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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
<i jan eee eee Clypeus
> _ _.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 «<a 9
. Mature nymphs not over half an inch in length; body usu-
ally freckled with small brown dots; cerci almost as long
as body and composed of about 25 long segments; second
tooth of lacinia very large and not followed by a fringe of
WER WS, S 3 SANE A Site en ae are Cee enna Perlesta (p. 76)
Mature nymphs usually much more than half an inch in
leneth; body concolorous or with yellow and brown pat-
tern, but not freckled; cerci usually of more than 30 seg-
24 THOMAS SAY FOUNDATION
ments; licinia with a fringe of hairs below the second
Loothe. ols pala MS ae eee at ene ae 10
10. A distinct occipital ridge extending transversely across the
head from the posterior margin of one eye to the other’
Bee Lee a Rae ea te Gill bearing Perla (p. 46)
wer No occipital ridge present; mostly strikingly patterned
“ nymphs Acroneuria (p. 80)
©
vn 11. Very small, inconspicuous, single, finger-like gills at the outer,
base of the submentum, and sometimes also on the lateral
margins of the thorax between the bases of the legs....
poo he SRR oan OSS af te antes Senin eae ie eno Perlodes (p. 41)
No gills on submenttim 2). .0-.00. 202... eee 12
12. Head very long, squarish; eyes small and set far forward so
that the distance from the hind margin of the eye to the
posterior border of the head is much greater than the
diameter of the eyés.a. a. eee Paraperla (p. 64)
Head not strikingly long; distance from the hind border of
the eye to the posterior margin of the head not much more
than the diameter of the eye ........ 2.2) 13
13. Very wide through the wing pads and with the lateral mar-
gcins of the pads broadly rounded; lacinia unidentate ;
maxillary palpus with the first four segments about equally
large in diameter, but with the apical segment strikingly
slender and the tip of the fourth segment somewhat pro-
duced beyond the base of the apical segment?...........
scien tlde le Ronda or Alloperla and Chloroperla (p. 58 and 63)
Not exceptionally wide through the wing pads; lateral mar-
gins of wing pads straight or sinuate but never broadly
rounded; lacinia bidentate, or, if unidentate then the galea
is much reduced and less than half as long as the lacinia;
apical segment of maxillary palpus not strikingly thinner
than the previous ones, although the segments are succes-
sively. reduced#in. size..h...0....054...05 40 14
* Acroneuria ruralis and A. depressa will also key out here since they
each possess a distinct occipital ridge. However, A. ruralis will be recognized
by its nearly uniform light brown color, the wide pronotum with wide
flanges, and the long cerci which are longer than the body. A. depressa is a
Western species, possesses anal gills and therefore could be confused only
with P. capitata from which it differs greatly in color pattern, as shown in
the illustrations of these two species.
* Chloroperla which has only one species, cydippe, can not easily be
separated from Alloperla but in Chloroperla the anterio-lateral angles of
the submentum are not produced beyond the mentum while in the Alloperla,
ieee are known, they are produced to, or nearly to, the base of the labial
palpi.
14.
16.
Lifes
1 Perr
19.
PLECOPTERA NYMPHS OF NORTH AMERICA 25
Maxillae very large and projecting out laterally from the
head so as to be plainly visible from above; i.e. the elbows
of the eardo and stipes stand out so as to increase the ap-
parent diameter of the head. Gill-less Perla and Isogenus
no cas ROR eR ee Oo (p. 46 and 45)
Maxillae not unusually large and not plainly visible from
VOU RD 3 Bug NR re RSS oP Ae eta ee i ce oe 15
. Apical segments of maxillary and labial palpi slender and
drawn to a sharp point; lacinia almost equally wide up
to the base of the teeth; not brightly colored nymphs,
without longitudinal stripes on the abdomen..........
RP ie ce RYU te oe, Ai gs Clioperla (p. 68)
Apical segments of palpi not very slender and not drawn to a
sharp point; lacinia gradually narrowing to the base of
the teeth; mostly contrastingly colored nymphs with
longitudinal stripes on the abdomen...... Tsoperla (p. 71)
Hind wing pads diverging considerably outward from the
body (except in Leuctra where the wing cases are long
and narrow, the hind ones about as narrow as the front
ones and lying parallel with the body, and the labial palpi
extending far beyond the tip of the ligula); gills, when
present, either at the throat or as single filaments at the
amor be Gn CUS sae rete ects cae) ed Fs NEMOURIDAE 17 (p. 92)
Hind wing pads not much divergent from the body and wider
than the front ones; gills absent; labial palpi never reach-
ing beyond the tip of the ligula...... CAPNIIDAE 19 (p. 109)
First and second tarsal segments subequal in length; hind
wing pads very wide and diverging almost at right angles
from the body, i.e. the anal margin; gills, if present,
3-seemented single filaments attached to coxae ...........
5 Se ae eee ee Taenmopteryx (p. 101)
First segment of tarsus much longer than second; gills, when
fenecent el OGaredent-the.toroatr: «ac gam ska cr. ale eres 18
Body stocky and hairy; usually a fringe of hairs around
margin of pronotum; hind wing pads much wider than
front ones; gills, if present, at throat; labial palpi not
ERLE INCAS VOM MIG UI Awlsce: ces capese\eees ot: Nemoura (p. 92)
Body slender, smooth; hind wing pads hardly wider than
front ones; no gills; labial palpi extend beyond ligula
2 er EES ER cel Se eee Leuctra (p. 96)
Anal field of hind wing pad extends far beyond middle of
GURL YOO Rik og ea a ea ere Allocapnia (p. 111)
Anal field of hind wing pad does not extend much beyond
the middie of the wing case............. Capnia (p. 109)
Family PTERONARCIDAE
The nymphs of this family are readily distinguished from all
other stoneflies. They are the only ones that have tufts of gills
on the first two or three ventral abdominal segments. Their bodies
are cylindrical and their color is almost uniformly brown to
blackish.
Head rather small, narrower than prothorax; three ocelli
placed in an equilateral triangle; antennae long and slender with
prominent antennal plates; occiput rugulose; anterior to the ocel-
lar triangle a reddish V-shaped or M-mark. Mouth parts well
developed for masticating the vegetable food on which they
subsist.
Labrum narrow, about twice as wide as long.
Mandibles asymmetrical; the left mandible with five unequal
teeth followed mesad by a well-developed molar beyond which
there is a tuft of hairs; the right mandible usually possesses
only four unequal teeth.
Maxillae: maxillary palpus stout, five-segmented; galea rather
broad, and made up of two segments—a short basal, and a large
apical segment—tipped with a bunch of spinules; lacinia triden-
tate ; cardo about half as long as the stipes.
Labium much longer than wide, with glossae and paraglossae
subequal; the three-segmented palpus stout; mentum a small,
narrow transverse triangular band; submentum very large with
a sinuated posterior margin; hypopharynx rounded, hairy, and
projecting beyond the tip of the glossae.
Pronotum about twice as wide as long, the sides somewhat
flaring and the angles usually more or less produced; surface
somewhat rugulose. Legs stout; segments of tarsus unequal, the
second about half as long as the first, and the third more than
twice as long as one and two combined; margins of femur and
tibia with a fringe of hairs. Wing pads well developed.
Abdomen eylindriec, the abdominal segments either smooth or
with lateral teeth or hooks. Cerei hardly ever more than half as
long as the body. Thirteen to seventeen pairs of tufted gills,
located on the ventral side of the thorax and on the first two or
three abdominal segments.
General Distribution
Quite universally distributed over North America (except
Pteronarcella which is a Western genus) wherever small, cold,
upland spring brooks may be found.
PLECOPTERA NYMPHS OF NORTH AMERICA 27
Biological Notes
The nymphs of this family are all herbivorous and feed upon
almost any kind of fresh and decaying vegetable matter. Stomach
examinations often reveal large pieces of wood and other vege-
table matter in the intestines of the large nymphs. The nymphs
are not adapted to live in swift running water and normally in-
habit the small upland spring brooks which are not subject to
disturbance by floods. Here in the accumulated debris on the
bottom of the little streams one will find the nymphs well pro-
tected by the concolorous brown of their bodies which simulate
short pieces of dead and decaying wood. The nymphs are very
clumsy and are unable to move rapidly. Upon being taken out of
the water, they curl up, remain motionless for some time, and
thereby easily escape detection in the debris.
Smith (53) quotes Barnston as saying that ‘‘it [Pteronarcys
nymph] constantly resided in the water at the bottom of streams
and rivers,’’ and then states further, ‘‘I have always found it
clinging to the under side of stones in the most rapid parts of
streams.’’? Muttkowsky (21) reports Pteronarcys nymphs from
rapid water streams in Yellowstone Park. I have found them very
common only in the smaller spring brooks, and only occasionally
have I observed the nymphs in the swifter water. The nymphs of
this family lack the stream-line form of body and their food
habits would not seem to permit their remaining under stones
in the rapid part of streams.
Not much is known about the life history of the species of
this family. The life cycle occupies not less than two years, and,
in the genus Pteronarcys, in all probability occupies three years.
Emergence takes place during the summer months, and it is very
easy to rear the species if fresh running water is available.
Genus PIERONARCYS Newman
This genus includes our largest stoneflies, the mature nymphs
measuring up to fifty millimeters or slightly more, in length.
The nymphs are of an almost uniform chocolate to blackish color,
more cylindrical than any of the other large stoneflies, and are
further easily recognized by their copious white gills which cover
the entire ventral surface of the thorax, as well as the first two ab-
dominal segments.
Head rather small and much narrower than the prothorax
which flares somewhat over the head; antennae long, slender,
tapering, and made up of fifty-five to sixty, or more, segments;
the three ocelli forming an equilateral triangle, the hind ocelli
28 THOMAS SAY FOUNDATION
being a little closer to each other than to the eyes; on either side
of the ocellar triangle a rounded reddish spot, and a reddish V-
or M-shaped mark in front of the ocellar triangle; occiput with
longitudinal reticulations; supra-antennal plates well developed.
Prothorax about twice as wide as long with flaring sides and
with its angles more or less produced; surface of pronotum with
embossed markings; meso- and metanotum with coloration simi-
lar to that of pronotum but less rugose ; in some species the lateral
margins of pronotum and wing pads are lighter. Legs stout,
brown; femora usually with a narrow median lighter line above;
outer margin of femora and tibia fringed with hairs; first two
segments of tarsus short, the first about twice as long as the
second, the third at least twice as long as one and two together ;
two tarsal claws, each with a blunt tooth at the inner base.
Abdomen cylindric, segments either smooth or with lateral
teeth. In the female the tenth abdominal tergite is medially
produced into a sharp triangular conical process, while in the
male it is variously modified; cerci rather short, containing up
to forty or more segments.
The thirteen pairs of gills on the ventral side copious and long,
and arranged as follows: prothorax with five pairs, three pairs
in front of the prothoracic legs arranged as a transverse collar
along the neck, and two pairs just posterior to the front pair
of legs; three pairs on the mesothorax; three pairs on the meta-
thorax and one pair on each of the first two abdominal segments.
Mandibles asymmetrical, the dentation of the left and right
mandibles being different. The left mandible has the following
five sharp teeth: first, second, and fourth longest, largest, and
most pronounced; third and fifth teeth small, and, in some eases,
fifth rather inconspicuous. These five teeth followed by a large
molar, and beyond this the mandible bears a buneh of long
hairs. The right mandible has four teeth, the first two of which
are largest; following the fourth tooth which is the smallest, a
large quadrangular molar, and this is likewise followed by a
brush of hairs.
Labrum almost exactly twice as wide as long, with long hairs
on the front margin, which is concave in the center; hind margin
somewhat sinuate; posterior angles sharp; chitinous prolonga-
tion for muscle attachment about one-third as long as width of
labrum.
Maxillae: maxillary palpus composed of five rather stout seg-
ments; segment one a trifle longer than wide, segment two about
one-fifth longer than wide, segment three half again as long as
wide, segment four slightly less than twice as long as wide, seg-
PLECOPTERA NYMPHS OF NORTH AMERICA 29
ment five nearly three times as long as wide. Palpi sparsely
clothed with hairs. Galea rather broad and blunt, and slightly
longer than the lacinia; made up of two segments, a short basal
one about one-fourth the length of the entire galea, and larger
distal one clothed with hairs, and at the tip a bunch of spinules.
Lacinia bears three teeth at the tip, two of which are about equal
in length, the third short ; inner surface grooved, and the ventral
carina which borders the groove bears a row of long hairs.
Labium and hypopharynx: labium almost twice as long as
wide; glossae and paraglossae about equally long so that the
labium is made up of four subequal lobes, the lobes hairy and
bearing at their tips bunches of hairs or spinules, the glossae
always bearing a bunch of hairs, and the paraglossae bearing
either hairs or spinules. Mentum narrow and broadly triangular ;
submentum a little wider than long and widened posteriorly with
the posterior margin sinuate. Labial palpi with three segments,
first a little longer than wide, second half again as long as wide,
third almost twice as long as wide. Entire labium more or less
clothed with hairs.
Key to Nymphs of Pteronarcys
1. Abdominal segments with large lateral teeth or hooks..... 2
Abdominal segments without lateral hooks .............. 3
2. Hooks on abdominal segments large and directed outward,
those on segments seven and eight almost as large as the
preceding ones; ceri more than half as long as abdomen;
front angles of pronotum produced. .biloba Newm. (p. 30)
Hooks appressed to body, small on segment seven, and in-
conspicuous on eight; cerci less than half as fone as abdo-
men; front angles not noticeably produced .............
co oh SE a ee a proteus Newm. (p. 30)
3. Lateral prothoracie teeth long, slender, sharp, and directed
outward; supra-antennal plate prolonged into a sharp
tooth; wing pads pointed...... californica (Newpt. (p. 32)
Lateral prothoracic teeth short and not directed outward so
much; supra-antennal plate blunt; wing pads rounded.. 4
4. Eastern species; prothoracie teeth usually as long as wide;
ninth sternite of male produced beyond the tenth; tenth
tergite of female nearly straight...... dorsata(Say)( p. 31)
Western species; prothoracic teeth usually shorter than wide ;
ninth sternite of male narrow and not produced; tenth
tergite of female with the apex considerably elevated....
= 3 Mahe ee ee ere princeps Bks. (p. 33)
30 THOMAS SAY FOUNDATION
Pteronarcys biloba Newm.
(Plate 2, figs. 17-21; plate 11, figs. 171-172; plate 34, fig. 232; plate 35,
figs. 235-236.)
Length of body up to 40 mm.; antennae up to 16 mm.; cerci
up to 12 mm.
General color, chocolate brown to blackish, sometimes with in-
distinet lighter longitudinal stripes upon the abdomen; in living
nymphs, orange markings on the lateral margins of the pronotum,
and a yellowish orange band on the middle portion of the an-
tennae and cerci, which fades to pale yellow in alcoholic speci-
mens.
Head much narrower than prothorax; uniformly brown except
for the somewhat lighter smooth rounded marks each side of the
ocellar triangle, and usually with a lighter median area near the
posterior margin of the occiput, which possesses numerous longi-
tudinal rugosities; antennae of sixty or more segments, blackish,
but with a yellow band covering four to ten segments, just be-
yond the middle, and lighter toward the tip.
Pronotum almost twice as broad as long, widened posteriorly,
front angles considerably produced, hind angles sub-acute;
front margin somewhat concave, hind margin sinuate; dise of
pronotum with coarse but not very deep rugosities; dark brown
with lighter margins.
Legs brown with tips of the femora and the tarsi lighter, also
a narrow lighter longitudinal line on the femora; the femur, tibia,
and tarsus fringed with hairs.
Abdomen cylindric, dark brown with lighter markings; ab-
dominal segments one to eight with large lateral apical hooks
directed outward from the body. Although these hooks become
shorter posteriorly, they are very pronounced on the eighth seg-
ment; segments nine and ten of abdomen smooth; tenth tergite
much produced. Cerei of about forty segments, dark brown, with
a yellow band beyond the middle, and sometimes with the tip
lighter.
Many nymphs from: Ithaca, N.Y.; Oneida Co., N.Y.; Tarbel,
N.Y.; Allegany Co., N.Y.; Old Forge, N.Y.; Moffitsville, N.Y-.;
Osgood R., Adirondack Mts., N.Y.; Ammanoosie R., W. Milan,
N.H.
Pteronarcys proteus Newm.
(Plate 1, figs. 11-16; plate 11, figs. 169-170; plate 34, fig. 234; plate 35,
fig. 237.)
Length of body up to 40 mm.; antennae up to 21 mm.; ecerci
up to 7 or 8 mm.
PLECOPTERA NYMPHS OF NORTH AMERICA © 31
General color chocolate brown to dark brown, paler on the
ventral surface.
Head much narrower than pronotum; brown, with rounded,
smooth, yellowish dises on each side of the ocellar triangle; an-
tennal plates prominent but not much produced; occiput with ©
many longitudinal rugosities. Antennae brown, the middle third
usually paler, composed of sixty to sixty-five segments.
Pronotum nearly twice as broad as long, slightly widened
posteriorly, the angles all somewhat produced, but less than in —
biloba; front margin a little arcuate, hind margin convex; discs
rugose.
Legs brown, femur, tibia, and tarsus fringed with long hairs.
Abdomen brown, segments one to seven with lateral apical
hooks, and usually also a suggestion of a hook on segment eight.
These hooks are directed backwards and lie close to the body ;
tenth tergite much produced. Cerei brown, usually a lighter band
in the middle, and lighter at the tip; thirty to thirty-five seg-
ments.
The chief difference between proteus and biloba is the structure
of the abdominal hooks, the length of cerci and the shape of
the pronotum; biloba always has distinct hooks on segment eight
and all hooks are directed away from the body, proteus has only
a suggestion of hooks on abdominal segment eight, and even on
seven the hooks are often inconspicuous, while the remainder of
the hooks are always close to the body. The cerci are shorter in
proteus than in biloba; the front angles of: the pronotum are
less produced in proteus than in biloba. The gills are very simi-
lar to those of biloba.
A juvenile specimen, 10 mm. long has only ten pairs of gills
which are distributed as follows: three pairs in the cervical
region, two pairs between pro- and mesothoracic legs, two pairs
between meso- and metathoraciec legs, one pair between the hind
pair of legs, and one pair on each of the first abdominal segments.
From Ithaca, N.Y.; Danby, N.Y.; Boquet R., Elizabethtown,
N.Y.; Wilmington, N.Y.; Lake George, N.Y.; Blossburg, Pa.
Pteronarcys dorsata Say
(Plate 1, figs. 1-5; plate 11, figs. 173-174; plate 34, fig. 231.)
Length of body up to 40 mm.; antennae up to 23 mm.; cerci
up to 17 mm.
Color dark brown, sometimes almost uniformly so, but in
some specimens with lighter markings on thorax and abdomen.
Head brown, with a lighter area on each side of the ocellar tri-
32 THOMAS SAY FOUNDATION
angle; antennal plate more prominent that in proteus and biloba,
but with the outer angles broadly rounded ; antennae brown, with
about seventy segments.
Prothorax much broader than long, widened posteriorly ; front
margin nearly straight, hind margin convex; front angles pro-
duced laterally, but rather bluntly pointed ; hind angles also some-
what produced. Legs stout; femur, tibia, and tarsus fringed with
hairs. Wing pads broadly rounded at tip.
Abdomen eylindrie, brown, but with lighter markings, in some
specimens so pronounced that the abdomen presents a striped
appearance. The caudal end of the abdomen differs greatly in
the sexes. In the female, the last tergite ends in a triangular
conical process which is only shghtly upturned. In the male, the
tenth tergite is produced into a large process which turns down-
ward and ends in asmall tubercle; ninth sternite broadly rounded
and produced considerably beyond tenth sternite. The cerei are
long and composed of some forty-five segments.
Spring Creek, Seminole Co., Ga.; Alma, Wis.; White Pigeon,
Mich.; Otter R., Portage Co., Mich.; Washington, D.C.; Sweet-
water Branch, Fla.; Fairport, Iowa.
Pteronarcys californica Newport
(Plate 1, figs. 6-10; plate 11, figs. 175-176; plate 34, fig. 233.)
Length of body up to 50 mm.; antennae up to 22 mm.; cerei
UDsosidemme:
Color dark brown, sometimes with lighter spots on thorax and
abdomen, and in some specimens the abdomen with longitudinal
lighter stripes.
Head much narrower than pronotum, brown, with smooth,
round areas on each side of ocellar triangle; occiput corrugated,
antennal plate large with the posterior angles produced into a
sharp process. Antennae brown, of about seventy segments.
Pronotum much wider than long; front margin slightly con-
vex; hind margin very convex; widened posteriorly, and with all
four angles produced laterally into a long, upeurved, pointed
processes; discs somewhat rugose. Fore and hind wing pads tri-
angular and sharply pointed. Femur, tibia, and tarsus each with
a thick fringe of hairs.
Abdomen cylindric, the sexes very distinct in the mature
nymphs. In the female, the tenth tergite is produced into a
long triangular conical process which turns upward at the tip.
In the male, the tenth tergite is very large, humped up and
PLECOPTERA NYMPHS OF NORTH AMERICA = 33
suddenly turned down, with a sharp tooth at the tip, directed
caudad; on each side near the base of the tenth tergite a swol-
len area; ninth sternite not at all produced.
Pecos, N. Mex.; Yellowstone R., Yellowstone Nat’l. Park;
Weber R., Utah; Redwood Creek, Humboldt Co., Calif.; Poudre
Canon, Col.; Boseman, Mont.; Ogden, Utah; Logan R., Utah;
Voleano Creek, Calif.
Pteronarcys princeps Banks
(Plate 35, fig. 238.)
Length of body up to 38 mm.; antennae up to 16 mm.; cerci
up to 11 mm.
General color dark brown, sometimes with a few lighter spots
on the abdominal segments.
Head much narrower than pronotum; surface somewhat ru-
gose; brown except the frontal M-line, the lateral rounded marks,
and the line along the elypeal-labral area, all of which are yellow-
ish.
Antennae uniformly brown, and composed of about sixty seg-
ments. Antennal plates low and inconspicuous.
Pronotum much wider than long, a little widened posteriorly ;
all angles produced into short blunt processes, the front ones
being directed outward and the hind ones rearward; surface ru-
gose. Wing pads broadly rounded. Abdomen cylindric; brown,
but in some specimens with small lighter dots on the tergites.
Cerci brown, somewhat lighter toward the tip, and containing
about forty segments.
The sexes are readily recognized, and in the structural char-
acters of the abdomen, the nymphs are very similar to Pt. cali-
fornica, but they are readily distinguished from californica by
the more bluntly pointed wing pads, the shorter prothoracic
processes, and the blunt supra-antennal tubercles.
Seemann (51) records this species from California, and states
that she collected one adult and numerous nymphs. The adult
male was determined by Dr. Needham as Pt. princeps, and Mrs.
Seemann assumed the nymphs to be of the same species. I have
the nymphs which she collected in Andreas Canyon, Cal., and
the above description has been made from these specimens. In-
asmuch as princeps and californica are very closely related,
and inasmuch as these nymphs are very similar to those of cal-
formca and yet show specific differences, I feel quite certain that
the identification is correct.
34 THOMAS SAY FOUNDATION
Pteronarcys sp.
I have before me a unique Pteronarecys nymph which was col-
lected from the Boquet River, Elizabethtown, New York, July
20, 1929 by Mr. Sid Robinson. This nymph is not fully grown,
and measures only 16 mm. in body length. It.is most closely re-
lated to Pt. biloba, but differs from biloba in several respects.
The color is almost black, with a yellow, transverse elongate spot
on each side of the posterior margin of the pro-, meso-, and meta-
notum. Antennae blackish, with a yellow band in the middle, and
yellow at the tips. Cercei also with a middle yellow band. At the
base of the mesothoracic wing pad there is a sharp lateral spine,
and the wing pads are sharply pointed. Abdominal segments one
to seven with large lateral hooks, and just a suggestion of a hook
each side of the eighth segment.
The spine at the base of the mesothoracic wing pads, the colora-
tion, and the absence of hooks on the eighth abdominal segment
preclude this from biloba. It may possibly prove to be Pt. com-
stockt Smith.
Genus PTERONARCELLA Banks
This genus is very closely allied to Pteronarcys, but the
nymphs, when fully grown, are much smaller (not over one inch
in length), and are readily distinguished from Pteronarcys by
the fact that, in addition to having tufted gills on the first two
abdominal segments as in Pteronareys, they also have tufted
gills on the third abdominal segment. The genus occurs only in
the Western States.
Color nearly uniform brown, mostly with inconspicuous lighter
markings, and sometimes with light longitudinal lines on the
abdomen.
Head much narrower than prothorax; brown, sometimes with
a blacker area over the ocellar triangle, and with a rounded light
spot on either side of the ocellar triangle; three small ocelli ar-
ranged in an equilateral triangle; antennae about as long as
pro-, meso-, and metathorax together, composed of fifty or more
seoments in the mature nymph; antennal plates narrow and low.
Mouth parts of the herbivorous type, very similar to those of
Pteronarcys.
Pronotum much wider than long with broadly rounded angles,
and with the lateral margin flaring out considerably ; dises brown
and somewhat rugulose, the lateral margins smooth and lighter
in color. Meso- and metanotum brown; wing pads large in mature
nymphs, and extending out far from the body. Legs quite stout ;
PLECOPTERA NYMPHS OF NORTH AMERICA — 35
femora and tibiae fringed with hairs, first segment of tarsus
about twice as long as second, third segment about twice as long
as one and two combined; two large tarsal claws.
Abdomen cylindric, segments smooth, tenth segment narrow
below, and above produced into a triangular pointed conical
process in both male and female; cerei nearly as long as ab-
domen, composed of thirty or more segments in the mature
nymph, somewhat hairy and each segment with a whorl of short
spines at the distal end.
In the mature nymph we find seventeen pairs of tufted gills
which are located as follows: three pairs in the cervical region ;
a small pair on the antero-lateral margin of the front legs; four
pairs encireling the body just posteriorly to the front pair of
legs; one pair between the mesothoracic legs; three pairs located
back of the base of the mesothoracie legs; one pair between base
of the metathoracic legs; one pair on the postero-lateral margin
of the metathoracie legs and one pair on each of the first three
abdominal segments.
This genus occurs only in the Western States. Pteronarcella
badva was reared by Dr. J. G. Needham from nymphs collected
in Logan River, Logan, Utah, the adults emerging June 23, 1926.
These are the only rearing records of the genus, but fortunately
mature nymphs in which the adult genital characters could be
distinguished have enabled me to identify also the immature
stages of Pt. regularis.
The nymphs are herbivorous, and from their body form and
general structure, I would infer that they generally inhabit the
smaller spring brooks where much dead and decaying vegetable
matter accumulates.
Key to the Nymphs of Pteronarcella
1. Filaments of gill tufts long; at least twice as long as the
basal conical process of gill tufts..... badia Hagen (p. 35)
Filaments of gill tufts short; less than twice as long as bases
gf) 3OO" 1 ARTA gad ee ae regularts Hagen (p. 36)
Pteronarcella badia Hagen
(Plate 2, figs. 22-26; plate 12, figs. 177-178; plate 13, fig. 185.)
Length of body up to 21 mm.; antennae up to 9 mm.; cerci
up to 9 mm.
Color almost uniformly brown but often with lighter markings
on the abdomen.
Head much narrower than pronotum, brown, sometimes with
36 THOMAS SAY FOUNDATION
a dark, squarish mark over the ocellar triangle; a pair of lighter
marks each side of the ocellar triangle; occiput slightly rugulose ;
antennae of about forty-five segments.
Pronotum nearly twice as broad as long; brown, with lhghter
lateral margins; discs somewhat rugose ; angles broadly rounded ;
front margin nearly straight, hind margin somewhat convex in
the central area. Legs brown, the tips of the femora and the
tarsi yellowish. Femora and tibiae fringed with hairs.
Abdomen eylindric, uniformly brown or with three, more or
less distinct, longitudinal lighter lines; tenth abdominal segment
produced into a sharp conical process in both sexes; cerci com-
posed of some twenty-two segments. Seventeen pairs of tufted
gills, which are considerably longer than in Pt. regularis and are
arranged as described under the genus Pteronarcella.
There seems to be very little difference in the size and structure
of the nymphs of the two species of Pteronarcella. Pt. badia has
longer gills than Pt. regularis but otherwise the nymphs appear
very similar. Pt. regularis probably has a somewhat wider fringe
of hairs on the tibiae and femora than Pt. badva.
Reared specimens of Pt. badia from Logan, Utah, and mature
nymphs of Pt. regularis from Colorado, in which the developing
genital plate of the female could be clearly seen, have enabled
me to separate the two species.
I also have three juvenile forms which apparently are Pt.
badia because they have been collected in Logan, Utah, where
the reared specimens of this species were found. These specimens
measure 5 mm. in length. The nymphs have large spines on the
legs, thorax and abdomen but seemingly not as numerous as in
regularis. There are nine pairs of gills located similarly to those
in the 3.5 mm. size of Pt. regularis. The antennae have about
twenty-three segments and the cerci about twelve segments.
Pteronarcella regularis Hagen
(Plate 12, figs. 179-180.)
Length of body up to 21 or 22 mm.; antennae up to 9 mm., or
as long as the entire thorax; cerci up to 9 mm.
Color brown with some lighter markings, especially noticeable
on the abdomen of some specimens.
Head much narrower than prothorax, brown, with lighter
rounded marks outside the ocellar triangle; occiput somewhat
lighter, and with faint reticulated markings; antennae of some
forty-five segments.
Pronotum almost twice as wide as long; angles broadly
PLECOPTERA NYMPHS OF NORTH AMERICA = 37
rounded; front and hind margins nearly straight, sides flaring ;
dises of pronotum somewhat rugose; lighter areas on lateral
margins, as well as near the front and posterior median areas.
Meso- and metanotum likewise with lighter spots. Legs brown ;
tips of femora and the tarsi lighter; femora and tibiae with a
fringe of whitish hairs.
Abdomen eylindrie, brown, with three more or less distinct
longitudinal stripes on the dorsum, one in the center and one on
each side along the median area of the lateral fields; tenth ter-
cite produced into a triangular process in both sexes. Cerei com-
posed of some twenty-five segments.
The gills are arranged as in Pt. badia but the individual fila-
ments of the tufts are shorter than in badua.
In the maturer nymphs, the genital characters, especially the
genital plate of the female, can often be observed underneath
the nymphal chitin, and thus specific identification becomes very
simple.
I have two juvenile forms from Estes Park, Colorado, which
probably belong to this species, although the specimens differ
much in appearance and structure from mature nymphs of either
badia or regularis. One of these nymphs is only 3.5 mm. long.
The most striking feature of this specimen is its spiny body.
The femora and tibiae are covered with large spines, as are also
the lateral margins of the meso- and metanotum and the abdom-
inal segments. There are only nine pairs of gills, and these are
located as follows: one pair anterior, and two pairs posterior to
the prothoracic legs; one pair between, and one pair posterior
to the mesothoracie legs, and one pair on each of the first three
abdominal segments. The antennae are composed of fifteen seg-
ments, and the cerei of thirteen segments.
The second juvenile form measures 6.5 mm. in length, and
resembles the smaller specimen in that the legs are covered
with large spines. However, the spines on the thorax and the
abdomen are fewer in number; the antennae are composed of
twenty-eight segments and the cerci of sixteen segments. In
this specimen there are ten pairs of gills distributed as in the
smaller specimen except that there are two pairs anterior to
the prothoracic legs, instead of one pair as in the smaller form.
Inasmuch as these two specimens were collected in the same
locality and at the same time as the mature nymphs of Piero-
narcella regularis, it seems very probable that they are the same
species. Furthermore, it would indicate that the life cycle of this
species occupies two years.
PELTOPERLIDAE new family
The genus Peltoperla has heretofore been placed in the fam-
ily Perlidae. In a general way the adults are not greatly differ-
ent from the adults of the other genera of the Perlidae, but
the nymphs are so unique in structure and so unlike in habits
from other genera that it seems best to place this genus in a
separate family.
The nymphs of Peltoperla are herbivorous while the nymphs
of all the other genera of the Perlidae are carnivorous.
The Peltoperlidae are readily recognized in the immature
stages by the roach-like form of the nymphs; the large shield-
like pro-; meso-, and metanotum; short abdomen; very wide
legs; short cerci; and the short head bent under the body. The
mouth parts are of the herbivorous type, and similar in struc-
ture to the mouth parts of Pteronarcidae.
The family is represented by a single genus Peltoperla which
is distributed over the Eastern, Southern and Western States.
Genus PELTOPERLA Needham
The nymphs of this genus are readily recognized by their
roach-like form. Body broad and flattened; the thorax consists
of large brown chitinized plates which extend laterally over the
side of the body; the head is curved under so as to be only part-
ly visible from above; the abdomen is very short, with usually
not more than five or six segments visible from above; on the un-
derside, the thorax consists of three large plate-like shields rep-
resenting the pro-, meso- and metasterna; the legs are broad and
flattened.
The wing pads are not clearly defined, but are present as con-
tinuations of the meso- and metathoracie tergites; legs broad.
and short; coxa very broad and posteriorly produced into a
rounded lobe; femur with a deep groove on the inner margin,
into which the tibia fits when the leg is folded; first and second
tarsal segments short, subequal, and the two together less than
half as long as the third segment.
Gills, when present, occur as single fleshy filaments attached
under the meso- and metasterna. According to Uéno, these fila-
ments are attached to the coxae but in Peltoperla arcuata they
are outgrowths of the meso- and metaplurae and originate near
the base of the legs.
The sexes are very similar in the nymphs but the females may
PLECOPTERA NYMPHS OF NORTH AMERICA — 39
be recognized by a small median notch on the hind margin of
the eighth abdominal sternite.
The mouth parts are of the typical herbivorous type: labrum
wider than long, densely covered with hairs, especially on the
anterior margin; mandibles broad and asymmetrical, each man-
dible with four or five unequal teeth followed by a broadened
molar which is slightly hairy or spinulose, and beyond this a
bunch of long hairs; maxillae broad; lacinia bidentate, the sec-
ond tooth nearly as long as the first, followed by a row of long
hairs; galea broad, flattened, somewhat hairy, and at the tip a
bunch of rather long hairs; maxillary palpus considerably longer
than the lacinia; labium with a large, wide submentum; men-
tum a narrow transverse band; the glossae shorter than the para-
glossae and beset with long hairs; the three-jointed labial pal-
pus, when fully extended, reaches beyond the tip of. the para-
elossae; hypopharynx rounded and produced normally to the
tip of the glossae.
The nymphs of this genus are herbivorous and are usually
found in small fresh-water spring brooks where the current is
quite slow, and where dead leaves and debris accumulate. In
such localities Peltoperla may usually be found in considerable
numbers. By collecting a handful of leaf-drift and sorting it
carefully, one can usually find these roach-ike nymphs. P. arcu-
ata, which is the most common species in the vicinity of Ithaca,
apparently has a two-year life cycle.
I have many nymphs collected from various localities, and all
of these agree with the above generic description, but P. arcuata
is the only species in the genus which has been reared to maturity.
The other nymphs, I have been unable to identify to species.
Peltoperla arcuata Needham
(Plate 2, figs. 27-32; plate 12, figs. 183-184; plate 14, figs. 186-187.)
Leneth of body up to 9 mm.; antennae up to 6.5 mm.; cerci
up to 3 mm.
General color chestnut-brown, with somewhat lighter areas on
the prothorax, antennae, legs, and cerci.
Because of the deflexed condition of the head, it appears to
be very wide and short. The head is much narrower than the
pronotum, and is bent over to such an extent that the clypeus and
labrum are directed rearward underneath. The color of the head
is uniformly brown except for a little lighter area around the
compound eyes, which are black and rather small; epicranial
suture very distinct; hind ocelli black, plainly visible, and about
40 THOMAS SAY FOUNDATION
as far from each other as from the inner margin of the compound
eyes; front ocellus only indicated by a small depression ; surface
smooth, with a feeble coating of fine hair; antennae light brown
in color, of fifty or more segments.
Pronotum about twice as wide as long; front and hind margins
nearly straight, much widened posteriorly; hind angles very
broadly rounded; front angles narrowly rounded; surface smooth
and densely coated with hairs, the postero-lateral angles with
branches of long hairs; the marginal groove in this species repre-
sented only back of the anterior margin; meso- and metanotum
longer than the pronotum, and slightly wider; surface smooth,
but with a general coating of fine hairs, and with longer spine-
like hairs on the lateral margin, as well as on the surface toward
the lateral margin.
Legs broad, short, and spiny; the coxa broad, and the outer
areas produced into a rounded lobe margined with long hairs,
the inner part of the coxa bears on the distal end a row of long
spines, and another shorter row of spines farther back ; trochanter
somewhat triangular, with a row of spines at the distal margin ;
femur about half as wide as long, on the inner margin with a
deep groove; on the outer margin with a fringe of hairs, and on
the surface with numerous short hairs and spines; tibia a little
shorter than the femur, with many short spines, and on the outer
margin with a fringe of long hairs; first two segments of tarsi
short, subequal, and the two together less than one-half as long as
the third.
Abdomen flattened; all except the last four or five segments
usually covered with the large metanotum; posterior margin of
the abdominal segments with a fringe of spines which are espe-
cially long on the last segment; cerci rather stout at the base,
gradually tapering to a slender point and made up. of about
twenty-five segments.
The pro-, meso- and metasterna developed into large flat
shields.
The five pairs of filamentous gills are located as follows: two
pairs at the outer base of the mesothoracic leg almost completely
covered by the mesonotum; two pairs on the metathorax; and
one pair on the underside of the metasternum, located at a
point half way between the base of the leg and the postero-lateral
angle.
This species occurs in the Eastern States where the nymphs may
be found in small spring brooks among the leaf drift and debris.
Many reared nymphs from Ithaea, N.Y.
Family PERLIDAE
This family includes most of the more brightly or strikingly
colored nymphs. They are all carnivorous. Head as wide or
shghtly wider than pronotum; either two or three ocelli; epi-
cranial suture distinct; clypeo-frontal suture absent; antennae
long and slender. Pronotum much wider than long, variously
marked. Meso- and metanotum with the wing pads either only
slightly produced and indistinctly set off from the body, or the
wing pads may be produced into long, distinct appendages. Gills
either present or absent. When present they may be small and
finger-like (Perlodes), and attached to the submentum or thorax,
or the gills may be present as tufted branches on the thorax,
and in some eases tufted gills are also found attached to the
subanal lobes between the cerci. The cerci are long and slender
and made up of many segments. The mouth parts are of the
carnivorous type and therefore differ in structure from the mouth
parts of the other families.
The labrum is very short and wide and bears a distinct epi-
pharynx which is very flexible and may be extended or retracted.
The mandibles are quite narrow, and beyond the teeth there is a
fringe of hairs, but no molar. The maxillae also differ in structure
from the maxillae of other families. The lacinia terminates in a
long sharp ineurved tooth, and in most cases possesses a second
long tooth. The galea is much reduced.
The most striking feature of the labium is the unequal size of
the glossae and the paraglossae. The glossae are reduced to small
lobes, while the paraglossae are developed into very large lobes.
The hypopharynx is normally produced to or beyond the tips of
the glossae.
The genera belonging to this family are such a varied lot that
very little can be said about the general biology which will apply
to the entire group. The majority of the genera are found in
rather swift running water. .
Genus PERLODES Banks
Stoneflies of this genus are restricted to the Rocky Mountain
region and the Western States. The nymphs are recognized by the
presence of a pair of small, single, finger-like, tracheal gills which
are attached to the outer, lower base of the submentum of the
labium. In addition to this pair of gills, some species of the genus
have the same type of gills on the conjunctivae on the ventral
42 THOMAS SAY FOUNDATION
side of the prothorax. The head is very thick and the maxillae are
very large, bulging out each side of the head so as to be visible
from above. General color yellowish brown with yellow markings.
Three ocelli placed in a triangle of which the base is longer than
the sides; eyes medium in size; a more or less plain occipital
ridge is noticeable, composed largely of short stout brown hairs;
epicranial suture distinct.
Pronotum narrower than head, wider than long, with broadly
rounded angles; surface of pronotum somewhat rugulose ; meso-
and metanotum marked similarly to pronotum ; wing pads almost
parallel to body; legs with a fringe of long fine hairs on the
femora and the tibiae; first and second tarsal segments very short,
subequal ; one and two together not over a fourth as long as third.
Abdomen slightly flattened; tenth tergite triangularly pro-
duced ; cerci more than a third as long as the body, with a fringe
of hairs on the dorsal surface, and each segment ending in a
whorl of short hairs.
The mouth parts are of the typical carnivorous type, the most
conspicuous feature in which they differ from other genera of
the Perlidae being the structure of the maxillae and labium.
Labrum about three times as wide as long, anterior margin
with long hairs, and with many others on the ventral surface.
Mandibles slightly asymmetrical, each mandible having five or
six teeth, placed in two groups, one of three, and the other of
three or two. Following the teeth there is a fringe of hairs on
the inner margin, and also a row of hairs on the ventral surface
and one on the dorsal surface.
Maxillae very large; lacinia wide at base and bidentate, with
the second tooth not much more than half as long as the apical
one; galea slender and eylindric, with a small, membranous, at-
tenuated, spinulose tip; palpus five-segmented; cardo and stipes
very large and massive.
Labium: glossae small and rounded; paraglossae large, pear-
shaped, and directed inward, with a membranous spinulose tip ;
mentum a narrow transverse band; submentum large and bearing
at each outer, basal corner a small single gill; hypopharynx
broadly rounded, and at the apex closely beset with fine bristle-
like hairs.
Nothing is known about the biology of this genus. No specimens
have been reared, and identification of the species treated in this
paper was made possible by studying the genital structures in
mature nymphs. The structure of the nymphs would indicate
PLECOPTERA NYMPHS OF NORTH AMERICA 48
that they live in swift water, are carnivorous, and probably have
a two-year life cycle.
Key to the Nymphs of Perlodes
1. Small finger-like gills present only on the outer base of the
submentum; no gills on thorax........ americana (p. 44)
Small finger-like gills on the sides of the thorax in addition
Pet UOR GLI ON LUessUDMENTUM, 41a vena dba cus anne etree hae es 2
2. Four pairs of finger-like gills; one pair on submentum, three
Dains.on the sides. of the thorax. 4.5. .3.- signata (p. 43)
Three pairs of finger-like gills; one pair on submentum and
ey Oa OREO GORE kien co yen sot once reek eee tibialis (p. 44)
Perlodes signata Hagen
(Plate 12, figs. 181-182.)
Length of body up to 28 mm.; antennae up to 10 mm.; cerci
up to 10 mm.
General color yellowish brown, varied with yellow markings;
the brown accentuated by the presence of an irregular coating
of short brown hairs.
Head about as wide as long, thick, with very large maxillae
which protrude each side so as to be visible from above; three
small ocelli arranged in a triangle whose base is greater than its
sides; yellow frontal M-line distinct; a yellow mark each side
of the ocellar triangle; the occipital ridge meets the epicranial
suture at the vertex, thus forming a triangular field on the inside
of each eye, these triangles each containing a large rounded area
of reticulate yellow markings; labrum and lateral portions of
clypeus brown; antennae of some fifty-five segments.
Pronotum narrower than head, broader than long; front mar-
gin nearly straight; sides a little convex; hind margin convex
but with the narrow marginal groove concave in center; all angles
rounded ; median line yellow; lateral field with yellow markings;
meso- and metanotum similarly marked; wing pads almost paral-
lel with body. Legs yellowish brown; thick fringes of long white
hairs on the outer margins of the femora and tibiae; first and
second tarsal segments very short, subequal.
Four pairs of single small, finger-like gills located as follows:
one pair at the outer base of the submentum; second pair at the
outer anterior base of the prothoracic legs; third pair on the
lateral margin of the conjunctivae between the pro- and meso-
44 THOMAS SAY FOUNDATION
sternum; and fourth pair similarly located on the. conjunctivae
between the meso- and metasternum.
Abdomen brownish; tenth tergite of female triangularly pro-
duced but not directed upwards, while in the male it is slightly
more produced and directed upwards; cerei of twenty-five or
more segments, basal segments very short, apical ones four to
five times as long as wide; a fringe of hairs on the upper surface
of the cerci, and each segment ending in a whorl of short hairs.
Mature nymphs from Boulder, Colorado, in which the genital
characters of the adults could be readily observed, enabled me to
identify this species.
Perlodes tibialis Banks
(Plate 3, figs. 44-49.)
Length of body up to 23 mm.; antennae up to 9 mm.; cerci up
to 11 mm.
Hairy nymphs, of a light brown color with markings on head
and thorax; ocelli and eyes small; three pairs of small, single,
finger-like gills located as follows: one pair at the outer base of
the submentum, one pair on the lateral margin of the conjunc-
tivae between the pro- and mesothoracic legs, and one pair on.the
outer conjunctivae between the meso- and metathoracie legs.
Head slightly wider than pronotum, thick, yellowish; three
small ocelli; eyes set far to side of head; frontal M-line distinct ;
on each side of ocellar triangle an oval mark; epicranial suture
very distinct; occipital ridge distinct on sides but fading out
in center; occiput. with an irregular pattern due to the peculiar
distribution of short brown hairs; antennae of about 70 segments.
Pronotum nearly twice as wide as long; front and hind mar-
gins slightly rounded; angles rounded, the hind ones more so
than front ones; discs with a few inconspicuous rugosites; sur-
face hairy. Wing pads broadly rounded at apex. Legs with a
fringe of hairs on femora and tibiae; femora closely beset with
brown hairs; first and second tarsal segments short, subequal;
third segment about four times as long as one and two combined.
Abdomen somewhat flattened; cerei with twenty-five to thirty
segments, each tipped with a whorl of short spines.
Mt. Rainier, Wash.
Perlodes americana Klap.
Length of body up to 24 mm.; cerci up to 14 mm.
General color yellowish brown.
PLECOPTERA NYMPHS OF NORTH AMERICA 45
This species has the general appearance of Perlodes signata but
differs in the following points: only one pair of fleshy, finger-like
gills present, located at the outer base of the submentum, with
no gills on the thorax. Head and thorax almost entirely devoid of
a coating of short brown hairs; fringes on femora and tibiae
thicker than in signata, and dorsal fringe of hairs on the cerci,
also, thicker.
There is a single female nymph without locality label in the
collection with the mouth parts and antennae removed but the
structure of the subgenital plate is so clearly indicated that
specific identification is possible.
Genus ISOGENUS Newman
The nymphs of this genus resemble those of Perlodes, however,
they possess no gills.
When fully grown, the nymphs measure less than 25 mm. in
body length. General color yellowish brown to brown. Head a
little wider than pronotum ; three ocelli; long antennae. Pronotum
about twice as wide as long; angles rounded; a wide median yel-
lowish longitudinal stripe with embossed markings on each side;
marginal groove distinct and about equally distant from the
margin all around. Wing pads quite large in mature nymphs.
Legs rather long, slender, and with a fringe of long hairs on the
outer margin. First and second tarsal segments very short; tarsal
claws with a basal tooth. Abdomen somewhat flattened, cerci long
and slender. Gills absent. Mouth parts typically carnivorous.
Isogenus colubrinus (?) Hagen
(Plate 3, figs. 59-43.)
Length of body up to 22 mm.
General color yellowish brown with darker markings on head
and pronotum.
Head a little wider than pronotum; a reticulate area on each
side of the occiput; occipital ridge indicated by a row of spinules
on each side, but totally absent in the central portion over the
stem of the epicranial suture; ocelli small, the hind ocelli closer to
each other than to the eyes; a yellowish spot within the ocellar
triangle. Pronotum twice as wide as long; a wide median yellow-
ish longitudinal stripe with embossed markings on each side;
hind angles more broadly rounded than front ones; marginal
grooves quite distinct all around and equally near the margin
on sides and front.
46 THOMAS SAY FOUNDATION
Wing pads long, rather slender, and pointed. Legs long, quite
slender and fringed with long hairs; tarsal claws with a small
sharp basal tooth.
Abdomen moderately flattened; posterior border of each seg-
ment with a fringe of very small spinules. Gills absent.
Mouth parts: labrum at least three times as wide as long; hairy
on the surface, and with a fringe of long hairs on the anterior
margin. Mandibles asymmetrical, each with five unequal teeth
followed by a fringe of long hairs. Maxillae: lacinia bidentate,
the second tooth about half as long as apical one, followed by a
series of long hairs; galea cylindric and reaching a little beyond
the base of the second lacinial tooth; maxillary palpus about as
long as lacinia. Labium about as wide as long; glossae small, and
at the apex a small membranous tubercle; paraglossae large,
hairy, and also tuberculate at the tip; labial palpi extending con-
siderably beyond paraglossae. Hypopharynx broadly rounded
and at the tip closely beset with very fine spinules.
A mature female nymph, without locality label, ready to
emerge, has enabled me to identify the species with some degree
of certainty. However the nymphs have been in alcohol so long
that the bodies are rather badly shriveled and the color pattern
eannot be observed clearly.
Genus PERLA Geoffroy
The limits of this genus are not easy to define, for it is made
up of a rather heterogeneous group of species. The known nymphs
fall into two rather distinct groups. The first of these groups
(capitata, media and immarginata) possess copious gills, a very
distinct occipital ridge, and the body is considerably depressed.
These species are typical of Perla sensu str., and agree with the
descriptions of the known European Perla nymphs.
The second group (bilobata, expansa, verticals and aestivalis)
possesses no gills, the occipital ridge is absent and the body is
more cylindrical. These nymphs fall under the subgenus Hemi-
melaena Klap. Perla hastata Bks., which is here included in the
genus Perla, was originally assigned to Isogenus by Banks, and
I am rather inclined to believe that the nymphs, and possibly the
adults, are more typical of Isogenus than of Perla. However, I
Shall not attempt in this paper to revise or change the nomen-
clature of any of the genera from that adopted by Needham and
Claassen (27). It is evident that some changes will have to be
made as soon as the immature stages of the various species are
PLECOPTERA NYMPHS OF NORTH AMERICA 47
better known, especially in the genus Perla, in order to arrange
the species in more natural groups.
Key to the Nymphs of Perla
Th, WETAMS WPe SST? Bee een lube ieee ali ad Oia ee a a 2
LES. BA OBISNAN ES. fur gos 3k oe ale, eR a 4
Pee alert SepTOSeN iinks. «cee ae ts eas ok capitata (p. 47)
COEERTRO EN, GU] REA GI) eR aaa petals an ROU ce ae en 3
3. Almost uniformly brown; abdomen not banded with yellow
and brown; no yellow spot in the ocellar triangle ........
37 2. cepa IEE RO Se ee sg media (p. 48)
Briehty patterned with yellow and brown or black; abdomen
banded with yellow and brown; a yellow spot in the ocel-
| PEPE 01g ERE Go se gene tee, Oo ea ummarginata (p. 50)
4. Lacinia composed of a single long tooth; galea very small, less
PreaMeatisaslON OAs ACINIO@ Aas A. eke sos Siena eve 9)
Lacinia bidentate; galea at least half as long as lacinia... 6
5. Western; length of mature nymphs 16 mm.; a narrow dark
line around margin of pronotum ........ expansa (p. 5d)
Eastern; length 10 mm.; apparently no dark line around
TUT eS oes ae bilobata (p. 54)
6. Oceiput of head, each side, with a roundish mottled area
Nouncdedsbyeardarkemeinaroin, 05... <2 ues hastata (p. a
DONE: ESL oot qycchsebe peas ea ace 6 ee naa ae
7. Head with a wide dark transverse band; pronotum aie
in center and dark all around; abdomen banded with yel-
low and brown or yellow and black ...... verticalis (p. 57)
SIL). (SLOP Yo Slag i teeth oe ae A eae aestivalts (p. 53)
Perla capitata Pictet
(Frontispiece; plate 31, fig. 220.)
Length of body up to 28 mm.; antennae up to 11 mm.; cerci
up to 14 mm.
These brightly colored yellow and brown or yellow and black
nymphs are easily recognized by the two dark transverse bands
across the head, the two dark transverse bands on the femora, the
presence of caudal gills and the yellow and dark banded abdomen.
Head a little narrower than pronotum; occipital ridge dis-
tinct ; hind ocelli at least twice as close to each other as to the eyes;
the wavy dark transverse band which passes through the ocellar
triangle extends backward in the middle to the hind ocelli, or
slightly beyond, but usually bears a V-shaped yellow area between
48 THOMAS SAY FOUNDATION
them; labrum dark brown; antennae yellowish, about half as
long as the body and composed of about eighty-five segments.
Pronotum nearly twice as wide as long, slightly widened pos-
teriorly; hind angles more broadly rounded than front ones;
front margin a little convex, hind margin slightly concave in the
middle; surface covered with fine hairs; margin bordered with
short spinules; marginal groove more distinct on front and hind
border than on lateral margins. Meso- and metanotum and wing
pads covered with fine hair, and the margins of the wing pads
with fine spimules. Legs flattened; femora with a dark blotch
or transverse band at the basal and distal ends; legs with a
thick fringe of long whitish hair on the outer margin.
Abdomen flattened; basal half of tergites one to nine yellowish,
the posterior half brown or blackish; the tenth tergite brown or
blackish at the base and at the sides but with the central apical
portion yellowish. The extent of the darker color varies consider-
ably but even in the darkest specimens, in which almost the
entire tergites are brown or blackish, the tenth tergite is yellow-
ish at the apex. Dorsum of abdomen pilose, each tergite bearing
on the posterior.margin a fringe of short spinules. Cerci reddish
brown, about two-thirds as long as the body and composed of
about fifty-five segments, each segment terminating in a whorl
of short spines. Ventral surface of abdomen yellow except for
a little brown on the abdominal segments, especially the posterior
ones. :
Eight pairs of bunched tracheal gills, arranged as in P. 1m-
marginata, except that the nymphs of P. capitata possess, in
addition to the thoracic gills, one pair of caudal gills which are
attached to the subanal lobes between the cerci. The mouth parts
do not differ materially from those described under P. immar-
ginata. |
New York: Ithaca; Dansville; Boquet R., Adirondack Mts.;
Oneida Co.; Potomae R., Brunswick, Md.; Harper’s Ferry,
W.Va.; Plummer’s Island, Md.; Guelph, Ont.
Perla media Walker
(Plate 16, fig. 190; plate 33, fig. 228.)
Length of body up to 22 mm.; antennae up to 10 mm.; cerei
up to 14 mm.
The general color of these nymphs is yellowish brown to dark
brown or almost black. The immature nymphs are generally al-
most uniformly brown, with a coating of long fluffy hairs on the
PLECOPTERA NYMPHS OF NORTH AMERICA 49
head and thorax; while the mature nymphs usually exhibit vari-
ous degrees of contrasting patterns on the head and thorax and
are usually without the coating of long hairs. Two characters by
which this species may be identified are the uniform brown color
of the abdomen, and the even curvature of the occipital ridge.
The species most likely to be confused with P. media are Acro-
neuria ruralis, and A. abnormis. In A. ruralis, however, the cerci
are longer than the body, and the occipital ridge does not follow
an even curve, but tends to be broken, and in the center is di-
rected inward toward the ocellar triangle. In A. abnormis there is
no occipital ridge.
Head slightly narrower than pronotum; occipital ridge uni-
formly distinct, evenly curved forward and in the center reaching
almost to the arms of the epicranial suture; hind oeelli nearly
twice as close to each other as to the eyes; each of the three ocelli
usually with a lighter area at the outer angles of the ocellar tri-
angle and a yellowish spot each side. Antennae about half as
long as body and composed of about ninety segments.
Pronotum about twice as wide as long, in some specimens a
little more; surface pilose; margin with a fringe of hairs which
are longest on the posterior margin; the markings on the lateral
fields of the pronotum vary considerably in intensity or dis-
tinctness, but usually show up more plainly in the maturer
nymphs; marginal groove distinct in front and behind; hind
angles more broadly rounded than front angles. Meso- and meta-
notum with surface more hairy in young than in older nymphs.
Legs flattened, with a wide fringe of long white hairs.
Abdomen quite uniformly brown and thickly covered with
short spinules. Cerei about two-thirds as long as body, with a
fringe of long hairs on the inner side, especially on the basal
portion, composed of about thirty-six segments, each ending in a
whorl of spines.
Seven pairs of gill tufts arranged as in P. immarginata. Anal
oills absent.
The sexes may be distinguished, in the more mature nymphs,
by the developing genital characters, but in the younger speci-
mens they cannot readily be separated.
As already stated, there is considerable variation in the inten-
sity of the color pattern. In some of the younger nymphs, espe-
elally, the general color is almost uniformly brown, and the
lighter markings on the head and thorax are only faintly indi-
eated. The younger nymphs are also more hairy than the older
ones. These long hairs are especially noticeable on the occipital
50 THOMAS SAY FOUNDATION
ridge of the head, the posterior margin of the pronotum, the
posterior margin and medical portion of the meso- and metanotum,
and along the mid-dorsal line of the abdomen. In many nymphs,
these hairs became coated with a brown slimy ooze and this gives
the specimens a dirty, fuzzy appearance.
In the very small nymphs (5 to 7 mm. in length) there are
only three pairs of gill tufts present. These correspond to the
three largest pairs in mature nymphs. In these small specimens
the pronotum bears a fringe of long spines; the meso- and meta-
notum and the abdomen are covered with long spines as well as
the femora, which in the young forms are very wide. The oe-
cipital ridge, however, is very distinct, and this, together with
the uniformly brown color of the abdomen, makes identification
of this species possible even in the very young stages.
This species occurs under stones in the larger streams, but
the nymphs apparently are able to live in somewhat quieter
waters than the nymphs of P. immarginata, for mature nymphs of
P. media have on several occasions been collected from the waters
of Beebe Lake, on the Cornell University campus, as well as from
Dwyer’s pond, in Cascadilla creek. It is interesting to note that,
whereas the adults of the above two species are very similar in
general appearance and it is at times difficult to separate the
females, the nymphs are very different in general appearance, the
nymphs of P. media being dull brown, while those of P. im-
marginata possess a very striking color pattern.
P. media is a typical carnivore and probably requires three
years to complete its life cycle.
Ithaca, N.Y.; Ogdensburg, N.Y.; Potomac R., Harpers Ferry,
Md.; Cleveland, Va.; Guelph, Ont.
Perla immarginata Say
(Plate 5, figs. 77-82; plate 31, fig. 219.)
Length of body up to 33 mm.; antennae up to 15 mm.; cerei
up to 22 mm.
This is the largest and one of the most beautiful nymphs of
this genus in the Eastern States.
It is almost impossible to describe the details of the striking
yellow and brown, or yellow and blackish color pattern, but the
photograph (Plate 31, fig. 219) illustrates this very well, and an
attempt will be made here only to point out some of the more
striking patterns which aid in identification of this species. It
PLECOPTERA NYMPHS OF NORTH AMERICA 51
will also be necessary to point out something of the limits of
variation in color pattern within the species.
The pattern on the head varies somewhat, but normally there
is an oval white spot in the center of the dark mark which covers
the ocellar triangle. There is always a long, dark elongate mark
on each of the femora. This mark extends about two-thirds of
the length of the femur, and at the distal end there may be seen
on the inner side (sometimes on both sides) another small dark
blotch. The abdomen is alternately barred with yellow and black
or yellow and brown, the basal half of each segment being dark
and the caudal half light. Here is to be found considerable varia-
tion, for in the darker specimens the entire segments are some-
times almost equally dark, but I have never yet seen a nymph
of this species in which the tenth tergite was not yellowish at the
apex, and in most most nymphs this yellow color cuts into the
basal dark band in a V-shaped manner.
Head slightly narrower than the pronotum; the occipital ridge
very prominent; epicranial suture distinct; hind ocelli closer to
each other than to the eyes; antennae more than half as long
as body and made up of about ninety segments.
Pronotum almost twice as wide as long; somewhat widened
posteriorly ; hind angles much more broadly rounded than front
ones; front margin nearly straight, hind margin slightly concave
in the center; surface feebly pilose, and the margin with a fringe
of very short spinules; marginal groove distinct in front and be-
hind, and more or less continuous around the entire pronotum.
Meso- and metanotum, including wing pads, with scattered
hairs and the margins of the wing pads with a fringe of fine
spinules.
Abdomen flattened; tergites with a fringe of spinules on the
posterior margin; surface with scattered short hairs and with
longer hairs along the mid-dorsal line. This line of long hairs
is especially noticeable-in the half-grown and smaller nymphs
where these hairs are especially thick on the caudal segments.
The cerei are about three-fourths as long as the body and are
composed of fifty or more segments, each segment terminating in
a whorl of short spines. On the inner dorsal margin the cerci
bear a fringe of long fine hairs, which are longest near the base
of the cerci.
The legs are much flattened and bear a thick fringe of long,
fine, whitish hairs on the outer margin.
Ventral surface of body quite uniformly yellowish. Seven pairs
D2 THOMAS SAY FOUNDATION
of compound gill tufts distributed as follows: two pairs at the
outer base of the prothoracic legs just underneath the lateral
shields of the pronotum; one pair each in a similar position on
the meso- and metathorax; one pair each on the outer conjune-
tivae between the pro- and mesosternum, and between the meso-
and metasternum ; and one pair just back of the base of the meta-
thoracic legs. Anal gills absent.
The sexes are not readily distinguished; however, in the ma-
turer nymphs the females may be recognized by the small median
notch on the posterior margin of the eighth abdominal sternite,
and often the abdomen is seen to be distended with dark eggs.
Mouth parts: labrum about three times as wide as long, with
a fringe of long hairs on the anterior margin; epipharynx broadly
rounded when fully extended, and closely beset with short spines.
Mandibles triangular and rather slender, somewhat asymmetrical,
each with five unequal sharp teeth, followed by a fringe of long
hairs. Maxillae: lacinia long and slender and terminating in two
long sharp teeth; following these teeth, a fringe of long, stout
hairs. Galea slender, two-segmented, tipped with papillae and
a few long hairs, and not reaching quite to the tip of the lacinia;
maxillary palpus slender and extending somewhat beyond the
tip of the lacinia.
Labium wider than long; submentum very large, mentum a
narrow transverse band; glossae very short and broadly rounded ;
paraglossae large, somewhat pear-shaped and directed inward;
both glossae and paraglossae hairy and at the tips closely beset
with papillae. Hypopharynx thickly covered with short spinules.
The nymphs of this species are common in the larger swift-
water streams with stony bottoms. They restrict themselves
largely to the underside of stones and are able to maintain a
foothold in very swift currents of water. They are voracious
feeders, feeding on mayfly nymphs, midges, blackfly larvae and
pupae, and even on stonefly nymphs. Examination of stomach
contents also reveals the presence of many diatoms which, how-
ever, are probably ingested incidentally while feeding on animal
prey. Miss Smith (52) found that in the younger stages the
nymphs of this species apparently ingested a greater number of
diatoms than they did as they grew larger, and this would in-
dicate that during the early stages diatoms form part of the
preferred diet of these nymphs.
No one has worked out the complete life history of this species,
but it apparently requires three years to complete its life cycle.
PLECOPTERA NYMPHS OF NORTH AMERICA 53
New York: Ithaca; Dansville; Wilmington; Moffitsville; Alle-
gany Co.; Montgomery, Mass.
Perla aestivalis (?) Needham and Claassen
Length of body up to 11 mm.; antennae up to 5 mm.; cerci up
to 5 (?) mm.
General color yellowish brown, with the outer margin of the
pronotum dark, and with the basal half of the abdominal ter-
gites darker than the caudal half. Head a little wider than pro-
notum, quite smooth, and almost equally brown all over; ocelli
large, the hind ones nearly twice as close to the eyes as to each
other; occipital ridge absent; antennae composed of about fifty
segments. Pronotum about twice as wide as long, transversely
oval, with the angles broadly rounded; surface nearly smooth;
marginal groove dark and very distinct all around. Wing pads
long, set far apart, and lying almost parallel with the body.
Legs long, slender, and not much flattened ; a fringe of long hairs
on the outer margin; femora with rather few hairs on the upper
surface; third segment of tarsus very long, about half as long
as tibia; tarsal claws with a prominent, sharp, basal tooth. Ab-
domen somewhat flattened, smooth, and with a fringe of spinules
on the posterior margin of each tergite; cerci with the tips
broken off, but one of the nymphal skins shows twenty segments,
and the total is probably twenty-five to thirty.
Gills absent.
Mouth parts of the carnivorous type. Labrum three times as
wide as long; front margin with a fringe of long hairs. Mandi-
bles rather slender, with four unequal teeth, followed by a
fringe of long hairs, and beyond this fringe the mandibles some-
what excavated or broadly notched. Maxillae: cardo very short;
stipes as long as lacinia; lacinia broad at base, bidentate, the
second tooth only half as long as the long terminal one and fol-
lowed by only a few long hairs; galea feebly developed, eylindri-
eal and only about half as long as lacinia; maxillary palpus
longer than lacinia, its apical segment very slender. Labium
longer than wide; glossae short, triangular, and produced into
blunt tubercles which are closely beset with papillae; para-
glossae large, hairy, directed inward, and bearing at the tip
tubercles similar to those of the glossae; labial palpi extending
far beyond paraglossae. Hypopharynx rounded and closely beset
with short stiff hairs.
d4 THOMAS SAY FOUNDATION
Described from three nymphal skins and one female nymph,
taken at the same time and place as were the male holotype
and the female allotype, Yellowstone Park, July 14, 1921. R.
Muttkowsky.
Perla bilobata Needham and Claassen
(Plate 4, figs. 50-54.)
Length of body up to 9.5 mm.
General color yellowish-brown, with the pronotal marginal
oroove dark brown.
Head wider than pronotum; quite smooth, occipital ridge ab-
sent; hind ocelli closer to the eyes than to each other; tips of
antennae broken off in the specimens before me but one partial
antenna has thirty-eight segments, so that the full number is
probably near fifty.
Pronotum about twice as wide as long; transversely oval; mar-
ginal groove distinct, brown, continuous around entire pronotum,
and equidistant from the margin all around. Wing pads large
and only slightly divergent from the body. Legs not much flat-
tened; with only a sparse fringe of hairs on the outer margin;
tarsal claws with a distinct basal tooth.
Abdomen not much flattened ; segments with a fringe of spines
and a few long hairs on posterior margin; segments of cercl
tipped with a whorl of long stout hairs.
Gills absent.
Mouth parts: labrum at least three times as wide as long,
covered with hairs and with a fringe of long hairs on the anterior
margin. Mandibles with four or five unequal teeth followed by a
fringe of long hairs, and beyond this fringe there is a deep,
rounded notch. Maxillae with very long stipes; lacinia broad at
the base, on the inside a large rounded knob, narrowing immedi-
ately to a long, single, smooth, incurved tooth, the entire sclerite
devoid of hairs; galea much reduced, hardly a third as long
as lacinia, and at the apex one long hair; maxillary palpus
slender and extending somewhat beyond the tip of the lacinia.
Labium a little longer than wide, and very similar in structure
to that of P. aestwals; glossae short; paraglossae large, hairy,
and directed inward; both glossae and paraglossae with small
papillae at the tip. Hypopharynx broadly rounded and closely
beset with short stiff hairs.
Described from two nymphal skins, from specimens reared by
J. G. Needham, Old Forge, New York, July 13, 1905.
PLECOPTERA NYMPHS OF NORTH AMERICA = 55
Perla expansa Banks
Length of body up to 16 mm.; antennae up to 6.5 mm.; cercl
up to 8 (?) mm.
The nymphs of this species resemble very closely those P. balo-
bata, but are larger in size and differ in a few details of struc-
ture. General color yellowish with a narrow brown marginal
eroove around the pronotum. Head much wider than pronotum ;
maxillae extending far out beyond the outer margin of the eyes,
ereatly accentuating the width of the head; hind ocelli about
as close to the eyes as to each other; occipital ridge absent.
Pronotum transversely oval, almost twice as wide as long; mar-
sinal groove dark and continuous around entire pronotum. Legs
slender, with a distinct but rather feeble fringe of fine hairs;
tarsal claws with a small basal tooth. Abdomen not much flat-
tened; each segment with fine spinules on the posterior margin.
Gills absent.
Mouth parts very similar to those of P. bilobata, but the lacinia
narrows down more gradually in expansa than in bilobata, is uni-
dentate and devoid of any hairs; galea feeble and very short.
The sexes are readily distinguished in the more mature nymphs
by the developing genital structures.
Identification of this species was made possible by a study of
the genitalia of both male and female nymphs which were col-
lected in the Big Thompson River, Estes Park, Colorado, August
4, 1921 (P.W.C.), and from Tolland, Colorado (G.S.D.).
Perla hastata Banks
(Plate 3, figs. 33-38; plate 15, fig. 188; plate 33, fig. 230.)
Length of body up to 25 mm.; antennae up to 10 mm.; cerci
up to 14 mm.
The nymphs of this species are readily recognized by the
variegated pattern of yellow and brown, absence of gills, large
head, which is much longer and wider than pronotum; and
especially by the two transversely oblong mottled areas on the
large occiput of the head. Body not much flattened.
Head at least half again as long as the pronotal disc and much
wider; the cardo and stipes of the maxillae very long, and thus
the maxillae protrude on the sides of the head so as to be plainly
visible from above, accentuating the width of the head; ocelli
set close together in a small triangle, the hind ocelli half again
as close to each other as to the eyes; eyes small; occiput long,
and on each side with a large transverse mottled area completely
56 THOMAS SAY FOUNDATION
surrounded by darker brown; no distinct occipital ridge present,
although the hind margins of these mottled areas are suggestive of
a ridge; frontal M-line distinet ; surface covered with short brown
hairs; antennae about one-third as long as body and made up
of about fifty to fifty-five segments. Pronotum nearly half again
as broad as long; almost transversely oval; the hind angles a little
more broadly rounded than the front ones; surface covered with
short brown hairs; a more or less distinct median longitudinal
yellow stripe; discs with embossed markings; marginal groove
distinct and equally close to margin of pronotum all around.
Front wing pads separated, parallel; hind wing pads more
divergent. Legs long, slender, and not much flattened; a rather
thin fringe of long hairs on the outer margin; tarsal claws each
with a distinct basal tooth.
Abdomen not much flattened, brown, but in the more brightly
colored specimens the basal half of tergites one to nine each has
three pairs of light spots, one being on the mid-dorsal line, and
one on each side; surface of abdomen covered with short brown
hairs, and the hind margin of each segment with a fringe of
fine spinules. Cerei more than half as long as body, composed of
about thirty-three segments, each segment terminating in a whorl
of short hairs, and with longer hairs on the inner dorsal side,
especially prominent on the basal part of the cerci.
Gills absent.
Mouth parts. Labrum about three times as wide as long, with
a fringe of long hairs on the anterior margin. Mandibles asym-
metrical; each with five unequal sharp teeth followed by a fringe
of long hairs. Maxillae with a long cardo and stipes; lacinia bi-
dentate, with a long terminal tooth and with the second tooth not
more than half as long as the terminal one; below the base of
the second tooth the lacinia suddenly widens in an angulate
manner and bears a fringe of hairs; galea rather weak and not
reaching quite to the tip of the second tooth of lacinia, and at
the apex with a small but distinct hairy tubercle; maxillary pal-
pus longer than lacinia, the last segment very slender. Labium
slightly wider than long; glossae short, triangular, and at the
apex a papillose tubercle; paraglossae rather narrow, converging
toward the tip, bearing at the apex a small tubercle similar to
that on each of the glossae; labial palpus much longer than
paraglossae. Hypopharynx broadly rounded and closely beset
with stout hairs.
Male. Tenth abdominal tergite broadly rounded; beyond this
a short, broadly triangular membraneous tubercle in which the
supra-anal process develops.
PLECOPTERA NYMPHS OF NORTH AMERICA 57
Female. Tenth abdominal tergite broadly rounded but without
median tubercle; genital opening indicated on the eighth ab-
dominal sternite.
The nymphs of this species occur in small upland spring brooks,
where they may be collected under stones. I have never collected
them in the large swift-water streams. The more or less cylindric
shape of the body is not so well suited for inhabiting the swifter
waters, and yet the total absence of gills necessitates their living
in cold spring brooks in which the water maintains a steady flow
and is richly supplied with oxygen.
The nymphs are carnivorous and apparently require two years
to complete the life eyele.
Ithaca, N.Y.
Perla verticalis (?) Banks
(Plate 4, figs. 55-59; plate 15, fig. 189.)
Length of body up to 12 mm.; antennae up to 6.5 mm.; cerei
up to 7.5 mm
General color yellow with a wide blackish transverse band
across the head; pro-, meso- and metanotum yellow in the middle
and dark all around except the tips of the wing pads, which are
yellowish ; abdomen transversely banded with yellow and brown.
Head much wider than pronotum, especially so because of the
large protruding maxillae, which are plainly visible from above;
a wide, transverse, dark band bounded in front by the M-line,
and in the rear by the epicranial suture; rest of head more or less
yellow; hind ocelli a little closer to the eyes than to each other;
antennae at least half as long as body and composed of about fifty
seoments; occipital ridge absent.
Pronotum almost transversely oval; less than twice as wide as
long; marginal groove distinct, continuous all around, and as
near the margin on the sides as in front and rear; middle field
yellow, rest dark brown or blackish; meso- and metanotum yel-
low in the center and blackish around the border ; wing pads most-
ly yellowish and with the outer margins about parallel with the
body. Legs long and slender, mostly yellow, but usually with a
dark area on the femora and with a rather thin fringe of long
hairs; tarsal claws with sharp basal tooth.
Abdomen not much flattened; tergites yellow, with the basal
part brown, but sometimes the posterior margin also brown; tenth
tergite blackish at base. Cerci more than half as long as body; a
fringe of long hairs on the dorsal line and each segment termi-
nating in a whorl of spines; about twenty-five segments.
Gills absent.
D8 THOMAS SAY FOUNDATION
The sexes are easily distinguished, because in the male the su-
pra-anal process is produced beyond the tenth tergite in the form
of a tubercle which may be almost as long as the tenth tergite.
The mouth parts are similar to those of P. aestivalis. Labrum
about three times as wide as long; mandibles with five sub-equal
teeth, followed by a fringe of hairs. Maxillae: cardo and _ stipes
long, the stipes about as long as the lacinia; lacinia wide at the
base and gradually narrowing toward the tip, with two long teeth,
the second tooth a little more than half as long as the apical one,
and, following the second tooth, only one or two hairs on the inner
margin; galea about half as long as lacinia and tipped with a few
hairs. Labium longer than wide; glossae short, triangular; para-
glossae large, hairy; both glossae and paraglossae attenuated at
the tips which are beset with papillae. Hypopharynx broadly
rounded.
Described from nymphs collected at Neversink, New York, May
11, 1929. P. R. Needham.
The nymphs are quite mature and the structure of the genitalia
indicates that they belong to verticalis.
Genus ALLOPERLA Banks
Small yellowish-brown nymphs measuring, when fully grown,
7 to 13 mm. in length. Body somewhat depressed. Head a little
wider than pronotum; brownish, with the median area usually
somewhat darker; three ocelli placed in an almost equilateral tri-
angle; front ocellus smaller than hind pair, which are usually
closer to the eyes than to each other; surface of head quite smooth
but with feeble pilosity ; sutures on head not very distinct; no oc-
cipital ridge; antennae about one-third as long as body and com-
posed of forty to fifty segments.
Pronotum wider than long; suboval, with the angles broadly
rounded; a narrow marginal groove, which in some species ap-
pears as a narrow darker line extending around the entire prono-
tum; surface of pronotum with long hairs, especially at the outer
angles. In the mature nymphs the pronotum often shows the
darker markings of the developing imago.
Meso- and metanotum with the wing pads very wide and with
the lateral margins broadly rounded; surface quite smooth, and
thickly covered with brownish hairs. Legs somewhat flattened and
covered with many hairs; a thin fringe of hairs is usually present
on the tibiae but not on the femora; first and second tarsal seg-
PLECOPTERA NYMPHS OF NORTH AMERICA 59
ments very short, sub-equal, and the two together about one-
fourth as long as the third segment. Abdomen somewhat flat-
tened. Cerei quite short, usually not much more than one-fourth
the length of the body; stout at base and tapering to a slen-
der tip; thirteen to fifteen, or possibly up to eighteen segments,
which are hairy and bear on the posterior margin a whorl of long
hairs.
Gills absent.
Mouth parts. Labrum very short and about four times as wide
as long, clothed with long hairs; front margin with long hairs.
Mandibles rather narrow; asymmetrical; left one with five more
or less distinct unequal teeth; right one with six unequal teeth
grouped by threes; following the teeth, on the inner margin of
each mandible, a series of long stiff hairs; a second row of hairs
on the ventral surface extends from the base of the teeth diago-
nally rearward to the inner base of the mandible. Maxillae: lacinia
broad at base, gradually tapering and ending in a single incurved
apical tooth, sometimes with an indication of a second short tooth ;
inner margin with a row of long stout hairs; galea slender, cy-
lindrie, shorter than the lacinia, and at the tip with a small
buneh of hairs; maxillary palpus with the first two segments
wider than long, subequal; third segment about three times as
long as second; fourth segment longer than third and slightly
produced on the inner apex, which bears a group of hairs; fifth
segment very slender and not more than half as long as fourth.
Labium. Glossae minute, triangular; paraglossae large, directed
inwards at tip and covered with hairs. First segment of palpus
not more than half as long as second; apical segment shorter than
second and not more than half as wide. Mentum a narrow, trans-
verse, broadly triangular band; submentum very large, wider
than long, hairy. Hypopharynx rounded, closely beset with hairs,
and normally extending to, or nearly to, the tip of the para-
olossae.
The sexes in this genus are not readily distinguishable.
Inasmuch as the coloration of the nymphs of this genus is
rather uniformly brown it is quite difficult to identify the dif-
ferent species. Identification of the following species has been
possible only through rearing records or by adult-genitalia char-
acters which could be detected in mature nymphs. Little is known
of the biology or life cycle of the nymphs of this genus, but the
life cycle appears to occupy one year.
Alloperla is generally distributed over the entire North Ameri-
can continent.
60 THOMAS SAY FOUNDATION
Key to the known Species of Alloperla
1. Eastern forms—length up to 9mm... 7. mediana (p. 61)
Western forms—various lengths...) .. 2. 2. 4...) eee 2
2. Length up to 13 mm.; cerci not more than 14 the length of
bod yet i sr Sn ed eee borealis (p. 60)
Length under 13 mm.; cerci often more than 1% the length of
body a0) Ut oe Le 3
3. Small yellowish nymphs not over 7 mm. long when fully
GROW (ieee | vein cs CR et ee Oe eee pallidula (p. 62)
Fully grown nymphs more than 7 mm. in length ......... 4
spatulata (p. 62)
coloradensis (p. 60)
lamba (p. 61)
Alloperla borealis Banks
(Plate 6, figs. 89-93; plate 17, fig. 192.)
Length of body up to 18 mm.; antennae up to 4 mm.; cerci
up to 3 mm.
This is the largest species of the genus. General color lght
brown with portions of head, thorax, and abdomen shaded with
darker brown. Head brownish with a small lighter area in front
of the anterior ocellus, and with a more or less continuous trans-
verse lighter band extending across the head from eye to eye;
labrum lighter at base.
Pronotum transversely suboval; surface hairy, with long hairs
on the margin; meso- and metanotum and wing pads hairy. Legs
somewhat flattened and covered with short hairs, but without dis-
tinet fringe of long hairs on the outer margin of either femora
or tibiae.
Abdomen hairy and quite uniformly brown. Cerci short, rather
thick at the base and tapering to a slender tip; thirteen to fifteen
segments. Gills absent.
The large size and the relative shortness of the cerci differen-
tiate borealis from related forms. Described from mature nymphs
from Temple Forks, Logan River, Utah, June 20, 1926. J. G.
Needham.
Alloperla coloradensis Banks
(Plate 6, figs. 83-88.)
Length of body up to 10 mm.; antennae up to 3.5 mm.; cerci
up to 3 mm.
General color yellowish brown, with the marginal groove of the
PLECOPTERA NYMPHS OF NORTH AMERICA 61
pronotum, and the meso- and metascutum, a dark brown. Head
sightly wider than pronotum; eyes and ocelli black; surface
smooth and sparsely clothed with hairs. Pronotum transversely
suboval; front and hind margins somewhat convex; hind angles
more broadly rounded than the front ones; surface somewhat
rugose, with long hairs around the margin. Meso- and metanotum
and wing pads covered with hairs; outer margins of wing pads
broadly rounded. Legs hairy, with a sparse fringe of long, silky
hairs on the outer margin of the tibiae.
Abdomen brown, hairy, the segments with a row of short stiff
hairs on the posterior margin. Cerci rather short and thick at
the base and tapering to a very slender tip; of about fifteen seg-
ments, each segment with a whorl of stiff hairs at the tip.
Deseribed from mature nymphs from Boulder, Colorado, in
which the genital characters could be plainly discerned.
Alloperla lamba (?) Needham and Claassen
Length of body up to 9 mm.; antennae up to 3 mm.; cerei up
to 2mm.
General color yellowish brown, with the head darker than the
rest of the body.
Head a little wider than prothorax; ocelli small, hind ocelli
closer to eyes than to each other ; surface smooth, somewhat hairy ;
antennae with about forty-five segments. Pronotum half again as
wide as long, suboval; hind angles more broadly rounded than
front ones; marginal groove continuous all around, darker in
front and rear, becoming dark brown all around in the maturer
nymphs; surface hairy, with long thin hairs on the margin.
Meso- and metanotum and wing pads hairy. Legs flattened,
hairy, with a fringe of hairs on the outer margin of the femora
and tibiae, but thinner on the femora than on the tibiae.
Abdomen brown, hairy. In the more mature nymphs there may
be seen the darker mid-dorsal line of the developing imago. Cerci
with about fifteen segments.
The structure of the genitalia of the nymphs collected by the
writer in Estes Park, Colorado, on Aug. 9, 1919, indicates that
they very probably belong to this species.
Alloperla mediana Banks
Length of body up to 9 mm.; antennae up to 3 mm.; cerci up
to 3 mm.
General color yellowish brown, with no contrasting markings
62 THOMAS SAY FOUNDATION
except as the adult colors are seen through the chitin of the
maturing nymphs. Head smooth and feebly pilose; rest of body
very hairy. Legs hairy, and tibiae with a feeble fringe of fine
long hairs. Cerci with fifteen segments, the distal segments with
hairs as long as the segments.
This species occurs in the Eastern States and the above descrip-
tion has been made from mature nymphs collected at Clinton.
New York, May 15.
Alloperla pallidula Banks
Length of body up to 7 mm.; antennae up to 2.8 mm.; cerei up
to 3 mm.
General color light brown; wing pads and abdomen covered
with long hairs.
Head slightly wider than pronotum; surface smooth and
sparsely clothed with hairs; eyes and ocelli black; hind ocelli
much closer to eyes than to each other; antennae with about
forty segments. Pronotum transversely oval, about half again
as wide as long; front and hind margins straight; all angles
broadly rounded; surface slightly rugose and somewhat hairy,
with a few long hairs on the outer margin. Meso- and metanotum
wide; wing pads broadly rounded on the sides; surface of meso-
and metanotum smooth, but covered with long hairs. Legs some-
what flattened, hairy; tibiae with a thin fringe of long hairs on
the outer margin.
Abdomen quite uniformly brownish, hairy; cerei with about
fifteen segments, the middle segments about four times as long as
wide, segments at the tip five to six times as long as wide.
Described from nymphs collected in the Big Thompson River,
Estes Park, Colorado, on August 2, 1921.
Little is known of the habits of these nymphs except that they
live in swift water and that the mouth parts indicate that they
are mainly carnivorous. At the time these nymphs were collected,
numerous adults were also collected from the alders and willows
along the Big Thompson River. Mr. Rowher informs me that he
has observed the adults of this species feeding upon the honey
dew which the aphids were secreting on the alders along the
streams in Colorado.
Alloperla spatulata Needham and Claassen
(Plate 17, fig. 191.)
Length of body up to 11 mm.; antennae up to 4 mm.; cerci
up to 2.5 mm.
PLECOPTERA NYMPHS OF NORTH AMERICA 63
General color yellowish brown; very hairy. Head yellowish with
the median area darker; surface smooth and feebly pilose.
Pronotum transversely suboval and covered with long brown
hair, the margin having a fringe of long hairs. Meso- and meta-
notum and abdomen covered with long hairs.
Legs hairy and the tibiae with a feeble fringe of long hairs.
Described from mature nymphs collected in San Antonio
Canyon, Claremont, California, on April 29 and May 12, 1923.
J. G. Needham.
Genus CHLOROPERLA Newman
This genus is represented in North America by a single species,
C. cydippe Newm. The nymphs are small, yellowish, and, when
fully grown, measure not more than 6 mm. in body length.
Chloroperla is very closely allied to Alloperla and identification
of the nymphs is largely dependent on reared specimens.
Head a little wider than pronotum; eyes large; three ocelli;
pronotum transversely oval, and much narrower than the meso-
and metanotum with the broad, rounded wing pads.
Entire body quite uniformly yellowish or yellowish brown, and
sparsely clothed with hairs. The description of C. cydippe depicts
the more detailed structures of this genus.
No study has been made of the biology of this genus, but it
seems safe to state that the nymphs are found in rather swift-
running water and that they are mainly carnivorous.
Chloroperla cydippe Newman
(Plate 6, figs. 94-99; plate 18, fig. 194.)
Length of body up to 6 mm.; antennae up to 2 mm.
General color yellowish brown, without a contrasting color pat-
uevug
Head a little wider than pronotum; eyes large, and set
considerably forward; postero-lateral angles of head broadly
rounded; antennae with about thirty-five segments; three small
ocelli.
Pronotum transversely oval, wider than long; all angles very
broadly rounded; front and hind margins straight; marginal
groove continuous all around; surface quite smooth; long hairs
at the anterior and posterior angles. Wing pads broadly rounded
at the tip. Legs somewhat flattened ; rather sparsely clothed with
hairs, and only the tibiae with a fringe of long hairs on the outer
margin. Segments one and two of tarsus very short, subequal, and
together hardly one-fourth as long as the third segment.
64 THOMAS SAY FOUNDATION
Abdomen subeylindric; posterior margin of each segment with
a fringe of short stiff hairs which become more numerous with
each succeeding segment.
Mouth parts. Labrum about three times as wide as long with a
fringe of hairs on the anterior margin. Mandibles nearly twice as
long as wide; slightly asymmetrical; left one with five unequal
teeth, the right one with four distinet teeth, and with an indica-
tion of a small fifth one; the teeth followed by a row of long
hairs. Maxillae: lacinia wide at the base, a single, large, ineurved
terminal tooth followed by a series of long hairs. Galea eylindrie,
reaching almost to the tip of the lacinia, and one or more long
hairs at the tip. First and second segment of maxillary palpus as
wide as long, or wider, third segment a little longer than one and
two together ; fourth nearly half again as long as the third, and
with the inner apex produced and covered with long hairs; fifth
segment less than half as long as fourth, and considerably less
than half as large in diameter, bearing at the tip a small tubercle
and a few hairs. Labium: glossae very small, triangular; para-
glossae large, with a few long hairs on the dorsal surface. First
segment of palpus longer than wide, second half again as long
as the first; third a little more than half as long as the second,
and hardly more than half as large in diameter; the apical seg-
ment with a small tubercle, as in the maxillary palpus. Hypo-
pharynx closely beset with short hairs at the tip.
The above description has been drawn from the cast skin
of a reared nymph taken at Ithaca, N.Y. This species is common
in the Eastern States.
Genus PARAPERLA Banks
The nymphs of this genus, of which only a single species is
known in western North America, are recognized by the slender
body; long head with small eyes set far forward, so that the
distance from the eyes to the hind border of the head is twice as
great as the diameter of the eyes; a transversely oval pronotum ;
and absence of gills.
Color yellowish; surface of head and thorax smooth. Head
slightly wider than pronotum; three small ocelli. Pronotum oval,
wider than long; marginal groove continuous all around; sides
and angles rounded. Legs sparsely fringed with hairs; first and
second tarsal segments very short, subequal. Wing pads broad,
and rounded on the lateral margins. Abdomen nearly cylindrical ;
cerci short and stout.
PLECOPTERA NYMPHS OF NORTH AMERICA 65
Mouth parts are of the carnivorous type and are described un-
der P. frontalis.
Paraperla frontalis Banks
(Plate 7, figs. 100-105; plate 10, figs. 167-168; plate 18, fig. 193.)
Length of body up to 18 mm.; antennae up to 7.5 mm.; cerci
up to 6 mm.
This species is recognized by its slender form, absence of gills,
long head with small eyes which are set far forward, a trans-
versely oval pronotum, and broadly rounded wing pads.
General color yellowish with a little darker color around the
margin of the pronotum.
Head about as wide as long; three small ocelli placed in an
equilateral triangle; eyes very small and placed far forward so
as to be nearly in line with the front ocellus; occipital ridge not
clearly marked; surface quite smooth; antennae with about
seventy rather short segments, the apical segments not more than
twice as long as wide.
Pronotum transversely oval, the sides and front and hind
margins rounded; marginal groove extending all around the
pronotum; surface nearly smooth; wing pads rounded on the
sides and at the tip. Legs with a sparse fringe of hairs on the outer
margins of femora and tibiae; first and second tarsal segments
very short, subequal, third segment about four times as long as
one and two combined. Abdomen nearly cylindrical; tenth tergite
medially produced into a rounded lobe; cerei rather short and
stout, gradually tapering toward the tip; about twenty-three seg.
ments, each segment terminating in a whorl of hairs.
Mouth parts. Labrum about four times as wide as long; the
anterior margin fringed with long hairs. Mandibles slightly asym-
metrical, each with four sharp teeth followed by a brush of long
hairs. Maxillae; first segment of maxillary palpus about as long
as wide; second segment as long as first; third segment a fourth
again as long as one and two combined; fourth segment three-
fourths as long as the third; and fifth a little more than half as
long as the fourth, and bearing at the tip a few short hairs.
Lacinia rather wide at base and ending in a large incurved tooth
which bears a smaller tooth midway on the inner margin and a
comb-like row of stout hairs. Below the base of the large tooth the
inner margin of the lacinia is fringed with hairs. Galea rather
slender, consisting of a single segment which reaches to the
middle of the lacinial tooth, and which bears at the tip, a few
66 THOMAS SAY FOUNDATION
short spines. Labium half again as long as wide; glossae short;
paraglossae very long, somewhat incurved at the tip and beset
with many long hairs; hypopharynx broadly rounded, very close-
ly beset with short hairs, and extending almost to the tips of the
paraglossae; mentum broadly triangular; submentum very little
wider than long, its anterior angles broadly rounded and pro-
longed; first segment of palpus a little longer than wide, second
segment twice as long as first, and third segment almost two-
thirds as long as second but less than half as wide; tip of third
segment with a few hairs.
This species bears no gills.
Described from one nymph and many nymphal skins collected
at Bozeman, Montana, by R. A. Cooley; and one nymphal skin
from Logan River, Utah, by J. G. Needham.
Nothing is known about the biology of this species, but, judg-
ing from the structure of the mouth parts, it is undoubtedly a
carnivore and probably lives in swift water.
Genus NEOPERLA Needham
This genus is readily recognized by the fact that the nymphs
possess only two ocelli, which are set close together. The color in
live or freshly killed specimens is a combination of yellow and
brown. The gills are very long and the legs bear fringes of long
delicate hairs.
Head as wide as prothorax, or slightly wider; labrum brown
on anterior margin, followed by a narrow transverse yellow band
which in turn is followed by a wide brown transverse band; rest
of head yellow except sometimes with brown around and behind
ocelli; occipital ridge very distinct; ocelli usually set very close
together, the distance between them hardly more than the diam-
eter of one occellus, although in immature nymphs they are spaced
a little farther apart; antennae yellow and at least half as long
as the entire body.
Labrum about four times as wide as long. Mandibles somewhat
asymmetrical. Right mandible with five sharp, unequal teeth,
the outer tooth the largest ; following the teeth, the inner margin
is fringed with long hairs. Left mandible with six unequal teeth
more or less arranged in groups of three each.
Maxillae: first segment of maxillary palpus short, and about
as long as wide, second about twice as long as first, third and
fourth subequal, each about as long as first and second together,
fifth segment about half as long as fourth and only about half
as large in diameter. Lacinia broad at base, produced into a long,
PLECOPTERA NYMPHS OF NORTH AMERICA — 67
sharp, incurved tooth, and with a second large tooth followed by
a row of five or six stout hairs.
Labium: first segment of palpus about half again as long as
wide, second nearly twice as long as first, third a little shorter
than second and much more slender; glossae short and rounded ;
paraglossae large, broadly rounded and extending much beyond
the glossae. Hypopharynx broadly rounded and beset with many
short hairs.
Pronotum much wider than long; angles broadly rounded.
Middle portion of pronotum yellow bordered by brown and with
a narrow yellow margin. Meso- and metanotum patterned with
yellow and brown; wing pads broadly rounded. Legs with a
_ fringe of hairs on the femora and tibiae; first and second segment
of tarsus very short, subequal; third concn at least four times
as long as one and two together.
Abdomen slightly depressed, alternately banded with yellow
and brown. Cerci about half as long as the body.
The gills are long and much branched. There are nine pairs
in the mature nymphs, located as follows: two smaller pairs at
the outer base of the prothoracic legs, one large pair attached to
the lateral margin of the conjunctivae, between the pro- and
metasternum; two smaller pairs at the outer base of the meta-
thoracic legs; one large pair attached to the lateral margin of
the conjunctivae between the meso- and metasterna; one smaller
pair at the outer base of the metathoracic legs; one large pair
on the metasternum posterior to the hind legs; and one pair of
eaudal gills.
In the immature nymphs, not all of the above gills are found.
Specimens which measure only 4 to 5 mm. in length may possess
only four pairs of gills, three pairs thoracic and one pair caudal.
Neoperla clymene Newman
(Plate 7, figs. 111-116; plate 19, fig. 195.)
Length of body up to 13 mm.; antennae up to 6 mm.; cerei
up to 6 mm.
General color yellowish with a brown-bordered pronotum, a
bar across the anterior part of the head, and brown transverse
bands on the abdominal segments.
The nymphs of this genus are at once recognized by the fact
that they possess only two ocelli, which are placed very close to-
gether. The head is as wide as the pronotum, yellow, with brown
over entire clypeus, the anterior margin of the labrum brown,
68 THOMAS SAY FOUNDATION
and brown between the ocelli, extending back to the posterior
margin of the head. Ocelli large, the distance between them about
as great as the diameter of a single ocellus; a sharp occipital
ridge extends across the entire head to the outer margin of the
eyes, and bears a group of hairs at the'postero-lateral angles.
Antennae yellowish, of about seventy-five segments; surface of
head quite smooth.
Pronotum twice as wide as long; front margin somewhat con-
vex, hind margin very slightly concave in the center, sides con-
vex, front angles more narrowly rounded than hind ones; middle
portion of pronotum yellow, bordered by brown, and the lateral
margins, as well as most of the posterior margin, yellow; surface
of pronotum smooth, the margins bordered with short hairs.
Meso- and metanotum brownish with middle field and the apical
half of the wing pads yellow. Legs yellow, the femora and tibiae
with a fringe of hairs.
Abdomen somewhat flattened; banded with yellow and brown,
the basal half of each segment brown, and the distal half yellow;
posterior margins of segments bordered by a fringe of short
spinules; caudal gills about as long as tenth tergite; cerci yellow,
of about forty segments, each segment terminating in a whorl
of hairs.
This species was reared by Dr. C. Betten some years ago, the
adult emerging on July 11. It was reared by the writer in 1927,
emerging on July 3. Both specimens are from Ithaca, New York.
The nymphs are found in the quieter pools in freshwater streams.
They are carnivorous, and feed apparently largely upon insect
larvae.
Genus CLIOPERLA Needham and Claassen
The nymphs of this genus, when fully grown, measure not much
over 15 mm. in body length. The general color, as far as is known,
is brown, or a combination of yellow and brown, as in C. clio.
Head a little wider than pronotum; three ocelli, the hind ones
about as close, or a little closer, to the eyes than to each other;
epicranial suture distinct; occipital ridge absent; antennae about
half as long as the body.
Pronotum transversely oval; about twice as wide as long;
marginal groove distinct in front and rear, but indistinct on the
sides. Wing pads well developed and elongated; front wing pads
lying almost parallel to the body, and sinuous on the lateral
margins; hind wing pads directed slightly outward. Legs rather
PLECOPTERA NYMPHS OF NORTH AMERICA — 69
slender; not much flattened; a thin fringe of long hairs on the
outer margin; first and second tarsal segments very short; tar-
sal claws each with a small basal tooth. Abdomen not much flat-
tened; cerci at least half as long as the body. Gills absent.
The mouth parts probably serve as the most reliable characters
for identification of this genus. The detailed description of the
mouth parts of C. clio applies to all three known species.
This genus is rather closely allied to Isoperla and the gill-
less species of Perla. The shape of the lacinia and the slender
pointed apical segments of the maxillary and labial palpi, are
especially helpful in the identification of the nymphs of Clioperla.
Little is known of the biology of the nymphs but the structure
of the mouth parts indicates that they are carnivorous. C. similis
occurs in small upland spring brooks, and the general shape of
the nymphs of this and the other two known species leads me to
believe that they do not inhabit the swifter parts of the larger
streams, but are restricted to smaller brooks.
Key to the Species of Clioperla
1. Western forms, almost uniformly yellowish brown but with
Wellowsmarks on the tiead 6.0.2 ....3 50.0... ebroa (p. 71)
Eastern forms with or without a contrasting pattern of yel-
VOR y SBMS Lea ORy A aac iS 2a oan OO a er 2
2. Head with a broad brown transverse band; pronotum yellow
in the middle, surrounded by brown; abdomen transversely
banded with yellow and brown ............... clio (p. 69)
INOtESO sa. a, De: oad Veg hal as RU 3 ear nee similis (p. 71)
Clioperla clio Newman
(Plate 7, figs. 106-110; plate 19, fig. 196.)
Length of body up to 15 mm.; antennae up to 7 mm.; cerci
up to 8 mm.
General color yellow and brown; head with a wavy brown
transverse band; pronotum yellow in center with brown all
around; sides of pronotal dise yellow; abdominal tergites brown
with a more or less distinct middle transverse band of yellow.
Head a little wider than pronotum, maxillae projecting out-
ward somewhat, so as to be visible from above; a dark wavy
transverse band passes over the front ocellus with arms directed
backward to the hind ocelli, thus leaving an inverted V-shaped
or rounded yellow spot between the hind ocelli; in more fully
70 THOMAS SAY FOUNDATION
patterned nymphs the clypeal area is brownish, also with some
brown on the occiput; hind ocelli a little closer to the eyes than
to each other ; occipital ridge absent ; antennae about half as long
as body and composed of about forty-eight segments.
Pronotum transversely oval, and about twice as wide as long;
marginal groove distinet in front and rear; sides somewhat
flanged and yellow; central area yellow, but completely sur-
rounded by brown; margin fringed with short spinules and a
few longer hairs. Meso- and metanotum mottled with yellow and
brown. Legs slender, yellow, with a fringe of long hairs.
Abdomen nearly gylindrical; tergites brown except for a me-
dian yellow transverse band. Cereci more than half as long as the
body and composed of about thirty segments, each segment ter-
minating in a whorl of short spinules. Subanal lobes rather long
and attenuated at the tip.
The sexes are not easily recognized. In the female, the posterior
margin of the eighth abdominal sternite shows a slight emargina-
tion in the center, and there are no spinules in this area. In the
male, the posterior margin of the eighth abdominal sternite is
either straight or slightly produced in the middle, and the row of
marginal spinules is continuous; the ninth sternite is slightly
more produced posteriorly in the male than in the female. In
mature nymphs the details of the genitalia can often be clearly
seen.
Mouth parts. Labrum more than three times as wide as long;
anterior margin with a fringe of long hairs. Mandibles with six
unequal teeth arranged in two groups of three each; following
the teeth is a fringe of long hairs. Maxillae: cardo and stipes
about equally long; lacinia very wide at the base, and equally
wide up to the base of the teeth; bidentate, the second tooth a
little more than half as long as the terminal one; margin beyond
teeth with a fringe of long stout hairs, also a couple of hairs be-
tween the teeth; galea about half as long as lacinia and tipped
with a seta; maxillary palpus long, slender, and with the terminal
segment much attentuated. Labium about as wide as long; glossae
small; paraglossae large, hairy, somewhat attentuated, and with
a few papillae at the tip; palpi long and slender, the apical seg-
ment as slender as the apical segment of the maxillary palpus.
Hypopharynx broadly rounded.
Many nymphs from Elkhart, Indiana, April to May (R.
Weith), and reared specimens from Work’s Brook, Ottawa, II-
linois, April 8, 1902.
PLECOPTERA NYMPHS OF NORTH AMERICA 71
Clioperla ebria Hay
Length of body up to 16 mm.; antennae up to 8 mm.; cerei up
to 9 mm.
General color yellowish brown to darker brown. Head a little
wider than pronotum; maxillae barely visible from above; a
yellow mark between the hind ocelli, one in front of the anterior
ocellus and one each side of the occiput just inside of the eyes;
occipital ridge absent; hind ocelli a little closer to the eyes than
to each other; antennae about half as long as the body, and
made up of about seventy segments.
Pronotum transversely oval; about twice as wide as long;
margin with a fringe of short hairs; marginal groove distinct in
front and rear but indistinct on the sides, which are somewhat
flanged and light yellow. Front wing pads long, widely separated,
-and lying almost parallel with the body; hind wing pads diverg-
ing outward from body. Legs slender, not much flattened, and
with a very feeble fringe of long hairs. Cerei composed of about
thirty-two segments, the terminal segments about five times as
long as wide.
Described from three mature male nymphs ‘collected by G. S.
Dodds in Tolland, Colorado, and one female nymph without
locality label.
Clioperla similis Hagen
Length of body up to 10 mm.; antennae 5 mm.
Color yellowish brown.
Head slightly wider than pronotum; hind ocelli about as close
to the eyes as to each other; occipital ridge absent; antennae
about half as long as the body and composed of about fifty-five
segments.
Pronotum transversely oval; about twice as wide as long; mar-
ginal groove distinct in front and rear but indistinct on the
sides. Wing pads well developed and very similar to those of
C. cho.
Legs slender, with a thin fringe of long hairs.
Mouth parts very similar in structure to those of C. clio.
Described from a single reared male nymphal skin from Ring-
wood, Ithaca, New York, April 17, 1922. P. W. Claassen.
Genus ISOPERLA Banks
This genus includes nymphs which, when fully grown, do not
measure much over 10 mm. in body length.
General color yellow and brown, often longitudinally striped.
12 THOMAS SAY FOUNDATION
Head about as wide as, or a little wider than, pronotum; three
distinct ocelli placed in an almost equilateral triangle; antennae
long and slender with from forty-five to fifty segments; occipital
ridge absent.
Pronotum about half again as wide as long; all angles broadly
rounded, the hind angles more so than the front ones; marginal
eroove more or less continuous around entire pronotum.
Meso- and metanotum, including wing pads, yellow, and
streaked with brownish markings; legs somewhat depressed, quite
uniformly brownish, hairy; tibiae with a fringe of long hairs on
the outer margin; first two segments of the tarsus very short,
subequal, and together not more than a third as long as the
third segment; claws large, with a small basal tooth.
Abdomen somewhat depressed; cerci composed of about thirty
segments. :
Mouth parts. Labrum three to four times as wide as long;
front margin nearly straight, and fringed with long hairs; upper
surface hairy; ventral surface on each side with long curved
hairs directed inward. Mandibles somewhat asymmetrical; each
with six teeth arranged in groups of three, the teeth followed
by a series of hairs. Maxillae: lacinia large, broad at the base,
bidentate; the second tooth more than half as long as the apical
one; inner margin of the lacinia slightly concave in the center
and with a series of long hairs. Galea cylindric, reaching to the
base of the laciniai teeth and bearing a few hairs at the apex.
Maxillary palpus with segments one to four progressively longer,
and the terminal segment about two-thirds as long as the fourth.
Labrum large; glossae small, triangular; paraglossae large, di-
rected inward, hairy, with long thin hairs on the margins; tips
of glossae and paraglossae with small sensory buds. Hypopharynx
large, rounded, normally produced to the end of the paraglossae
and with a spinulose area at the tip.
The nymphs of this genus are common in most of the fresh-
water streams. They are carnivorous, but in their younger stages
one sometimes finds plant remains, such as diatoms and algae,
in their digestive tract.
Isoperla is distributed over the entire United States, and is
of considerable importance as food for trout and other fish.
Key to the Species of Isoperla
1. Abdomen with three longitudinal dark stripes ............
LE an ek ee AO ke ae ee), ee ee ae bilineata (p. 73)
PLECOPTERA NYMPHS OF NORTH AMERICA 73
2. Caudal half of abdominal segments dark, and the basal half
UL UGSO Lege Sala onk aa gegen signata (p. 75)
Abdomen with a wide, median, longitudinal yellow stripe. 3
3. Wing pads well developed; legs with fringes of long hairs... .
RGM rte Octet acts, dds fo de hs 5-punctata (p. 74)
Wing pads absent, i.e. the postero-lateral angles not pro-
duced; legs without prominent hair fringes.............
TT eet OTs ee Aap Pe Weds petersont (p. T4)
Isoperla bilineata Say
(Plate 8, figs. 123-128.)
Length of body up to 10 mm.; antennae up to 5.5 mm.; cerci
up to 5.5 mm.
General color yellowish with dark brown markings. Easily
recognized by three longitudinal dark stripes on the dorsum of
the abdomen and by the color pattern of head and thorax.
Head very little wider than pronotum, yellowish with dark
brown to blackish markings varying somewhat in different in-
dividuals. In the lighter specimens there is a wide, irregular,
transverse, dark bar across the center of the head, extending from
the base of one antenna to the other. In addition to this bar, there
are darker markings in front of the clypeus, and dark blotches
behind the posterior ocelli and back of the eyes. In the darker
specimens, the entire head is almost uniformly brown except
for a yellow spot in the ocellar triangle, another in front of the
anterior ocellus, and a narrow one behind the ocellar triangle. The
three ocelli are placed in an almost equilateral triangle, the hind
ones being a little closer to the eyes than to each other; surface
of head smooth and rather sparsely clothed with brown hairs;
antennae composed of about forty segments.
Pronotum about twice as wide as long; suboval; hind angles
more broadly rounded than front ones. A wide, median, longi-
tudinal yellow stripe; dise brownish; lateral margins yellow;
marginal groove distinct along the anterior and posterior margins
but indistinct on the lateral margins; surface nearly smooth
and moderately covered with short brown hairs.
Meso- and metanotum and wing pads yellowish with many
irregular dark markings. Legs somewhat flattened, hairy, the
femora and tibiae with a fringe of thin long hairs, more pro-
nounced on the femora than on the tibiae.
Abdomen yellowish, with three wide, dorsal, longitudinal dark
stripes and in some specimens also with darker interrupted
74 THOMAS SAY FOUNDATION
markings on the sides of the abdomen; surface hairy; posterior
margin of each segment with a row of short spinules. Cereci
brownish; about twenty-five segments, each of which ends in
a whorl of short spinules and with longer hairs on the dorsal
surface.
This is one of the most common stoneflies in the Central and
Eastern States.
Ithaca, N.Y.; North Lansing, Mich.
Isoperla 5-punctata Banks
Length of body up to 12 mm.; antennae up to 7 mm.; cere
up to 6 mm.
General color yellow with brown markings; easily recognized
by the wide median yellow stripe running the entire length of
the abdomen and a broad brown stripe on each side.
Head a little wider than pronotum; brown, with a few lighter
spots in front of the ocellar triangle, and a large yellow irregular
spot between the eyes; surface smooth, with a rather sparse coat-
ing of short brown hairs; antennae with about fifty segments.
Pronotum approximately half again as wide as long, more or
less uniformly brown except for a wide median longitudinal
yellow line, and the yellow lateral margins; angles rounded, the
posterior ones more so than the anterior ones; surface nearly
smooth and covered with brown hairs which are longer on the
outer margin than on the surface.
Meso- and metanotum yellowish with longitudinal darker mark-
ings, especially noticeable on the wing pads. Legs uniformly
brownish, bearing a fringe of long hairs.
Abdomen with a broad median longitudinal yellow band, on
either side of which there is a longitudinal brown band. Sides
and ventral surface of abdomen more or less uniformly yellow-
ish brown; cerci composed of about twenty-eight segments.
This species was described from a nymphal skin of a female
which was reared by Miss Robinson, at San Jose Creek, near
Pomona, California, March 20, 1923. I have, also, nymphs from
San Antonio Canyon, California, May 12, 1923; Logan River,
Utah, June 238, 1926, J. G. Needham; Santa Fe, New Mexico,
June 1, 1904, P. B. Powell.
Isoperla petersoni Claassen
(Plate 20, fig. 197:)
Length of body up to 9 mm.; antennae up to 4.5 mm.; cerci
up to 4.5 mm.
PLECOPTERA NYMPHS OF NORTH AMERICA 75
General color brown with a wide, yellow median longitudinal
stripe running the length of the thorax and abdomen, and with
a narrow yellow stripe on each side of the abdomen.
Head about as wide as pronotum; a yellow spot in front of the
anterior ocellus, and a yellow area inside the eyes, extending
from the base of the antennae to the hind margin of the head.
Pronotum with a wide median yellow longitudinal stripe; a
yellow spot on each lateral field, and the lateral margins also
yellow. Meso- and metanotum similar in coloration to pronotum,
and, since the adult is apterous, or very nearly so, the postero-
lateral angles are not prolonged.
Legs slender and without a fringe of long hairs.
Abdomen marked with three longitudinal stripes as noted
above. |
The nymphs of this species were collected by J. G. Needham at
Peterson’s Springs, Logan, Utah, July 26, 1926.
Isoperla signata Banks
(Plate 20, fig. 198.)
Length of body up to 10 mm.; antennae up to 5.5 mm.; cerci
up to 5.5 mm.
Color yellow with brown markings. Recognized by two dark,
transverse bands across the head; pronotum margined with
brown; abdominal segments with the basal half yellow and the
caudal half brown.
Head not wider than pronotum; yellow with brown markings
as follows; a broad transverse band just back of the yellow la-
brum ; this band connects at the outer margins with another wavy
band extending across the head in line with the front ocellus, and
-in the middle extending caudad over the ocellar triangle, leaving
a yellow spot in the center of the ocellar triangle. In some speci-
mens the occiput is somewhat darker; hind ocelli a little closer
to the eyes than to each other; antennae composed of about forty-
eight segments.
Pronotum suboval, in some specimens almost rectangular; half
again as wide as long; angles rounded; the large middle yellow
area bordered with brown but with the lateral margins also yel-
low. Meso- and metanotum yellow with brown markings on the
anterior and posterior margins, and with two longitudinal brown
stripes on the front wing pads. Legs yellow with a fringe of long
hairs on the outer margin, most pronounced on the tibiae.
Abdominal segments one to nine each with the basal half yel-
ie THOMAS SAY FOUNDATION
low and the caudal half brown; last segment yellow except for a
small, basal, median brown spot; surface hairy, each segment with
a fringe of short hairs on the posterior margin. Cerci yellow, of
about twenty-two segments, each segment ending in a whorl of
short hairs.
Described from reared specimens, May 19 to 381, 1926, Ithaca,
N.Y. |
Genus PERLESTA Banks
The nymphs of this genus resemble the nymphs of Perla but
the segments of the cerci are longer in Perlesta than in Perla. The
body is generally covered with small brown spots, giving the
nymphs a freckled appearance.
Length of the full-grown nymphs is about 10 mm.; color yel-
lowish to yellowish brown, usually with a darker transverse band
between the eyes, crossing the ocellar triangle; head a little nar-
rower than pronotum; eyes moderately large; three ocelli ar-
ranged in an isosceles triangle with the hind ocelli closer to each
other than to the eyes; occipital ridge noticeable, although not as
prominent as in most of the species of Perla. Antennae of medium
length and composed of approximately fifty segments. Pronotum
transversely oval, sides broadly rounded; surface quite smooth
and lateral margins somewhat produced in the form of flattened
flanges ; meso- and metanotum large, wing pads broad. Abdomen
somewhat flattened, posterior margins of segments fringed with
medium-sized spinules. Legs flattened, hairy, with long fringes
of hairs on the outer margin of the femora and tibiae; first and
second tarsal segments short, subequal, and together less than
half as long as the third; cerci very long, about four-fifths as long
as body with the segments beyond the middle four to five times
as long as wide; each segment terminating in a whorl of long
hairs.
Seven pairs or groups of branched filamentous gills. Entire
surface of body covered with long hairs, more noticeable in the
younger specimens than in the fully mature ones.
Mouth parts. Labrum about four times as wide as long, the an-.
terior margin fringed with hairs. Mandibles asymmetrical, each
with five sharp teeth followed by a series of long hairs. Maxillae
rather long and slender; lacinia unique in that the inner margin
below the large terminal tooth is devoid of a series of hairs, ex-
cept for one long hair at the base of the second tooth, which is
very long; galea very slender, extending about to the middle of
the terminal tooth; tip of galea bearing a small bunch of hairs;
PLECOPTERA NYMPHS OF NORTH AMERICA 17
maxillary palpus long and slender reaching far beyond the tip
of the lacinia; the terminal segment tapers to a rather fine point ;
stipes about as long as lacinia. Labium wide; submentum about
twice as wide as long; glossae short, triangular; paraglossae large
and rounded at the tip; both glossae and paraglossae with a few
tubercles at the tip.
Perlesta placida Hagen
(Plate 4, figs. 60-65; Plate 21, fig. 199.)
Length of body up to 10 mm.; antennae up to 5 mm.; ecerci up
to 6mm.
General color yellowish brown, with a tendency toward having
the entire body covered with small brown dots, giving it a freckled
appearance. Head a little narrower than the pronotum, yellowish
with a darker transverse band across the head through the region
of the ocellar triangle; hind ocelli closer to each other than to the
eyes; occipital ridge not very prominent but plainly indicated by
a series of very short hairs, and by brown markings; antennae
long and slender and composed of at least fifty segments.
Pronotum at least twice as wide as long; front margin convex,
hind margin nearly straight; angles broadly rounded; surface
slightly rugose, yellowish brown with lighter areas on the lateral
margins and along the middle of the anterior and posterior mar-
gins; a shallow groove extends around entire pronotum; sides
of pronotum with rather wide flanges; surface quite hairy, with
rather long hairs all around the margin; meso- and metanotum
very broad, sides usually much rounded.
Legs flattened; femora and tibiae fringed with long hairs;
first and second tarsal segments short, subequal, the two together
less than half as long as third segment. Abdomen depressed ; sur-
face hairy; posterior margin of each segment with a row of
spinules. Cerci long and slender and composed of about twenty-
five segments, the ones beyond the middle very long.
Seven pairs of branched gills; two pairs on the prothorax at
the outer base of the legs; two double pairs on the mesothorax,
the first at the antero-lateral margin of the mesosternum, the
other at the outer base of the legs; two pairs on the metathorax,
the first at the antero-lateral margin of metasternum, the other
at the outer base of the legs. One pair of anal gills.
The nymphs are carnivorous and occur mostly in swift water.
This species is widely distributed over the Central and Eastern
States.
78 THOMAS SAY FOUNDATION
Ithaca, N.Y.; Elkhart, Ind.; Lake Forest, Ill.; W. Ottawa, IIL;
Potomac R., Brunswick, Md.
Genus ATOPERLA Banks
Length of body not over 12 mm. The nymphs of this genus
possess copious thoracic gills but no anal gills. The lacinia of the
maxilla terminates in a single tooth; posterior ocelli distinct,
and anterior ocellus either entirely absent or indicated by a
small depression.
In general appearance Atoperla is similar to Perlinella but is
smaller in size and has no anal gills.
Atoperla ephyre Newman
(Plate 8, figs. 129-134; plate 22, fig. 200.)
Length of body up to 9 mm.; antennae up to 3 mm.; cerci up
to 3 mm.
These small brownish nymphs possess long gill tufts on the
thorax, have only two distinct ocelli, set much farther apart
than in Neoperla, and have the lacinia unidentate.
The specimens which I have are old and shriveled, hence there
is some question whether the rather uniform brownish color repre-
sents the true color of fresh specimens.
Head slightly wider than pronotum; hind margin of eyes in
line with posterior ocelli, which are as close to the eyes as to
each other; front ocellus either absent or only indicated by a
small depression ; occipital ridge absent.
Pronotum nearly twice as wide as long; hind angles very
broadly rounded, front ones more narrowly rounded; marginal
groove continuous all around; surface only slightly rugose. Wing
pads considerably prolonged; broadly rounded at the tips.
Legs flattened ; femora and tibiae with a fringe of long hairs;
first and second tarsal segments very short, subequal; third seg-
ment about four times as long as the two preceding combined.
Abdomen brownish, slightly depressed. Cerei of about twenty-
five segments. Labrum about three times as wide as long, with a
fringe of hairs on the front margin. Mandibles rather narrow,
asymmetrical; each with four rather large teeth followed by a
fringe of hairs. Maxillae: lacinia unidentate; inner margin with
six or seven very stout hairs, the one next to the apical tooth
so large as to suggest a second denticle. Galea slender and shorter
than lacinia. Labium; glossae very short, triangular; paraglossae
large and widened toward the tip.
PLECOPTERA NYMPHS OF NORTH AMERICA 79
Three alcoholic specimens from Fox River, Ottawa, Illinois,
May 31, collected by W. A. Howard.
Genus PERLINELLA Banks
This genus, of which only one species, P. drymo Newman, is
known from North America, is readily recognized by its almost
uniformly yellowish brown color; its long head with small eyes
set far forward on the head so as to be located on a line almost
even with the front ocellus; its long, branched, copious gills
on the thorax; and a pair of small caudal gills. The mature
nymphs are medium sized, measuring less than an inch in length
when fully grown. Antennae and cerci each almost half as long as
the body; three ocelli, the anterior one small.
Pronotum transversely oval; wing pads wide, rather broadly
rounded on the sides and at the apex. Legs fringed with long
hairs. First two segments of tarsus very short, the third one
about four times as long as one and two combined.
Abdomen slightly flattened; tenth tergite produced into a
median rounded lobe; cerci long and slender with the apical seg-
ments very long.
Generally distributed east of the Mississippi River.
Perlinella drymo Newman
(Plate 8, figs. 117-122; plate 22, fig. 201; plate 32, fig. 225.)
Length of body up to 22 mm.; antennae up to 10.5 mm.; cerci
up to 12 mm.
Yellowish brown. Readily recognized by its long head, small
eyes set far forward, and by its much-branched, copious, long
tracheal gills. Head almost as long as wide, slightly wider than
pronotum; yellowish with an irregular transverse dark band,
and with darker areas on the eclypeus and occiput; ocelli small,
placed in an equilateral triangle; eyes small, set forward in the
head so as to be nearly in line with the front ocellus; antennae
yellow, long and slender.
Pronotum transversely oval, about half again as wide as long,
almost uniformly brownish, with a dark narrow marginal groove ;
_ surface nearly smooth; sides and angles broadly rounded. Meso-
and metanotum irregularly marked with brown and yellow; wing
pads broadly rounded on the sides and with tips broadly rounded.
Legs fringed with long hairs; first and second tarsal segments
very short, subequal, the third about four times as long as one
and two together.
80 THOMAS SAY FOUNDATION
Abdomen depressed, quite uniformly yellowish brown; cerci
long and slender, and composed of about forty segments, each
segment tipped with a whorl of spines or hairs.
The gills of this species are longer in proportion to the size of
the body and more copious than in any other known nymphs.
They are located as follows; two pairs at the outer base of the
front legs; one pair, each consisting of two main trunks, on the
lateral margin of the conjunctivae between the pro- and meso-
thorax; two pairs at the outer base of the lateral margin of the
conjunectivae between the meso- and metathoracic legs; one pair,
each with three main trunks, at the postero-lateral base of the
metathoracic legs, and one pair of small caudal gills attached to
the subanal lobes. In the more immature forms, the caudal gills
are either absent, or so small as to be easily overlooked.
Mouth parts. Labrum about four times as wide as long. Man-
dibles slightly asymmetrical, each with four teeth followed by long
hairs. Maxillae: first segment of palpus about as wide as long;
second half again as long as wide; third and fourth subequal,
each about as long as one and two combined; fifth about three-
fourths as long as fourth, and half as wide. Galea slender, two-
segmented, the basal segment a little longer than the apical one,
which is tipped with a few hairs. Lacinia broad at base and gradu-
ally tapering to a long incurved tooth, which has at its base a
second long tooth; this second tooth is followed by a series of
about six long stout hairs and a series of more slender hairs.
Labium: first segment of palpus twice as long as wide, the second
half again as long as first, third about as long as first but much
more slender; glossae small; paraglossae produced into large
rounded lobes.
Little is known about the biology of this species. The nymphs
occur in pools of streams and have been taken several times from
Beebe Lake, a small lake formed by an artificial dam in Fall
Creek, Ithaea, New York. Specimens have been reared as follows:
Elkhart, Indiana, April 2, by A. Weith; Lake Forest, Illinois,
April 15, 1902, by J. G. Needham.
Genus ACRONEURIA Pictet
The nymphs of this genus are rather large, mostly more than
an inch in length when fully grown. Body depressed; gills under
thorax, and some species with anal gills also. Color varying from
uniform brown to strikingly colored patterns of yellow and
brown.
In general appearance these nymphs resemble very closely the
PLECOPTERA NYMPHS OF NORTH AMERICA § 81
nymphs of Perla (sens. str.) but in most of the known Acroneuria
nymphs, the occipital ridge is absent (except in ruralis and
depressa). In many specimens it is often possible to observe the
venation in the wing pads, and this, together with a study of the
genital structures of mature nymphs, aids in placing the speci-
mens in the correct genus.
Head rather wide and short; three ocelli; antennae long and
slender.
Pronotum much wider than long; rounded; marginal groove
more distinct in front and rear than on sides. Wing pads wide
and not much produced. Legs with a wide fringe of hairs on
the outer margin; first and second tarsal segments very short
and subequal.
Abdomen depressed; the sexes not easily recognized except
in mature nymphs where the developing genital characters may
be observed. Cercei long and slender.
Mouth parts very similar to those of the nymphs of Perla.
So far as is known the nymphs inhabit swift-water streams
where they occur underneath the stones. The life cycle extends,
apparently, over three years in most, if not all, species. This
genus ranges over the entire United States and Canada.
Key to the Nymphs of Acroneuria
i BWA) GAMTIRE OS CaS aT ee can en cre 2
ENT EAM ENE. SUSE veg Sy Pe ol an ee +)
2. A distinct occipital ridge present.......... depressa (p. 86)
rte eral SO lie meters shies oon A esate sho eg ak os 3
3. Western; anal gills very copious; head with a pronounced
blaze, i.e. a yellow mark extending from the labrum to the
anterior ocellus; pronotum without pronounced yellow
TPO MAD BU atigest New ola. gs eae ere ee eee pactfica (p. 88)
Eastern or Southern; anal gills of rather few filaments; head
without a blaze; a dark transverse band extends across the
entire head in front of the anterior ocellus; pronotum with
mide wvellow langes:-on ithe: side 2% a. nig ace cre so ees 4
4. Last abdominal tergite uniformly brown ............. arida
Last abdominal tergite darker on the posterior margin; espe-
cially noticeable in the middle prolongation arenosa (p. 84)
5. A distinct occipital ridge present; cerci longer than body;
PolGreuni orm iyeTO Wiles cess seei ee none: ruralis (p. 89)
No distinct occipital ridge; cerei shorter than ee ; eae
with striking color J MENSA Nie as yoo aye Rerun NGC . 6
82 THOMAS SAY FOUNDATION
6. Abdominal tergites with basal half yellow and caudal half
dark (even in the darkest colored nymphs the last ab-
dominal tergite has a yellow basal spot with the caudal
half black)i-7 Bastern so. on = oe ee lycorias (p. 87)
Abdominal tergites not distinctly banded with yellow and
dark; and never with the hind margin of the abdominal
tergite blackish 2 -...7 000.0040 se ee rr Hl
7. Eastern; abdomen uniformly dark brown or blackish; femora
with a longitudinal dark band on the upper surface .....
ae UM TR Ete SR ond Vote iid V5 abnormes (p. 82)
Western; mostly yellowish ...277..3). 2.2.2 7.0 7 8
8. A yellow spot over the ocellar triangle; head and thorax very
strikingly patternede. ts san ere californica (p. 85)
Ocellar triangle dark; head and thorax not strikingly pat-
TEIN eee eee ae ee ee ee theodora (p. 90)
Acroneuria abnormis Newman
(Plate 5, figs. 66-70; plate 31, fig. 221.)
Length of body up to 29 mm.; antennae up to 16 mm.; cerci
up to 22 mm.
The nymphs of this species normally are dark brown to black-
ish in color, with lighter markings on the head, pro-, meso-, and
metanotum, but with the abdomen usually uniformly brown, and
with the last abdominal segment dark brown or blackish; the
cerci are usually as long as, or slightly longer than, the body
and possess long hairs on the inside, especially near the base.
The legs bear thick fringes of very long hairs.
Head slightly wider than pronotum, dark brown to blackish;
occiput yellow; a yellow spot outside of hind ocelli; a yellow
M-line, which in some specimens is more interrupted; clypeus
yellow; labrum dark brown; hind ocelli about half again as close
to each other as to the eyes; area behind eyes with short spines
on the caudo-lateral angles; surface smooth; antennae with about
ninety segments.
Pronotum a little less than twice as wide as long; front margin
broadly convex; hind margin nearly straight; sides rounded;
angles broadly rounded; surface brown to blackish, with yellow
markings, as indicated in Plate 31, fig. 221. Lateral margins also
lighter; marginal groove extends completely around pronotum,
but is narrower and deeper on the anterior and posterior margins
than on the sides; meso- and metanotum dark brown, with yellow
markings.
PLECOPTERA NYMPHS OF NORTH AMERICA = 83
Legs broad and much flattened; femora covered with fine
hairs, interspersed with stout spines; along their middle a nar-
row, longitudinal line, in which the hairs are absent; the entire
leg bears a thick fringe of long hairs on the outer margin.
Abdomen somewhat flattened and usually uniformly brown
or blackish in color, although in some of the lighter specimens
there is a tendency for a yellowish spot to appear on the posterior
half of each segment along the median dorsal line; the abdominal
segments are all bordered posteriorly with a fringe of short
spines; on the tenth tergite these are a little longer. Cerei very
long and on the inside with a thick, wide fringe of long hairs,
especially copious at the base, gradually becoming shorter and
thinner toward the tip, and extending the entire length of the
cerci; the individual segments, of which there are about sixty,
each bearing a whorl of spines on the posterior margin.
Hight pairs of branched, tracheal gills as follows: two pairs
at the outer base of the prothoracie legs; one pair each on the
outer conjunctivae between the pro- and mesothorax, and between
the meso- and metathorax; two pairs at the outer base of the
mesothoracic legs; one pair at the outer base of the metathoracic
legs, and one double pair at the caudal base of the metathoracie
legs; anal gills absent. |
Mouth parts. Labrum about three times as wide as long; black-
ish, the front margin having a fringe of long hairs. Mandibles
somewhat asymmetrical, each with five distinct, sharp teeth, of
which the first, second, and fourth are the largest; following
these teeth is a fringe of long, stout hairs. Maxillae with laeinia
bidentate, with a series of long, stout hairs; galea distinctly two-
seomented, cylindrical, slender, shorter than the lacinia, and with
a small bunch of hairs at the apex; maxillary palpus five-segment-
ed, first about as long as wide, second a little more than twice as
long as wide, the apical segment only about half as long as the
fourth, and much more slender. Labium very broad; submentum
much broader than long; glossae short, more or less triangular ;
paraglossae large with long hairs on the inner margin; the three-
segmented labial palpus extends beyond the paraglossae; the
first segment about twice, or a little more than twice, as long as
wide ; second about a third again as long as first, the third about
two-thirds as long as the second, and much more slender. Hypo-
pharynx rounded and normally extending nearly to the tip of
the glossae. ;
This species is common in the larger swift-water streams of
the Eastern States. The long thick fringes on the legs and the
84 THOMAS SAY FOUNDATION
copious fringes of hairs on the inner side of the cerci, in which
considerable silt and dirt collect, gives the nymphs a rather
unique appearance and is an aid in identifying them in the field.
The nymphs are, of course, carnivorous in habit, and they ap-
parently have a three-year life cycle. In some of the specimens
which have been collected around Ithaca, I have found on the
wing pads, and on the legs, small Chironomidae larvae. Whether
these larvae are parasitic upon the nymph has not been definitely
established, but it appears that this is not a mere accidental as-
sociation, and that possibly these larvae may, to some extent, at
least, be parasitic upon the stonefly nymphs.
Ithaca, N.Y.; Moffitsville, N.Y.; Potomac R., near Harper’s
Ferry, Md.
Acroneuria arenosa Pictet
Length of body up to 24 mm.; antennae up to 15 mm.; cerci
up to 24 mm.
This genus is represented in our collection by a single speci-
men, collected from the Potomac River at Great Falls, Virginia,
April 10, 1926. Identification was made possible by a study of the
venation of the wing pads, which were far enough developed to
clearly indicate the peculiarly much-branched condition of the
anal veins of the front wings, a condition unique to this species.
Nymphs rather strikingly patterned with yellow and brown.
Head a little narrower than pronotum, the area posterior to the
epicranial suture mostly yellow, with the portions behind the
eyes darker brown; clypeus, frontal M-line, and a spot on the
outside of each hind ocellus, yellow, remainder dark brown. Hind
ocelli nearly twice as close to each other as to the eyes. Antennae
yellowish, with about one hundred segments.
Pronotum nearly twice as wide as long, dises and lateral mar-
gins yellow, the rest dark brown; front margin fairly convex;
hind margin slightly concave in center; angles broadly rounded ;
surface nearly smooth and covered with a fine coating of hair.
Meso- and metanotum patterned with yellow and brown, outer
portions of wing pads brown, inner portions yellowish.
Legs quite uniformly yellowish, with a median, longitudinal,
narrow smooth line on the dorsal surface of the femora; margins
of legs with a thick fringe of whitish hairs.
Abdominal segments brownish, with a row of roundish, yellow
spots along the median dorsal line, and with similar spots on
the lateral margin of the posterior segments. Posterior margin
of last abdominal tergite dark brown or blackish. In this respect
PLECOPTERA NYMPHS OF NORTH AMERICA 85
it resembles lycorias somewhat, but this dark band is narrower in
arenosa. Cerci yellowish, with a rather thin fringe of hair on the
inner margin; composed of about sixty segments, each segment
terminating in a whorl of short spines.
Gills very similar in size and location to those of abnormis,
however, arenosa possesses a pair of small caudal gills in addition
to the thoracic ones.
Nothing is known of the life history of this species, although
the mouthparts indicate that it is carnivorous in habits, and the
general structure suggests that it normally inhabits the larger
swift-water streams.
Potomac River at Great Falls, Va.
Acroneuria californica Banks
(Plate 26, fig. 205.)
Length of body up to 24 mm.; antennae up to 10.5 mm.; cercei
up to 14 mm.
General color yellow and brown; entire body thickly covered
with short brown hair. The yellow spot over the ocellar triangle
serves as a good identification mark of this species. This yellow
spot is bounded on the rear by the arms of the epicranial suture,
extends laterally beyond the hind ocelli to a sharp point, and
reaches anteriorly almost to the front ocellus. Hind ocelli much
closer to each other than to the eyes; occipital ridge faintly indi-
cated by a row of spinules, especially in the center of the occiput.
Entire surface of head thickly covered with short brown hair,
usually more noticeable on the darker areas; antennae nearly
half as long as body and made up of about eighty segments.
Pronotum a little narrower than head, slightly widened posteri-
orly; front and hind margins convex; hind angles more broadly
rounded than front ones; marginal groove distinct ; lateral flanges
narrow and yellow; median longitudinal yellow line narrow.
Meso- and metanotum and wing pads covered with hairs, and on
the outer margins with short spinules.
Legs flattened ; with a fringe of long hairs on the outer margin.
Abdomen not much flattened, yellowish but with the posterior
margins of the tergites brown, covered with brown hairs and
the posterior margins of the tergites with a fringe of spinules.
Cerci about half as long as the body and composed of about
thirty-five segments, each segment ending in a whorl of spines.
Nine pairs of gill tufts; two pairs at the outer base of the
prothoracie legs; two pairs in similar locations on the meso-
86 THOMAS SAY FOUNDATION
thoracic legs; three pairs at the postero-lateral base of the meta-
thoracic legs; one pair on the lateral conjunctivae between the
pro- and mesosternum, and one pair in a similar location between
the meso- and metasternum. Anal gills absent. In the male
nymphs the ninth sternite is somewhat produced, and in mature
nymphs the elongate ‘‘hammer’’ is noticeable. The female nymphs
are larger than the males, the ninth abdominal tergite is not
much produced and the developing genital opening is plainly
indicated in the middle of the posterior margin of the eighth
sternite.
Mouth parts of the carnivorous type and very similar in struc-
ture to the mouth parts of other species in this genus.
This species has not been reared, but I have before me a num-
ber of mature nymphs in which the genitalia can be clearly seen,
and this has made possible the identification.
Nothing is known of the life history or biology of this species,
but the life cycle probably is not completed in less than three
years.
Eel R., Calif.; Evey’s Canyon, Calif.; San Jacinto, Calif.; San
Antonio Canyon, Claremont, Calif.; Logan R., Utah.
Acroneuria depressa (?) Needham and Claassen
(Plate 27, fig. 207.)
Length of body up to 31 mm.; antennae up to 15 mm.; cerci
up to 20 (?) mm.
Head about as wide as pronotum; ocelli very large, hind ones
closer to each other than to the eyes; between the transverse dark
band, which passes through the ocellar triangle, and the lateral
arms of the epicranial suture, there are three inverted V-shaped
yellow spots; one between the ocelli and one outside of each hind
ocellus; occipital ridge strongly developed and uniformly prom-
Inent across the occiput; antennae about half as long as body
and made up of about eighty to eighty-five seements; surface of
head with many short brown hairs.
Pronotum about twice as wide as long; hind angles very broad-
ly rounded, front ones more narrowly so; lateral dises yellow with
brown markings; marginal groove distinct and continuous; entire
margin of pronotum dark brown around the edge.
Meso- and metanotum with a variegated pattern of yellow and
brown, covered with short brown hairs, and the outer fields of the
wing pads with short spinules. Legs flattened; yellowish with a
transverse brown band across the middle of the femora, and the
PLECOPTERA NYMPHS OF NORTH AMERICA 87
proximal end of tibiae brown; outer margin with a fringe of
long hairs.
Abdomen flattened ; basal half of tergites usually darker brown
than caudal half; tenth tergite usually brown except for a small
oblong yellow spot in the center; surface covered with brown
hairs; each segment with a fringe of short spinules; cerei more
than half as long as body and made up of forty or more seg-
ments (tips broken off).
Gill tufts as in A. californica, except that this species has, in
addition to the thoracie gills, a pair of large anal gill tufts.
The mouth parts are very similar in structure to those of A.
californica.
The above description is made from four specimens; two im-
mature nymphs and a east skin from Left Branch, Provo River,
Logan, Utah, July 28, 1926, J. G. Needham; and one almost
mature nymph which bears the label Nez Perces Cr., above Basin,
Rocky ‘‘ripples,’’ Aug. 15, 790, 26918.
It was at first thought that these nymphs might belong to the
genus Perla, because of the distinct occipital ridge, but the large
ocelli, the general structure, and the faint indication of a ‘‘ham-
mer’’ on the ninth abdominal sternite of the male nymphs in-
dicate that they very probably are the nymphs of A.. depressa.
wyopne”?
; : car?’
Acroneuria lycorias Newman yg? Sion 5 SOK)
$ 2
(Plate 10, figs. 165-166; plate 31, fig. 222.) (131 aan f
Leneth of body up to 24 mm.; antennae up to 15 mm.; cerei
up to 18 mm.
The nymphs of this species are strikingly marked with brown
and yellow.
Head a little narrower than the pronotum; transversely banded
with yellow and dark brown. Entire occiput behind the epicranial
suture yellow, except for a small area behind the compound eyes;
area in front of the epicranial suture up to the region of the
fronto-clypeal suture dark brown, except for the transverse M-
mark and a small yellowish mark on the outside of the posterior
ocelli. Clypeus yellow ; labrum dark brown; hind ocelli about twice
as close to each other as to the eyes. Antennae yellowish, of about
one hundred and five segments.
Pronotum nearly twice as wide as long, slightly widened pos-
teriorly, front margin somewhat convex, hind margin nearly
straight; all angles broadly rounded.
Legs much flattened; coxa, trochanter, and the basal part of
88 THOMAS SAY FOUNDATION
femur, brown, and the femora with another transverse brown
band just before the apex.
Abdominal segments normally with their basal half yellowish,
and the posterior half dark brown to blackish. In some of the
more darkly colored specimens the segments are almost entirely
brown or blackish, with only the median portion of the basal parts
yellowish. Cerei composed of about fifty segments and bearing on
the inner surface a fringe of long, fine hairs, which are longer
and more dense at the base than beyond. Entire surface of the
nymph covered with a fine coating of brownish hairs, except the
head, which is quite smooth.
Gills and the mouth parts as in A. abnormis. Anal gills absent.
These nymphs are commonly found in swift-running water under
stones, and although little is known of their habits, they are of
the carnivorous type, and apparently have a three-year life cycle.
The narrow black band on the posterior margin of the tenth
abdominal tergite readily distinguishes lycorias from related
forms.
Ithaca, N.Y.; Dansville, N.Y.; Lake George, N.Y.; Clinton,
N.Y.; Ft. Ann, N.Y.; Guelph, Ont.
Acroneuria pacifica Banks
(Plate 5, figs. 71-76; plate 25, fig. 204; plate 32, fig. 224.)
Length of body up to 23 mm.; antennae up to 19 mm.; cerci
up to 11 mm.
This is a western form and is most readily recognized by the
blaze upon the head in front of the anterior ocellus.
General color chestnut brown to dark brown, with lighter areas
on head and thorax.
Head a little narrower than pronotum, brown, with lighter
areas on the occiput, and lighter spots on the outside of the hind
ocelli, and with a whitish blaze extending forward from the an-
terior ocellus as indicated in Plate 32, fig. 224.
Pronotum a little more than twice as wide as long, somewhat
convex on the anterior margin and slightly concave on the
posterior one; lateral margins convex, angles broadly rounded ;
marginal groove distinct near the anterior and posterior margins,
but rather faintly noticeable on the sides, which are not produced
into distinct flanges.
Legs somewhat flattened, fringed thickly with long hairs.
Abdomen somewhat depressed, brown, each segment with a
round yellowish spot near the posterior border along the median
PLECOPTERA NYMPHS OF NORTH AMERICA — 89
line; surface covered with fine hairs, and posterior margins with
a fringe of spinulose hairs; cerci composed of about thirty-five
segments, each with a whorl of short spines on the posterior
margin; the cerci are devoid of long hairs.
Gills. Ten pairs of much-branched, filamentous gills; two small
pairs at the outer base of the prothoracic legs; one on the outer
conjunctivae between the pro- and mesothorax; two pairs at the
outer base of the mesothoracic legs; one pair on the outer con-
junctivae between the meso- and metathoracic legs; and one pair
of large caudal gills. Some of these gills are so closely crowded
that superficially the nymph appears to have only six pairs of
gills, including the anal gills.
Mouth parts. Labrum about three times as wide as long; an-
terior margin with a fringe of long hairs. Mandibles slightly
asymmetrical, each with five distinet teeth, of which the first,
second, and fourth are the largest ; beyond these teeth is a fringe
of long hairs. Maxillae: lacinia bidentate, with the second tooth
a little more than half as long as the first; following the second
tooth there is a fringe of long hairs; galea distinctly two-seg-
mented, shorter than the lacinia, and at the tip with a small
eroup of hairs; maxillary palpus extends considerably beyond
the tip of the lacinia. Labium: submentum very broad; glossae
small, triangular; paraglossae large and fleshy, directed inward
at the tips, and bearing a series of long hairs.
This species is quite common in the swift-running streams of
the Western States.
Logan R., Utah; Provo R., Utah; Estes Park, Colo.; Boulder,
Colo.; Yellowstone National Park; Pecos, N. Mex.; Jocko R.,
Mont.
Acroneuria ruralis Hagen
(Plate 24, fig. 203; plate 32, fig. 223.)
Length of body up to 24 mm.; antennae up to 11 mm.; cerci up
to 25 mm.
The nymphs of this species are readily recognized by their
uniform light brown to chestnut brown color, their very broad
pronotum, with wide, flaring flanges ; antennae not more than half
as long as the body; cerci extremely long, equaling or surpassing
the entire body.
Head a little narrower than pronotum, uniformly brown, ex-
cept for somewhat lighter areas around the ocelli and eyes; eyes
small, black, and set forward some distance from the postero-
90 THOMAS SAY FOUNDATION
lateral angle of the head; hind ocelli almost twice as close to each
other as to the eyes; a wavy occipital ridge present. Antennae
yellowish with about seventy-five short segments.
Pronotum a little less than three times as wide as long; front
margin nearly straight or slightly convex; hind margin rather
deeply concave in center; sides and angles broadly rounded, the
former produced into wide flanges. Meso- and metanotum similar
to the pronotum in color and markings; sides of wing pads broad-
ly rounded and bearing on the lateral margin a series of spinulose
hairs; legs flattened; femora and tibiae with a thick fringe of
white hairs.
Abdomen flattened, posterior margin of each segment with
a row of stout hairs; cerei very long, and tapering from a rather
stout base to a very slender apex; composed of about fifty-five
segments, the basal segments very short, apical ones long and
slender, each segment terminating in a whorl of short spines;
inner margin of cerei with a fringe of hairs.
Nine pairs of branched, filamentous gills as follows; two pairs
on each of the outer bases of the pro- and mesothoracie legs; one
pair at the outer base of the metathoracic legs; one pair at the
lateral conjunctivae between the pro- and mesothorax; one pair
between the meso- and metathorax; and two pairs on the meta-
thorax. Each of these nine pairs of gills is much branched, and
extends outward beyond the margin of the pro-, meso-, and meta-
notum; anal gills absent.
Fairport, Iowa.
Acroneuria theodcra Needham and Claassen
(Plate 26, fig. 206.)
Length of body up to 34 mm.; antennae up to 14 mm.; cerci
up to 19 mm.
The nymphs of this species are easily confused with the nymphs
of A. californica because of their close general resemblance. In
A. theodora however the ocellar triangle is completely covered
with brown except for a small round yellow spot in the center
of the triangle in some of the nymphs, while in A. californica the
hind ocelli are always surrounded by a transverse yellow spot.
In A. califormca the femora are uniformly yellowish, while in A.
theodora the middle portion of the femora is darker than the
rest. A. theodora is also larger than califormea.
General color yellow and brown, the entire body covered with
short brown hairs.
PLECOPTERA NYMPHS OF NORTH AMERICA 91
Head a little wider than pronotum ; a dark spot over the ocellar
triangle except that in some nymphs there may be seen a small,
round yellow spot in the middle of the ocellar triangle; hind
ocelli much closer to each other than to the eyes; occipital ridge
absent ; antennae less than half as long as body and composed of
about eighty-five segments.
Pronotum almost twice as wide as long, transversely oval; hind
angles more broadly rounded than front ones; lateral flanges
narrow, yellow; marginal groove distinct; surface thickly coated
with brown hairs and the margin fringed with small spinules
and a few longer hairs, especially on the posterior margin. Meso-
and metanotum patterned with yellow and brown, and thickly
coated with brown hairs. Legs flattened, and with a fringe of
long white hairs.
Abdomen moderately flattened; basal half of tergites usually
darker than caudal half; posterior margins brown. Cerci at least
half as long as body, each of the thirty-five segments terminating
in a whorl! of spines.
Gills arranged similarly to those of A. californica, but more
copious, and the gill tufts at the base of the meso- and meta-
thoracic legs are bunched so closely together that they appear as
single tufts.
The mouth parts are very similar in structure to the mouth
parts of A. californica.
Of this species I have several reared specimens from Yellow-
stone National Park.
Family NEMOURIDAE
This family consists of the genera Nemoura, Taeniopteryx,
Leuctra, and Perlomyia. The nymphs are small, for the most part
under 15 mm. in length, and are almost wholly concolorous. They
inhabit largely the small upland spring brooks and are herbivor-
ous in food habits. The life cycle appears to be one year. It is
rather difficult to assign to nymphs of this family any character-
istics which will apply to all the genera included. The mouth
parts are typically herbivorous. The labrum is somewhat wider
than long and the epipharynx is absent. Mandibles with four
or five blunt teeth followed by a molar which bears a comb of
short, stout hairs, and beyond this a group of long hairs. Lacinia
wide at base, at the apex with two small teeth, and partially
separated from the stipes by a short incision or suture; maxil-
lary palpus stout and much longer than galea. Glossae and para-
glossae of labium almost equally long and at the tips with numer-
ous papillae. Labial palpi short and stout, and in Taeniopteryx
and Nemoura usually not extending beyond the tips of the
paraglossae, while in Leuctra they may extend considerably
beyond the ligula.
The wing pads in Taeniopteryx and Nemoura are wide and are
directed away from the body, while in Leuctra they are narrow
and le parallel to the body.
Gills mostly absent. In some species of Taeniopteryx coxal gills
are present, and some species of Nemoura possess gills in the cer-
vical region.
In mature nymphs the venation of the wing pads can often
be seen clearly, and in many nymphs the genital characters aid
in identification.
Genus NEMOURA Latreille
The nymphs of this genus measure mostly less than 10 mm. in
body length. They are most easily recognized by the stocky form
of body, the fringe of spiny hairs around the margin of the pro-
notum, the spiny legs, and when gills are present they occur in
the cervical region between the head and the anterior margin of
the prosternum.
Head no wider than pronotum; rounded behind, somewhat
hairy; ocelli noticeable in the more mature nymphs, hind ocelli
a little closer to the eyes than to each other; antennae about half
as long as body and composed of less than fifty segments; epi-
cranial suture distinct.
PLECOPTERA NYMPHS OF NORTH AMERICA 93
Pronotum narrowed posteriorly ; angles rounded; margin with
a fringe of spiny stout hairs; a distinct median pale line divides
the pronotum; marginal groove indistinct. Wing pads well de-
veloped; hind wing pads much wider than front ones; the latter
almost parallel to the body, the former diverging outward. Legs
stout, the femora and tibiae covered with long spines; middle seg-
ment of tarsus very short; third segment as long as, or longer
than, first and second combined.
Abdomen cylindrical; the segments with a row of spines on the
posterior margin. Cereci more than half as long as body, each
segment ending in a whorl of long hairs.
Gills are either present or absent. When present, they occur
in the cervical area either as four single gill filaments or in four
groups of bunched finger-like gills.
The mouth parts are of the herbivorous type. Labrum hardly
half again as wide as long; front margin nearly straight, and
beset with fine hairs. Mandibles asymmetrical, with four to six
unequal teeth followed by a well-developed molar which is fringed
with a comb of short, stout hairs and beyond this there is a
bunch of long hairs. Maxillae stout ; lacinia ending in two or three
teeth, followed by a fringe of hairs; galea subeylindric, extending
slightly beyond the tip of lacinia, and bearing at the tip a
small bunch of hairs; maxillary palpus stout, even the longest
segments hardly twice as long as wide. Labium longer than wide;
submentum large, wider than long; mentum a narrow transverse
band; glossae and paraglossae subequal in length, but the para-
olossae about twice as wide as the glossae; labial palpus stout,
scarcely reaching beyond the tip of the paraglossae ; last segment
of palpus more or less egg-shaped and directed inward. Hypo-
pharynx rather small and normally not extending beyond the
tip of the glossae.
The sexes differ as follows: in the male the tenth abdominal
tergite is somewhat prolonged into a short rounded supra-anal
lobe; the ninth sternite is produced, and the tenth sternite di-
vided. In the female the tenth abdominal tergite is broadly
rounded; the ninth sternite is not so much produced and the
tenth sternite although very narrow is not so completely divided
as in the male. In fully mature nymphs the detailed genital
structures often may be distinctly noted.
The nymphs of this genus occur in small upland brooks where
they live chiefly in leaf drifts. They feed upon decaying vegeta-
tion and various forms of algae, such as diatoms. Wu (57) has
worked out the complete life history of N. vallicularva which he
94 THOMAS SAY FOUNDATION
found to pass through twenty-two instars, and the life eycle oc-
cupied one year.
Key to the known Nymphs of Nemoura
Je No gillsin cervicalreciony. «2 ater N. vallicularia (p. 95)
Gills present’. 02. 0.4053 0s ene stereos er 2
2. Gills consisting of four single filaments. .Nemouwra sp. (p. 96)
Gills consisting of four groups of filaments >. 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.
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THOMAS SAY FOUNDATION
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4.
PLECOPTERA NYMPHS OF NORTH AMERICA 119
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120 THOMAS SAY FOUNDATION
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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 <Acroneuria pactfica Banks.
77-82 Perla immarginata Say.
The mouth parts of these three species are very similar and.do not
show characters sufficiently different to be useful in specific deter-
mination.
PLECOPTERA NYMPHS OF NORTH AMERICA 185
nS
Ny,
Wat
NAA i
AU Wh ise
NAN y we bath 4
VM ated WP
ERs ANG
Ba iage atu d 8
i ‘ \ “
1 rl ANN ayy
'
‘,! ar “ye
dans ea, yl
Ny Sosy wl
ry Weve!
vA eA pe
ce Nin WAL
Wana sss
\\ XY Sy
Perla immarginata
136 THOMAS SAY FOUNDATION
PLATE 6
FIGURES 83-99
83-88 Alloperla coloradensis Banks
89-93 Alloperla borealis Banks
In the above two species note that the inner apex of the fourth
segment of the maxillary palpus is produced and bears a bunch
of hairs; the lacinia appears to be unidentate but there is a
suggestion of a second small tooth.
94-99 Chloroperla cydippe Newm.
Very similar to the above two species but lacinia is distinctly uni-
dentate; and the submentum is not so much produced at the an-
terio-lateral areas.
PLECOPTERA NYMPHS OF NORTH AMERICA 187
PLATE 6
Chloroperla cydippe
138 THOMAS SAY FOUNDATION
PLATE 7
FIGURES 100-116
100-105 Paraperla frontalis Banks
Note the long narrow Jabium and the lacinia with a long in-
curved terminal tooth, bearing a small tooth and a ‘‘comb’’
of stiff hairs.
106-110 Clioperla clio Newm.
Note the very wide lacinia; the small galea and the attenuated
terminal segments of the maxillary and labial palpi.
111-116 Neoperla clymene Newm.
PLECOPTERA NYMPHS OF NORTH AMERICA 1389
PLATE 7
Taher
/ 1 106///'/,
aed
\
\\ fi
aye
LAN
aN ra
kg
BUNNY
0
Why
a)
TRA
\
‘ \t)
\*
1. Sh
4 a
14!
\
Seon ee 2
S Ses ;
‘ Sea
,
Neoperla clymene
140 THOMAS SAY FOUNDATION
PLATE 8
FIGURES 117-134
117-122 Perlinella drymo Newm.
123-128 Isoperla bilineata Say
129-134 <Atoperla ephyre Newm.
PLECOPTERA NYMPHS OF NORTH AMERICA 141
Perlinella drymo
Atoperla ephyre
PLATE 8
week vag a
WAN 124 07,70, , 7
\\ \ . \\y 7
ANN 4
ro
ELOY 126
142 THOMAS SAY FOUNDATION
PLATE 9
FIGURES 135-152
135-140 Taeniopteryx nivalis Fitch
141-146 Nemoura venosa Banks
147-152 Leuctra sibleyi Clsn.
All three species are herbivores. The labrum is long and narrow,
the mandibles have short, blunt teeth, a large molar and below
this a ‘‘comb’’ of stout hairs; the ligula is four-lobed and the
suture between the glossae does not extend to the mentum; the
galea is stout; the lacinia bears two small terminal teeth and
the suture separating the lacinia from the stipes is only par-
tially indicated.
PLECOPTERA NYMPHS OF NORTH AMERICA 1438
PLATE 9
< t \
I" wit
Sa
TSS iae Oe
Mkt f Tpke
Nemoura venose
TOW
TSR ea
OG RCE
Leuctra sibleyi-
144
153-158
159-163
164
165-166
167-168
THOMAS SAY FOUNDATION
PLATE 10
FIGURES 153-168
Allocapnia pygmaea Burm.
Capnia vernalis Newpt.
Herbivores; galea large, lacinia tridentate.
Nemoura sp.
Acroneuria lycorias Newm.
Wing pads showing venation.
Paraperla frontalis Banks.
Wing pads showing venation.
PLECOPTERA NYMPHS OF NORTH AMERICA 145
PLATE 10
146 THOMAS SAY FOUNDATION
PLATE 11
FIGURES 169-176
169-170 Pteronarcys proteus Newm.
169. Terminal segments of male nymph
170. Terminal segments of female nymph
171-172 Pteronarcys biloba Newm.
171. Male
172. Female
173-174 Pteronarcys dorsata Say.
173. Male
174, Female
175-176 Pteronarcys californica Newpt.
175. Male
176. Female
PLECOPTERA NYMPHS OF NORTH AMERICA 147
PLATE 11
Pteronarcys californica
148
Lilie
179-180
181-182
183-184
THOMAS SAY FOUNDATION
PLATE 12
FIGURES 177-184
Pteronarcella badia Hag.
177. Male
178. Female
Pteronarcella regularis Hag.
179. Male
180. Female
Perlodes signata Banks.
181. Male
182. Female
Peltoperla areuata Ndm.
183. Male
184. Female
PLECOPTERA NYMPHS OF NORTH AMERICA 149
PLATE 12
Perlodes signata
Peltoperla arcuata
ee cata tal a
nf ae bee re 7 . a roy oa) Sy _ age . ~
7 x = ~, |S ee: ay Son en), Be
_* Bij enn fe WEL Wh kde ee aw (=
150 == THOMAS SAY FOUNDATION |
®, rc“ = ; ve ca
4
‘
PLATE 13 ae
FIGURE 185
185 Pteronarcella badia Hagen te a
Inch or less in length; blackish; gills on first three abdomin:
ments. Western. :
2
va
J
\
) 2 }
fA a ' U a
) .
an ; fee
' : "ea ra
; cal. 8 fy: ae & Ye ae
fe te is aa oy oes Vi REEe
| » : Ld git its ar
' > 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 <Acroneuria ruralis Hagen
Nearly uniformly yellowish brown; occipital ridge present; wide
pronotal flanges; cerci as long as, or longer than body; no caudal
gills.
224 Acroneuria pacifica Banks
Blaze or white elongate mark in front of anterior ocellus; body
nearly concolorous; copious anal gills; Western.
225 Perlinella drymo Newman
Long head; small eyes; oval pronotum; very long gills; wing pads
with rounded sides; anal gills absent.
226 Nemoura sinuata (7?) Wu
Uniformly brown, spiny and stocky body; gills at throat; hind wing
pads diverge greatly from body.
PLECOPTERA NYMPHS OF NORTH AMERICA
PLATE 32
1
+
i
;
190
227
228
229
230
THOMAS SAY FOUNDATION
PLATE 33
FIGURES 227-230
Acroneuria arida Hagen
Striking color pattern; wide pronotal flange; occipital ridge absent;
small anal gills; abdomen nearly uniformly brown.
Perla media Walker
Short, broad flattened; dark brown to blackish; hairy and usually
with a dirty appearance; heavy fringes of long hairs on legs; ab-
domen brown.
Taeniopteryx nivalis Fitch
Light strip on body; diverging wing pads; coxal three-segmented
gills; very long slender antennae and cerci.
Perla hastata Banks
Mottled areas on head; large maxillae; rather square pronotum;
color olivaceous; slender legs; no gills.
PLECOPTERA NYMPHS OF NORTH AMERICA 191
PLATE 33
192
231
232
233
234
THOMAS SAY FOUNDATION
PLATE 34
FIGURES 231-234
Pteronarcys dorsata Say .
Dark brown, sometimes striped; angles of pronotum not much
produced; wing pads rather broadly rounded; abdominal segments
without spines or hooks; antennae and cerci not banded with yellow.
Pteronarcys biloba Newman
Antennae and cerci with a yellow band near the middle; angles
of pronotum quite sharp; hooks on abdominal segments large and
directed away from body; cerci half or more than half as long as
abdomen.
Pteronarcys californica Newport
Angles of pronotum produced into sharp processes; wing pads
sharply pointed; abdominal segments smooth; antennae and cerci
quite short and without lighter bands.
Pteronarcys proteus Newman
Angles of pronotum not produced; hooks on abdominal segments
appressed; antennae and cerci with light bands near the middle;
cerci less than half as long as abdomen.
PLECOPTERA NYMPHS OF NORTH AMERICA 193
PLATE 34
194 THOMAS SAY FOUNDATION
PLATE 35
FIGURES 235-238
235 Pteronarcys biloba Newman
Ventral view showing gills.
236 Pteronarcys biloba Newman
Young nymph. Note the light lateral margins of the thorax.
237 Pteronarcys proteus Newman
Ventral view.
238 Pteronarcys princeps Banks
Pronotum rather square; angles hardly produced; abdomen smooth;
antennae aud cerci banded with yellow. Western.
PLECOPTERA NYMPHS OF NORTH AMERICA 195
PLATE 35
INDEX
Pe MOTI CR eke Uk cats Wo soe 18
abnormis, Acroneuria ......... 82
ONT hg (GM ia Se ie ated aa rr 80
Acroneuria, key to species ...... 81
A HIIOPIIN yon ees Sos bee et ee 82
Tle PNG kel ies SUR ale Gat aia Recararae 84
PRMMPAR LOY TUCO 9 sacs. isin ec «ws oes 85
ES EGY D2. oA ie RO ee eee rae 86
Jee SA ET d OVA il Se Ae ea 87
PRTIDCEMCH Acar etic ece 85 sync eg mo: 88
PT RE ead adds saa. od sch oe 6 3 89
EMR IROCU UTA rtiace sik sie via « Foss ss ss 90
BE SUPA Se OTIS! oie s cucu ne Les a 53
Oa DID Me 3. Shtte ta ong ea «s 111
Allocapnia, key to species ...... 112
EPP AMAN ALA na tole Ot gos Pe gt ess 114
PICISU EA Sot) ie Pes aso Gs ts 115
RPMI UNC treet hoa Sie wing sno « 116
sah j (ogee UN UGe Yada A ERO in a 112
hn, Geta wal A Gees RAD sare ED a 113
PPEMIN OAL eM Sic efohe cA eis ceca as 114
PRED DOE ees erie cette RF ser iS, grahs 5 os 58
Alloperla, key to species ........ 60
PNPM DOTES LIS Mise © Wvesaute we sieve ace me 8 60
Pea COPOFAGCIISIS. |) cle 5 sutters 0 wrocs 60
BAMPUATING Aes 5h 35 etitteiate dtm te ae cs 61
PAS ETCOIANE 5 )s 4) coe <x aie a) 8 5 Fayed os 61
AOU esas bak vleo aoae 62
PD OSLUMLUR et «oie a Sales el 62
americana, Perlodes............ 44
SOTA STE TET ole Mile 7 grit ig A ore ae aE 17
ercuaia, PF eltoperla 54.4 .5..65% 5% 39
arenosa, Acroneuria ........... 84
MSDOE Vis cosiirc a aicle sep swale a aisle & 78
UM NV EC oie a akclo es soy Been « 78
Dadian, --teronarcella, ... 05.5... % 30
VCS RT gg 00 TN ee gi a a al
Dilmmeata,[soperla. 0. occ ss v0 73
Wilebae PECTONATCYS «2.55 002000 30
RNa bebe OTL Sot Neko sie 5 oases 54
ISON COPON Ofsre sige. ey od 06 mac's 20
TBO COGN ee niece ais coo ee wes oe 16
PRIEORIIN PA HODOTION oie a{e esse 60
SO i ad, ae ne a 13
californica, Acroneuria ........ 85
californica, Pteronarecys ....... 32
californica, Taeniopteryx ...... 107
Ceo A ead Sod) gE ea 47
ROEM Bates 2. G0a cds sctte ns ace sposePe 8 ae le 109
PCOETIOIIS CPi es is heey tie aa es > 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 <i 18
Emergence tablea-. sto: ses 122
ephyre, Atoperla .............. 78
Epicranial suture ...........-- 17
PpiIpnanyikeetee var: soe hee ne 17
Sxpansa, @ Perla 2, We. ew sistance 59
Wanailyskeyiese ttt ae ce nnn te 22
fasciata, Taeniopteryx ......... 106
five-punctata, Isoperla ......... 74
Flange, laterali..<...--5..2.'... 18
OOUENADIES wnt ae. aaate ef mea vere 3
Porm 0f bodys .8 chy 70s 8 eee, 16, 20
Fringe, marginal .............. 19
frontalis, Paraperla ........... 65
(Senua key oceania lee ae ere a 22
Gills, taxonomic value of ...... 18
GHlety pest. ot vce. okey sata: 5
granulata, Allocapnia .......... 114
Habitat of Wymphsac-s wae. +m 3
hagtatass Perla evra aets «cote + 55
(Plead \ahape Of se wer eae es 20
Hea de struclure: Olme tet: ste a Wy
ELypopharyux es skein ote 21
Illustrations, preparation of ..15, 16
immarginata Perla i. 6:6). .2 «es 50
mcisura, Allocapnia |=...2...-.. 115
InStarsinvmpual so. ss 2 ou ans 8
IL SOPOHUGI Rt ac aan oe < 45
COUNTING ist es es ee 45
ERO POP a Geter ees Oke ay taiie ta te ee (ai
Isoperla, key to species ........ 72
ORDER OS LS Ne et ents tararerta cores wo 73
Ae he PUTO GEL: at oe takers tt otis, ahr 74
Ex POtersontits 2 utc anes sit. c 74
LE SISTA tt Al etattcct yale it rcees 79
198 THOMAS DAY
Key to families and genera .... 22
Sua bivrnn Soest) eretane teeters 21
Ha bru Se ote ats oe eer eer eeeacre 17
Jamba, A lloperlagys. 6 0 es 61
Ioateral anger. che eens 18
Mercy Mucwaicioe Mies toch 7p Mea 19st
Length of :pody wae tear 16
Lleuctra. tae oo tee. o teat ote 96
Ts Claasseni®, neritic 100
Ty, Tdeceptary fee ce is oe oes 99
Tie Sibley i sey. puietene aes teers 98
Life cycler... ce tpyee ne ee 7
Linesmedian Gierastt. se en BLO
lyeorias, Acroneuria ......5,.-6. 87
Marginal/ fringe: 24-2... 44. 19
Marginal @roove eo. -enrin ea cen 18
maura, Taeniopteryx ¢..%..-« «1. 104
Medis,. erate Bes tener eee 48
Median line 7... setes Scr es 18
mediana.<A lloperla vaen oece 2 aie 61
Meésothorax® #2.) a eee 18
Metamorphosism™ 2.02 tae in tet re
Metathoraxiee.-3.0 ys so eee a 18
Mouthparts) soe «eee 18, 20, 21
mystica, A loca pnigg cs meme ao 116
NG@MmOUTS 4.8.cer tetera a eee 92
Nemoura, key to species ........ 94
Ne coloradensisa. cote oe 96
Noevallienlariag. «2. ee kee 95
INS VGUOSA Batic e.s een or re eee eee 95
Nemouridae as: p79 piace eee 92
Neaperlan anc einen Sees 66
Ne clymene Saye ee 67
nivalis, Taenioptenyx. a 2a 103
Oceipitaliridgela. ca. ee een 17
Ql put ena. oop uae ee eee ee Vi
Ovcel Hi aiscctee che: eces eg anek eeee e lwp
pacilica; Acronentiaua as. oe. 88
pallidula,cAloperlas: oe ae. 62
Paraperlancsce cnc ae eee eee 64
BP... trontalis es ee tee eee 65
parvula, “laeniopteryx.. = ee 105
Peltoperlag: at, ti eee ee 38
Pf arcuate 7h t...iecat eae ee 39
Peltoperdidde. 2... chee ere 38
Perlad: Satara eee Tee 46
Perla, key to species) ase... <.6 47
Py BeStivalis’: ace ware eee 53
Pabiobe tae psa oe 54
Pia Ga pita. taste ee eae ee 47
PS expanse ree a ce te cele ee tte 55
Pelastata sa. ccc os eee ee 55
ESI Mar ois ba ae ee ere ene 50
PA TIMCCI Ar Aire ven, one eet at eee eee 48
Ra Verticalis sa he.cra ae nee 57
Perlestasiotat on ari tree eae 76
DAplicilacsa . cna eae 77
PerlineliateJ) 0.) tt nee ie 9
AGMA E Edges Gor sities Sete intees re pt)
FOUNDATION
Perlidae’ ...4.: 00+ ses eer 41
Perlodes:......- 22. sven eee 41
Perlodes, Key to species ....... 43
P. americana... .«< +0. see 4t
P.stibialis . 3... s <5 a4
P. signata. ...... «can spe 43
petersoni, Isoperla 77723 74
placida, Perlesta, .< 1. @..0anane fly
Plecoptera, key to families and
PONELA 2... sss che 22
Preservation of nymphs........ 14
princeps, Pteronarcys .... 3... 33
Pronotum”™).... 0.2). =a 18,2)
proteus, Pteronarcys >...) .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
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PLECOPTERA NYMPHS
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SE OPTERA NYMPHS oF AMERICA (NORTH OF M
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