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PlecopteraStoneflies |
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 © John Pickering, 2006-2010 Plecoptera wings |
 © John Pickering, 2006-2010 Plecoptera |
 © John Pickering, 2006-2010 Plecoptera |
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| Kinds |
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| Overview | ||||||||||||||
| Click here for Stonefly checklist in the Great Smoky Mountains. Plecoptera (stoneflies) are a small order of insects of about 2000 species worldwide, with their long but fragmented fossil record dating back to the early Permian. The living suborders, Arctoperlaria and Antarctoperlaria, easily contain the earliest fossils. The more modern fossils are easily indentifiable from Miocene (38 - 54 MYA) fossils. -- (University of Texas) | ||||||||||||||
| Identification | ||||||||||||||
Stoneflies can be easily recognized by a few simple characters. They have three segmented
tarsi but their hind legs are not modified for jumping to the extent of Orthoptera (crickets
and grasshoppers). Their filiform antennae are at least half the length of the body. The
cerci are generally long as well, especially in the aquatic nymphs. The wings are almost
always present but are sometimes very short. They are folded horizontally back over the body.
These characters help distinguish them from Dermaptera and Embioptera which they superfically
resemble and to which they are probably closely related. The immatures are variously called
nymphs or naiads, but are most frequently referred to as nymphs. All nymphs are aquatic, and
resemble the adults in many respects. They also have three-segmented tarsi. The nymphs always
have long cerci and never a third central tail or median caudal filament. Gills, if they have
them, can occur on various parts of the thorax and abdomen and are composed only of filiments,
not plates.-- (University of Texas).
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| Phylogeny | ||||||||||||||
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| Geographic distribution | ||||||||||||||
Common in and around fast-moving streams in temperate and boreal climates.
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| Natural history | ||||||||||||||
Stoneflies probably represent an evolutionary "dead end" that diverged well over 300
million years ago and are regarded as the earliest group of Neoptera. Immature stoneflies
are aquatic nymphs (naiads) that usually live under stones in fast-moving, well-aerated
water. Oxygen diffuses through the exoskeleton or into tracheal gills located on the thorax,
behind the head, or around the anus. Most species are herbivorous, feeding on algae and
other submerged vegetation, but two families (Perlidae and Chloroperlidae) are predators
of mayfly nymphs (Ephemeroptera) and other small aquatic insects. Adult stoneflies emerge
from their streams and can generally be found on the banks next to their previous habitat.
They are not active fliers and usually remain near the ground where they feed on algae or
lichens. In many species, the adults are short-lived and do not have functional mouthparts.
Stoneflies are most abundant in cool, temperate climates. --
(University of Texas)
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| How to encounter | ||||||||||||||
| With a few exceptions in the southern hemisphere living on damp soil, stonefly nymphs dwell in aquatic habitats. The preferred habitat is rocky streams with at least a noticeable current. Some species can live in damp sandy areas. Although we know much less about lakes as habitats than rivers and streams, lakes can provide suitable habitat in the north and at high latitudes.The usual habitat in running water contains rocky, stony, or gravel substrata with more diversity in cooler, swifter water. Some studies have shown a correlation between certain species and certain habitats. For instance, Perlidae and Perlodidae are usually encountered under large stones, while Chloroperlidae tend to occur in gravel and Pteronarcyidae are frequently found in leaf packs.-- (University of Texas). | ||||||||||||||
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| Acknowledgements | ||||||||||||||
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This page written by Michael Howell, Ecology major at the University of Georgia, Athens. Thanks to Sabina Gupta, Denise Lim, and Dr. John Pickering for technical and web support in developing this page. 1. http://www.cals.ncsu.edu/course/ent425/compendium/stonef~1.html 2. http://www.sbs.utexas.edu/jcabbott/courses/bio321web/labs/plecoptera/Plecoptera.pdf | ||||||||||||||
| Following modified from University of Guelph |
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| Following served from AEGA |
| Following modified from Mississippi College |
American Stonefly Web Page
Stoneflies form the insect order Plecoptera. Adults are typified by a pair of tail-like cerci, two pairs of soft folded wings over the abdomen, well developed antennae, three tarsal segments, two tarsal claws, and an elongated anal region on the hindwings.
(fig.1)
Nymphs
(fig. 2)
are usually found in relatively clean streams, particularly those in mountainous reigions. More than 600 species occur in North America, a current
North American Stonefly List
is available on this website. Nine families of Stoneflies occur in North America. CapniidaeCapniidae are winter-emerging Stoneflies . Usually, they are small (less than 10 mm in length), black, and short-winged individuals are often seen. Adults have multisegmented cerci and small wedge-shaped mid-tarsal segments. They are often collected walking on snow near streams or they may be found on bridges, rocks, or streamside vegetation. Allocapnia (fig. 3) is common in eastern North America and Capnia (fig. 4) is common in the west. Dr. Riley Nelson , University of Texas-Austin , Department of Zoology, is an authority on the systematics of the Capniidae.
LeuctridaeLeuctridae are small dark stoneflies, generally similar to the Capniids. They differ in having 1 segmented cerci and the wings are rolled around the sides of the body. Emergence is somewhat variable, but most species are spring or summer emergers; a smaller number of primarily southern and midwestern species emerge in the fall or winter. Leuctra (fig.5 ) is the most common genus in eastern North America. Megaleuctra (fig.6 ) is an uncommon group of large, spring seep-inhabitating, Leuctrids found in the Appalacians, northern Rocky Mountains, Cascades, Sierras, and northern Coast ranges.
NemouridaeNemouridae are small brown stoneflies with 1-segmented cerci. The Wings are held flat over the abdomen and most species have a distinctive "X" pattern of venation near the wing apex. Amphinemura is a common North American genus, and a few other Nemouridae genera such as Zapada (fig. 7 ) , have ventral gills in the neck region. Nemouridae are typically spring emerging stoneflies. Dr. Richard Baumann (mail), Brigham Young University , Department of Zoology, is an authority on Neumorid systematics.
TaeniopterygidaeTaeniopterygidae is a group of medium sized, dark bodied stoneflies. Emergence times range from winter through spring for most species. Males have 1-segmented cerci but females have short multi-segmented cerci. Adults are usually recognized by their relatively large mid-tarsal segment which is about the same size as the basal segment. Taeniopteryx (fig. 8) is a common eastern and northern genus and Taenionema (fig. 9) is the common western group.
ChloroperlidaeChloroperlidae is a group of small to medium size, mostly pale yellow or green stoneflies. Most species are spring or summer emerging and adults are often collected while sweeping streamside vegetation during their emergence season. Adults have a reduced anal area to the hindwings. Triznaka (fig. 10 ) and Sweltsa (fig.11 ) are common genera. Dr. Rebecca Surdick, Laboratory of Entomology, Winchester, Virginia is an authority on this group. Mary Leigh Lyon and Mark Lyon are currently studying the epiproct complex for several Alloperla (fi g. 12 ) species found in western North America and southeastern North America respectively. Kevin Alexander is currently working with Dr. Ken Stewart, University of North Texas , Depar tment of Biology on Suwallia
PeltoperlidaePeltoperlidae is a small group of medium sized stoneflies found primarily in the mountains of eastern North America and the west. These stoneflies are somewhat roachlike in appearance and they emerge in spring and summer. Ad ults have only two ocelli and the labial palps are short and are usually not visable from above. Tallaperla (fig. 13 ) is a common peltoperlid found in streams of the southern Appalachians. Dr. Bill Stark , Mississippi College , Biology Department is an authority on this group.
PerlidaePerlidae is a family of mostly medium or large summer-emerging stoneflies. Nymphs have branched gills on their thoracic segments and the adults often retain these as vestiges around the leg bases. The front femora of adult perlid s bears an anterovenural row of long bristles. Acroneuria (fig. 14 ) is a common large perlid of the east while Hesperoperla (fig.15 ) is common in the west. Dr. Bill Stark , Mississippi College , Biology Department is an authority on this group.
PerlodidaePerlodidae includes stoneflies that are similar to perlids in general apperance but most lack gill vestiges and long bristles are absent from the front femora. Perlodids usually emerge in spring. Isoperla (fig.1 6 ) is a common North American Perlodid genus and Frisonia (fig.17 ) is found in the pacific northwest. Dr. Boris Kondratieff , Colorado State University , Department of Entomology and Dr. Stan Szczytko , Universit y of Wisconsin-Stevens Point , Colllege of Natural Resources are authorities on this group.
PteronarcyidaePteronarcyidae include the giant salmonflies famous among flyfishers. Adults are usually recognized by the presence of two or more cross vein rows in the forewing anal area. Pteronarcys (fig. 18 ) is fou nd in both eastern and western North America. Dr. Charlie Nelson(mail) , University of Tennessee-Chattanooga , Department of Biology, is an authority on this group. Return to Mississippi College HomepageQuestion, Comment?? Send Mail!This page coded by Mark Lyon |
| Following modified from New York State Departement of Environmental Conservation |
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» Representatives of Stonefly Families (Plecoptera)
Representatives of Stonefly Families (Plecoptera)Tips for identification - Stoneflies look similar to certain flattened mayflies and many beginners have trouble distinguishing the groups. The relative length of the antennae may be used to tell flattened mayflies from stoneflies. Stoneflies have antennae that are many times, four to six times, longer than the width of their head, while those of flattened mayflies are only about twice the width of their head. Here are some other tips.
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| Following modified from Soil and Water Conservation Society of Metro Halifax |
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Disclaimer & Copyright Notices; Optimized for the MS Internet Explorer Order Plecoptera(Stonefly)Soil & Water Conservation Society of Metro Halifax ( SWCSMH )
July 26, 2006
Contents:
Linnean system of hierarchical classification ( Williams & Feltmate, 1992 ):
IntroductionThe Plecoptera (stoneflies), all of which are aquatic as nymphs, are considered to be the most primitive order of living Neoptera. Plecopterans number about 1718 species in 239 genera belonging to 15 families. Nymphs feed on fresh or decayed vegetable matter, but may be carnivorous in later instars.The order Plecoptera belongs to the infraclass Neoptera because stoneflies' wings fold over their backs at rest. Wings develop in external wingpads, a characteristic that places Plecoptera in the division Exopterygota. North American stoneflies are generally divided into two groups, Euholognatha and Systellognatha, based on major differences in mouthpart morphology and, hence, feeding biology. The taxonomy of this order, like that of the Ephemeroptera, is poorly known because the larvae of many species have not been associated with adults. Modern plecopterans are thought to have been derived from the Protoperlaria of the Permian (360-286 million years B.P.) and the fossil record is quite respectable with more than 30 species described from the different strata of the Permian to the middle Tertiary.
Life HistoryThe stoneflies are terrestrial as adults, but in the nymphal stages they are strictly aquatic, and most are restricted to flowing waters of relatively high oxygen concentrations. Fertile eggs, laid over or in the water, requite two to three weeks for hatching in many species, and several months among some larger forms. The nymphal instars, from 10 to over 30 moltings, occur in one to three years. Adults live from 1 to 4 weeks. Most adults are winged, although a few species are wingless (apterous) or have short wings (brachypterous). None fly well and this has prevented them from crossing even small geographical barriers. Thus, like the mayflies, stoneflies are useful tools in studies of historical biogeography.Temperate species that overwinter as nymphs often do not stop growing even in water temperatures close to 0°C. It seems that it is warm water temperatures rather than cold ones that punctuate stonefly life cycles. The ability to spend the summer in diapause enables some species to live in temporary streams .
FeedingGenerally, stonefly nymphs are either shredders or predators. Some groups that are predaceous as late instars have been reported to be herbivorous or detritivorous in early instars, while late instars of large detritivores may consume some prey. Predators are engulfers, that is, they swallow their prey whole or bite off and swallow parts of prey. They are active search or pursuit predators, using their long filamentous antennae to locate prey using tactile, wave disturbance, and chemical cues. Many species are opportunistic feeders, consuming prey in proportion to their relative abundance. Other species are selective for prey species or sizes. In some families adults feed, and in others they do not.
Habitat and Ecological preferencePlecopteran nymphs are restricted to cool, clean streams with high dissolved oxygen content. some species, however, may be found along the wave-swept shores of large oligotrophic lakes. When subjected to low dissolved oxygen concentration, the nymphs of many species exhibit a characteristic "push-up" behaviour that increases the rate of movement past the gills. The gills are variously placed among species on the neck, thorax and abdomen. However, some species have no gills and respiration in these is assumed to be across the cuticle surface.The high water quality requirements of the nymphs bars all but a very few species from habitats subject to low oxygen levels, siltation, high temperatures and organic enrichment, and this has led to their effective use as biological indicators of environmental degradation. Field surveys clearly show that the nymphs of many species are associated with particular sections of a stream bed or lake shore. The specific microhabitat occupied depends on a variety of environmental factors such as the nature of the substratum (particle size and configuration), current regime, presence of other organisms, and local variations in water chemistry and temperature. Habitat preference often changes as the nymphs develop and with season. Prior to emergence, final instar nymphs tend to migrate towards the bank where they crawl out of the water to shed their skins. Most stoneflies are classified as clingers or sprawlers, as they are closely associated with the substrate or leaf litter. A few species have been reported from the hyporheic zone. Some physiological and ecological tolerances and requirements ( Mackie , 2001)
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