org aioe Seth ees sieve cf : ; ; way ate erm . “ Cees wry art : ee ot SEE 4 chs abbey - ape, ie ty MK 14) Pensa BETSEY? ie Deis teeth ats ‘4 ohreyese meme "hee tple gas 4 itad ale Taine THE UNIVERSITY OF ILLINOIS LIBRARY 595.7 C Sbh Natural History Surve Library i NATURAL RESOURCES NOTICE: Return or renew all Library Materials! The Minimum Fee for each Lost Book is $50.00. The person charging this material is responsible for its return to the library from which it was withdrawn on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for discipli- nary action and may result in dismissal from the University. To renew call Telephone Center, 333-8400 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN APR 24 2001 L161—O-1096 PLECOPTERA NYMPHS OF AMERICA (NORTH OF MEXICO) THOMAS SAY FOUNDATION PUBLICATIONS ¢ THE THomas Say FOUNDATION was organized in 1913 by the Entomological Society of Amer- ica for the purpose of publishing works of a monographie or bibliographic character on the insects of North America. The volumes published include: VOLUME I. Sarcophaga and Allies in North America. By J. M. Aldrich, Curator of Diptera, United States National Museum. 1916. 301 pages, 16 plates. $3.00, postpaid. A complete monograph of an important group of flies. It is the recognized authority on this family of the order Diptera. VouuME II. Plecoptera of North America. By J. G. Needham, Cornell University, and P. W. Claassen, Cor- nell University. 1925. 397 pages, 29 figures, 50 plates. $5.00, postpaid. The only complete monograph of North American stone flies by the two American authorities on this interesting and little known order. VOLUME III. Plecoptera Nymphs of North America. By P. W. Claassen, Cornell University. 1931. VI +199 pages, 4 figures and 35 plates. $4.00, postpaid. A com- panion volume of Volume II, this monograph contains a very complete series of fine illustrations, including one color plate. (Orders from outside North America or United States Possessions should add fifty cents to the prepaid price of each volume as given above.) PERLA CAPITATA PLECOPTERA NYMPHS OF AMERICA (NORTH OF MEXICO) BY PETER W. CLAASSEN PROFESSOR OF BIOLOGY CORNELL UNIVERSITY PUBLISHED FOR THE THOMAS SAY FOUNDATION BY CHARLES C. THOMAS - PUBLISHER SPRINGFIELD ° ILLINOIS BALTIMORE * MARYLAND 1931 COPY RIGHT S193 eB x. CHARLES C THOMAS MANUFACTURED IN THE UNITED STATES THE INVESTIGATION upon which this volume is based was in part supported by a grant from the Heckscher Foun- dation for the Advancement of Research, established by August Heckscher at Cornell University. 595.7 CSbp ¥# PLECOPTERA NYMPHS OF AMERICA (NORTH OF MEXICO) 787857 On} | avn (5/3 £ ; hy. ™y Ly poy 4 de A a poh wen 4 ng) Ly ype. mM wary rrow ah) uvt ) AA\ars) 9% @ Wea em > Lew ytd CONTENTS Introduction.) in. eee ee Acknowledgements 25 <:2%).7. cts tes ee ee Distribution’ and. Habitat. 9. ee ee Food Habits. 20). 250% Shs cree een eee Respiration™ 3... ¥agi. <2oGie ee oe ee ae Life Cycle and Metamorphosis’)... .22... 2. Collecting, Transporting and Rearing Stoneflies ....... Preservation for Study .2, 23. .4 «2s. 69 ee Technique. i. .6. oe oes eet ee ee OSS ae, Illustrations ...5. 25. sgh peer et ene Explanation of Terminology .-0 7224...) se Classification (Summary of Characters) .............. Key to the Families and Genera of the Nymphs ........ PTERONARGIDAH @7e). 700) 3 ee Pteronareys sic ise. fs ee ae ee Pteronarcella® 2/22 ye. Be ee es Peltoperla <0... 4 Pe ee ee PERLIDAE Sty © Saga ek Oe | Perlodes <2. 3 San cig hp eee ee Pe toe Oe ee Tsogenus 45 yt. ba yg ope oie 2 ee ee Perla. | cence cis ede ee ae ier Pos... Alloperla. 2 oiy.ge ack vse « soe et ee Chloroperla (1. es... ee Paraperla 0) oe. 0A: apes 2 Neoperla 2.00000. 5s seancceb es Deel eee er Clioperla: 2.0 wea. eg ee a Tsoperla. oc. eo ee etescope ee ees Perlesta! i305 0 Oa ei ae Atoperla ... 5g. 0. to os dae Perlineéllayg. 064 3.48 ae ee Leuctra + 0c fe os agg ae ote Taeniopteryx: . 0%). stoke wie ea eke ee CAPNIIDA He earings ee Capmla: oor used te ee Ole Ne eg ee A llocapmia: iy 3.27a ain eR ocd lar ee te cee ae Selected References ................ alt Wecen. fe Distribution and Emergence Table .................... Plates and Explanations: 95... 2.6.0.0. Index sis 2 Sa Oe ene ee ee ee INTRODUCTION Ape first American stonefly nymph was recorded by Newport? (34) in 1851 when he published a brief description and an excellent figure of Pteronarcys regalis=Pt. dorsata Say. Hagen (8) in 1873 describes, also, the nymph of the above species, and in addition to this, he describes the nymph of Pteronarcys proteus Newm., and mentions the nymph of Pteronarcys californica Newpt., from Logan River, Utah. Needham (24) in 1905 described briefly the nymphs of Jsoperla bilineata Say and of Leuctra tenella Prov., and in another paper (23) he mentions the unusual appearance of the nymphs of Peltoperla arcuata Ndm. Garman (7) describes the nymphs of three species: ‘‘No. 1,’’ ‘‘No. 2,”’ and ‘‘No. 3,’’ and illustrates No. 1 and No. 3 with beautiful fig- ures. No. 1 represents Acroneuria, probably arida Hag. No. 2 is not figured, but the description indicates that it is either [soperla or Alloperla. No. 3 is the nymph of Peltoperla sp. Smith (52) in 1913 published a paper on the biology of Perla wmmarginata Say in which she describes and figures the nymph of this species, and in 1917 (53) she described the nymphs of the following six spe- cies: Pteronarcys dorsataw Say, P. californica Newpt., P. proteus Newm., P. biloba Newm., Pteronarcella torosa Smith=P. badia Hag., and Perlodes signata Hag. Wu (57) in 1923 gives an account of the morphology, ethology, and anatomy of Nemoura vallicularia Wu. This is perhaps the most careful and most complete biological study yet made of any stonefly. Needham and Christensen (29) record the following nymphs from Utah: Pteronarcys califormca Newpt., Pieronar- cella badia Hag., Acroneuria pacifica Bks., Alloperla pallidula Bks., and Isoperla petersoni Clsn. Seemann (51) records the nymphs of the following four species from California: Ptero- narcys princeps Bks., Acroneuria californica Bks., Isoperla 5-punctata Bks., and Isoperla sordida Bks. Frison (6), in his ex- cellent paper on the fall and winter stoneflies of Illinois, describes and figures the nymphs of the following ten species: Taemopteryx nivalis Fitch, T. parvula Bks., T. (Strophopteryx) fasciata Burm., Allocapma vivipara Clsn., A. pygmaea Burm., A granu- lata Clsn., A. forbesi (?) Frison, A. mystica Frison, A. recta Clsn., and Leuctra claassent Frison. Muttkowsky (21) lists the nymphs of Pteronarcys californica Newpt., Acroneurta pacifica Bks., and Perla verticalis Bks., from Yellowstone Park, with data on the food habits of these nymphs. * Figures in parentheses refer to the bibliographic citations, page 116. 2 THOMAS SAY FOUNDATION Since the publication of the Monograph of the Plecoptera of North America by Needham and Claassen (27), the writer has devoted some time to the study of the morphology, biology and taxonomy of the immature forms of stoneflies, and within this paper are embodied the results of this investigation. Descriptions and notes on the nymphs of sixty-eight species are included, and these represent all the genera of the order except Kathroperla, a rare Western genus; Perlyomyia, a very close ally of Leuctra; and Capnura, a genus closely related to Capnea and containing only one known species. Probably one of the most striking results obtained from the study is the fact that the nymphs of only one family, the Perlidae, are essentially carnivorous, while the nymphs of all other families are herbivorous. Peltoperla, which has heretofore been included in the family Perlidae, is here placed in a separate family, Peltoperlidae. This seems desirable since the nymphs of Peltoperla are true herbivores, and in structural characters differ markedly from the nymphs of any of the other genera now included in the family Perlidae. In addition to the many structural characters which have been used in separating genera and species, the color patterns of the nymphs, especially those of the Perlidae, have been found remark- ably reliable for use in identifying different species. However, in the Pteronarcidae, Peltoperlidae, Nemouridae, and Capnidae, where the nymphs are almost wholly concolorous, and where closely allied nymphs do not exhibit structural differences, specific identification is often very difficult or impossible. ACKNOWLEDGMENTS In this investigation the writer has been aided in various ways by his colleagues and students at Cornell University. The draw- ings of the nymphs were made by Elizabeth K. Burkmyer. Naomi Argo and Sid Robinson assisted in the rearing work of the insects, and the drawings of plates one to ten are largely the work of Mr. Robinson. Mr. Yuanting T. Chu has also assisted materially in this study. The photographs were made by the author with the assistance of Mr. Robinson. A grant from the Heckscher Research Council has made possible the pursuance of the work and as- sistance in the publication of the manuscript. The frontispiece is a photograph which was colored by Ellen Edmonson. Nymphs have been received from the following individuals: Virgil Argo; H. S. Barber; C. Betten; S. C. Bishop; P. J. Chap- PLECOPTERA NYMPHS OF NORTH AMERICA 5) Mae iene ooley: GC. kk. Crosby; Y. T. Chu; G..S. Dodds: T..H. Frison; J. G. Greeley; W. A. Howard; O. A. Johannsen; P. Ken- nedy; Elsie B. Klots; M. D. Leonard; R. Muttkowsky; J. G. Needham; P. R. Needham; Sid Robinson; Theressa R. Seeman ; C. K. Sibley; R. J. Weith; C. F. Wu. DISTRIBUTION AND HABITAT So far as is known, stoneflies are world wide in their distribu- tion, and may be found wherever suitable water for their develop- ment occurs. Of the two hundred eleven known North American species, the greater number are found in the Eastern States, the Rocky Mountain area, and in the far Western States, wherever cold, fresh-water streams exist. However, stoneflies also occur in places where the streams are usually sluggish and where the water becomes quite warm. Thus there have been recorded fourteen spe- cies from Kansas and twenty-four species from Ilinois. The nymphs of Plecoptera may be collected at any time of the year. Some species normally inhabit the very small, cold, upland spring brooks, while others are to be found only in the big swift- water streams, especially in those with stony beds. There may be decided differences in the physical character of streams which the various species require, but, foremost of all, they must have reasonably pure and well-aerated waters. Most of the stoneflies are very sensitive to polluting substances, and the absence of nymphs in permanent fresh-water streams often is an indication of some type of pollution. Any substance which possesses toxic properties, or any organic material which in its oxidation process reduces the oxygen content of the water, may kill the entire stonefly fauna before the water becomes un- bearable to much of the other aquatic life. Whereas it is not safe to assume that fresh water streams in which stoneflies are absent are necessarily polluted, it is always safe to assume that, wherever they are present, the waters are relatively clean. The greater majority of nymphs are found in running water ; some species inhabit lakes and ponds also, but only when the ponds are part of a stream which continually brings in a fresh water supply, and usually only near the lake shores where the water is kept in motion. FOOD HABITS In the earlier literature on Plecoptera we usually find that stonefly nymphs ‘‘are carnivorous,’’ and that the adults ‘‘do not take food.’’ Even in some of the more recent textbooks on en- 4 THOMAS SAY FOUNDATION tomology the food habits of the nymphs are described as ‘‘ear- nivorous.’’ (Imms, Handlirsch, et. al.) This misconception has undoubtedly been due primarily to the fact that the large and more strikingly colored nymphs of the genus Perla and Acro- neuria are voracious carnivores, and these are the nymphs which are most frequently observed and collected. The European work- ers (Lestage, Samal, Schoenemund, Mertens, et. al) have reported from time to time that certain of the Plecoptera nymphs are herbivorous and feed on algae and other plant products. In America, Newcomer (32) was the first to report that some of the adults of Taeniopteryx feed upon leaves and buds, and at times become injurious to young fruits. Wu (57) in his paper on Nemoura reports the nymphs to be feeding on vegetation, par- ticularly on decaying leaves. Frison (6) found that all of the nymphs of Leuctra, Taeniopteryx, and Allocapnia, which he studied, were herbivorous. He found also the adults of Taeniop- teryx and Allocapnia feeding on Protococcus and was able to keep them alive for extended periods of time only when he sup- plied them with Protococcus and water. Some twelve years ago Dr. C. H. Kennedy studied the stomach contents of Pteronarcys nymphs in Ithaca, New York, and found only plant material present in the digestive tract. A more detailed study of the entire order indicates that, of the five North American families herein recognized, the nymphs of four (Pteronarcidae, Peltoperlidae, Nemouridae, and Capni- idae) are herbivorous, and that in only one family (Perlidae) are the nymphs essentially carnivorous. In the herbivorous type (Pteronarcidae, Peltoperlidae, Nemouridae, and Capniidae) the mouth parts are adapted for manipulating plant material. The labrum is longer and narrower than in the carnivorous type; it possesses no distinct epipharynx, and the clypeal suture is dis- tinct. The mandibles are wide and massive, and are provided with four to six short, mostly blunt, teeth, and following these teeth there is a well-developed molar for grinding the plant material. The maxillae, likewise, are fairly massive, the lacinia is wide, and more or less scooped on the inside, and bears at the apex two or three short blunt teeth. It is well fitted for wafting plant material into the mouth. The galea is strongly developed, and is usually as long, or nearly as long, as the lacinia. The maxillary palpus is much stouter than in the carnivorous type. The essential charac- teristics of the labium are the almost-equal development of the Ea and the paraglossae, and the stout and shortened labial palpi. PLECOPTERA NYMPHS OF NORTH AMERICA = 5 In the carnivorous type (Perlidae) the mouth parts are built very differently. The labrum is very wide and short and is pro- vided with a fleshy epipharynx which may protrude beyond the anterior margin of the labrum, or may be retracted underneath. The elypeal suture is obsolete. The mandibles are quite slender, the teeth are long and sharp, and the molar is lacking. The maxil- lae are slender. The lacinia terminates in either one or two long, sharp incurved teeth, fitted for holding prey. The galea is much reduced in size and apparently is almost without function. The maxillary palpus is long and slender. The labium is large; the glossae are reduced to small triangularly rounded lobes, while the paraglossae are enlarged into big lobes. The labial palpi are long and slender. In addition to the differences in the structure of the mouth- parts, the herbivorous nymphs are generally more cylindrical in shape, more or less concolorous, and are found more often in small, upland, spring brooks, and in quieter waters where vege- table material accumulates. The carnivorous nymphs, on the other hand, are usually more flattened, more strikingly colored, and in- habit chiefly the larger and swifter waters. A eareful study of the musculature of the mouth parts in the two types shows many differences, and the structures of the di- gestive tract in the herbivores are different from those of the earnivores. Examination of stomach contents often reveals plant material, such as diatoms, etc., in the carnivorous nymphs, but such material is probably ingested incidentally to capturing ani- mal prey, although in the early stages the nymphs apparently feed partly on algae. Similarly, one may. find at times small ani- mals, such as protozoans and crustaceans, in the digestive tracts of the herbivores. RESPIRATION Respiration is of the closed or apneustic type. The nymphs either absorb oxygen directly through the integument, or through tracheal gills. Many species lack gills altogether ; some forms, like Perlodes, Peltoperla and a few others possess only a few single gill filaments, while others, such as Pteronarcys, Acroneuria, and Perlinella, are provided with many copious gill tufts. Wu (57) found what he considered retractile anal blood gills in Nemoura vallicularia. In this species he found also that ‘‘part of the res- piratory function is performed by tufts of tracheoles that arise from the tracheal branches of the body and extend outward to lie immediately entad of the thin ventral body wall. These tufts are 6 THOMAS SAY FOUNDATION present in the submentum, the coxae, the ventral side of the femora, and the first eight abdominal sternites. In the abdomen several tufts arise from each ventral abdominal commissure and extend to the posterior margin of the segment.’’ (Plate 29, fig. 211.) In the following genera tracheal gills are absent: Isogenus, Clioperla, Paraperla, Kathroperla,? Isoperla, Alloperla, Chloro- perla, Perlomyia,? Leuctra, Capnia, Allocapnia, Capnura,? and certain species of Taeniopteryx, Nemoura and Perla. Perlodes possesses two or more small, fleshy, finger-like gills. In P. ameri- cana, which possesses only one pair, they are attached to the outer base of the submentum. P. tibialis has, in addition to the gills on the submentum, two pairs on the pleural conjunctivae of the thorax and P. signata has three pairs of thoracic gills in addition to the pair on the submentum. In Peltoperla arcuata five pairs of single, long, pointed, gill filaments may be seen to protrude from under the large sternal plates of the thorax where they are at- tached to the soft integument at the base of the legs.° Of the genus Taeniopteryx; 7. mvalis, T. maura, and T. par- vula each possesses three pairs of coxal gills. These gills are three- segmented and occur as single filaments attached, one to the coxa of each leg. In certain of the species of Nemoura (JN. venosa, N. sinuata, ete.) we find tracheal gills in the cervical region.* These gills have been called prosternal tracheal gills by Wu (57) and he describes them as follows for NV. venosa and N. sinuata: ‘‘ Hach gill consists of two tufts of hair-like gill filaments, the number of which varies with the species. In N. venosa, each tuft is com- posed of five to six filaments. In N. sinwata, there are five to six vill filaments in each outer tuft, and about fifteen in each inner tuft. A gill trachea extends downward to the base of each gill from the longitudinal trunk near the anterior margin of the prothorax. This gill trachea divides into many branches, each of which enters one of the gill filaments and subdivides into a large number of tracheoles. Loops are formed by these tracheoles in the gill-filament at its distal end.’’ The nymphs of the following genera possess copious gill tufts underneath the prothorax, and in some of the species gill tufts are found also on some of the abdominal segments, while in others *The nymphs of Kathroperla, Perlomyia, and Capnura are not known, but when they are discovered they will doubtless be without gills. *Uéno (56) reports a species, from Japan, of Peltoperla which possesses no gills whatsoever. *Imms (11) says, ‘‘in Nemoura, for example, they [gills] assume the form of lamellate outgrowths on the pronotum.’’ In all the nymphs of Nemoura which I have seen these gill filaments are cylindrical. PLECOPTERA NYMPHS OF NORTH AMERICA 7 anal gills may likewise be present. Pteronareys possesses gills on the underside of the thorax and on the first two abdominal seg- ments. Pteronarcella has gills on the first three adbominal seg- ments in addition to the thoracic gills. Acroneuria and the larger species of Perla possess copious thoracic gill tufts, and some of the species are also provided with one pair of anal gills. Perlesta; Neoperla and Perlinella have both thoracic and anal gill tufts. Atoperla has long gill tufts under the thorax but no anal gills. It is impossible to say what correlation exists between habitat and presence or absence of gills, or type of gills, until we have more detailed information about the habitat and behavior of the various species. LIFE CYCLE AND METAMORPHOSIS It is only within recent years that attempts have been made to observe the complete life cycle of stoneflies. The time required to complete the postembryonic development varies in different Nemoura vallicularia Wu Tire Dates of Actual widths | Computed width molting of head* of head 1 July 2 Qe2o Diao 2 July 6 2°50 20 3 July 11 2.66 eT 4 July 18 2.75 e219 5 July 23 3.00 ook 6 August 1 3.25 3.3 7 August 8 3.50 3.6 8 August 13 4.00 3.9 9 August 22, 4.25 4.2 10 September 4 4.50 4.5 tt September 12 4.75 4.8 12 September 24 5.00 sea 13 October 2 5.50 5.4 14 October 14 Delo 5.7 15 October 23 6.00 6.0 16 November 11 6.50 6.4 17 November 30 Gi He 6.8 18 December 21 7.00 Tee 19 January 10 7.50 7.6 20 January 30 8.00 8.0 21 February 29 8.50 8.5 22 March gil 9225 9.4 Transformation| March 29 10.00 9.9 * “Hach division on the micrometer was 160 micra and was taken asa unit of measurement. The ratio of increase in the width of the head be- tween two molts, was found to be 0.95, from which a series of computed widths of head in the instars was made to compare with the actual widths taken from the specimens.”’ 8 THOMAS SAY FOUNDATION species. In some of the smaller forms, such as the Nemouridae and Capniidae, the life cycle is completed in one year while in the larger forms, such as Pteronarcys, Acroneuria, and certain species of Perla, two to three years are required for each genera- tion. Samal (48) estimates that Perla abdominalis requires three and one-half to four years to complete its development. The number of nymphal instars may vary considerably but in the forms studied it is twenty-two or more. Tillyard (54) says, ‘‘The number of instars is not known for certain, but appears to be usually six.’’ Wu (57), in studying the life history of Nemoura vallicularia, recorded twenty-two instars ‘‘from the hatching of the naiads on July 2, 1921, to the emergence of the adults on March 29, 1922.’’ The table on page 7 is taken from Wu. Samal (43) found that Perla abdominalis also passes through twenty-two nymphal instars, which, according to his estimates, ex-. tended over a period of three and one-half to four years. His data are given in tabular form as follows: Samal’s Table of Larval Stages of Perla abdominalis Number of Number of Length of Length of Stage segments segments body without body with in cerci in antennae cerci cerci 1 3 9 — 0.8—- 1mm 2 3 9 — 1 —1.5 3 4 11 — 2-83 + 5 12 — 2.5- 2 5 6 14 _- 2.5- 2 6 7 1 — 2.7— 3.2 7 9 16 (?) — 3 -— 3.8 8 10 sae — 3.6- 4 9 11 19-20 — 3.8- 4.2 10 13 23-24 — 4 — 4.8 11 17 28 — 4.5- 5 12 19 31 — 5.3- 6 13 20 33-37 -— 6 -7 14 26-28 36-39 4.6- 5mm 8.2- 9 15 32 33-41 5.5- 6.7 9.5-10 16 35 44-47 7 -8 12 -13 17 35-40 48-52 8 -— 9.4 12 -14 18 36-40 58 9 -10 15 -17 19 44-45 60-65 10 —-ll1 15.14 20 240-43 60-67(70)| 914 —15 22 -23 v10 -11 17-19 21 49-50 79-85 918 -22 25 —28 G12 -15 18 -21 104 48-50 79-91 925 -28 35 40 S19 —24 19 —24 23 50-54 85-96 930 -32 44 -48 PLECOPTERA NYMPHS OF NORTH AMERICA 9 Schoenemund (44) reports that the female nymph of Perla cephalotes sheds its skin thirty-three times before reaching ma- turity ; eighteen times during the first year, nine during the sec- ond, and six times during the third year. The male nymph, he says, being much smaller, passes through fewer instars than the female. However, according to Samal (43) both male and female nymphs of P. abdominalis have an equal number of molts. The nymphs are less active in cold weather than when it is warm, but they feed more or less during the entire winter. Molting is less frequent during cold weather, and the nymphs cease feeding during the process of ecdysis. There is a period of several days before the mature nymphs emerge when they take no food what- soever, and such nymphs will usually be found to have an empty digestive tube. COLLECTING, TRANSPORTING, AND REARING STONEFLIES Collecting stonefly nymphs is rather a simple matter. Where only a few specimens are sought, or where only a superficial qualitative survey is to be made, nymphs can usually be procured by hand picking. The large nymphs of Perla, Acroneuria, and others will be found chiefly in the large swift-water streams where ‘they occur underneath the stones. Upon quickly lifting such stones out of the water, the nymphs often remain attached to the underside, and can then readily be taken. In the smaller streams or in the upland brooks which are in- habited by Pteronarcys, Peltoperla, Nemoura, Leuctra, and oth- ers, the nymphs are found among the leaf drifts and in the debris. A handful or two of such debris will usually yield several speci- mens. Since the nymphs which occur in these smaller streams are mostly concolorous, they so nearly harmonize with the color of the dead leaves and sticks that they are not easily recognized. It is well, therefore, to spread out the debris on a flat surface or in a pan, and earefully search out the nymphs, especially the smaller ones, which often can be detected only after they start moving around. The most efficient manner in which to obtain the smaller forms is to bring a good supply of trash to the labora- tory where it can be spread out in a large shallow pan in a little water. The nymphs soon start to crawl about and are then easily picked out. Where a large number of specimens is to be collected, or when a thorough qualitative collection is to be made, it becomes desir- 10 THOMAS SAY FOUNDATION roe ee Antenna S A Segooes Maxillary palpus og yen ~$0 ---------- Labial palpus Opt gO ee Labrum _ _.Ocellus f7—_ Lateral tubercle —--Compound eye _.~Occipital ridge RN —— Occiput __.Pronotal disc +. --- Flange ——-~Marginal groove : A\\ cy ry ., ¢Pronot ths te! Tt Fe Pak ae 5 Gill tuft MS ee RAR ae Ra Se Eye alee Trochanter : Metathorax - = milastester atlas oe fag Cap slg. wl. hl eR ae A es Wing case ee easels ee ee Femur Tibia ll. - Hair fringe re-- - ABDOMEN ~--- Fig. 1. A generalized stonefly nymph showing the main structural parts used in the descriptions and keys of the various species. PLECOPTERA NYMPHS OF NORTH AMERICA 11 able to employ a few collecting implements. In the larger swift- water streams, a piece of wire screen may be placed in the water in such a way that the current sweeps the specimens against the sereen as they are dislodged from their hiding places under the stones, when the stones are stirred up by means of a stick, hoe, or rake. By nailing a piece of wire sereen on two short handles, the net can more readily be held in place in the stream (text fig- ure 2). 1 Ks acetate: =a 2° 2S Se oe an 85 Be Fic. 2. Wire screen used for collecting stonefly nymphs in rapid streams. For all-round collecting of stonefly nymphs, the sieve net is most desirable (text figure 3). This net may be placed in the stream and used as a sereen for collecting the nymphs as they are carried down by the current, while the collector holds the sieve net by the handle, and, by means of a stick, or with his feet, dis- lodges the specimens from underneath the stones above stream. The net is also very useful for dragging material out of the stream as one stands on the bank, and after specimens have been collected, it serves, likewise, as a washing sieve, and much of the detritus 12 THOMAS SAY FOUNDATION can be washed out by swishing the net back and forth in the water. If made of strong material this net will stand considerable abuse. Transporting Live Nymphs. Since most of the stonefly nymphs live in moving and well-aerated water, they cannot be transported Fig. 3. Sieve net for collecting stonefly nymphs. nor kept for any length of time in water-filled containers unless the water is continuously aerated. A minnow pail with a com- pressed-air chamber, from which a small stream of air bubbles passes through the water, has been found very useful in carrying nymphs from the field to the laboratory. A very satisfactory meth- PLECOPTERA NYMPHS OF NORTH AMERICA § 13 od of transporting nymphs is to wrap them in a clean piece of wet cheese cloth. This keeps the specimens moist and well supplied with air. Wrapped up in this manner, specimens of Perla and Acroneuria, which are extremely sensi- tive to suffocation, have been kept alive for a week or more. Nymphs packed in sphagnum may likewise be kept alive over a considerable period of time. In the laboratory where the nymphs are to be kept under observation for some time, they should be placed either in an aerated container or else in a pan which contains barely enough water to cover the specimens. In such pans the nymphs may often be seen to move their bodies up and down in a rhythmic manner, ap- parently for the purpose of better aera- tion. Rearing. In rearing nymphs, it is de- sirable to keep them under conditions closely resembling or paralleling their natural habitat. Where a small cold spring brook is conveniently located, and insured against disturbance from man and animals, the nymphs can be kept satisfactorily. The most satisfac- tory breeding cage is one made of wire sereen (text figure 4). These screens can be made in various sizes, are easily transported, and are very adaptable for varying conditions. For rearing the larger species, 14 or 16 mesh screen is entirely satisfactory, but for the smaller species of Nemoura, Leuctra, Capnia, ete., screen with a finer mesh is necessary. After the nymphs have been put into the cages, they are placed in the water, leaving the upper half of the cage exposed to the air so as to allow for emergence of the adults. Food must be supplied to the nymphs. For the herbivores, such as the Pteronarcidae, Peltoperlidae, Nemouridae, and Capnudae, decaying leaves, algae, and detritus may be used, and for nymphs of the Perlidae, living insects, such as Mayflies and Chironomids, should be added. Inasmuch as the nymphal stage extends over a long period of time, it is desirable to choose the maturer nymphs for rearing. By observing the conditions of the wing pads, one tre Ee ol soorlrrare Mes tH fe ik Fe tt ed san is ' "y i ity cA SRN i" ie: Be is B| ‘& Ht a By fi ay Ha HF Fig. 4. Wire screen cage used in rearing stonefly nymphs. 14 THOMAS SAY FOUNDATION soon learns to pick out the nymphs which are approaching emer- gence. At the time of transformation the nymph crawls up on the screen out of the water and after the adult has emerged the nymphal skin remains attached to the screen. The adult and nymphal skins may then be placed together in a vial of alcohol and preserved for study. Where an outdoor natural stream is not available for rearing purposes, the nymphs, if quite mature, can sometimes be reared by keeping them in moist sphagnum. Frison (6) reared a number of nymphs in small tins containing moist leaves. Aquaria, in which the water does not get too warm, and through which a constant stream of air is kept flowing, may also be utilized for rearing. Tap water is, in most eases, toxic to the nymphs, and therefore cannot be used. PRESERVATION FOR STUDY The most satisfactory manner of preserving nymphs for study is to place them in 80 to 85% alcohol. Pinning or preserving the nymphs or nymphal skins dry is not satisfactory since the gills and the other delicate structures shrivel up so badly that identifi- cation becomes difficult or impossible. Alcohol tends to fade out the colors to some extent but usually not sufficiently to make determination impossible. Nymphs which are to be examined for food contents should be placed in alcohol or in a 4% formalin solution immediately after being taken from the water. Identifica- tion of the intestinal contents will be easier if examination is made as soon as possible after the specimens have been brought to the laboratory. If this is not feasible, the nymphs should be slit before they are placed in the preservative to insure ee preservation of the food contents of the intestine. TECHNIQUE The technique involved in the study of stonefly nymphs is quite simple. In most instances it is possible to recognize the genera, aS well as many of the species, by examining the entire specimen under the binocular microscope, while the larger species ean often be identified with a simple lens, or even with the un- aided eye. In some specimens, identification to genus can readily be made by a study of the details of tracheation or of venation. In such eases it is usually better to cut off the wing pads and mount them on slides. The wing pads may be readily snipped off with a sharp scalpel, a razor blade, or with a pair of fine- PLECOPTERA NYMPHS OF NORTH AMERICA = 15 pointed scissors. In the nymphs of Acroneuria, Peltoperla, ete., care should be taken to cut off enough of the inner portion of the wing pad to prevent unnecessary disturbance of the delicate veins or tracheae. If the mount is to be temporary only, the wing pads may be examined in a drop of aleohol or of water under the microscope, or a somewhat more permanent mount may be made in a glycerine jelly. For permanent mounts, however, it is best to stain the wing pads in a rather weak solution of aleohol eosin, leaving them in the stain for half an hour or more, and thereafter clearing the wing pads and transferring them to balsam. Such staining brings out the venation more plainly and places the preparation on permanent record. Figures 165 to 168 show how clearly the venation may be observed in permanently mounted wing pads. The mouth parts are readily dissected out in the larger speci- mens, but in the smaller, more delicate species, care must be exercised to prevent tearing the appendages and the sclerites. In some eases it is advisable to carry the entire head through the dehydrating, clearing, and staining process, and to separate the mouth parts after the head has been transferred to the balsam. In the larger forms it will often be found advisable to soak the mouth parts in caustic potash for a short period. This softens and clears them and aids in getting rid of much of the muscle tissue. Appendages, such as legs, cerci, and antennae, may be mounted in a similar manner. In many instances, identification of the nymphs is possible by a careful study of the developing genital structures. Mature nymphs will often show these structures re- markably well. In some nymphs it becomes necessary, however, to ‘‘peel off’’ the nymphal skin before the genitalia can be dis- tinetly seen. This process is somewhat tedious, and is best ac- complished by the use of a pair of fine and very sharply pointed needles. Specimens which have been in alcohol for a considerable period of time usually respond to such treatment more readily than the fresh ones. After the nymphal skin has been removed, it is often possible to make positive identification, even though the genitalia may appear much distorted or flattened. ILLUSTRATIONS The drawings of the mouth parts, wing pads, and legs were made by means of a projecting drawing apparatus after the parts had been mounted on slides. The drawings of the nymphs were made on Ross stippling paper. The photographing of nymphs 16 THOMAS SAY FOUNDATION requires time and patience, and best results can be obtained only with freshly collected specimens. After the nymphs had been killed in weak alcohol they were placed in a tray containing a wax bottom to which the specimens could be fastened by means of small pins. Minutien Nadeln served very well for holding the ap- pendages in place after the nymph had been properly spread. The nymphs were then dehydrated in alcohol, and after they had been in 95% aleohol for several hours the entire specimens had hardened so that the pins could be removed without any further danger of distortion or of movement of appendages out of place. Each nymph was then placed in a clean petri dish, a piece of glass was laid on the nymph to hold it in place, and sufficient aleohol was poured into the dish to cover the specimen. To ob- tain a white background, the petri dish, containing the specimen, was placed on a glass plate underneath which a sheet of white paper was inserted about a quarter of an inch below the sur- face of the glass. For a black background, a piece of black velvet was fastened to the bottom of a tray. Fine pins were then used to hold the specimens up about a quarter of an inch above the velvet. After pouring enough alcohol into the tray to cover the specimen it was photographed. Artificial light was used in making all the photographs included in this paper. EXPLANATION OF TERMINOLOGY To facilitate the interpretation of the structures or characters which are referred to in the text and in the descriptions of the species, the following explanations are given (see also text figure De Length of body. This refers to mature nymphs, unless other- wise indicated, and includes the length as measured from the front of the head to the tip of the abdomen, exclusive of antennx and cerci. The terms long and short are unfortunate ones to use but in many instances it is almost impossible to express relative sizes and measurements in any other way; so these relative terms cannot convey full meaning until after one has become somewhat acquainted with the group. Form of body. The bodies of all the nymphs are somewhat flattened but the term ‘‘flattened,’’ as used here, refers to such forms as Acroneuria in which the body is very much depressed, while ‘‘eylindrie,’’ or ‘‘eylindrical,’’ denotes such forms as Pteronarcys, in which the body is only slightly depressed. PLECOPTERA NYMPHS OF NORTH AMERICA 17 Color. ‘‘Brown’’ must be interpreted as ranging from light brown to dark brown or even to almost black as the depth of color varies considerably in a series of nymphs of the same species. ‘““Yellow’’ varies from white or straw color to deep yellow, in some forms verging on brown or reddish. Color pattern. There is some variation in the color pattern of nymphs of the same species, and this must be kept in mind when interpreting the descriptions and illustrations. In the darker- colored nymphs of Perla media, for example, the entire nymph appears almost uniformly brown, especially where the vestiture of the body has collected silt which adheres to the hairs, while in the lighter forms the thorax, in particular exhibits a distinct color pattern of yellow and brown markings. In utilizing the color patterns in the keys, an attempt has been made to refer only to those patterns which show the least amount of variation. Vestiture. The degree of hairiness varies in the nymphs of dif- ferent species, but also varies in individuals of the same species. The younger nymphs of Perla immarginata apparently have more and longer hair on the body than have the mature forms. Varia- tion in the amount of hairs is also due to the fact that in some specimens the hair seems to have worn off. Head. The width of the head in relation to the width of the pronotum refers to the maximum width of the head across the eyes, as compared to width of the pronotal disc. The epicranial suture, while apparently not of particular significance as a diag- nostic character, serves as a convenient landmark for reference to structures or patterns. The ocelli vary in size and position and may be either two or three in number, or in some instances they appear to be wholly absent. Wherever only two ocelli are present, the anterior one is lacking. On either side of the ocellar triangle may be seen a rounded or oblong, slightly raised spot—these spots are known as lateral tubercles. The occiput is that portion of the head posterior to the ocellar triangle. In some species there is a distinct occipital ridge extending transversely across the occiput from one eye to the other. This ridge may be very distinct, as in the larger species of Perla, or only indicated by a more or less continuous line of short hairs. The clypeal-labral suture is obsolete in some forms and distinct in others. The labrum is always wider than long, and in the Perlidae is provided with a distinct epi- pharynx, which however may be so completely rolled under the labrum as to be hidden from view. Antennae. These are long and slender and composed of many (30-100) short segments, 18 THOMAS SAY FOUNDATION Mouthparts. These offer excellent characters for taxonomic use, but inasmuch as they are described under each genus and are figured they need not be further discussed here. Pronotum. The relative width of the pronotum to its length refers to the chitinized pronotal disc. The marginal groove is the groove which in some nymphs can be traced around the entire pronotum while in others it can be definitely seen only along the middle of the anterior and posterior margins. The lateral flange is that portion of the pronotal disc, lateral to the marginal groove, especially where the sides of the pronotal dise flare out over the general prothorax, as in Acroneuria ruralis Hag. The markings on each side of the pronotum are sometimes referred to as rugosities or embossings. The median line is the middle longitudinal line along which the pronotum splits when the imago emerges. rs Meso- and Metathorax. The wing pads (wing cases) vary in shape, size, and in their relative position to the rest of the body. In immature nymphs they are naturally smaller and less con- spicuous than in the more mature forms. In such forms as Acroneuria, the wing pads form a definite part of the meso- and metanotum and do not project in the form of long appendages; while in other genera, Nemoura, Leuctra, etec., the wing pads develop into long appendages, extending far beyond the general posterior margins of the meso- and metanotum. In Taeniopteryx ° and Nemoura, the wing pads, especially the hind ones, are di- rected away from the body at a wide angle, while in Leuctra ete., they lie parallel to the body. Abdomen. The abdomen is composed of ten segments. In some genera the sexes can readily be distinguished in the nymphs, while in others the sexes are not so apparent. Where the develop- ing genitalia are large and conspicuous, identification can be made with a greater degree of certainty than where the genitalia cannot be observed. The cerci are composed of many segments, and an attempt has been made to record their number; however, the basal segments are usually so short and often so indistinctly in- dicated, that the recorded number can only be regarded as ap- proximate. Gills. These serve as excellent characters in separating some of the genera, and also are useful in the grouping of species within a genus. The very small finger-like outgrowths at the base of the labium, and on the conjunctivae of the thorax in Perlodes are in this paper referred to also as gills. Whether they actually possess any respiratory functions is not certain. PLECOPTERA NYMPHS OF NORTH AMERICA § 19 Legs. The hairs on the outer margin of the legs are referred to as the outer or marginal fringe. There is considerable difference in the length and density of the hairs in these fringes. The relative length of the tarsal segments, unless otherwise stated, is to be considered as meaning the length as viewed from the side, and not as seen from above. CLASSIFICATION SUMMARY OF CHARACTERS 4 pew nymphs of Plecoptera are aquatic, living mostly in run- ning water. They are said to resemble the adults, but in some genera, such as Peltoperla for example, the resemblance of nymph to adult is quite remote. The mature nymphs range in size from the small Capniidae and Nemouridae, in which some species do not measure over six or seven millimeters in length, to the large nymphs of Pteronareys which attain a length of two inches or more. The general color of the nymphs is yellowish brown, to dark brown or blackish; or patterned with yellow and brown, or yellow and. black. Four of the five North American families (Pteronarcidae, Pelto- perlidae, Nemouridae, and Capniidae) may be said to be quite uniformly brown in color and in only one family (Perlidae) are found the brightly colored or more strikingly patterned nymphs. The general form of the body is elongate, subeylindrical, or considerably depressed, the nymphs of the Perlidae being, in gen- eral, more flattened than the nymphs of the other families. The body regions are well defined ; the pro-, meso-, and metathorax each are large and distinct, and the entire thorax is about as long as the abdomen. The head is more or less triangular in shape and is about as wide as, or a little wider than, the pronotum, except in the Peltoperlidae and the Pteronarcidae where the head is much narrower than the pronotum. The compound eyes are well developed and there are usually either two or three ocelli present. The V-shaped epicranial suture is not apparent in the Perlidae, but is distinct in all other families. The antennae are filiform, composed of many segments, and normally half, or nearly half, as long as the body. The mouth parts are of the chewing type and are strongly de- veloped. In general structure they resemble the Orthopteroid mouth parts. The labrum is wider than long and fringed with hairs on the anterior margin. In the Perlidae, the labrum bears on the median anterior area a fleshy epipharynx which is closely be- set with very fine bristles and may be rolled out or retracted. The mandibles are asymmetrical, more or less triangular in PLECOPTERA NYMPHS OF NORTH AMERICA 21 shape, and provided with about four to six teeth. There are two distinct types of mandibles: (1) those of the family, Perlidae, in which the teeth are long and sharp and without a molar, (2) those _ of all other families in which the teeth are usually shorter and less pointed, and a well-developed molar is present. On the portion im- mediately following the teeth, the mandibles bear a fringe of long stiff hairs. The maxillae are of two distinct types. In the Perlidae the lacinia terminates in one or two long, slender, ineurved teeth while in the other families the lacinia is rather wide at the tip with two or three very short, blunt teeth. The galea is weak in all Per- lidae and large and strongly developed in all other families. The five-segmented palpus is long and slender in the Perlidae, and shorter and more robust in the other families. The labium varies considerably in size and shape, but here again may be found two types. In the Perlidae, the glossae are short and triangular, while the paraglossae are large and extend far beyond the tips of the glossae. In all other families the glossae and para- glossae are subequal and almost equally long. The three-segmented labial palpus is long and slender in the Perlidae, and robust and short in all others. The mentum is reduced to a narrow transverse band, while the submentum is very large. The hypopharynx is well developed, and bears at the apex a large number of short stiff bristles. The pronotum is much wider than long, and in most nymphs the lateral discs are embossed with various-shaped markings. The marginal groove is more distinct in the Perlidae than in the other families. The meso- and metanotum are large, and bear the developing wing pads. In some of the nymphs the wing pads are small, and consist of the slightly produced postero-lateral angles of the meso- and the metanotum, while in others, the wing pads develop into long sac-like appendages. The legs are rather long and may be very much depressed or only slightly flattened. Usually the outer margin bears a fringe of long hairs. This fringe is especially long and thick in those forms which inhabit swift water. The tarsus is composed of three seg- ments of which the first two are shorter than the third. There are two tarsal claws but no pulvillus. The abdomen may be either flattened or subcylindrical. There are ten abdominal segments, one supra-anal lobe, and two subanal lobes. The supra-anal lobe is fused with the tenth abdominal tergite and is not always distinct, 29 THOMAS SAY FOUNDATION — The cerei are long and slender, and in most nymphs they are half or more than half as long as the body.® Gills may be absent or present. Whenever they are present they are found on the ventral or pleural regions. The gills may occur in tufts underneath the thorax, on the first few abdominal seg- ments, attached to the subanal lobes, or they may occur as single filaments in the cervical region, attached to the coxae or to the submentum. It is not always easy to distinguish the sexes, especially in im- mature nymphs, but in some genera the sexes may be recognized very readily, and in all mature nymphs the sexes may be separated by studying the developing genital characters. Perhaps one sure way of recognizing female nymphs is to examine the posterior margin of the eighth abdominal sternite. Even if no other char- acter is discernible, the marginal fringe of fine spinules will be absent in the spot where the genital opening develops. Key to the Families and Genera of the Nymphs of Plecoptera 1. Gills on first two or three abdominal segments as well as under the thorax; pronotum wider than head; ligula 4-lobed, Le. glossae about as long as paraglossae; mostly large dark brown nymphs; herbivores...... PTERONARCIDAE 2 (p. 26) No gills on first two or three abdominal segments........ 3 2. Gills on first and second abdominal segments only; large nymphs, 114 inches or more in length when fully grown; corners of pronotum usually produced. Pteronarcys (p. 27) Gills on first, second and third abdominal segments; not over 1 inch in length; corners of pronotum not produced; West- ern LonmMs 1s sed Cae eee Pteronarcella (p. 34) 3. Brown, roach-like in form, head bent under; terga and pleura of thorax developed into very large wide shields from under which usually small white gill filaments protrude ; herbivores APR Me EY ee) NEE Safi Tis gt io PELTOPERLIDAE (p. 38) One genus Peltoperla (p. 38) Body elongate, head directed forward, pro, meso, and metano- tum not unusually-developed—). ..... .).. 92). or 4 *Imms (11) page 246, in speaking of stonefly nymphs says: ‘‘in some cases (e.g., Nemouridae) however, the latter appendages (cerci) are in the form of minute single-segmented structures.’’? This misconception has undoubtedly resulted from the fact that, in the adults of Nemoura, Leuctra, ete., cerci are composed of a single small segment. So far as known all stonefly nymphs have long, many-segmented cerci. PLECOPTERA NYMPHS OF NORTH AMERICA — 23 . First and second tarsal segments very short, subequal, to- gether less than half as long as third; labrum three to four times as wide as long; labial palpi slender and reaching far beyond the tip of labium, which is 2-lobed (i.e., glossae are much reduced) ; mandibles slender and without a molar; body mostly flattened; carnivores; all strikingly colored Peruse DELON O NETO ab... er an 6G leds: PERLIDAE 0 (p. 41) First and second tarsal segments together about as long as third or at least more than half as long; labrum not very much wider than long; labial palpi stout and usually not reaching beyond the tip of labium, which is 4-lobed, (i.e., olossae and paraglossae are subequal) ; mandibles with a molar; body not brightly colored; more or less cylindric; under 1 inch in length when fully grown; herbivores 16. . Only two distinct ocelli present; copious gill tufts under CUNOTED SS. oh dupe ie ey0n 2 erlie eaiet ce AR ai ne ay eka ago 6 Pieecaoce le with or without gillg 01.2. 2454... eee ee fi . Two ocelli set very close together ; caudal gills present ; oceipi- tal ridge present ; lacinia of maxilla bidentate .......... gs 2S a are eee ea Neoperla (p. 66) Two ocelli separated by several diameters of a single ocellus ; caudal gills and occipital ridge absent; lacinia unidentate 1 ny RM eR ARR on eae Atoperla (p. 78) . With branched filamentous gill tufts on the under side of the SOM e LoL UOaDASeEROM LNG ACLS fo vet «at cis eds ce ete eee 8 Without branched gill tufts; in some nymphs there are, how- ever, small, single, inconspicuous gill protuberances.. 11 . Head very long; eyes small and set far forward so that the distance from the posterior border of the eye to the hind margin of the head is much greater than the diameter of the eye; gills much branched and about as long as the front femora; small caudal gills........ Perlinella (p. 79) Head shorter; distance behind the eyes less or at. most not much greater than the diameter of the eye; gills usually mideushorier than theiront femora... 52.5.6 «. oe 3 3. Inner group of gills composed of about 17 filaments, outer Proups Ol BOUL Tote ee eee N. sinwata (p. 94) All groups of gills with about an equal number of filaments 4 4. Each group composed of 6-7 filaments...... N. venosa (p. 95) Hach group composed of 8-9 filaments. NV. coloradensis (p. 96) Nemoura sinuata Wu (Plate 28, fig. 209; plate 32, fig. 226.) Length of body up to 6.5 mm.; antennae up to 4 mm.; cerei up to 4.5 mm. General color yellow to yellowish brown. Head about as wide as pronotum; surface covered with fine hairs; basal stem of epicranial suture more than half as long as the lateral arms; hind ocelli (showing in mature nymphs) a little closer to eyes than to each other; antennae of about forty- five segments. Pronotum narrowed posteriorly; front margin somewhat con- vex or nearly straight; angles rounded; surface dirty brown; margin fringed with short blunt spinules. Meso- and metanotum with some long hairs and with short spinules on the lateral mar- gins, especially at the antero-lateral angles; front wing pads nar- rower and longer than the hind ones, which diverge greatly from the body. Legs stout, the femora and tibiae covered with many stout spine-like hairs. Abdominal segments with a fringe of hairs on the posterior margin. Cerei long and slender, of about thirty-two segments, each segment terminating in a whorl of long hairs. In the male the tenth abdominal tergite is produced into a short broad supra- anal protuberance, which is absent in the female; eighth sternite of female with a depressed area in the center of the posterior margin, denoting the developing genital opening. Four groups of gills in the cervical region just anterior to the prosternum ; two outer groups contain seven gill filaments each, and the inner ones about seventeen. PLECOPTERA NYMPHS OF NORTH AMERICA 95 Mouth parts. Labrum nearly half again as wide as long; an- terior margin nearly straight and with a fringe of short hairs. Mandibles with four or five unequal teeth followed by a well- developed molar which is fringed with a comb of short, closely set, blunt hairs; beyond the comb is a bunch of longer hairs. Maxillae stout; lacinia terminating in two or three denticles, followed by a fringe of hairs; galea cylindric, extending a little beyond the tip of lacinia and at the tip with a few hairs; maxil- lary palpus stout and extending far beyond the tip of the lacinia. Labium : mentum very narrow; submentum large, subquadrangu- lar; glossae and paraglossae about equally long but the para- glossae much wider than the glossae; at the tip the glossae and paraglossae bear small papillae; labial palpi very stout and not extending much beyond the tip of the paraglossae; third seg- ment of labial palpus very large. | In general appearance these nymphs are of a dirty brown color, due to the adherence of small particles of organic matter. The spiny legs and the fringe of short stout spines around the margin of the pronotum as well as at the anterior angles of the meso- and metanotum are characteristic of Nemoura. The nymphs occur largely in small upland streams where they may be found in the leaf drift. Ithaca, N.Y. Nemoutea vallicularia Wu Length of body up to 7 mm.; antennae up to 4 mm.; cerei up to 4 mm. In general appearance very similar to NV. sinwata. The nymphs, however, have no gills in the cervical region. Wu (57) who has studied the morphology and biology of this species found that it passes through twenty-two instars and completes its life cycle in one year. Ithaca, N.Y. Nemoura venosa Banks (Plate 9, figs. 141-146.) Length of body up to 6.5 mm.; antennae up to 3.8 mm.; cerci up to 3.7 mm. General color yellowish brown to darker brown. Very similar in appearance to N. sinuata but differs as follows: the gills in the cervical region are in four groups, each group made up of six to seven finger-like gills. The fringe of hairs around the margin of the pronotum and on the antero-lateral angles of the meso- and _ 96 THOMAS SAY FOUNDATION metanotum seem to be a little longer in this species than in N. sinuata but this difference is not sufficient to be of much aid in separating the species. In fully mature nymphs the developing genital structures are of considerable aid in identification. TthacayeN sy: Nemoura coloradensis Banks Length of body up to 6.8 mm.; antennae up to 4 (?) mm.; cerel up to 4 (?) mm. General color brown to dark brown. It is with some doubt that I include this species, for the nymphs before me have not been reared. However, they are mature and show the genital structures fairly well. The gills are present in the cervical region in four groups, with eight gill filaments in the outer group, and eight to nine in the inner group. The fringe of hairs on the pronotum, and the arrangement of the spines on the legs, are similar to N. sonwata. In the male nymphs the subanal lobes are large, somewhat subquadrate, and a little upturned. Nymphs from Bozeman, Mont. Nemoura sp. Among the collection of Nemoura nymphs, I have a number of aleoholic specimens from Colorado which differ markedly from any of the Nemowra nymphs described in this paper. In the cervical region, there are four single large finger-like gills. The legs are covered with spiny hairs, and on each of the femora, beyond the middle, there is a diagonal transverse row of long spine-like hairs. This row of spines is continuous in the femora of the pro-, and mesothoracic legs, but in the femora of the metathoracic legs the row of spines is interrupted by a gap. In other details these nymphs resemble other species within the genus. Genus LEUCTRA Stephens The nymphs of this genus are most readily recognized by the slender form of body and the shape and position of the wing pads. The wing pads are long and narrow and lie parallel with the body, the mesothoracic ones are set far apart at the base, while the metathoracic are set close together. General color yellowish brown to darker brown. Fully mature nymphs measure 10 mm. or less in body length. Antennae and cerci well developed, being normally about half as long as the body. PLECOPTERA NYMPHS OF NORTH AMERICA 97 Head wider than pronotum; broadly rounded behind; rather smooth; three ocelli, the posterior ones about twice as close to the eyes as to each other. Pronotum about as wide as or slightly wider than long; sides nearly straight; angles rounded; surface somewhat hairy, espe- cially around the outer margin; anterior marginal groove in- distinct. Legs rather stocky and only sparsely clothed with long hairs; first segment of tarsus at least twice as long as second; sometimes the second is indistinct; third much longer than one and two combined. Abdomen eylindrie, covered with short hairs, and with a fringe of short hairs on the posterior margin of each segment. Gills absent. The sexes are not so readily recognizable as in some other genera. The males are smaller and a little more slender than the females. In the males may be noticed a small protuberance in which the supra-anal process develops. The mouth parts are of the herbivorous type and indicate that all the species in the genus are vegetable feeders. The labium is different in structure from the labia in related genera, in that the glossae are only about half as wide as the paraglossae, and the labial palpus extends much beyond the paraglossae. In gen- eral, the structure of the mouth parts is so similar in the different species within a genus that the description and figures of the mouth parts of L. sibley2 may well be said to describe the general structure of the mouth parts of the entire genus. The nymphs are commonly found in small upland streams where they occur in leaf drifts and other forms of vegetable mat- ter. Because of théir inconspicuous brown color and small size, and their habit of clinging to brown leaves and sticks, the nymphs are not readily observed, and are therefore quite scarce in col- lections. Although we have no records of any life-history studies within the genus, they probably require one year to complete the life eycle. The adults of most species emerge in the summer, although some are found emerging as early as March and others as late as November. I have been able to identify with certainty the nymphs of only two species, LZ. decepta and LD. sibleyr. Judging from the close similarity in the shape, size, color, and structure of the nymphs of these two species to the many other nymphs in the collection from various localities, it appears that specific identification in this genus will be very difficult. No reliable characters have yet 98 THOMAS SAY FOUNDATION been discovered which will separate the two above species or which distinguish them from L. claassent Frison, recently de- scribed by Frison (6). Identification can, therefore, at present be made only by rearing each nymph, or else by careful dis- section and examination of the developing genital structures in mature nymphs. Leuctra sibleyi Claassen (Plate 9, figs. 147-152.) Length of body up to 8 mm.; antennae up to 3.8 mm.; cerci up to 4 (?) mm. General color yellowish brown to darker brown. Head considerably wider than pronotum; rounded behind; hind ocelli at least twice as close to the eyes as to each other; front ocellus placed on a line in front of the anterior margin of the compound eyes; surface smooth; antennae about half as long as body, with about forty-eight segments. Pronotum only slightly wider than jong; sides nearly straight ; angles rounded, the posterior ones more so than the anterior ones; surface nearly smooth, slightly hairy, and with longer hairs on the outer margins at the angles; anterior marginal groove narrow and not prominent. Hind wing pads set closely together so that the inner margins are almost contiguous. Legs rather short, stocky and not much flattened; sparsely covered with short hairs, and only a very few longer hairs on the femora and tibiae; first tarsal segment more than twice as long as second ; third almost twice as long as one and two combined. Abdomen cylindrical, rather slender and -somewhat widened near the middle; sides of segments nearly straight; surface covered with short stout hairs, and the posterior margin with a series of short spinules; tenth tergite broadly rounded in both male and female nymphs. In the male there appears a small lobe-like protuberance just below the tenth abdominal tergite ; within this protuberance, the supra-anal process may be seen in mature nymphs. Cerci rather stout and at least half as long as the body; the basal segments slightly wider than long; near the middle they are about three times as long as wide, and at the tip at least six times as long as wide; there are about eighteen or twenty segments in each cercus, each segment with a whorl of long hairs near the apex. Mouth parts. Labrum at least half again as wide as long; an- terior margin slightly concave in the middle and fringed with PLECOPTERA NYMPHS OF NORTH AMERICA 99 many short hairs. Mandibles asymmetrical, four unequal, rather blunt teeth, followed by a well-developed molar which on the dorsal surface is fringed by wide blunt hairs resembling a comb; beyond this comb, a small group of long hairs. Maxillae: lacinia terminating in two ineurved teeth followed by a fringe of stout hairs; galea cylindrical, extending somewhat beyond the lacinia, and bearing at the apex a group of small papillae and a few setae. Maxillary palpus nearly twice as long as galea, stout, the fifth segment with a small cup at the apex in which may be noted small papillae. Labium with submentum very large and almost as long as wide; mentum very narrow; glossae and paraglossae small; the glossae only about half as wide as paraglossae and not extending beyond the paraglossae. Both glossae and paraglossae eovered at the tip with small papillae, but only the paraglossae with long hairs; labial palpus stout and reaching far beyond the tip of the paraglossae; third segment ending in a cup-shaped depression. Hypopharynx large, rounded in front, and normally extending far beyond the tips of the paraglossae. Ithaca, N.Y. Leuctra decepta Claassen (Plate 28, fig. 208.) Length of body up to 8 mm.; antennae up to 4 (?) mm.; cerci up to 3.5 (?) mm. . General color brown with the appendages a little lighter. Head wider than pronotum; hind ocelli more than twice as close to the eyes as to each other; antennae composed of about forty-five segments. Pronotum a little wider than long; sides nearly straight or slightly convex; angles rather narrowly rounded; surface quite smooth, covered with hairs, and with longer hairs on the outer margin, especially noticeable at the angles. Cerci with about twenty segments. In fully mature nymphs, the genital structures of the developing adult may be observed. In the male there oc- curs a small tubercle just beyond and below the tenth tergite. Within this tubercle may be seen the developing supra-anal processes. | No nymphal structures have been found by which this species ean definitely be separated from other species, and identification is possible only through rearing records or by careful study of the genital structures in mature nymphs. Ithaca, N.Y. 100 THOMAS SAY FOUNDATION Leuctra claasseni Frison The following description is taken from Frison (6). Nymphal Male. General color yellow-brown, general body form elongate; about 8 mm. long. Head much wider than prothorax, widest at compound eyes, rounded behind; epicranial stem about as long as one-half of width of prothorax; developing ocelli in same relative positions as in adult; labrum somewhat perpendicular to plane of front. Antennae long and slender, fifty or more segments in each an- tennae; first segment very large, basal segments wider than long, succeeding segments gradually becoming more elongate and with apical segments several times as long as wide, a few setae on segments. Labium with glossa divided into two parts by an incision which extends longitudinally as a suture less than one-half the length of the ligula; paraglossae about as broad as glossae combined, and not extending beyond them; palpiger distinct and almost appearing as short basal segment of palpus; labial palpus three- segmented, basal segment shortest, second and third segments longer than first, and of about equal length, third or terminal, segment less broad than second, and gradually rounded and taper- ing at apex. Hypopharynx about as large as leula, lobe-like, rounded at apex, and not extending beyond glossae. Maxillae well developed; lacinia with two slender, sharp teeth curved in- wards at apex, beneath which on inner side is a row of long stiff setae; galea extending slightly beyond lacinia, curved and taper- ing to a point at apex; palpifer indistinct, and appearing as basal segment of palpus, maxillary palpi five-segmented and about twice as long as labial palpi, basal or first segment very short and likely to be confused with palpifer, second segment shortest and about one-half as long as fifth, third and fourth segments sub- equal, fifth segment a little longer than third. Mandibles heavily chitinized, with several teeth directed inwardly near apex, be- neath which on inner margin is a well-developed molar with short stiff setae. Pronotum with darkly chitinized area almost quadrate, with front angles slightly rounded and hind angles conspicuously so. Meso- and metathorax supporting wing pads which extend back- wards nearly parallel with body. Fore wing pads long and nar- row, overlapping basal third of hind wing pads. Hind wing pads likewise, long and narrow, with anal lobe not extending much beyond middle of wing pad; venation of wing pad, when dis- PLECOPTERA NYMPHS OF NORTH AMERICA 101 tinguishable, typical of genus, with numerous cross-veins between medio-cubital longitudinal veins. Legs short, prothoracic legs shortest, metathoracic legs longest, femur and tibia of about equal length, femur much broader than tibia; tarsi three-seg- mented, second segment very small, third segment two or three times as long as first, and provided with two simple claws at apex; tibia at apex lower on side with two spines about one-third as long as the first tarsal segment; some short stout setae on ventral aspect of all segments. Abdomen appearing cylindrical, with lateral margins of seg- ments almost straight and not noticeably tapering towards the apex; first seven dorsal segments of about equal size, and slightly broader than long, eighth and ninth dorsal segments about twice as broad as long, tenth dorsal segment rounded behind, and from lateral aspect somewhat lobe-like and humped up at apex; ninth ventral segment with faint indication of lobe-like appendage visible through body, which is a large anal area somewhat pointed on posterior margin and longitudinally bisected by an incision for one-half of its length. Anal cerci, at least nineteen in one specimen; first few basal segments about as long as wide, suc- ceeding segments rapidly becoming much longer than wide, those towards apex much broader at apex than at base, and with a row of long stiff setae around each segment near apex. Nymphal Female. Similar in general to the male. Abdominal segments as a whole much broader than long, apical dorsal seg- ment broadly rounded behind and without hump-like lobe at apex, when viewed from lateral aspect. Harrisburg, Ill.; Herod, Il. Genus TAENIOPTERYX Pictet The nymphs of this genus are mostly blackish in color, in some instances yellowish brown, and in some species with a median, narrow, yellowish, longitudinal line, especially notice- able on the thorax; antennae and cereci very long and slender. The nymphs, when fully grown, measure from 10 to 14 mm. in body length. Head a little narrower than pronotum; three small ocelli, of which the posterior ones are at least twice as close to the eyes as to each other ; occiput marked with numerous granular markings. Pronotum somewhat widened posteriorly, angles rounded, and the sides slightly convex; surface somewhat rugulose; marginal sroove rather indistinct ; front wing pads slender and somewhat 102 THOMAS SAY FOUNDATION directed outward, so that the posterior margin is almost at right angles with the long axis of the body. Legs long, slender, and not very much depressed; outer margins of femora and tibiae with a thin fringe of long hair; first and second tarsal segments sub- equal, the two together about as long as the third. Abdomen nearly cylindrical; cereci long and slender. In some of the species there are present three pairs of three- segmented, filamentous gills attached to the inner side of the ecoxae. These gills are telescopic in nature and may be shortened or lengthened. Mouth parts of the herbivorous type; the labrum not more than half again as wide as long, slightly emarginate in the middle of the anterior border which bears a fringe of hairs. Mandibles somewhat asymmetrical, with four or five rather blunt teeth; these teeth are followed by a molar and a fringe of short stout hairs with longer hairs beyond. Maxillae: lacinia triangular, broad at the base, terminating in a broad bluntly pointed tooth which is followed by a series of long hairs. Galea large, two-segmented, reaching to the tip of the lacinia, and bearing at the apex numer- ous small tubercles. Maxillary palpus, when fully extended, reach- es beyond the tip of the lacinia; first and second segments not longer than wide; third segment a little longer than first and second combined; fourth a little shorter than third, and the last segment about as long as the third; entire palpus very stout. Labium much longer than wide; glossae and paraglossae about equal in length, although in some specimens the glossae seem to be a little longer than the paraglossae; both glossae and para- glossae bear at the apex numerous small tubercles, and the para- glossae also bear long hairs; labial palpi very short and heavy; first segment only about half as long as wide; the second hardly longer than wide, and the third very slightly longer than wide; entire palpus does not reach beyond the tips of the paraglossae. Mentum quite wide; hypopharynx rounded at the tip and extend- ing nearly to the tip of the glossae. The nymphs of this genus are found in slowly-running water, and at times may occur in fresh-water ponds or pools. They are herbivorous, feeding entirely on vegetation. The life cycle ap- parently occupies but one year; they mature early in spring, and in the vicinity of Ithaca, begin to emerge in February. Adults may be found as late as April. When ready to transform the nymphs crawl up on the vegetation bordering the ponds and streams, and cast skins may often be found there. The adults are PLECOPTERA NYMPHS OF NORTH AMERICA 1038 poor fliers, and remain near the streams where they may be col- lected by sweeping the vegetation, or sometimes they may be clubbed off the trees along the banks. Very little is known about the habits of the nymphs and adults except that Newcomer (32) has reported that the adults of 7’. pacifica sometimes cause injury by feeding upon fruit buds in the orchards along streams, and Frison (6) reports them to be feeding on Protococeus. Key to the Nymphs of Taeniopteryx 1. Coxae with segmented tracheal appendages ............. 2 Soeace without tracheal rilis! aoe. 6<- didemae)s ait ct dee 4. 2. Usually with a distinet mid-dorsal stripe extending from head to tip of abdomen; mature nymphal males showing the ventral lobe-like appendage on the ninth abdominal sternite MeprCmevOLODING SACU Lig ere a Pecans ers, «cise Rte miseela, wha ta a 3 Without a distinct mid-dorsal stripe; males without ventral Pope KCI D DCNOAVC sn os ed Geis st parvula (p. 105) 3. Length of body up to 14 mm., general color dark brown to blackish; males without tooth on hind femora; common- est of the eastern species of this genus. ....ntvalis (p. 108) Length up to 10 mm., general color yellowish to ight brown ; males with a tooth on hind femora ........ maura (p. 104) 4. Ventral appendage of ninth abdominal sternite triangularly produced in the female, while in the male this appendage is more square and slightly upturned at the tip ......... 5 ahd Mee Pina eh cee fascrata (p. 106) Ventral appendage in both male and female broadly rounded “Ue TPA Sead Sooo aor Sin os ees eee califormea (p. 107) Taeniopteryx nivalis Fitch (Plate 9, figs. 135-140; plate 29, fig. 210; plate 33, fig. 229.) Length of body up to 14 mm.; antennae up to 9 mm.; cerci up to 8 mm. General color dark brown to blackish, with lighter markings, and usually with a very distinct median, dorsal, yellow line ex- tending from the head to the tip of the abdomen. Head somewhat narrower than pronotum; yellowish or brown, with darker mottled areas over the occiput behind the ocellar triangle, and a dark area in front of the latter, as well as a darker spot at the base of the antennae near the eyes. Three small ocelli, the posterior ones at least three times as close to the eyes as to each other, and set forward on the head so as to be in almost 104 THOMAS SAY FOUNDATION direct line with the center of the compound eyes. In the lighter specimens, the ocelli are readily seen because of the small darker markings inside of the ocelli. Antennae long and slender, with about eighty segments. Pronotum a little wider than long, with rounded angles; sides somewhat convex; front margin shghtly concave in the center; surface quite rugose; brown or black in color, with the lateral margins yellowish, and in most specimens with a distinct yellow median line, or else a slight indication of one. Meso- and meta- notum yellowish brown or darker, smoother than pronotum ; meso- thoracic wing pads diverge from the body at an angle of about thirty degrees, with the outer margins nearly straight; the hind wing pads diverge more from the body than do the front wing ones, so that the posterior margin is almost at right angles to the long axis of the body, especially noticeable in mature nymphs. Legs slightly flattened, somewhat hairy; outer margins of the tibiae with a sparse fringe of long fine hairs; first and second tarsal segments subequal, the two together about as long as the third segment. Abdomen nearly cylindrical; surface covered with very short brown spinules; basal half of each segment usually darker than the distal half, and in most specimens the median line is very noticeable; cerci brown at the base, becoming lighter towards the tip. Gills. There are three pairs of gills attached to the coxae on the inner base of the legs and they are made up of three segments, the basal largest, and the following two segments successively smaller. These gills are telescopic, and when fully extended they reach to about the middle of the femora. In the more mature nymphs the sexes can readily be differen- tiated. In the male, the supra-anal process projects beyond the posterior margin, of the tenth tergite in the form of a slightly upturned, short knob and the ventral lobe of the ninth sternite is often plainly visible through the integument. In the female nymph the tenth tergite terminates in a flattened rounded pro- longation. Ithaca, N.Y.; Clinton, N.Y.; Illinois. Taeniopteryx maura Pictet Length of body up to 10 mm.; antennae up to 7.5 mm.; cerci _ up to 6 mm. General color yellowish with brown markings. PLECOPTERA NYMPHS OF NORTH AMERICA 105 Head a little narrower than pronotum; entire occiput covered with mottled brown marks; there is also a brown spot each side of the ocellar triangle at the base of the antennae, and another in front of the anterior ocellus; hind ocelli at least twice as close to the eyes as to each other; surface very feebly pilose; antennae long, slender, brown at the base and lighter toward the tip; of about seventy-five to eighty segments. Pronotum a little wider than long, slightly widened posteriorly ; angles rather broadly rounded; a broad, median, yellow stripe, on each side of which the rugose dises are of a darker brown color, or else there are dark markings upon a lighter background ; meso- and metanotum brownish; metathoracic wing pads di- rected away from the long axis of the body, so that the hind margins are almost at right angles to the body. Legs somewhat flattened; tibiae with a sparse fringe of long, fine hairs on the outer margins; first and second tarsal segments about equal in length, the two together at least as long as the third segment. Abdomen nearly cylindrical, more or less uniformly brownish, but in more mature nymphs, the mottled appearance of the de- veloping adult may be seen through the chitin; ventral surface of body light in color. There are three pairs of segmented, tele- scopic, filamentous gills attached at the mner base of the coxae as in T. mvals. The sexes in this species are readily separated. In the female the ninth abdominal sternite is hardly produced at all; the tenth tergite is broadly rounded on the posterior margin. In the male, the ninth sternite is somewhat produced rearward, and the tenth tergite bears in the center of the posterior margin a projected lobe in which the developing supra-anal process lies. In the mature nymphs, the detailed genital structures can readily be observed through the chitin, especially after the specimens have been in alcohol for some time. Likewise, the tooth on the femora ean readily be seen in the male. The smaller size and the relatively lighter color distinguish this species from 7’. nivalis. Plummer’s Island, Md.; Washington, D.C. Taeniopteryx parvula Banks Male. Length of body up to 7 mm.; antennae up to 5 mm.; cerci 4 mm. General color yellowish brown with some darker mottlings on the head and some more or less indistinct darker markings on the rest of the body. 106 THOMAS SAY FOUNDATION Head about as wide as pronotum; mottled brown; a dark spot in front of the anterior ocellus; two dark spots on the inner margin of each eye; hind ocelli a little more than twice as close to the eyes as to each other; antennae with about seventy-five segments. Pronotum a little wider than long, brown, with a hghter mar- gin, especially noticeable in front and rear; angles broadly rounded; surface not very rugose. Meso- and metanotum brown- ish; legs somewhat flattened; tibiae with a sparse fringe of long hairs on the outer margin; first and second tarsal segments sub- equal, together as long as the third. Abdomen nearly cylindrical, yellowish brown; cerei yellowish with about forty sezments. There are three pairs of filamentous, three-segmented, telescopic gills attached to the inner base of: the coxae; ninth abdominal sternite somewhat swollen and shghtly produced rearward; tenth tergite medially produced into an upturned, rounded knob, in which develops the supra-anal process. Two males from Plummers Island, Maryland, February 24, 1923, Warner, Barber and Currie. The above description is made from two mature male nymphs in which the genital structures can be seen very clearly. Taeniopteryx fasciata Burmeister (Plate 29, figs. 215-216.) Length of body up to 8.5 mm.; antennae up to 5 mm.; cerei up to 8 mm. General color yellow, mottled with brown. Head a little narrower than pronotum, yellowish with brown mottled markings on the occiput, and with a more or less distinct brown band across the ocellar triangle reaching from the base of one antenna to the other; a brown U-shaped mark in front of the anterior ocellus; hind ocelli about twice as close to the eyes as to each other; antennae yellowish with the first two basal seg- ments darker and also somewhat darkened toward the tip, com- posed of about sixty-five segments. Pronotum a little wider than long, yellowish, with darker, rugose lateral fields; the front and hind margins also somewhat darker ; front angles rather narrowly rounded, hind ones broadly so; lateral margins somewhat convex, so that the pronotum ap- pears to be somewhat broadened posteriorly. Meso- and meta- notum yellowish, with brown markings; wing pads almost uni- PLECOPTERA NYMPHS OF NORTH AMERICA 107 formly yellowish brown; the hind wing pads directed away from the body slightly more than the front ones, but not quite so much so as in 7’. nivalis. Legs flattened, yellow; the femora with a more or less distinct transverse band beyond the middle; both femora and tibiae with a fringe of long hairs on the outer margin; first two tarsal segments about equal in length, and together a little shorter than the third segment. Abdomen somewhat flattened ; yellowish, with brown mottlings over the basal half of each segment, and with brown, short hairs over the entire surface; cerci long and slender. Gills absent. The sexes are easily distinguished. In the female, the ninth abdominal sternite is prolonged into a hairy, tongue-like plate which projects normally beyond the tip of the abdomen. In the male the ninth abdominal sternite is produced in a wide, flattened plate which gradually tapers almost to the tip, then turns up in a square process, very similar to the subgenital plate of the adults; the tenth tergite has a small median projection on the posterior margin, within which develops the supra-anal process. The larger size of the subgenital plate, and the fact that in the male it turns up and projects far beyond the end of the abdomen, readily distinguish the male from the female. Plummer’s Island, Md.; Illinois. Taeniopteryx californica Needham and Claassen Male. Length of body up to 10 mm.; antennae up to 7 mm.; cerci up to 8 mm. General color yellowish brown with darker markings on the body and with wide, brownish, transverse bands on the femora, sometimes only faintly indicated. Head narrower than pronotum; brown, with a yellow area just back of the ocellar triangle, and with a lighter yellow area in front of the anterior ocellus; hind ocelli at least twice as close to the eyes as to each other; antennae light brown, slightly more infuscated toward the tip. Pronotum a little wider than long, brown, with a lighter area in the center of each lateral disc; surface nearly smooth, except for the more or less crescentic, irregular, embossed markings; angles broadly rounded. Meso- and metanotum marked with yel- low and brown; front wing pads diverging only slightly from the body; hind wing pads diverging at about a 20° angle. Legs 108 THOMAS SAY FOUNDATION somewhat depressed; the femora with a faint transverse, brown- ish band; a fringe of long hairs on the outer margin of femora and tibiae; first segment of tarsus shorter than second; from a dorsal view it appears to be only one-third as long, but on the ventral side it is nearly as long as the second; segments one and two together shorter than three. Abdomen very nearly cylindric, light brown with a few scat- tered brown freckles on the basal half of each segment; cerei yellowish except for a very narrow, brown band at the apical margin, and composed of about fifty segments. The tenth ab- dominal tergite in the male is produced into a tuberele-like pro- jection; ninth abdominal sternite produced into a broad, flat- tened, subgenital plate, which is produced to the tip of the abdomen. Gills absent. Described from three male nymphs collected at Spencer Creek, Ithaca, New York, April 5, 1926. P. R. Needham. This species was originally described from California, but within the last few years it has been found in several localities in New York. Adults have been collected at Spencer, New York, April 5, 1926 (P. R. Needham), and at Copak Falls, New York, April 11, 1924 (Crosby and Chapman). Family CAPNIIDAE Small brown or blackish nymphs, under 10 mm. in body length. They are true herbivores and largely inhabit the small upland spring brooks. The life cycle is completed in one year. Antennae and cerci are long and slender; second tarsal segment much shorter than first; third tarsal segment at least twice as long as first and second combined. Legs with a sparse fringe of long hairs. Gills absent. Mouth parts similar to those of the Nemouri- dae. Wing pads when present lie parallel to the body, and the hind are wider than the front ones. In the males, the last ab- dominal tergite ends in a conical projection, while in the female nymphs it is only slightly produced, and broadly rounded. Genus CAPNIA Pictet The nymphs of this genus resemble those of Allocapnia, but differ in the shape of the wing pads. The metathoracic wing pads are similar to the mesothoracie ones except that they are a little wider. The anal field of the hind wing pad is narrow and short, only reaching a little beyond the middle of the wing pad. Since the nymph of only one species (C. vernalis Newpt.) is known it is impossible to give an adequate description of the genus. Capnia is essentially a western genus, eighteen of the nineteen described species being known from the Rocky Mountains and the western states. Of these not a single species has been reared. I have several western nymphs before me but they are not fully mature and cannot be specifically determined. C. vernalis, the only species of the genus occurring east of the Rocky Mountains, has been col- lected in a number of places in New York State, where the adults may be found during March and April. Since C. vernalis is a herbivore, it is probably safe to assume that all the species within this genus are herbivorous. Capnia vernalis Newport (Plate 10, figs. 159-163; plate 30, fig. 217.) Length of body up to 7.5 mm.; antennae up to 3.6 mm.; cerci up to 4 mm. General color brown, becoming darker as the nymphs near maturity. Head a little wider than pronotum; rather sparsely coated with long hairs; surface quite smooth; hind ocelli about twice as 110 THOMAS SAY FOUNDATION close to the eyes as to each other; antennae long and made up of about fifty-six segments. Pronotum hardly longer than wide; widened posteriorly, the sides normally broadly convex with rounded angles; surface rather smooth, and covered with long hairs, especially around the margin; marginal groove noticeable only along the anterior margin. Wing pads of female much larger than those of male. In some of the male nymphs the wing pads are very small, and such nymphs undoubtedly give rise to the brachypterous adults. Front wing pads nearly as wide as hind ones, lying either parallel with the body, or more often somewhat converging posteriorly ; hind wing pads more or less parallel, the anal area hardly reaching beyond the middle of the wing case; wing pads with long hairs, especially around the margins. Legs hairy and with a sparse fringe of long hairs on the outer margin; first tarsal segment at least twice as long as second. Abdomen subeylindric; widest in the middle portion, hairy, especially on the posterior margins of the individual segments; cerci made up of thirty to thirty-five segments, each terminating in a whorl of hairs, some of which are longer than the segments. The sexes are readily recognizable. In the female, the tenth ab- dominal tergite is broadly rounded and slightly produced, but otherwise unmodified. In the male, the tenth tergite is similar to that of the female except that in the middle, and somewhat below the posterior margin, it bears a short tubercle less than half as long as the tenth tergite. Within this tubercle develops the supra- anal process of the adult male. Gills absent. Mouth parts of the herbivorous type, as in Allocapnia. Labrum less than twice as wide as long; front margin normally somewhat concave in the middle; surface sparsely coated with long hairs and on the anterior margin with a thick fringe of short ones. Mandibles asymmetrical, with about five or six teeth, which in some specimens are sharp, and in others quite blunt; beyond these teeth a rather narrow molar and a series of stiff hairs. Maxil- lae: lacinia terminating in several blunt denticles followed by a fringe of hairs. Galea about as long as lacinia, at the apex a num- ber of small tubercles and long hairs. Labium similar in structure to that of Allocapnia except that the glossae in C. vernalis are as long as, or slightly longer than, the paraglossae. Both glossae and paraglossae bear at the tips many small tubercles and hairs. Labial palpus does not extend to the tip of the paraglossae. Hypo- PLECOPTERA NYMPHS OF NORTH AMERICA 111 pharynx broadly rounded and normally extended beyond the olossae. The nymphs of this species are herbivorous and may be found in small upland streams where they usually occur in leaves and debris. : Ithaca, N.Y. Genus ALLOCAPNIA Claassen Allocapma Claassen, Annals Ent. Soc. Amer., vol. 21, 1928, p. 667, to replace Capnella Claassen, preoccupied. The nymphs of this genus are most readily recognized by the Shape of the hind wing pads. It is the only genus in which the anal field of the hind wing extends almost to the tip of the wing, giving the wing pad a broadly triangular shape. The front wing pads are slender, set far apart at the base, and lie parallel to the body. The nymphs when fully grown seldom measure more than 8 mm. in length, exclusive of antennae and ecerci. General color yellowish to dark brown. Head as wide as, or slightly wider than pronotum. Three oeelli, the hind ones about twice as close to the eyes as to each other. An- tennae long and slender, about half as long as body, and made up of about forty-five to forty-eight segments. Pronotum subquadrate with rounded angles ; somewhat widened posteriorly ; surface moderately hairy ; marginal groove noticeable along the anterior margin. Wing pads present in all species except in the males of A. viwpara where they are either absent or ves- tigial. Legs rather short; femora and tibiae covered with hairs and with a sparse fringe of long hairs on the outer margins; first segment of tarsus about twice as long as second; third about twice as long as first and second combined. Abdomen cylindrical. The sexes are readily distinguishable. In the male, the tenth tergite is produced into a long triangular protuberance (supra-anal lobe) which is directed slightly up- wards. In the female, the tenth tergite is only slightly produced into a broadly rounded lobe. Cerci long and slender, normally about half as long as body, composed of about twenty-five to thirty segments, each segment ending in a whorl of long hairs. Gills absent. The mouth parts are of the herbivorous type, and their struc- ture is so similar in the different species of the genus that they apparently are of little taxonomic value in separating the species. Very little detailed work has been done to determine the exact 112 THOMAS SAY FOUNDATION food habits of the nymphs of this genus. Examination of stom- ach contents, however, has shown that they are herbivores, feed- ing largely on decaying vegetation. Frison (6) has studied the food habits of several species in this genus, and he found them to feed on ‘‘fragments of decaying leaves and diatoms.’’ Key to the Nymphs of ALLOCAPNIA 1. Last segment of abdomen prolonged into a conspicuous coni- cal protuberance (males*) —. ..a..---- +4 «<0 See 2 Last abdominal tergite broadly rounded, without a protuber- ance (females*). 2. Wine pads absentior vestigial’ 20a... ee. viveipara (p. 114) Wing pads well developed (in some cases the wing pads are abbreviated.) if). sicc. t's + +1 4s sein teal openly oe eae B) 3. Protuberance of tenth tergite no longer than the ninth ab- dominal tercitec 3 gn ee recta (p. 113) probably incisura (p. 115) Protuberance longer than ninth abdominal tergite ........ EE ee Rt, 8 ets Ges Sk, Wb pygmaea (p. 112) granulata (p. 114) mystica (p. 116) Allocapnia pygmaea Burmeister (Plate 10, figs. 153-158; Plate 30, fig. 218.) Length of body up to 8 mm.; antennae up to 3.2 mm.; cerci up to 3 mm. General color brown, becoming darker as the nymphs mature. Head slightly wider than pronotum; surface nearly smooth but in the maturer nymphs the occipital rugosities of the developing adult are quite noticeable; ocelli indistinct in some specimens; hind ocelli about twice as close to the eyes as to each other; an- tennae brown, smooth, with about forty-six to forty-eight seg- ments. Pronotum about as wide as long, somewhat widened posteriorly ; angles rather broadly rounded; front margin convex, hind mar- gin nearly straight ; surface somewhat rugose, pilose, with longer hairs on the outer margins. In mature nymphs the dark brown markings of the developing adult are very noticeable. Wing pads large; front ones far apart, directed backward and parallel to the body; hind ones much wider than the front pair, broadly tri- angular, and much closer together. Legs yellowish, flattened and * Mature male nymphs can usually be specifically identified by the struc- tures of the developing genitalia. In female nymphs the species can not be separated. PLECOPTERA NYMPHS OF NORTH AMERICA 113 hairy; femora and tibiae with a sparse fringe of long hairs on the margins; first tarsal segment about twice as long as second; third about twice as long as first and second combined. Abdomen nearly cylindrical, uniformly brown in younger nymphs but transversely banded in mature ones; segments widened posteriorly ; surface somewhat hairy, with a fringe of long hairs on the posterior margin of the segments. Cerci of about twenty-six segments, each terminating in a whorl of hairs. Mouth parts. Labrum not quite twice as wide as long; anterior margin slightly emarginate in the middle, and fringed with hairs. Mandibles slightly asymmetrical, with four to five unequal, rather bluntly pointed teeth. These teeth are followed by a well-de- veloped molar which bears very short spine-like hairs on the eenter, and on the outer margin is fringed with longer hairs. Maxillae: lacinia with two or three small terminal teeth followed by a few short spines and a fringe of stout hairs. Galea as long as lacinia, rather wide in the middle, rounded at the tip, which bears a few long hairs; maxillary palpus nearly twice as long as galea, stout; first and second segments about as wide as long; third segment a little less than twice as long as wide; terminal segment about as long as third but much more slender. Labium much longer than wide; submentum very large, a little wider than long; mentum a narrow transverse band; the paraglossae extend slightly beyond the glossae; tips of the glossae and paraglossae with long hairs and a few papillae; palpus short and stout, nor- mally not extending beyond the tip of the paraglossae. Hypo- pharynx broadly rounded, closely beset with short hairs and normally extending beyond the glossae. This is the most common species of the genus. Allocapnia recta Claassen Length of body up to 7.5 mm.; antennae up to 3.5 mm.; cerci up to 4 mm. General color brown with the appendages somewhat lighter. This species very closely resembles A. pygmaea.in appearance, but the caudal protuberance of the male in recta is much shorter than in pygmaea. | Head a little wider than pronotum; surface nearly smooth, with a feeble coating of fine hairs; antennae composed of about forty-seven segments; hind ocelli about twice as close to the eyes as to each other. Pronotum widened posteriorly; angles broadly rounded; sur- face hairy; anterior marginal groove rather prominent; wing 114 THOMAS SAY FOUNDATION pads prominent; front ones of the male somewhat overlapping the hind ones, while in the mature female nymph the front ones may extend as far as the posterior margin of the metanotum; hind wing pads broadly triangular. Abdomen cylindrical and some- what hairy; tenth tergite of male produced into a short, triangu- lar tubercle which is directed slightly upwards, and no longer than the ninth tergite. Cerci made up of about thirty segments, each segment terminating in a whorl of hairs. Positive identification is possible only in mature nymphs in which the genital structures may be noted. Ithaca, N.Y.; Oakwood, Il. Allocapnia granulata Claassen Length of body up to 8 mm.; antennae up to 4.8 mm.; cerci up to 3.8 mm. General color ight to darker brown. Head as wide as or slightly wider than pronotum; hind oeelli about twice as close to the eyes as to each other; antennae of about forty-five segments. Pronotum widened posteriorly, hairy, angles broadly rounded ; anterior marginal groove distinct but shallow. Wing pads present in both male and female, but larger and more fully developed in the female. In the mature males the front wing pads overlap the hind wing pads only slightly, while in the females the front wing pads may extend back as far as the middle of the hind wing pads. Abdomen cylindrical; cerci composed of about thirty segments, each of the segments ending in a whorl of hairs. Tenth abdominal tergite of male produced into a prominent protuberance which is longer than in A. recta but not quite as long as in A. pygmaea; in side view the protuberance, as measured from the base of the cereus to the apex, is longer than the ninth tergite, and is directed slightly upwards. The mouth parts are similar in struc- ture to those of A. pygmaea. Allocapnia vivipara Claassen Length of body up to 8.5 mm.; antennae up to 4 mm.; cerci up to 3.4 mm. The nymphal males of this species are readily recognized by the absence of wing pads. General color brown with the appendages somewhat lighter in color. Head slightly wider than pronotum; surface quite smooth, with PLECOPTERA NYMPHS OF NORTH AMERICA 115 a feeble coating of fine hairs; epicranial suture distinct; hind ocelli about twice as close to the eyes as to each other; antennae with about forty-five to forty-six segments. Pronotum a little longer than wide, widened posteriorly ; front angles more narrowly rounded than hind ones. Meso- and meta- notum hairy, without wing pads in the male, or with only very small rudiments; female with conspicuous wing pads, although they are rather wide and short. Abdomen eylindrical. In the male, the tenth tergite is pro- duced into a prominent protuberance which is directed slightly upwards; in dorsal view this protuberance is broadly rounded at the tip but in side view it is rather square at the tip or roughly boot-shaped. In mature nymphs the genital structures of the developing adult may readily be observed. Cerei with twenty- seven to twenty-eight segments. Frison (6) has questioned my statement (3), that this species is viviparous. Although I have no experimental evidence to con- firm my statement, I have again checked over the material and find that in some of the females there occur fully formed nypmhs, with their bodies completely extended, and measuring 1 mm. in length. Frison suggests ‘‘the possibility that the nymphs observed by Claassen in a dissected female were disclosed by the accidental rupture of the egg shell.’’ However, the young nymphs were first noted in the alcoholic female specimens underneath the abdomi- nal wall before any of the specimens had been dissected. In these females the anterior portion of the abdomen contained eggs only while in the posterior part a number of fully developed nymphs could be clearly observed. Dissection dislodged eggs and nymphs and the eggs were not brittle or easily ruptured. Frison found some of the females laying eggs under laboratory conditions and he says ‘‘it was found that the embryonic nymphs of this species (wipara) are in a rather advanced stage when the eggs are laid.’’ Lake Forest, Oakwood, and many other localities in Illinois. Allocapnia incisura Claassen Of this species no males have been reared. I have, however, several adults, both males and females, in which some of the females still have the nymphal skin attached to their bodies. These specimens bear the following label: ‘‘ Adults reared in labora- tory, taken from aquaria; 15 Jan. 1909. Larvae collected 20 Dee. 1909, Charleston, Ill. Sta. 57. No. 1201. T. L. Hankinson.’’ These nymphal skins are in such poor condition that it is im- possible to make an adequate description of the nymph. 116 THOMAS SAY FOUNDATION Allocapnia mystica Frison The following description of this nymph is taken from Frison (6). Nymphal male.—Similar in general form, color, and struc- ture to A. vivipara. Wing pads conspicuous, fore wing pads over- lapping base of hind wing pad. Dorsal lobe-like protuberance at apex of abdomen nearly twice as long from base of anal cerei to apex as length of ninth dorsal segment. Nymphal female.—Differs from male in being somewhat larger and with apex of abdomen rounded and not with a long protuber- ance. In some specimens an indication of the projection on the posterior margin of the eighth ventral abdominal segment may be seen through the integument. This species has thus far been found only in Illinois. 16. SELECTED REFERENCES . Burmeister, H. 1839. Handbuch der Entomologie, Band 2, Part 2: 863-881; T. C. F. Enslin, Berlin. . Claassen, P. W. 1923. New Species of North American Plecop- tera. Canad. E'nt., 55: 257-263 ; 281-292. . 1924. New Species of North American Capniidae. (Plecoptera) Canad. Ent., 56: 43-48; 54-57. . ——. 1928. Additions and Corrections to the Monograph on the Plecoptera of North America. Ann. Ent. Soc. Amer., 21: 667-668. . Comstock, J. H. 1920. An Introduction to Entomology. Com- stock eae Co. Ithaca, N.Y. . Frison, Theodore H. 1929. Fall and Winter Gronefies or ie lacanipow of Illinois. /W. Nat. Hist. Sur. Bull., 18, Art. 11: 345-409. . Garman, H. 1912. A Preliminary Study of Kentucky Lo- calities where Pellagra is present. Ky. Agr. Exp. Sta. Bull, 159. . Hagen, H. A. 1873. Report on the Pseudoneuroptera and Neuroptera of North America in the Collection of the late Theo, W 2 Harris. Proc. Bost. Soc. Nat. Hist., 15: 263-301. , ——. 1877. Beitrage zur Kenntniss von Pteronarcys. Stett. Ent. Zcit., 38: 477-489. . Hubault, E., and J. A. Lestage. 1926. Etudes sur la Biologie des Plécoptéres. IV. Un nouveau type Larvaire de Nephel- opteryx. Ann. Biol. Lacustre., 14: 217-233. . Imms, A. D. 1925. A General Textbook of Entomology. Lon- don. ‘‘Plecoptera’’: 248-248. . Klapalek, F. 1909. Die Siisswasserfauna Deutchlands, Heft 8, Plecoptera: 33-95. . Kathariner, Ludwig. 1901. Zur Biologie von Perla maxima Scop. Allg. Zeits. Ent., 6: 256-260. . Lestage, J. A. 1919. Etudes sur la Biologie des Plécopteéres La larve de Leuctra geniculata Stephens. Ann. de Bool. Lacustre, 9: 257-268. . 1920. Note preliminaire sur la découverte de la Larve de Leuctra geniculata Stephens. Bull. Soc. Ent. Belg., 2 43-44. . 1921. Etudes sur la Biologie des Plécoptéres. 11. La Larve de Nephelopteryx nebulosa L. Ann. de Biol. Lacustre 10: 231-260. 118 ie 18. Loe 20. 21. 22. 23. 24. 20. 26. at 28. 29. 30. afl 32. THOMAS SAY FOUNDATION ——. 1928. Etudes sur la Biologie des Plécoptéres (Suite). 111. Notes sur Perla abdominalis Burm., IV. La théorie de la persistance des tracheobranchies larvaires chex les Per- laria adultes. Ann de Biol. Lacustre, 12: 335-389. . 1927. Etudes sur la Biologie des Plécopterés IV. Le type Larvaire Peltoperlien. Recueal Inst. Zool. Torley-Rous- seau, 1: 83-98. Lauterborn, Robert. 1903. Tracheenkiemen an den Beinen einer Perliden-Larve (Taeniopteryx nebulosa L.), Zool. Anz., 26: 637-642. Mertens, Hermann. 1923. Biologische und Morphologische Un- tersuchungen an Plekopteren. Arch. Nat. Jahrg. 89A Heft 2:. 1-38. Muttowsky, R. A. 1929. The Ecology of Trout Streams in Yellowstone National Park. Roosevelt Wild Infe Annals, 2, No. 2: 155-240. and Gilbert M. Smith. 1929. The Food of Trout Stream Insects in Yellowstone National Park. Roosevelt Wild Lrfe Annals, 2, No. 2: 241-263. Needham, J. G. 1901. Aquatic Insects in the Adirondacks: Plecoptera. NV. Y. State Mus. Bull. 47: 412-418. ——. 1905. New Genera and Species of Perlidae. Proc. Bvol. Soc. Wash., 18: 107-110. —. 1918. ‘‘ Aquatic Insects’’ in Ward and Whipple: Fresh Water Biology: 882-885. and P. W. Claassen. 1922. The North American Species of the Genus Acroneuria. Can. E'nt., 54: 249-255. and P. W. Claassen. 1925. A Monograph of the Plecop- tera or Stoneflies of America North of Mexico. Thomas Say Found. of Ent. Soc. of Amer. 2: 1-397. and P. R. Needham. 1930. A Guide to the Study of Fresh Water Biology (Plecoptera pp. 8-10). Charles C. Thomas, Springfield, Illinois. . and R. O. Christensen. 1927. Economic Insects in Some Streams of Northern Utah (Plecoptera pp. 17-19). Utah Agr. Exp. Sta. Bull. 201. Neeracher, Fred. 1908. Beitrage zur Kenntnis der Insekten- fauna des Rheins bei Basel. Zool. Anz., 33: 668-670. . 1910. Die Insektenfauna des Rheins und seiner Zufliisse bei Basel. Revue Sursse de Zool., 18, No. 2, 497-590. Newcomer, E. J. 1918. Some Stoneflies Injurious to Vegeta- tion. Jr. Agr. Res., 13, No. 1, 37-42. 33. 4. PLECOPTERA NYMPHS OF NORTH AMERICA 119 Newport, George. 1843. On the Existence of Branchiae in the Perfect State of a Neuropterous Insect Pteronarcys regalis. Ann. Mag. Nat. Hist., 13: 21-25. . 1851. On the Anatomy and Affinities of Pteronarcys regalis Newm.: with a Postscript, containing Descriptions of Some American Perlidae, together with Notes on their Habits. Trans. Linn. Soc. Lond., 20, part IIT: 447-452. . Palmen, J. A. 1877. Zur Morphologie des Tracheensystems. Leipzig. . Percival, E. and H. Whitehead. 1929. Observations on the Ova and Oviposition of Certain Ephemeroptera and Plecoptera. Pro, Leeds. Phil. Soc., 1, Part V1: 271-288. . 1929. A quantitative Study of the Fauna of some Types of Stream Bed. Jr. Ecol. 17: 282-314. . Pictet, F. J. 1832. Memoire sur les Larves Nemoures. Ann. sci Nate france:22.: 1-24. . 1841-42. Histoire naturelle generale et particuliere des Insectes Neuropteres. Prenuere Monographie: Famille des Perlides. Geneve, Kessman: 1-423. . Pograez, Sandor. 1918. A. Perla-larvak mozgasarél. Allatt. Kozlem. Két., 17: 67-68. . Rousseau, Lestage, Schouteden. 1917. Les Larves Aquatiques des Insectes d’Europe: Plecoptera: 304. . Rousseau, E. 1921. Les Larves et Nymphes Aquatique des Insectes d’Europe. Lebeque, Bruxelles, 1: 274-320. . Samal. Jaromir. 1923. Etude Morphologique et Biologique de Perla abdominalis Burm. Ann. Biol. Lacustre, 12: 229-272. . Schoenemund, Eduard. 1912. Zur Biologie und Morphologie einiger Perla-Arten. Zool. Jahrb. Abt. Anat., 34: 1-56. . 1924. ‘‘Plecoptera’’ in: Schglze’s Biologie der Trere Deutschlands, Lief. 10, Teil 32: 1-34. . 1925. Beitrage zur Biologie der Plecopteren-Larven mit besonderer Beriicksichtigung der Atmung. Arch. f. Hydro- biol., 15: 339-369. . 1925. Die Larven der Deutschen Perla-Arten. Ent. Mitt., 14: 113-121. . 1927. ‘‘Steinfliegen, Plecoptera,’’ in Brohme, Ehrman, Ulmer, Die Tierwelt Mittleuropas, 4, Lief. 2: 1-18. and H. Stadler. 1920. Zur Kenntniss der Ephemeriden und Plekopteren-Fauna von Unterfranken. Verhandl. Phys., Med. Ges. u. Wiirzburg, N.E. Bd. 40, Heft 5. . Schwermer, W. 1914. Beitrige zur Biologie und Anatomie 120 THOMAS SAY FOUNDATION von Perla marginata. Zool. Jahrb., Abt. F. Anat., 37: 267- 312. 51. Seemann, Theresa M. 1927. Dragonflies, Mayflies and Stone- flies of Southern California. Jr. Ent. and Zool., 19: 1-70. 52. Smith, Lucy W. 1913. The Biology of Perla immarginata Say. Ann. Ent. Soc. Amer., 6: 203-211. . 1917. Studies of North American Plecoptera (Pteron- areinae and Perlodini). Trans. Amer. Ent. Soc., 43: 483- 489. o4. Tillyard, R. J. 1926. The Insects of Australia and New Zea- land. Sydney. (‘‘Plecoptera’’: 111-119.) 55. Uéno, Masuzo. 1928. Peltoperla. (A Nymph of Peltoperla from Formosa.) Trans. Nat. Hist. Soc. Formosa, 18, No. OT 219-223. . 1929. Studies on the Stoneflies of Japan. Mem. Coll. Sci. Kyoto Imp. Umv. Ser. B, Vol. IV, No. 2, Art 5: 97- 155. 57. Wu, Chenfu Frances, 1923. Morphology, Anatomy and Ethology of Nemoura. Bull. Lloyd Inbr. No. 28, Ent. Ser. No. 8: 1-81. D3. 56. DISTRIBUTION AND EMERGENCE TABLE HE genera are arranged in the same sequence as they occur in the Monograph of North American Plecoptera (27). The species of which the nymphs are known, and which are treated in this paper are marked with an *. The black lines cover the time at which the various species have been collected in the adult stage. Where no emergence is indi- eated, the species have been described originally from specimens without date of collection. Under distribution column the follow- ing abbreviations are used: E.S. = Eastern states; M.S. = Mid- dle states; S.S. = Southern states; W.S. = Western states; N.W. = Northwestern states; N.S. = Nova Scotia; Can. Rock. = Cana- dian Rockies. The other abbreviations denote States or Provinces. 122 THOMAS SAY FOUNDATION Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Pteronarcys *biloba *californica comstocki *dorsata nobilis *princeps *proteus Pteronarcella badia *regularis Perlodes *americana aurea bradleyi dolobrata ignota irregularis lineata minor *signata slossonae *tibialis yosemite vagans lsogenus *colubrinus elongatus frontalis Perla *aestivalis alaineda *bilobata *capitata crosbyi duplicata *expansa fugitans *hastata *immarginata innubila kansensis languida luctuosa *niedia modesta nona obscura phalerata postica ramosa sabulosa sorpta tincta varians venosa *verticalis =o ae SI] aq Hazezs on nin Pimpdink 4 PLECOPTERA NYMPHS OF NORTH AMERICA 123 Jan. Alioperla albertaensis *borealis *coloradensis continua fidelis imbecilla *lamba lateralis lineosa marginata *mediana nanina novascotiana pacifica *pallidula pilosa serrata signata *spatulata Chloroperla * *cydippe Paraperla *frontalis Kathroperla perdita — Neoperla *clymene Clioperla annecta *clio *ebria gravitans marmorata *similis slossonae sobria Isoperla bellona *bilineata fusca *5-punctata longiseta marlynia marmona minuta Sererirnn COteri: Soe reere rer r rere errr rer Perry eedacncdanesderscnvrcscasbheveccctassecdeesecceesesedoreesasseser montana *petersoni *signata sordida ventralis Perlesta *placida Atoperla *ephyre Perlinella *drymo 124 Peltoperla anna *arcuata brevis cora cornelia maria thyra Acroneuria *abnormis *arenosa *arida *californica carolinensis: *depressa evoluta | georgiana internata *lycorias *pacifica pennsylvanica pumila *ruralis *theodora trijuncta xanthenes Nemoura bifu rcata biloba californica carolinensis cinctipes columbiana ’ cornuta delicatula depressa divergens flexura frigida glabra interrupta nevadensis oregonensis produeta prolongata . Jan. THOMAS SAY FOUNDATION punctipennis SVE ee Bar nie) Wine At al Pee 2 a Dae eH rotunda serrata similis *sinuata stigmata trispinosa truncata *yallicularia *yenosa venusta Sa4egah PLnnOnee a Soa ORD Ann mone Z i= < 16) oyaned a! Ke nRDRPn® tPA te oe, . . a a Rr, PLECOPTERA NYMPHS OF NORTH AMERICA 125 Leuctra augusta biloba bradleyi carolinensis *claasseni *decepta duplicata glabra grandis hamula infuscata occidentalis *sibleyi tenuis triloba truncata Perlomyia collaris utahensis Taeniopteryx banksii. *californica contorta *fasciata grinnelli *maura nigripennis *nivalis occidentalis oregonensis pacifica pallida *parvula Capnia bakeri barberi brevicauda californica columbiana crinita decepta elongata excavata fibula glabra gracilaria grandis manitoba nana nearctica teresa tumida *yernalis Capnura venosa Allocapnia *forbesi *granulata *incisura *mystica *pygmaea “Frecta *vivipara 126 THOMAS SAY FOUNDATION PLATE 1 FIGuRES 1-16 1— 5 Pteronarcys dorsata Say 1. Labrum 2. and 3. Mandibles 4, Labium 5. Maxillary palpus 6-10 Pteronarcys californica Newpt. 11-16 Pteronarcys proteus Newm. 15. Front leg In the above species, note the rather short, blunt teeth and the large molar of the mandibles; the four-lobed ligula; the large galea, and the flattened tridentate lacinia of the maxilla. PLECOPTERA NYMPHS OF NORTH AMERICA 127 PLATE 1 Vig keyyy Amani \! Rhy mn Tay ae \ \ Tite eae, op alteye re Pteronarcys californica Jp aN ‘ ACY a “i Fy ME /1) ' 16 |! am ! uf 1; 4 128 THOMAS SAY FOUNDATION PLATE 2 FIGURES 17-32 17-21 Pteronarcys biloba Newm. 22-26 Pteronarcella badia- Hagen Note the similarity of structure of the mouth parts of this genus with Pteronarcys. 27-32 Peltoperla arcuata Needham Note the wide hairy and spiny front leg; the lobe-like appendage of the coxa; the wide short, four-lobed labium; the large galea of the maxillary palpus with a terminal brush of hairs, and the blunt teeth and large molar of the mandibles. PLECOPTERA NYMPHS OF NORTH AMERICA 129 PLATE 2 wy w/in HAWN We ' vat " Shani yi} M ‘ Lar ty Dee \ Bette ae le ge ANC ay Peltoperla arcuata’ 130 THOMAS SAY FOUNDATION PLATE 3 FIGURES 33-49 33-38 Perla hastata Banks Note the epipharynx on the labrum; the sharp tooth mandibles without molar, the small glossae and the large paraglossae, each terminating in a spinulose papilla; the slender galea, the bidentate lacinia, and the long cardo and stipes. 39-43 Isogenus colubrinus Hagen Mouth parts very similar to those of above species 44-49 Perlodes tibialis Banks The mouth parts of this species are very similar to those of the previous species but the galea is distinctly two-segmented, and the lacinia is quite wide at the base of the terminal teeth. PLECOPTERA NYMPHS OF NORTH AMERICA 121 PLATE 3 sot % wk Ma AN ade at San Ny ‘ N "4 Vv ae Me wy mis “ye Aik “ya sN Perlodes tibialis 132 THOMAS SAY FOUNDATION PLATE 4 FIGURES 50-65 50-54 Perla bilobata Ndm. and Cisn. Note the unique structure of the maxilla. The galea is reduced to a very small appendage and the lacinia is smooth and uniden- tate. 55-59 Perla verticalis Banks Mouth parts similar to those of the above species but the galea is a little longer and the lacinia is bidentate and possesses a few hairs. 60-65 Perlesta placida Hagen The submentum of the labium is short and wide; the second tooth of the lacinia is followed by a single hair. PLECOPTERA NYMPHS OF NORTH AMERICA 133 PLATE 4 ipa Spare yi Ly Genet ae aie \ wet | Witt Hot ay WWE \ ww Wen \Vv svat \\V “pean Nena wwe . SEES \\ oy al Vl / ss Re - ea NN vii Perla bilobata Perlesta placida gn 134 THOMAS SAY FOUNDATION PLATE 5 FIGURES 66-82 66-70 Acroneuria abnormis Newm. 71-76 gee Yee ; Pe s®) (Un . ; PE '; ae - ae ah. ‘hs i = cd a ih te bf Tb ; a 4) o -— La Re Nee eS) rey ae tat ot eae ‘ : 7 PLECOPTERA NYMPHS OF NORTH AMERICA 151 PLATE 13 oe, = —— Pteronarcella badia Y 185 152 THOMAS SAY FOUNDATION PLATE 14 FIGURES 186-187 186 Peltoperla arcuata Ndm. Dorsal view of nymph. 187 Peltoperla arcuata Ndm. Ventral view of nymph. Roach-like; brown; head bent under; pro-, meso- and metanotum very wide; pro-, meso-, and metasterna very large; gills composed of single filaments; cerci very short. ; PLECOPTERA NYMPHS OF NORTH AMERICA 1538 PLATE 14 Byensie epiedoyag 3 Fror ert —) ae ew ae N32. EI 154 THOMAS SAY FOUNDATION PLATE 15 FIGURES 188-189 188 Perla hastata Banks Mottled areas on head; huge maxillae; rather square pronotum; color olivaceous; slender legs; no gills. 189 Perla verticalis Banks Huge maxillae; somewhat square pronotum; no gills; pro- and mesonotum yellow in center and blackish all around. PLECOPTERA NYMPHS OF NORTH AMERICA 155 PLATE 15 Perla verticalis Perla hastata 189 188 156 THOMAS SAY FOUNDATION PLATE 16 Figure 190 190 Perla media Walker Short, broad, flattened; dark brown to blackish; hairy and usually with a dirty appearance; strong occipital ridge; very heavy fringes of long hairs on legs; abdomen quite uniformly brown. PLECOPTERA NYMPHS OF NORTH AMERICA 157 PLATE 16 Perla media 190 158 THOMAS SAY FOUNDATION PLATE 17 FIGURES 191-192 191 Alloperla spatulata Needham and Claassen 192 Alloperla borealis Banks Wide rounded wing pads; short cerci; legs sparsely fringed; no gills; yellowish color; body eylindrical. PLECOPTERA NYMPHS OF NORTH AMERICA 159 PLATE 17 {/ /] Alloperla Alloperla t/ spatulata i borealis , 491 i} 192 160 THOMAS SAY FOUNDATION PLATE 18 FIGURES 193-194 193 Paraperla frontalis Banks Long slender body; head rather square; small eyes set far for- ward; oval pronotum; no gills. 194 Chloroperla cydippe Newman Wide rounded wing pads; short cerci; no gills; yellowish. PLECOPTERA NYMPHS OF NORTH AMERICA 161 PLATE 18 \ es = S 2 oes ca] 5 he cae mo) wR GEE pa 6 HES 7 813 £80 : a ERPS; acre: BEES : &» Oo me SRE Go bh Se aw <8 ~s, i, me? { 162 THOMAS SAY FOUNDATION PLATE 19 FIGURES 195-196 195 Neoperla clymene Newman Two ocelli set close together; thoracic and anal gills; abdomen transversely banded. -196. Clioperla clio Newman i No gills; front wing pads straight or sinuate; palpi attenuated to sharp points. PLECOPTERA NYMPHS OF NORTH AMERICA 163 PLATE 19 Clioperla clio 196 164 THOMAS SAY FOUNDATION PLATE 20 FIGURES 197-198 197 JIsoperla petersoni Claassen Wing pads lacking or very short; wide median yellow stripe with a narrower yellow stripe each side of the abdomen. 198 Isoperla signata Banks Yellow pronotum, bordered with black; yellow spot between hind ocelli; banded abdomen. PLECOPTERA NYMPHS OF NORTH AMERICA 165 PLATE 20 Isoperla petersoni Isoperla signata \ 197 A 198 PLATE 21 : FIGURE 199 ae 199 Perlesta placida Hagen Broad sete wing pads; a freckled; anal gills. . PLECOPTERA NYMPHS OF NORTH AMERICA 167 PLATE 21 DP Perlesta placida -199 168 THOMAS SAY FOUNDATION PLATE (22 FIGURES 200-201 200 Atoperla ephyre Newman Two ocelli, spaced considerably apart; oval pronotum; long tufted gills; long fringes on legs. 201 Perlinella drymo Newman Long gills under thorax; small anal gills; eyes set far forward on head. PLECOPTERA NYMPHS OF NORTH AMERICA 169 PLATE 22 \\ : \ Atoperla ephyre Perlinella drymo " 200 201 | ] ‘THOMAS SAY -POUNDATTO PLATE cs) Ae FIGURE 202 = - 202 Acroneuria arida Hagen * Striking color pattern; wide pronotal flange ; anal gs quite uniformly brown. PLECOPTERA NYMPHS OF NORTH AMERICA 171 PLATE 23 Acroneuria arida 202 172 THOMAS SAY FOUNDATION PLATE 24 FIGURE 203 203 Acroneuria ruralis Hagen Yellowish; wavy occipital ridge; wide pronotal flange; cerci as long or longer than body. PLECOPTERA NYMPHS OF NORTH AMERICA PLATE 24 Acroneuria _ruralis 203 173 174 THOMAS SAY FOUNDATION PLATE 25 FIGURE 204 204 Acroneuria pacifica Banks Blaze on front of head; wide pronotum; very copious anal gills. Western. PLECOPTERA NYMPHS OF NORTH AMERICA 175 PLATE 25 ae om y Bs Acroneuria 204. aif. 7 ar a. ; . eae r ote Pee ee A ¥ ; Ln * oi te Bi mast > be. 4 hae Soy ad a at ey ». * 4 Pee 7 ey t i aa 1 r ek 4 ms ‘ = ; . SW Beri os * 7, x PLATE 26 FIGURES 205-206 205 Acroneuria californica Banks Yellow spot over ocellar triangle; color baat clear ‘cut “no a - gills. ‘206 Acroneuria theodora Needhan and Claassen Dark over ocellar triangle. ts » ‘ ‘ / * ) d 4 ; 4 i \ r: Oh ep ny rT Pic 8 é (soe } Yikes, be ls >a ~ 3 . ee " ied Paine: THOMAS SAY FOUNDATION cg ’ PLECOPTERA NYMPHS OF NORTH AMERICA 177 PLATE 26 Acroneuria Acroneuria _californica theodora 206 ‘205 z a i = tary 1750 eee THOMAS SAY FOUNDATION i a 2 PLATE 27 FIGURE 207 207 Meron depressa Needham and Claassen ty, Distinct occipital ridge; anal gills; yellow mark be en en hind | ocelli. é 5 bd f 4 es - 4 et ee ERICA 179 PLECOPTERA NYMPHS OF NORTH AM PLATE 27 180 THOMAS SAY FOUNDATION PLATE 28 FIGURES 208-209 208 Leuctra decepta Claassen Long slender body; wing cases long, narrow and parallel to the body; sparsely clothed with hairs; no gills. 209 Nemoura sinuata Wu Stocky body; pronotum fringed with stout hairs; cervical gills; hind wing pads diverging from body. PLECOPTERA NYMPHS OF NORTH AMERICA 181 PLATE 28 IOI ye ff ff Leuctra decepta \ ff Nemoura sinuata \ ; 208 \ i, 209 \ ? eee , 182 210 211 THOMAS SAY FOUNDATION PLATE 29 FIGURES 210-216 Taentopteryx nivalis Fitch Yellow stripe along body; diverging wing pads; coxa three-seg- mented gills; cerci and antennae long. Nemoura vallicularia Wu (after Wu) Tracheal system of nymph, showing also tufts of peripheral tra- cheoles. Prosternal gills and their attachment to the trachea in N. venosa Bks. (after Wu) Prosternal gills of N. venosa Bks. (after Wu) Prosternal gills of N. sinuata Wu (after Wu) Male, Taentopteryx fasciata Burm. Female, Taeniopteryx fasciata Burm. PLECOPTERA NYMPHS OF NORTH AMERICA 183 PLATE 29 213 Nemoura 214 / Taeniopteryx nivalis SS Ua 210 iS Taeniopteryx fasciata 184 THOMAS SAY FOUNDATION PLATE 30 FIGURES 217-218 217 Capnia vernalis Newport Small blackish nymphs; anal field of hind wing pads not extending much beyond middle. 218 Allocapnia pygmaea Burmeister Small blackish; anal field of hind wing pads extending beyond middle. PLECOPTERA NYMPHS OF NORTH AMERICA 185 PLATE 30 2 io a x , 2 y > , ’ LQ (\ ty x I, \\ N oD re ? // N Capnia vernalis fi Allocapnia pygmaea N 217 ff 218 \ 186 219 220 221 222 THOMAS SAY FOUNDATION PLATE 31 FIGURES 219-222 Perla immarginata Say Light spot in ocellar triangle; longitudinal dark stripes on femora; basal half of abdominal tergites dark; last abdominal tergite with an inverted V-shaped notch; prominent occipital ridge. No caudal gills. Perla capitata Pictet Wavy, dark, transverse band on head through ocellar triangle; femora with dark blotches or bands at both ends; caudal half of abdominal tergites dark, except the last which is dark on sides only; prominent occipital ridge; caudal gills present. Acroneuria abnormis Newman Dark, hairy; five, more or less distinct, small light spots on head; abdomen uniformly dark; legs and cerci with long thick fringes of hairs; occipital ridge and anal gills absent. Acroneuria lycorias Newman Resembles P. capitata but lacks the occipital ridge and anal gills; caudal half of abdominal segments dark, basal half more or less yellow. PLECOPTERA NYMPHS OF NORTH AMERICA 187 PLATE 31 188 THOMAS SAY FOUNDATION PLATE 32 FIGURES 223-226 223 109 WES TILEULLG recast (a veo tete tat ea. ws toe 109 SSRs NOs are is hesn ss cae oo gen 3 Se 22 Characters, summary of ........ 20 BE MOEODOTINS Mave visia tie 6 wie oe ahs ok 63 PEROT ALD OG a igigte cole 5s Feil nut eos « 63 claasseni, Leuctra ....65-...5: 100 LG CIO MOTI © sue stite wee a se eet hos 69 CHGDOR TS ate pak cars os ws ee 68 Clioperla, key to species ...... 69 CRCHIOU eras nn tine ac aicke tls so oe 69 ROO TIAN tes reek © 2aks rane 71 CU SUNILIS Ae viet we tose ie 3 a ole etol are rps clymene, Neoperla ............. 67 Collecting implements ......... 11 Collecting -nympus ya. qs ss to's ae 9 Color, interpretation of......... 1? coloradensis, Alloperla ......... 60 coloradensis, Nemoura ......... 96 colubrinus, Isogenus ........... 45 eydippe, Chloroperla .........-. 63 decepta sLeuctra ici. eho a ot 99 depressa, Acroneuria .......... 86 DISU PIE GION IOs hates eer te seers = 3 Distributionytable, oases ee 122 dorsata, Pteronarcys .3 0.060: 31 drymo, Perlinella ... 20... 6.2.0... 79 ebria, Clioperid q... .¥. 01.28 <': cis 71 STINE QSREN OS yes tore: ena otsperet ae ern ...) .50 30 Pteronarcella .-...0. 3.9 ee 34 Pteronarcella, key to species . 30 Py, badia. oi... 2). 302 30 P. reguiaris ..2.... «rer 36 Pteronareidaé ...... 2. see 26 Pteronareys. .. 2. Js. 27 Pteronarcys, key to species ..... 29 P...biloba:... «+ .\«. s -22sn ee 30 P. californica, ..... 4262. 32 P, dorsata “ss is °+ays see ee ol P. princeps <....../5. seen 30 P. proteus. , «../: .’. «s/c 1h) See 30 pygmaea, Allocapnia . 1.2mm 112 Rearing nymphs°....2 5 eee 13 recta, Allocapnia’ |. - 2. seem 113 regularis, Pteronarcella ....3n 36 Respiration ..........sai¢es==aaae 4) Rugosities .....2.. 3: 18 ruralis, Acroneuria . j.)0¢reeee 89 Sereen cages ........ + seen 13 Sexes, determination of ........ 22 sibleyi, Leuctra ......) seen 98 Sieve net for collecting, ..... 11,412 signata, Isoperla ..<. 3 eee 75 signata, Perlodes ... 2 ..esuem 43 similis, Clioperla. .. . 46). eee ra spatulata, Alloperla (322 ema 62 Staining preparations ......... 15 Study, preservation for .... ..0. 14 Summary of characters ........ 20 Suture, clypeal-labral .. 5 ve. ake Suture, epicranial .. *... 2. eee a lieg Table, distribution and emer- PENCE. 05 Jes. ss ee 121 Taeniopteryx: 9. 1...) 101 Taeniopteryx, key to species ....103 T. californica... .... 32.2. 107 T, fasciata ..... 2... 2.5) oe 106 T..MAUTA . yess es ss «oe oe 104 TT’. nivalis”. 2.0. 4) ae 103 T..parvula . 2. .'.0s'. sae 105 Technique .....,. «+050 eee 14 Terminology used ..2, 3. .saneem 16 theodora, Acroneuria .......... 90 tibialis, Perlodes ....3 -\a aaa 44 PLECOPTERA NYMPHS OF NORTH AMERICA 199 TTADS DOL Dy PHS tres wis es 4 12 SEMD@ECIOS wasnt ccc 5.6 eiccei et vale eels a 30 vy vallicularia, Nemoura .......... 95 Men Gsd He NeMOUTS. £65 «0c ke, eo Ses 95 vernalis, Capnia VETRICA LR AE OFLA Peete care ten iettre tae 57 BVOSELUUT Citrus sate sien, Hats Sinton aut Wiaee uy vivipara, Allocapnia .....+....-. 114 WT On SOTeGIias cers ta srctetsts > cr Sonaat a 11 THIS BOOK PLECOPTERA NYMPHS OF AMERICA was set, printed and bound by The Collegiate Press of Menasha, Wisconsin. 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