States of America 7 June 1954
5806 Pteronarcys californica Gunnison River Gunnison [Gunnison] Colorado United States of America 7 June 1954
5807 Pteronarcys californica Gunnison River Gunnison [Gunnison] Colorado United States of America 7 June 1954

Kauwe,JSK and Shiozawa,DK 2004 Phylogeographic and nested clade analysis of the stonefly Pteronarcys californica (Plecoptera: Pteronarcyidae) in the western USA. Journal of the North American Benthonlogical Society 23(4)824-838. PDF

Luedtke,RJ and Brusven,MA 1976 Effects of sand sedimentation on colonization of stream insects. Journal of the Fisheries Board of Canada, 33(9), pp.1881-1886. PDF
     P. californica was one of the species that was limited in thier ability to to crawl upstream through slow moving sandy sections. They tended to drift downstream instead.
Abstract: " Driftnets, basket samplers, and artificial streams were used to investigate the influence of heavy sand accumulations on insect drift, colonization, and upstream movements in Emerald Creek, northern Idaho. Most riffle insects successfully passed through low-velocity, sandy reaches 80 m long. Upstream movements on sand were impeded by flows as low as 12 cm/s, except for the heavily cased caddisfly Dicosmoecus sp."

Malison,RL; DelVecchia,AG; Woods,HA; Hand,BK; Luikart,G and Stanford,JA 2020 Tolerance of aquifer stoneflies to repeated hypoxia exposure and oxygen dynamics in an alluvial aquifer. Journal of Experimental Biology, 223(16). PDF

Malison,RL; Ellis,BK; DelVecchia,AG; Jacobson,H; Hand,BK; Luikart,G; Woods,HA; Gamboa,M; Watanabe,K and Stanford,JA 2020 Remarkable anoxia tolerance by stoneflies from a floodplain aquifer. Ecology, 101(10), p.e03127. PDF
     Abstract: "Alluvial aquifers are key components of river floodplains and biodiversity worldwide, but they contain extreme environmental conditions and have limited sources of carbon for sustaining food webs. Despite this, they support abundant populations of aquifer stoneflies that have large proportions of their biomass carbon derived from methane. Methane is typically produced in freshwater ecosystems in anoxic conditions, while stoneflies (Order: Plecoptera) are thought to require highly oxygenated water. The potential importance of methane-derived food resources raises the possibility that stonefly consumers have evolved anoxia-resistant behaviors and physiologies. Here we tested the anoxic and hypoxic responses of 2,445 stonefly individuals in three aquifer species and nine benthic species. We conducted experimental trials in which we reduced oxygen levels, documented locomotor activity, and measured survival rates. Compared to surface-dwelling benthic relatives, stoneflies from the alluvial aquifer on the Flathead River (Montana) performed better in hypoxic and anoxic conditions. Aquifer species sustained the ability to walk after 4-76 h of anoxia vs. 1 h for benthic species and survived on average three times longer than their benthic counterparts. Aquifer stoneflies also sustained aerobic respiration down to much lower levels of ambient oxygen. We show that aquifer taxa have gene sequences for hemocyanin, an oxygen transport respiratory protein, representing a possible mechanism for surviving low oxygen. This remarkable ability to perform well in low-oxygen conditions is unique within the entire order of stoneflies (Plecoptera) and uncommon in other freshwater invertebrates. These results show that aquifer stoneflies can exploit rich carbon resources available in anoxic zones, which may explain their extraordinarily high abundance in gravel-bed floodplain aquifers. These stoneflies are part of a novel food web contributing biodiversity to river floodplains."

Myers,LW and Kondratieff,BC 2017 Larvae of North American species of Pteronarcys (Plecoptera: Pteronarcyidae). Illiesia, 13(16):192-224. https://doi.org/10.25031/2017/13.16 PDF
     Abstract: " Larvae of the eight North American Pteronarcys (Plecoptera: Pteronarcyidae) species have been difficult or impossible to identify over the past century. This stems from the lack of rigorous comparisons of reared material. The absence of a reliable key diminishes the importance of Pteronarcys larvae in aquatic ecological and biomonitoring studies. We provide comparative larval descriptions and a key illustrated with high resolution photographs of important diagnostic characters for the eight North American species of Pteronarcys. Earlier descriptions are reviewed and supplemented with new photographs, illustrations and morphometric data to aid in the separation of morphologically similar species."

Needham,JG and Claassen,PW 1925 A Monograph of the Plecoptera of North America. Entomological Society of America, Lafayette, Indiana. 397 pages.

Nehring,RB 1976 Aquatic insects as biological monitors of heavy metal pollution. Bulletin of Environmental Contamination and Toxicology 15 2, 147-154.
     The author established TL50s of 10.1 - 13.9 mg/l for Copper, greater than 19.2 mg/l for Lead, .004 -.009 mg/l for Silver and greater than 13.9 for Zinc. A TL 50 is the median lethal concentration at which half the population dies. This is a standard laboratory toxicity test used for chemicals (among other things). [Yikes, these are such handsome animals, this would be a difficult experiment to do.] Nehring also measured bioaccumulation of the metals. Clean Pteronarcys that were placed in artifical streams with various amounts of metals concentrated those metals 100 times and more over background levels. The author suggests using bioaccumulation in these animals or others to estimate small amounts of metals in water. Analysis of metals in aquatic insects may help figure out what happened if collected shortly after a fish kill.

Nelson,CH 2009 Surface ultrastructure and evolution of tarsal attachment structures in Plecoptera (Arthropoda: Hexapoda). Aquatic Insects, (31)523-545. Html
     The author used scanning electron microscopy (SEM) to image the plantar surfaces of the stonefly tarsomeres and pretarsus of Pteronarcys californica and a number of other species.

Newport,G 1848 On the anatomy and affinities of Pteronarcys regalis Newman; with a postscript containing descriptions of some American Perlidae, together with notes on their habits. Transactions of the Linnean Society of London 20: 425-452.

Richardson,JW; Gaufin,AR 1971 Food habits of some western stonefly nymphs. Transactions of American Entomological Society 97, 91-121.
     They examined the guts of 275 nymphs from the Provo River in Utah and the Gunnison River in Colorado. Their results were that on average, P. californica guts contained 79.7% detritus. 99.6% of the animals they looked at had sand particles in their guts as well. Filamentous green algae was 6.6% of the diet while diatoms were only 2.1 percent. Traces of animal material were found in 149 of the 275 nymphs. Baetidae and Ephemerella sp. were the most common mayflies found in the guts.

Rockwell,IP and Newell,RL 2009 Note on mortality of the emerging stonefly Pteronarcys californica on the Jocko River, Montana, USA. Western North American Naturalist 69(2) 264-266.PDF

Ruesink,JL and Srivastava,DS 2001 Numerical and per capita responses to species loss: mechanisms maintaining ecosystem function in a community of stream insect detritivores. Oikos 93(2) 221-234. Abstract

Sanders,HO and Cope,OB 1968 The relative toxicities of several pesticides to naiads of three species of stoneflies. Limnology and Oceanography 13(1) 112-117. First page

Schultheis,AS; Booth,JY; Vinson,MR; Miller,MP 2008 Genetic evidence for cohort splitting in the merovoltine stonefly Pteronarcys californica (Newport) in Blacksmith Fork, Utah. Aquatic Insects: International Journal of Freshwater Entomology, 1744-4152, 30(3) 187 - 195.

Sheldon,AL 1999 Emergence patterns of large stoneflies (Plecoptera: Pteronarcys, Calineuria, Hesperoperla) in a Montana river. Great Basin Naturalist 59: 169-174. PDF

Smith,LW 1917 Studies of North American Plecoptera (Pteronarcinae and Perlodini). Transactions of the American Entomological Society 43(4)433-489.
Lucy Smith's description of the salmonfly Pteronarcys californica page 449 Lucy Smith's description of the salmonfly Pteronarcys californica, page 450
Plate 29 illustrations of adult male and female Salmonfly genitalia

PLate 31, illustrations of salmonfly nymph genitalia

Sutton,MQ 1985 The California salmon fly as a food source in northeastern California. J. Calif. & Great Basin Anthropol. 7(2): 176-182.
     The Modoc, Wintu, Achumawi and Atsugewi Indians along the Pit River and other rivers in Northeastern California ate lots of salmonflies. References within this paper said the Wintu people collected adults in the morning and then boiled them to eat now or dried them for later use. The Atsugewi people also collected Salmonflies in the morning and removed their wings before boiling the bodies.

Townsend,GD; Pritchard,G 2000 Egg development in the stonefly Pteronarcys californica Newport (Plecoptera: Pteronarcyidae) Aquatic Insects: International Journal of Freshwater Entomology, 1744-4152, 22(1)19-26.

Walters,DM; Wesner,JS; Zuellig,RE; Kowalski,DA and Kondratieff,MC 2018 Holy flux: spatial and temporal variation in massive pulses of emerging insect biomass from western US rivers. Ecology, 99(1)238-240. HTML

Ward,JV, Kondratieff,BC and Zuellig,RE 2002 An Illustrated Guide to the Mountain Stream Insects of Colorado. 2nd ed. University Press of Colorado, Boulder, Colorado. 219 pages.
     Illustration of P. californica nymph on page 66, figure 26.

Ziegler,DD and Stewart,KW 1977 Drumming behavior of eleven Nearctic stonefly (Plecoptera) species Annals of the Entomological Society of America. 70(4)495-505.

"There is no such thing as a blank day for a fisherman. It will be saved for him by the white-throated weasel, who watches his fishing from a hole in the wall under which is lying a fish that refused all flies; or by the excitement of identifying insects; or by the apple-blossom in a nearby orchard; and no one would call that day a blank on which he has seen a king-fisher." -- Arthur Ransome Rod and Line, 1929
Brown, WS 2004 Plecoptera or Stoneflies of Gunnison County, Colorado