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Stoneflies - Plecoptera: Perlodidae of Gunnison County, Colorado

Kogotus modestus - Sickle Springfly

(Banks 1908)
Updated 19 Jan 2019

Kogotus modestus nymphs and their reflections. The top stonefly is eating a flatheaded mayfly, the bottom is munching on a small minnow mayfly. Upper East river, early August 2011


Streams and rivers throughout the county.

Local Research Results

K. modestus nymphs have been popular research subjects in the upper Gunnison Basin. Common and easy to catch in the summer, these stoneflies are robust and relatively easy to handle and observe. Both the Peckarsky and Allan Labs at RMBL have worked with this species. The Stewart Lab based out of Texas has published life history data from a population near Pitkin. In fact there are so many papers published on Kogotus, please go to the references to admire them all.

Locations Collected

Copper Creek, Cement Creek, East River, Hall´s Gulch, Hooper Creek


Older publications may refer to this species as Perla modestus.

Good Links

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


Allan,J David 1982 Feeding habits and prey consumption of three setipalpian stoneflies (Plecoptera) in a mountain stream. Ecology 63(1), 26-34. Abstract

Allan,JD; Flecker,AS and McClintock,NL 1987 Prey size selection by carnivorous stoneflies. Limnol. Oceanogr. 32(4), 864-872.
      Small stoneflies preyed on small prey and big stoneflies preferred medium sized prey. Percent attacks/encounter by small K. modestus were strongly biased towards small prey, large K. modestus were weakly biased towards large prey. Capture success was greater and handling times were shorter with small prey compared to large prey. To summarize, choice of prey size captured varied with predator size.

Banks,N 1908 Neuropteroid insects - notes and descriptions. Transactions of the American Entomological Society 34:255-267.
     Described as Perla modesta.

Baumann, RW Gaufin, AR, Surdick, RF 1977 : The stoneflies (Plecoptera) of the Rocky Mountains. Memoirs of the American Entomological Society 31, 1-208.
     Quote from page 129: "This species is common in creeks and rivers. The adults emerge from April to August."

Kerans,BL; Peckarsky BL and Anderson,C 1995 Estimates of mayfly mortality: is stonefly predation a significant source?. Oikos 74(2):315-323. PDF
     Abstract: " Field experiments and surveys were carried out in a Rocky Mountain alpine stream during the summers of 1990 and 1992 to estimate the proportion of natural losses of the mayfly Baetis bicaudatus resulting from the co-occurring, predatory stonefly, Kogotus modestus. Functional response experiments determined the number of prey consumed by male and female Kogotus by manipulating the densities of prey and the presence or absence of predators in stream-side chambers. Estimates of losses of Baetis and density of Kogotus were based on ten benthic samples collected weekly (except for last sampling date) from one study reach. Concurrently, drift density of Baetis was estimated upstream and downstream of the reach to determine gains or losses of Baetis resulting from migration. In the functional response experiments Kogotus consumed the same number of prey regardless of prey densities. Female predators tended to consume more prey (~ 2 d-1) than males (~ 1 d-1), although the result was only statistically significant in one out of three experiments. Per-capita mortality rates of Baetis declined from 0.01 to 0.001 d-1 (predator m-2)-1 with increasing prey density. In the study reach Baetis density declined 70% during the 4.5 wk and per-capita losses averaged 3.8% d-1. We estimated that predation by Kogotus could cause between 1.6 and 9.5% of the losses of Baetis from the study reach. This occurred because high losses of Baetis were combined with low consumption rates and densities (1.83 individuals m-2) of Kogotus. Baetis drift density was higher at night than during the day. Drift densities of Baetis tended to be higher leaving than entering the reach in nighttime estimates, although the results were not statistically significant. Few replicates resulted in low power to detect differences in upstream and downstream drift densities; therefore, it is possible that some losses could be the result of drift out of the study reach. Nonetheless our results suggest that Kogotus populations had little direct, lethal effect on Baetis populations in this study reach."

Kondratieff,BC and Baumann,RW 2002 A review of the stoneflies of Colorado with description of a new species of Capnia (Plecoptera: Capniidae). Transactions of American Entomological Society 128 3, 385-401.
     Quote from page 397: "A common species found on the higher elevation small to medium sized streams of the Mountain region. Adults can be collected from July to October."

Maketon,M; Stewart,KW; Kondratieff, BC and Kirchner,RF 1988 New descriptions of drumming and evolution of the behavior in North American Perlodidae (Plecoptera). Journal of the Kansas Entomological Society, pp.161-168.
     Abstract: " The drumming behavior of six Plecoptera species, Clioperla clio, Diploperla robusta, Oconoperla innubila, Osobenus yakimae, Perlinodes aurea and Yugus arinus, are described for the first time, and additional data for Isogenoides zionensis are provided. Patterns and evolution of drumming in the family Perlodidae are discussed, and an out-group comparison shows that: (1) a simple call-answer exchange between sexes in seven species is ancestral, and (2) bi-grouped calls of Hydroperla crosbyi and the complex, grouped exchanges of Isogenoides zionensis are derived expressions of drumming. Similarly, grouped calls of some Isoperla and grouped bi-beat calls of Calliperla luctuosa and Kogotus modestus are derived. The grouped drumming pattern is known only in Perlodidae, and the European Leuctra pseudosignifera (Leuctridae)."

Needham,JG and Claassen,PW 1925 A Monograph of the Plecoptera of North America. Entomological Society of America, Lafayette, Indiana. 397 pages.
     Discussed as Perla modesta on page 88.

Peckarsky,BL 1980 Predator-prey interactions between stoneflies and mayflies: Behavioral observations. Ecology 61 4, 932-943.

Peckarsky,BL 1983 Biotic interactions or abiotic limitations? A model of lotic community structure. In: Dynamics of Lotic Ecosystems. Eds: Fontaine III,Thomas D; Bartell,Steven M Ann Arbor Science, Ann Arbor, Michigan, 303-323.

Kogotus eating a Cinygmula larvae

Peckarsky,BL 1985 Do predaceous stoneflies and siltation affect the structure of stream insect communities colonizing enclosures? Canadian Journal of Zoology 63, 1519-1530.

Peckarsky,BL 1987a Mayfly cerci as defense against stonefly predation: deflection and detection. Oikos 48 2, 161-170.

Peckarsky,BL 1988 Why predaceous stoneflies do not aggregate with their prey. Internationale Vereinigung für Theoretische und Angewandte Limnologie Verhandlungen 23, 2135-2140.
     Investigating optimal foraging theory, she found that contrary to theory K. modestus and Megarcys signata larvae did not hang out in high concentrations of prey.

Peckarsky,BL 1991a A field test of resource depression by predatory stonefly larvae. Oikos 61 1, 3-10.

Peckarsky,BL 1991b Is there a coevolutionary arms race between predators and prey? A case study with stoneflies and mayflies. Advances in Ecology 1, 167-180.

Peckarsky,BL 1991c Mechanisms of intra- and interspecific interference between larval stoneflies. Oecologia 85(4) 521-529. Abstract

Peckarsky,BL 1996 Alternative predator avoidance syndromes of stream-dwelling mayfly larvae. Ecology 77 6, 1888-1905. Abstract

Peckarsky,BL; Cowan,CA 1991 Consequences of larval intraspecific competition to stonefly growth and fecundity. Oecologia 88, 277-288.

Peckarsky,BL and Cowan,CA 1995 Microhabitat and activity periodicity of predatory stoneflies and their mayfly prey in a western Colorado stream. Oikos 73(4)) 513-521. PDF
     Abstract: " Experiments were conducted to determine whether overlap between microhabitat preferences and activity periodicities of four mayfly species and their stonefly predators could explain species-specific differences in predator-prey encounter frequencies. Preferences for rock type (slate or granite), flow microhabitat (high or low), rock surface (top, bottom, upstream or downstream sides), and periodicity of drift and the use of rock tops were measured in a stream-side system of flow-through circular Plexiglas chambers receiving natural stream water and light levels. These parameters were compared among the predatory stoneflies, Megarcys signata or Kogotus modestus, and four species of mayflies that vary in their encounter rates with the stoneflies. Based on predator-prey encounter rates previously observed in similar chambers, we expected greater overlap between Megarcys and Ephemerella infrequens and the overwintering generation of the bivoltine mayfly, Baetis bicaudatus than with Cinygmula sp. Likewise, we expected Kogotus microhabitat use to overlap more strongly with that of summer generation Baetis than with later instars of Cinygmula and Epeorus deceptivus. Results ran counter to our predictions, indicating that microhabitats of the prey species with high predator encounter rates did not overlap more strongly with the stoneflies than did mayflies with low predator encounter rates. Most mayflies and stoneflies preferred the bottom surfaces of granite rocks, and showed few flow preferences. Most were nocturnal in their use of top rock surfaces, in drift and feeding activity periodicity. Therefore, nocturnal activity periodicities of both mayflies and stoneflies confirm that mayflies have not evolved feeding periodicity to avoid encounters with foraging stonefly predators. We conclude therefore, that neither temporal nor spatial microhabitat overlap is a reasonable explanation of differential encounter rates between predatory stoneflies and their mayfly prey. Alternative explanations for differential encounter rates are that more abundant or more mobile mayflies have higher encounter rates with predators, and effective pre-contact predator avoidance responses of other mayflies reduce their encounter rates with stoneflies."

Peckarsky,BL; Cowan,CA; Penton,MA; Anderson,CR 1993 Sublethal consequences of stream-dwelling predatory stoneflies on mayfly growth and fecundity. Ecology 74 6, 1836-1846. Abstract

Peckarsky,BL; Dodson,SI 1980 An experimental analysis of biological factors contributing to stream community structure. Ecology 61 6, 1283-1290.

Ricker,WE 1992 Origin of stonefly names proposed by Ricker and collaborators. Perla, 18(1) 12 pages. PDF
      Quote from page 6: "Kogotus Ricker 1952 (as sg. of Isogenus). Russian kogot =claw or nail. Refers to the lobe on the 7th sternite of the male. "

Ruse,LP and Herrmann,SJ 2000 Plecoptera and Trichoptera species distribution related to environmental characteristics of the metal-polluted Arkansas River, Colorado. Western North American Naturalist 60 (1) 57-65. PDF
     They looked at the Arkansas River above and below some notorious heavy metal mine pollution sources, California Gulch and the Leadville Drain. They found that adult Kogotus were eliminated by the Leadville Drain, recovered and reappeared a ways downstream, then were present below California Gulch at one site before disappearing for good. After freshwater was added to the Arkansas River from the western slope, Kogotus reappeared at one site. They were probably missing farther downstream due to warmer water temperatures and would have been missing from a clean river as well.

Stanford,JA and Ward,JV 1989 Serial discontinuities in a Rocky Mountain river. I. Distribution and abundance of Plecoptera. Regulated Rivers: Research and Management 3, 169-175.

Stewart, KW and Sandberg, JB 2003 The life history of a Colorado population of Kogotus modestus Research Update on Ephemeroptera and Plecoptera E. Gaino (Ed.) University of Perugia, Perugia Italy pp.195-200. PDF available on Sandberg's website
     They studied Kogotus in Hooper Creek and Halls Gulch near Pitkin. They observed a synchronized emergence of adults in late August and early September. They include scanning electron micrographs of K. modestus eggs and lacinia (a mouthpart). Looking at the gut contents of 30 larvae, they found that K. modestus ate almost entirely Chironomid larvae. The males stopped feeding before emerging, while the females kept eating. They tested the eggs for diapause and found that the eggs diapause through at least the first winter and hatch in the spring, while other eggs diapaused longer and hatched the following spring.

Vance,SA; Peckarsky,BL 1997 The effect of mermithid parasitism on predation of nymphal Baetis bicaudatus (Ephemeroptera) by invertebrates. Oecologia 110, 147-152.
     They found that Kogotus modestus ate significantly more parasitized than unparasitized B. bicaudatus. However, Rhyacophila hyalinata caught and ate equal numbers of parasitized and unparasitized nymphs. They attribute this to the behavior of parasitized nymphs and different hunting behaviors of the predators. Parasitized nymphs drifted less, which increased encounter rates with Kogotus nymphs. However R. hyalinata larvae are ambush predators and catch parasitized and unparasitized nymphs equally. They hypothesize that avoiding fish predation by drifting less is a greater advantage to the parasite than the losses suffered by increased stonefly predation.

Mesosternal Y-arms.
Only visible easily on mature nymphs.

Brown,WS 2004 Stoneflies of Gunnison County, Colorado