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12/09/2002
****
IDENTIFICATION,
HABITAT, LIFE HISTORY,
TOLERANCE
AND DISTRIBUTION
****
Jane Earle
Department of Environmental Protection
Bureau of Watershed Management
The stoneflies are a small = order of primitive insects with a little over 600 North American species and 2000 species worldwide. Stoneflies= have three segmented tarsi, long filiform antennae at least half the body length= and usually long cerci. Wings are present in adults of all but one or two species and are folded horizontally back over the body when at rest. All nymphs are aquatic and inhabit only flowing water, springs or se= eps, or cold wave-swept shores of cold northern lakes.
Stonefly nymphs are general= ly most common in cold water; however, many nymphs live in warm creeks and rivers, especially capniids, taeniopterygids, perlids, and pteronarcyids. Stoneflies of warm water habitats = have a long diapause period to avoid warm summer temperatures or have highly branc= hed gills to aid in respiration. Perlid= s and Pteronarcys are the only PA stoneflies able to live in warm rivers without undergoing a summer diapause. Stoneflies a= re generally intolerant of man-made influences, especially organic enrichment = and clearing of the land and are, therefore, generally good indicators of healt= hy streams and rivers. Published pollution tolerances are usually based on organic pollution and may be generalizations based on the family or genus level. Tolerances can vary considerably b= y species within a family and genus. So= me stoneflies, however, are tolerant of acid mine drainage, acid precipitation= and natural acidity, moderate siltation, and moderate organic enrichment. Stoneflies that have a summer diap= ause or large gills are generally better able to tolerate warm water, organic enrichment and other pollutants.
This guide contains only ge= nera that have been confirmed in PA or that have been collected as adults or nym= phs and have not yet been added to official list. Other North American genera that h= ave not been confirmed in PA are not included except as an occasional side note= .
Life histories of many ston=
eflies
are poorly known. Studies are
scarce and may be valid for only for the region of
Identific= ation:
Definitions:
_____________________________________=
___________________________________________
CAPNIIDAE:
Only 2 PA =
genera. Our smallest stoneflies. Nymphs are uniformly brown and usu=
ally
slender. Gills are absent. Adults are easily collected in win=
ter on
bridges, on smooth-barked tree trunks and rocks along streams.
Allocapnia: Very common,
present in all sizes and temperatures of streams except those grossly
polluted by industrial chemicals, also springs and seeps. Nymphs are somewhat hairy and usua=
lly
are slender, but occasionally may be rather robust with long hind legs. Wing pads of Allocapnia are always=
much
less flared away from the center of the body than those of nemourids. Late instar nymphs may also have v=
ery
small dark wing pads. Nymphs
diapause during the spring and summer and are not collected in benthos exce=
pt
during fall and winter. Nymph=
s generally
tolerant of acid precipitation and natural acidity, acid mine drainage, iron
precipitate, aluminum precipitate, organic enrichment, intermittent flow and
warm water. Many PA species,
tolerance and habitat vary on species level. Emergence may start in early Novem=
ber in
some
Paracapnia: Common.&nbs=
p;
Nymphs are much hairier than Allocapnia and Leuctra=
. Nymphs are very hairy even in early
instars. Restricted to sma=
ll
streams; not present in medium or large warm water creeks or rivers.
Other Genera: Other Capniidae genera are NOT likely in PA; others are either
restricted to western US or much farther north in US and
_____________________________________=
_________________________________________
LEUCTRIDAE:
3 PA gener=
a. Nymphs are very small and slender =
and
uniformly brown. Gills are
absent. Nymphs are very simil=
ar to
capniids, but are generally less hairy, and the abdomen has parallel
sides. Wing pads are usually =
much
longer than wide.
Paraleuctra: Adults are co= mmon and readily collected adjacent to smaller streams; nymphs are extremely = rare and essentially never collected, are likely hyporheic(?). The late instar nymphs have longit= udinal abdominal stripes of adult visible through skin. Tolerant of natural acidity/acid precipitation, iron and aluminum precipitate, acid mine drainage, intermitt= ent flow.
Megaleuctra: A spring/s= eep specialist; extremely rare, collected only in spring runs close = to source, or in spring houses. = Nymphs are large and more robust than other leuctrids. Spring emergence.
Other genera: Zealeuctra has not yet been collected from PA, although =
PA
is within its range. It has b=
een
collected in
_____________________________________=
_________________________________________
 = ; Amphinemura: Most common PA genus; found only in small to medium streams and spri= ngs and seeps; most common in colder streams.&= nbsp; Only PA genus with neck gills. Egg diapause through summer and into early fall; nymphs present in stream from fall to spring or late summer emergence. Tolerant of acid mine drainage, ir= on and aluminum precipitate, natural acidity and acid precipitation, silt, intermittent flow. Emergence = can occur as early as late February in springs and may extend into late August in spr= ings and creeks.
Nemoura: One PA species. Extremely rare. Habitat is small cold streams and
springs. Adults unconfirmed i=
n PA,
but late instar nymphs identified from a small, cold stream in
Ostrocerca: Mainly in s= prings and seeps, but nymphs may also be collected in small cold water stre= ams. Abundant only in acidic streams (a= cid precipitation/natural acidity). Nymphs have pronotum with anterior edge rounded without a notch, = and without a distinct lateral fringe of setae. The fore tibia of the nymphs ha= ve a fine hair fringe and 2 rows of heavy bristles. Adults and nymphs are small. Long spring through fall egg diapa= use, so nymphs present in stream only from December to spring. Adults emerge in mid to late spring. Nymphs may be abundan= t and dominant in small cold, naturally acidic or acid precipitation affected streams. Tolerant of natural acidity/acid precipitation, intermittent flow.
Paranemoura: One PA specie= s.&nbs= p; Less common than other genera, usually in small, cold streams. Nymphs are small= and robust. Nymphs have a squa= re pronotum without a notch and with a large raised globular area on each side= . The fore tibia do not have a hair fringe. Tolerant of natural acidity, acid precipitation, intermittent flow. Probably have a summer egg diapaus= e, so nymphs are present only from fall to spring. Emergence in April to May.
Prostoia: 2 PA species, bo=
th
species found in same stream in
Soyedina: Spring/spring run/seep specialist, rarely found elsewhere. Nymphs are relatively large and robust. The pronotum is sq= uare and fringed, with definite notch near anterior edge. The legs are rather short. Emergence is from late February to May. Not believed to diapause= .
Other genera: Shipsa is a possibility in PA; however, it is apparently restricted to large warm creeks and rivers and not likely to be encountered= in streams normally sampled for benthos. It also has a long egg diapause so nymphs are not likely to be encountered except in winter to early spring. Adults have never been confirmed i= n PA, so nymphs are very unlikely to be collected too.
_____________________________________=
_________________________________________
TAENIOPTERYGIDAE:
5 PA genera.&= nbsp; Nymphs relatively long and slender and are either uniformly brown or yellow or brown with dark spots. Wing pads are strongly divergent from the body axis. Nymphs can be separated from the nemourids, which also have divergent wing pads, by the first and second tar= sal segments which are about the same length.&= nbsp; Gills are absent or located on coxae. Nymphs without coxal gills can be dificult to separate. All gen= era are believed to have a spring to early fall diapause as early instar nymphs= and are not collected in benthos except in late fall and winter. Adults emerge from winter to late = spring and can be seen walking around on snow or congregating on bridge rails on w= arm sunny days. Most species have= long emergence periods to help survive extreme cold spells.
Bolotoperla: One species.&nbs= p; Extremely rare, only a few PA records from SC PA. Nymphs are shorter and more robust= than other genera in family. Emerg= ence late April to mid-May.
Oemopteryx: One PA species=
.&nbs=
p;
Restricted to 1st
to 3rd order streams.
Nymphs have dorsal cercal fringe on last 10 to 12 segments; the 9
Strophopteryx: 2 PA specie=
s.&nbs=
p;
Common in all but the coldest headwater streams; most com=
mon
in large warm water creeks and rivers.&nbs=
p;
Nymphs are yellow-brown and have patterned head and prothorax;
the 9th sternal plate is narrow and rounded at the tip. Nymphs are found only during fall =
and
winter due to long diapause as early instar nymphs. Emergence February to April. Somewhat tolerant of mine drainage=
and
iron precipitate and organic enrichment.
Taenionema: Mainly in
medium-sized streams or downstream reaches of trout-stocked streams.
Taeniopteryx: The most =
common
genus in family; most abundant in warm water creeks and rivers. Only one species found in cold hea=
dwater
trout streams. Nymphs have a
distinctive telescoping gill at base of each leg. The gill is huge in comparison to =
the
body size, especially in earlier instar nymphs and is, therefore, very
visible. Some species have a =
pale
stripe the length of the body.
Generally tolerant of most pollutants, although tolerance varies by
species. Some species are tol=
erant
of organic enrichment, alkaline and neutralized mine drainage, iron precipi=
tate
and aluminum precipitate; one species is tolerant of natural acidity and ac=
id
precipitation. Nymphs are fou=
nd
only during fall and winter due to long diapause as early instar nymphs.
_____________________________________=
_________________________________________
CHLOROPERLIDAE:
6 PA genera.&=
nbsp;
Only Sweltsa is commonly collected as nymphs; other ge=
nera
are collected mainly just prior to emergence. Nymphs are medium sized and unifor=
mly
brown or yellow brown. Nymphs=
have
relatively short, stiff cerci and wing pads that are rounded on the outside=
and
slightly divergent on the inside edge.&nbs=
p;
Gills are absent. Nymp=
hs are
difficult to separate to genus.
Keys rely on placement of hairs on cerci, which are often difficult =
to
see. Use information on habit=
at,
emergence times, and abundance described below along with keys. Nymphs are generally intolerant of
organic pollution and warm water.
Adults are bright or pale yellow or pale green and emerge from May
through August.
Alloperla: Common as adult= s but uncommonly collected as nymphs. Nymphs are mostly hyporheic and found mainly just prior to emergence, late spring = to summer. Nymphs have prono= tal setae that are largely restricted to corners; most Alloperla species have hairs on the on the apical half of the cerci that appear feathery. A. usa, which has eyes some= what forward on head, is the one species more likely to be collected in earlier instars. Two species, A. imbecilla and A. chloris, are tolerant of alkaline and neutraliz= ed mine drainage and iron precipitate. A. imbecilla and the common eastern PA species, Alloperla atlantica, are somewhat tolerant of warmer (transitional temperature) w= ater and organic enrichment. The b= right green or pale yellow-green adults emerge from mid-May through July.
Haploperla: One PA species= . Nymphs are smaller and more robust= than other PA genera. The protnotal bristles are rather long, and sparse at the anterior edge and absent on the lateral edges. Inner margins = of wing pads are close together and parallel.= Nymphs usually collected only just prior to their May to June emergence. Most tolerant = genus in family to organic enrichment and silt.&= nbsp; Most common in small streams but also found in lower-order medium transitional temperature streams. Adults are pale yellow or greenish yellow.
Rasvena: One species. Extremely rare, only a few confirmed adult records in PA North Central region. Mature nymphs are small, less than= 5.5 mm and resemble Haploperla. The abdomen has a pale dorsal stripe. Nymphs are probably restricted = to small, pristine cold streams. Emergence occurs in mid-May. Adults pale yellow.
Suwallia: One PA species.<= span style=3D'mso-spacerun:yes'> Rarer than Alloperla and Sweltsa. Restricted to cold, clean strea= ms, most common in forested headwater brook trout streams. Fringe of pronotal hairs around mo= st of edge except for upper half of lateral edge. Nymphs have short hairs on cerci t= hat do not appear to be feathery. Nymphs are not likely to be collected except just prior to emergence, generall= y in late summer. Adult males are occasionally collected in mid-June. Adults are yellow.
Sweltsa: The most commo=
n PA
Chloroperid. Most like=
ly PA
chloroperlid nymph to be encountered in routine benthos collections.
Utaperla: One PA species.<=
span
style=3D'mso-spacerun:yes'> Extremely rare in PA. Probably found only in springs and headwaters of spring-fed streams. Lacina of nymph has terminal to=
oth at
a 90o angle. C=
erci
with long bristles that are not feathery.&=
nbsp;
Distinctive dark color pattern of adult head is visible through skin=
of
nymph. Only three confirmed a=
dult
records in PA, two sites in
_____________________________________=
_________________________________________
PELTOPERLIDAE:
2 PA gener= a, one species in each genus. Nymphs= are roach-like and have shield-like thoracic sternal plates. Nymphs have one or two finger-like= gills under the edges of thoracic sterna near base of coxa. Nymphs are leaf shredders so requi= re forested habitats.
Peltoperla: One PA species= . Less common than Tallaperla= . Nymphs have a dark pigment spot= on meso and metanotum on each side of mid-line. More common in colder habitats and headwater stream reaches than Tallaperla, but can occur in same stre= am as Tallaperla. Somewhat tolerant of acid mine drainage if water is cold; also tolerant of natural acidity/acid precipitation and intermittent flow. Emerges later than Tallaperla= i>, June through August.
Tallaperla: One PA species= . Common. Nymphs without a dark pigment s= pot on each side of mid-line of meso and metanotum. More common in slightly warmer, downstream reaches than Peltoperla.= Nymphs are believed to have a 2-year life cycle, so should not be present in intermittent streams. Can be very abundant in small to medium cool or transitional tempera= ture forested streams. Appears to = be less tolerant of acidity than Peltoperla and believed to be intolerant of acid or alkaline mine drainage. Emerges in late May to early June.&= nbsp; Adults are relatively difficult to find.
___________________________=
___________________________________________________
PERLIDAE:
9 PA gener= a.&nbs= p; Most common in larger, warmer creeks and rivers. Nymphs have highly branched gills = on sides and ventral of all 3 thoracic segments. Generally more tolerant of warm wa= ter and organic pollution than other stoneflies. Perlids and Pteronarcys<= /i> are the only PA stoneflies able to live in warm rivers without undergoing a summer diapause. Gills aid in tolerance of lower oxygen conditions.
Acroneuria: Many PA species. Most common perli= d in small, cold streams. Nymp= hs have obvious setae only around eyes. Cerci have a inner fringe of long silky hairs. Nymphs of many species have large “W” on head. Some species have anal gills, but not A. carolinensis and A. abnormis<= /i>, the two species commonly collected in cold water and small to medium streams. A. carolinensis may = be only species in limestone influenced streams. Other species found mainly in warm= water and larger creeks and rivers and are more rarely collected. A. carolinensis is somewhat tolerant of acidity (>5.7 pH) and iron and aluminum precipitate from acid mine drainage, natural acidity and acid precipitation. Summer emergence; some adults are = large and readily fly to lights. Ny= mphs of most species have a two-year life cycle, so nymphs of more than one size= are usually collected. Adults are= hard to find, but the exuvia can be collected from undersides of bridges and tree trunks. Most nymphs and exuvi= a can be identified to species.
Agnetina: 3 species. Nymphs are highly patterned, have a complete row occipital setae and anal gills. Nymphs are most similar to Para= gnetina, but Agnetina has complete row of setae on posterior of ste= rnum 7, whereas Paragnetina does not. Also, Agnetina nymphs do= NOT have an inner fringe of long hairs on their cerci, whereas Paragnetina= i> do have a fringe on the cerci. Adults have black or brown wings and yellow and black bodies. Most common in larger, warmer stre= ams and rivers or medium to large cool streams; also in limestone influenced streams. One species, A. capi= tata, is found in a variety of habitats including small warm creeks. Emerges in June and July. Adults are active during the day a= nd are more easily collected than other perlids.&= nbsp; Nymphs and exuvia can usually be identified to species. Previously known as Phasganopho= ra and Neophasganophora.
Attaneuria: One species. Extremely rare; found only in large warm water creeks or
rivers. Nymphs are very h=
airy
with pronotum and abdominal terga fringed with long bristles; occipital set=
ae
form an irregular but complete transverse row. Adults have not been collected =
in PA
for many years, nymphs also have not been confirmed in PA for many years. Adult confirmations are from the
Susquehanna River, a few larger
Eccoptura: One species.
Hansonoperla: One species.=
Extremely rare and not normally
collected in routine riffle benthos samples. Nymphs similar to Perlinella,
with eyes forward on the head; but does not occupy same habitat as <=
i>Perlinella. Confirmed from only a few cold =
water
PA streams, two of which are acidic, from either natural acidity/acid
precipitation or mine drainage.
Most common in the Poconos and the low gradient glaciated streams of=
Neoperla: Many PA species.= Nymphs are distinctive, with only = two ocelli. Most common in la= rger warm water creeks and rivers, but one species also may be found in downstre= am reaches of cooler or transitional temperature trout stocked streams. Adults emerge in summer and early fall.
Paragnetina: 2 PA species.= Nymphs robust. Paragnetina is most similar= to Agnetina but Paragentina has less developed anal gills and basal cercal segments = are fringed with long silky hairs; also posterior fringe of setae on abdominal sternum 7 is incomplete.&nbs= p; P. media nymphs are uniformly light brown, P. immarginata<= /i> nymphs are highly patterned. = Most common in medium, warmer streams, but also found in cool streams. Tolerant of organic pollution, neutralized or alkaline mine drainage and iron precipitate. P. media is one of the most tolerant stoneflies to organic enrichment, althought this seems to be true = more so in the Midwestern U.S. Eme= rges from June through September. = Nymphs and exuvia can be identified to species.
Perlesta: Many PA species.=
Late instar nymphs are yellow-brow=
n and
much smaller than most other perlids.
Occipital ridge in nymphs may not be obvious; the ridge is
usually wavy with setae widely spaced; in some cases there may only be
scattered setae along the rear of the head. Nymphs have numerous short black
bristles on the abdominal terga.
Nymphs have a long egg diapause and are not usually collec=
ted
except just before their summer emergence. Earlier instar nymphs have been
collected more often in
Perlinella: 2 PA species.<= span style=3D'mso-spacerun:yes'> Nymphs have eyes forward on head a= nd most resemble Hansonoperla, but not in same habitat as Hansonoper= la. Nymphs essentially never collec= ted in benthos samples except just prior to their June emergence. One of the most hyporheic PA stoneflies. Found only in = warm water creeks and rivers. Emergence in June and July.
Other Gene=
ra: Belaneuria is often listed=
as
present in PA aquatic water pollution studies; however, this genus has n=
ot
been confirmed in PA and is NOT li=
kely
to be confirmed in PA. It=
is restricted
to specialized habitats in the
_____________________________________=
_________________________________________
PERLODIDAE:
8 genera in PA. Nymphs can be relatively large.&nbs= p; PA genera either do not have gills or have a small finger-like gill under the neck. Nymphs are us= ually highly patterned. Nymphs can = be difficult to key to genus. Th= e shape and the arrangement and size of the hairs on the lacina are distinctive for most PA genera and should be used as major key characters. Isoperla is the most common= ly collected genus. Adults are u= ncommon except for Isoperla and Remenus. Nymphs are generally most common in small, cool streams. Two subfamilies, Isoperlinae and Perlodinae.
IS= OPERLINAE:
Clioperla: One species.
Isoperla: Highest number of
species of any North American stonefly genus and the most variable. Nymphs of many species are distinc=
tively
patterned, with longitudinal bands on abdomen. Most nymphs are small and slender.=
But one group of nymphs is =
robust
and uniformly tan or yellow brown.
Usually Perlodid nymphs that don’t readily appear to be Iso=
perla
but don’t quite fit the key elsewhere will be these non-typical Is=
operla. Nymphs generally have a lacina =
that
is wider at the tip than that of the Perlodinae genera. One group of nymphs is non-typical=
ly (
PE= RLODINAE:
Cultus: 2 PA species. Rare, confirmed from only a= few sites scattered throughout PA. Nymphs are most similar to Diploperla, but Cultus= i> has a dorsal fringe on cerci and a small tuft and scattered hairs on the in= ner margin of the lacina. Nym= phs are most likely in medium-sized creeks.&nb= sp; Emergence is in April to May.
Diploperla: 2 PA species.<=
span
style=3D'mso-spacerun:yes'> Uncommon. Nymphs are similar to Cultus, but
Diploperla does not have a dorsal fringe on the cerci. Habitat is small, cool streams.
Helopicus: One PA species.=
&nbs=
p;
Rare. A =
medium
to large creek and river specialist; also in limestone influenced
streams. Nymphs can be separa=
ted
from other PA Perlodinae by the combination of prominent submental gills=
and
a dark band across the middle of the head through the anterior
ocellus. Relatively large.
Isogenoides: One PA species. Uncommon. A possible indicator of clean, = cold water habitats. Nymphs ha= ve submental gills and rather narrow lacina with a row of setae on inner margin. Nymphs have a median suture thr= ough the mesosternal “Y”. Adults are extremely rare and may be collected from late April to May. = span>
Malirekus: 2 species. More common than previously report= ed, early keys did not key nymphs properly.&nb= sp; Most common in small streams, including 1st order tributaries. The common PA sp= ecies, M. iroquois, does not have submental gills, the other species, M. hastatus, has submental gills. <= /span>M. hastatus is extremely rare. I have never seen nymphs with submental gills. Nymphs have outer ventral surfa= ce of lacina with thick basal patch of dark hairs; lacina also with most of i= nner margin hairs concentrated near tip. Nymphs are superficially similar to Yugus; both have highly patterned head with a “W” and a highly patterned pronotum. Somewhat tolerant of neutralized m= ine drainage. Emergence is from m= id-May through June.
Remenus: One PA species. Restricted to small cold, clean st=
reams,
where it can be common. Disti=
nctive
nymph: only PA perlodid with only one long terminal tooth on lacina;=
no
hairs on lacina. Adults can be
rather common in proper habitat and can be collected from late May through
early August.
Yugus: One PA species. The PA species is not Yugus bul= bosus but recently described new species, Y. kirchneri. Not in Pecarsky’s key= . More of a southern US genus. Nymphs are similar to Malirekus= and can be very large especially in very small streams. Nymphs have a lacina with a margin= al knob; the inner margin has a fringe of hairs along inner edge and a tuft= of hairs near the knob. Outer ventral surface of lacina with a thin sparse patch of dark hairs. Labrum of nymphs with a yellow = mesal stripe. Found in small, c= ool streams. The very rarely coll= ected adults emerge from April to early June.
_____________________________________=
_________________________________________
PTERONARCYIDAE:
5 PA speci=
es; one
genus, two subgenera, Pteronarcys (ss.) and Allonarcys. Giants of the stonefly world. Nymphs are dark brown and have gill tufts present on undersides=
of
all thoracic segments and on abdominal sterna 1 to 2 or 1 to 3. Nymphs can be very common in proper
habitat, but adults are very difficult to find and may move into treetops.<=
span
style=3D'mso-spacerun:yes'> A 2 or 3-year life cycle, so 2 siz=
es of
nymphs are generally present all year.&nbs=
p;
Nymphs roll up into a ball when handled. Nymphs feed on leaves and debris.<=
span
style=3D'mso-spacerun:yes'> Leaves are poorly digested and pass
through the gut in small pieces, which become available as fine particulate=
organic
matter for colonization by microbes and as food for collector gatherers.
P. Pteronarcys: 2 species.= Nymphs do not have lateral exte= nsions on sides of abdomen. PA n= ymphs are found only in warm rivers where they live in accumulated debris and in trash racks; also in larger, clean warm water and limestone influenced creeks. Emergence is in April= .
P. Allonarcys: 3 PA
species. Nymphs have later=
al
extensions on sides of abdomen.
Nymphs are found only in perennial, cold to transitional temperature,
small to medium forested streams.
Nymphs are intolerant of most pollutants. Emergence is in mid to late May. Adults are rarely collected but the
exuvia can be readily collected from tree trunks and undersides of
bridges. Second year nymphs a=
nd
exuvia can be keyed to species.