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Comparative Studies of the .-c..o.&._�--...u.tti
and Internal Anaton1y of rfhree
Species of Caddis Flies (Trichoptera)
BY
KATHERINE KORBOOT
DEPARTMENT OF ENTOMOLOGY
Volume II
FRY,
QL
461
d!66
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N01l
1
1964
Number 1
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Comparative Studies of the External
and Internal Anatomy of Three
S pecies of Caddis Flies (Tricl1optera)
by
KATHERINE KORBOOT
Price: Six Shillings
University of Queensland Papers
Department of Entomology
Volume II
Number
1
THE UNIVERSITY OF QUEENSLAND PRESS
St. Lucia
7 February
1964
WHOLLY SET UP AND PRINTED IN AUSTRALIA BY
WATSON, FERGUSON AND COMPANY,
BRISBANE, QUEENSLAND
J964
REGISTERED IN AUSTRALIA FOR TRANSMISSION llY POST AS A DOOK
COMPARATIVE STUDIES OF THE EXTERNAL
AND INTERNAL ANATOMY
SPECIES OF CADDIS FLIES
(TRICHOPTE.RA)
OF
THREE.
A comparison is made of the external anatomy of the larva, pupa, and adult, and of the
internal anatomy of the larva and adult of Cheumatopsyche modica (McLachlan) (Hydro­
psychidae), Triplectides volda (Mosely) (Leptoc eridae) and Anisocentropus latifascia (Walker)
(Calamoceratidae). Special reference is given to the head, mouthparts, digestive system,
nervous system, reproductive system, and larval glands.
Method of Study
THE EXTERNAL ANATOMY OF THE LARVAE
The larvae were fixed in Carnoy's fixative and preserved in 70 per cent alcohol.
They were not removed from their cases until ready for study, when they were dropped
into boiling caustic potash solution t o clear and soften. The heads were removed and
studied separately.
Two types of larvae are re cogn iz ed in the Tricho pt era the ca mp ode ifo nn and
cruciform, with the following chief characteristics:
,
Campodeiform
Eruciform
Head prognathous
Mouth directed forward
Body d epressed
L eg s lon g , general ly all about the same
len gth
Abdominal segments sharply
co nstrict ed
Prolegs long, slender, and movable
Head hypognathous
Mo ut h di rected ven tr a d
Body cylindrical
Front legs much s ho r ter than the
others
Abdominal segme nts faintly indicated
Prolegs short, thick, and fixed
KATHERINE KORBOOT
4
Lateral line generally present
Prosternal horn sometimes present
Abdominal tubercles present
Rectal blood gills wanting
Builders of portable cases.
Lateral line wanting
Prosternal horn wanting
Abdominal tubercles wanting
Rectal blood gills generally present
Free living or net builders
The larva of Cheumatopsyche modica (McLachlan) (Hydropsychidae) is of the
campodeiform type but is unusual in that the abdomen is cylindrical. The larvae of
Triplectides volda (Mosely) (Leptoceridae) and Anisocentropus la t ifasc i a (Walker)
(Calamoceratidae) are of the eruciform type, but A. latifascia is ex tre mely depressed,
and neither species bears the prosternal horn.
Long , stout bristles arise from the head, thoracic nota, legs, and anal segments.
They are dark in colour with a light-coloured ring at the base, which according to
Hickin (1946) is probably a thinning of the m embr a ne , allowing the bristle to
articulate. The bristles are the "Borsten" of Siltala (1 906) , and the thick spines which
are a characteristic feature of the ventral edge of the femur and tibia are tl1e "Sporne"
of Siltala.
Head
Average Dimensions of Head of Last lnstar Larvae:
C. modica
T. volda
A. /atifascia
Lengtl1
mm.
1.5 mm.
J .5 mm.
1.6
B read th
mm.
mm.
mm.
1.4
1.0
0.7
Colour of the Head: In C. modica the dorsal surface of the head is dark brown,
and the ventral surface is a li ghte r brown. A light band encircles the posterior ventral
part of the head. ln T. volda the dorsal surface is dark brown except for a pale fronto­
clypeus, area round the eyes, and various small light patches. The ventral surface is a
light brown and agai n bears various small light patches. ln A. /at(fascia the dorsal
surface is dark brown except for the characteristic small light patches and a light
fronto-clypeus. Ventrally the head is dark except for three small pale areas on either
side of the midline. Hickin (1946) states that the attachment of the head muscles to
the head sclerites is the cause of the characteristic small, ellip tical light-coloured
marks.
The head capsule of trichopterous larvae is heavily sclerotized, in the shap e of a
truncated cone with two large openings, the occipital fommen and the oral foramen .
The head capsule is co m posed of three main sclerites: fronto-clypeus, vertex, and gula.
Fronto-clypeus:
"This s hield-shaped sclerite presents a fascinating study in its
variation, for here Nature has escutcheoned the genealogy of the order"-Krafka
(1923). The fronto-clypeus is a Hat plate , bounded laterally by the arms of the
epicranial suture; to its anterior margin is attached the membranous ante-clypeus.
The epipharynx is fleshy , arises from the undersurface of the labrum, and proj ect s
behind the ante-clypeus. Orcutt (1934) and Lloyd (1921) refer to the fronto-clypeus
as the frons, but, as H i ckin (1946) follow i ng Snodgrass (1935) points out, the frons
has the muscles of the labrum attached, and so far the presence of this musculature
in trichop terous larvae has not been made out. Du Porte (1.957) refers to the area
apical to the anterior tentorial pits as the clypeal region and that dorsal to the pi ts
as the frontal region. There is some confusion and difference of opinion on the
homologies of certain regions of the head and mouthparts th at are of taxonomic
importance. MacDonald ( 1950) discusses these differences of opinion in some detail.
T he si m plest type found among the three larvae studied is t h a t of C. modica.
The lateral margins are formed by the epicranial arms, which at first diverge w idely
and converge o nly slightly to m eet the ante - clyp eus . In T. vo/da and A. /a tifascia ,
THREE.
S P E CI ES OF
CADDIS
FLIES
(TRICHOPTERA)
5
the fronto-clypeus differs from this in bearing indentations of the lateral margins in
association with the anterior tentorial arms. In C. modica, as in other Hydropsychidae,
the anterior tentorial pits are removed from the epicranial arms. According to Krafka
the anterior tentorial pits have retained their original position on the head, and the
epicranial arms have moved out and away from them, due to the tendency to broaden
the head.
Vertex: The vertex forms the greater part of the head capsule, extending laterad
and ventrad to form the lateral and the greater part of the ventral aspect of the head.
The area which T have called here the vertex has been referred to by some authors as
the epicranial sclerite, and by others as the gena. The region of the vertex which bears
the eyes and antennae could be referred to as the genal region, being demarcated by
a line drawn from the anterior tentorial pits to the eyes.
Eyes. In most trichopterous larvae the eyes consist of six simple, closely
adjacent, lateral ocelli. They are always black in colour and are usually surrounded
by an area where pigmentation of the cuticle is absent. The eyes are slightly elevated,
and their position on the vertex varies from a point near the antero-lateral margins
of the head to a point as far caudad as the separation of the epicranial arms. There is
only slight variation in the positi on of the eyes on the vertex in the three species
studied. They are situated furthest anteriorly in T. volda. The larvae appear to use the
eyes only in differentiation or light and dark; the food is met accidentally by the fore
legs and passed to the mouth, where it is accepted or rejected.
Antennae. The antennae are small, simple, and easily overlooked. Siltala
(1906) recognizes two types: one with two distal pieces, the other with only one distal
piece. Their position varies with the eyes, from immediately behind the mandibles
to a point far up on the head. The first type of Siltala's has a basal segment upon
which are mounted two so-called palps and numerous sensory setae. The second type
has a single palp. The first type is stated to be common in the campodeiform group,
while the second is p ec u lia r to the cruciform group.
I have found no trace of antennae in C. modica. The antennae of T. volda and
A. lat(fascia have a similar position near the base of the mandibles. A. latifascia has
a long slender "palp" set on a raised base while in T. volda the "palp" is reduced in
size.
Gula: Siltala (1906) has pointed out that the gular sclcrite is not strictly homo­
logous throughout the order. Tn some cases Siltala considers this sclerite to be the
mentum and in others the true submentum. Das (1937) is also of the opinion that a
true gular sclerite is totally absent in trichopterous larvae, the so-called gular scleritc
being the submentum. Hickin points out that the modifications of the gular sclerites
amongst the families of Trichoptera are closely associated with the feeding habits of
the larvae.
1 have followed Krafka (I 923) in applying the term "open" to a gula which
reaches the occipital foramen and "closed" where the two parts of the vertex are
contiguous, preventing the gula from reaching the occipital foramen. T. volda shows
a great development of the open type; the gula is a broad plate widely separating the
vertex. 1 n A. latifascia the gula is of the closed type, being a small triangular sclerite
at the proximal end of the labium. C. modica has a closed gula which is irregularly
pentagonal. At the base of the gular suture is a minute area which represents a
vestige of the posterior piece found in other Hydropsychids.
Chaetotaxy: The chaetotaxy of the head has been worked out by Ulmer (1909).
According to this author, the clypeus (here referred to as the fronto-clypeus) bears
typically thirteen bristles of which seven are situated on the anterior margin, one of
these being in the middle and three associated with each lateral angle; of the
remainder, three bristles are situated near each lateral margin, one being aborally
placed and two orally placed.
KATHERINE KORBOOT
6
In C. modica the bristle arrangement is obscured by the presence of a large
number of secondary bristles. The number of primary bristles differs from that
proposed by U lmer by diminution of the bristles alon g the anterior m argin there
being one central and two lateral on each side. On the vertex three stout bristles occur
in front of each eye and three behind. In T. volda six bristles occur on the anterior
margin of the fronto-clypeus, three associated with each lateral angle, and three occur
on each side associated with the lateral margin On the vertex a stout bristle occurs
in front of each eye and another behind the eye. ln A. latifascia the fr onto clypeus
bears four bristles. The seven bristles of the anterior margin which are mentioned by
Ulmer are absent. There are two lateral bristles on either side, one aboral and one
oral. There are six pairs of bristles on the vertex, one large oral bristle on either s\de,
one on the inner side of the eye, one above the eye, and three posterior bristles in a
,
.
-
row.
Endoskeleton: The endoskeleton of the head is greatly reduced. The tentorium
consists of an extremely slender, fibre-like bridge, and 11exible, fibre-like anterior and
posterior arms extending through the head from the dorsal to the ventral wall. The
anterior arms arise about half way along the epicranial arms in T. volda and
A. latifascia, but in C. modi c a they arise a short distance mesad of the epicranial
arms. The posterior i n vaginations are located in the angles formed by the gula and the
vertex in T. volda, and near the caudal ends of the gular sutu re in A. latJfascia and
C. modica.
Mouthparts: The mouthparts of trichopterous larvae are well d eveloped and of
the mandibulate type. The mandibles are always heavily sclerotized and well adapted
for gripping and tearing. The articulations are of the acet abulum condyle type.
The dorsal articulation has the acetabulum on the mandible and the condyle on the
vertex, while in the ventral one the conditions are reversed. The labru m is separated
fr om the fronto-clypeus by the ante-clypeus, which forms a hinge allowing the
labrum to fold back within the capsule of the head.
-
The l abium and m axi llae are united to form the underlip. The labium has its
basal attachment on the anterior margin of the gula It is cone-like in shape, with a
broad basal section repre s enting the postmentum, and term inating in a segment
which rep re sents the prementum. This segment bears a pair of one- or two-segmented
labial palps or th e palps are absent. The dorsal surface of the prementum probabl y
represents the hypopharynx The combined structure may be called the premento
h ypop h aryngeallobe as has been done by S nodgr ass (1935).
.
,
­
.
,
The cardo of the maxilla is attached to the postmentum of the labium on each
side. The stipes is not capab l e of independent movement but moves with the labium.
The c ardo and stipes are broad structures bearing many small hairs. Lying close to
the maxillary palp which is four- or five segmented is the inner lobe or galea
,
-
,
.
In C. mo dica the labrum is sclerotized, brown in colour, with p ale semicircular
are as posteriorly and p rovided with dense lateral brushes of long hairs and two lon g
anterior bristles. The labrum of T. volda is lightly sclerotized, except for tw o heavily
sclerotized areas at the posterior angles A small median anterior incision is present,
and the outer angles of the anterior margin are provided with a dense group of short
hairs. In A. lat(fascia the labrum is slightly sclerotized and sub-rectangular. Again
the median anterior incision is shallow and dense brushes of fme bristles are borne
on the anterior lateral angles. Ten stout bristles on either side project anteriorly
from the upper surface.
,
.
,
In C. m odica the mandibles are amber coloured and symmetrical. The cutting
edge is along the inner margin, and six sharp teeth are borne apically. Two bristles
are present on the outer edge of each mandible, and a brush of small hairs on the inner
edge. In T. volda the mandibles are asy m metrical and black in colour. A pically the
left bears two sharp teeth, and the right four blunt teeth. Again two bristles are present
THREE SPECIES OF CADDIS
FLIES
(TRICHOPTERA)
7
on the outer edge of each mandible. The mandibles of A. lat!fascia are symmetrical
in shape, but asymmetrically pigmented, the dark irregular pattern occupying different
areas on each. There are three stout, blunt, apical teeth and a dense brush of fine,
yellow hairs on the inner margin.
In T. volda the maxillary lobe and palp are densely haired, the palp being five­
segmented. In the three genera the lobe is shorter than the palp. In C. modica the
palp is four-segmented with two warty knobs at the tip, while the palp of A. latifascia
is four-segmented with papillae at the tip. In C. modica the ligula is a distal beak-like
projection of the labium bearing the opening of the spinning gland. In T. volda and
A. latifascia there is no such projection. Hickin considers this distal region between
the palps as probably being the fused glossae and paraglossae. Labial palps are
minute in the three species. No division of the postmentum into mentum and
submentum is evident.
Thorax
The thorax consists of three distinct leg-bearing segments. The pronotum is a
heavily sclerotized plate which extends over the sides of the prothorax. The anterior
margin of the prothorax of T. volda bears a number of stout forwardly projecting
serrations, and the posterior margin of the pronotum of C. modica bears a number of
backwardly projecting serrations. In C. modica the meso- and metanota are well
sclerotized. In T. volda the mesonotum is well sclerotized, but marked with pale,
weakly sclerotized patches, and the metanotum consists of four small, isolated
sclerotized plates. In A. !at(fascia the mesonotum bears a slightly sclerotized central
shield, and the metanotum is entirely membranous.
On the sides of the three thoracic segments are sclerotized plates which represent
the episternum and epimeron. ln the propleural region of C. modica the episternum
and epimeron are distinct plates. The episterna and epimera of the meso- and meta­
pleura are dark, narrow, band-like sclerites which give support to the bases of the
coxae. In T. volda and A. latifascia the pleural sclerites are large and plate-like, with
distinct pleural sutures. In all three species the propleurae bear a trochantin, one edge
of which is free and projecting, appearing as a scraper. The posterior edge articulates
with the episternum by a membranous connection. In A. lati;fascia the outer edge of
the trochantin is finely serrated.
Long and short bristles are arranged in characteristic positions on the thoracic
nota. In C. modica the nota are covered with fine secondary bristles. The pronotum has
a stout antero-lateral bristle on each side and also a posterior bristle on either side of
the midline. The meso- and metanota have the posterior-median bristles. In T. volda
the pronotum has a lateral fringe of long, fine bristles, and the other thoracic nota
are bare of bristles. The thoracic nota of A. latifascia are well supplied with bristles.
The pronotum bears ten bristles along the anterior margin, three bristles along each
lateral-anterior margin, and two lateral, two submedian, and two dorso-lateral
bristles. The mesonotum bears eight anterior bristles and, on each side, three antero­
lateral and four dorsal. The metanotum bears on each side four antero-lateral, one
mid-dorsal, and four dorso-lateral bristles.
Legs: Trichopterous larvae have three pairs of well-developed jointed legs.
The coxa is large and entirely sclerotized. An incision on the dorsal surface of the
distal margin is covered with a thin membrane and allows the short triangular tro­
chanter to move in an upward direction. The femur is broad and flattened, usually with
a series of spines along the ventral edge. The femur is inserted deeply into the distal
end of the trochanter, with a strong membranous sheath forming a hinge between
the segments. The tibia is undivided, except in some Leptocerids. The tarsus is
undivided, with a large claw armed with a basal tooth.
KATHERINE KORBOOT
8
In C. modica the three pairs of thoracic legs do not differ greatly in size. The tibia
and tarsus are covered with short hairs which, according to Lestage (1921), serve in
Hydropsyche sp. as a brush for cleaning the nets. The ventral surface of the femur
bears numerous small spines. InT. volda the legs are long and thin, with dark, annular
patches on all segments. The middle and hind legs have a peculiar jointing. The tro­
chanter is unusually long, and the femur slightly shorter. The tibia appears to be two­
segmented, and the tarsus is long. The ventral surface of each femur has a few small
spines. ln A. latifascia the front and mid legs are short and stout, the hind legs long
and slender. The front legs bear a heavily pigmented band on the tibia and a light
band on the tarsus. The mid legs have heavy bands on the femur and tibia and a light
band on the tarsus. The hind legs bear two bands on the elongate tibia and single
bands on the femur and tarsus. The ventral surface of each femur is free of spines.
Abdomen
The abdomen is nine-segmented and almost entirely membranous. In C. modica
the abdomen is slightly sclerotized dorsally, and the eighth and ninth segments each
have two small ventral, sclerotized plates, which are fringed posteriorly with bristles.
The ninth segment also has two small lateral plates on either side. The abdomen is
widest at the second and third segments. In life, the colour is pale green. The tubercles
and lateral line are absent, and the intersegmental grooves are slight. In T. volda
the abdomen is light grey, the intersegmental grooves are shallow, and the abdominal
tubercles are well developed. The dorsal tubercles are fleshy, non-sclerotized, and
lobe-like, and bear two fine bristles. The lateral tubercles are two small sclerotized
protuberances, each bearing a single bristle. The lateral Line extends from the anterior
margin of segment three to the posterior margin of segment seven. In A. latifascia
the abdomen is creamish-yellow and entirely membranous, except for a slight sclero­
tization at the hind margin of the first abdominal segment. The abdomen is extremely
flattened dorso-ventrally, and has a laterally scalloped appearance as the inter­
segmental areas are narrower than the segmental areas. The intersegmental grooves are
distinct. The tubercles on the first abdominal segment are not very pronounced,
being slight, flattened swellings. The lateral line extends from the anterior margin of
segment three to the posterior margin of segment seven. The hairs of the lateral line
are very long and appear as a lateral fringe. The abdominal tubercles serve to keep a
space between the insect and its case for the free circulation of the respiratory currents
of water. The lateral line also keeps a continuous flow of water through the case.
Gills: The acquatic habit of trichopterous larvae has led to a closed tracheal
system and, in most, to gill development. A large proportion of oxygen absorption
however is cuticular. The gills are filamentous and may arise in tufts or singly. When
present they arise only at certain definite places on the body. There are three longitu­
dinal rows on each side of the abdomen:
(I)
A lateral series which is located near the mid-lateral surface of the body.
(2)
A subdorsal series, which is located above the lateral series, just below the
dorsal surface of the body.
(3) A
subventral series, which is located below the lateral series, just above the
ventral surface of the body.
Gill pattern.
In C. modica pale pink, branched tracheal gills are present on the
meso- and metathorax and abdominal segments one to eight. The gills are approxi­
mately two-thirds of tile length of the segment which bears them. Mesothorax--­
ten branched subventral series. Metathorax----ten branched mid-subventral series, and
ten branched posterior-subventral series. Abdominal segments one, two, three, four
-ten branched lateral and subventral series. Abdominal segments five, six, seven,
eight-two branched subventral series. In T. volda the tracheal gills are long, white,
unbranched, finger-like, and taper slightly at the distal end. In a fresh specimen
THREE SPECIES OF CA DDIS FLIES (TRICHOPTERA)
9
they are equal to the length of the segment which bears them, but on preservation they
shrink. The gills are borne on the cephalic end of abdominal segments one to eight
inclusive. Abdominal segment one-unbranched lateral, subdorsal, and subventral
series. Abdominal segments two to eight--unbranched subventral and subdorsal
s eries . ln A. /atifascia, as in T. volda, unbranched, long, white, finger-like tracheal
gills, which taper distally, and which are equal in length to the seg m ent which bears
them , are present on the abdomen. Abdominal segment two---unbranched lateral
series of three pairs, subdorsal series of three pairs, and subventral series of three
pairs. Abdominal segments three to eight--unbranched subdorsal series of thr ee
pairs and subventral series of three pairs.
Besides the external tracheal gi lls , C. modica possesses four white, transparent
anal gills projecting from the T-shaped anus. The gills are in direct communication
with the body cavity, and when retracted they lie in the rectum, of which they are
outgrowths. When the larva is in need of extra oxygen, blood passes from the blood
sinuses into the gills, and the resulting pressure extrudes the gills through the anus
to the exterior, where gaseous exchange takes p lace through the wall of the gill. At
rest the w idth of the gill is about one-third of its length, which is normally sl ightly
less than the width of the ninth segment. The gill is capable of extrusion to about
three times its retracted length.
Abdominal undulatory movements have been observed in C. modica and
A. lat�fascia. The abdomen is moved rhythmi cally in the vertical plane, causing a flow
of water over the gills and the surface of the body, thus aiding in respiration. These
rhythmic undulatory movem ents were also noted in the prepupal stages.
The ninth abdominal segment bears a pair of fleshy appendages or pygopods,
each of which terminates in a movable chitinous hook. In C. modica the appendages
are long and slender, and the claws are strong and serve to grip the silken net when
the larva is running backwards. The two appendages lie close together and are well
armed with stout bristles, a dense brush of bristles being present at the ba se of the
claws. In T. volda the anal appendages are more squat and the claw is shorter. The
two appendages are well separated and covered with an irregular pattern of long
bristles. The anus is slit-like. The anal appendages of A. lat(fascia are small and squat.
The cl aw is double and the bristles sparse. Three long bristles occur near the apex.
The appendages lie far apart and the anus is slit-like. Tn T. volda and A. latifascia
the claws are used to grip the silken lining of the case.
NOTE
Two larvae of Anisocentropus e/egans Walker were found in the habitat of
A. lat!fascia and in similar cas e s made of leaves. One specimen was killed for
examination of the larva, and the other was bred to the adult.
Features in which A.
elegans larva differs from A. latifascia:
Seven bristles are si tuated on the anterior margin of the fronto-clypeus arranged
in the way described by Ulmer. Four small bristles are associated with each lateral
margin. The labrum is lightly sclerotized and globular. The median anterior incision
is shallow, and dense brushes of fine hairs are present on the anterior lateral angles.
Two stout bristles project from the upper surface. The mandibles are dark brown and
symmetrical, each bearing two stout, blunt apical teeth.
The pronotum has three lateral and five anterior brist l es on either si d e . The meso­
notum has three antero-lateral and three median pairs, and the metanotum three
anterior and two p o sterior median pairs. The meso- and metanota are completely
membranous. The legs are short and stout, and there is slight variation in size from
the fore to the hind legs, the fore being the stoutest and shortest.
The abdomen is entirely membranous. lt is not flattened dorsoventrally, but is in
the form of a hairless cylinder . The lateral margins of the abdomen lack the scalloped
10
KATHERINE KORBOOT
appearance of A. latifascia. The hairs of the lateral line are short, and the lateral line
extends from the anterior margin of segment two to the posterior margin of segment
seven. Gills are lacking.
It is interesting to note that on one occasion a male of A. elegans and a female of
A. latifascia were taken in copula at the light trap in September at Enoggera Creek,
Brisbane. The female was kept alive in the breeding cage, and on the second day of
captivity a cream coloured spherical egg mass was observed protruding from her
abdomen. On her third day of captivity the female dropped the mass into the water
of the cage. The mucilage covering of the mass swelled to double its original size but
the eggs, which were arranged in a spiral fashion in the mass, failed to develop, the
whole mass finally disintegrating in the water.
THE INTERNAL ANATOMY OF THE LARVAE
Method of Study
H. E. Branch (1922) was followed to advantage in using hot water killing for
specimens to be used in gross dissection, but Carnoy's fixative, and not the Gilson's
fixing solution recommended by Branch, was used. The internal anatomy of the larvae
was studied from gross dissections, glycerin whole mounts, and eight to ten f.L
longitudinal and transverse microtome sections. Where possible larvae fresh from
ecdysis were used for sectioning, embedded in 4 per cent celloidin and wax. Specimens
which had been preserved for some time in alcohol became exceedingly hard, and a
special technique for softening was therefore necessary. The specimens were soaked
in diaphanol for twelve hours.
Digestive System
In C. modica the buccal cavity is large, occupying more than half of the space of
the head capsule. 1t leads into a narrow tube, the oesophagus, a slight anterior
distension of which could represent a very ill-defined pharynx. The oesophagus
expands slightly in the prothorax, at the posterior end of which it enlarges to form the
crop. At the posterior margin of the mesothorax the fore-gut constricts to about half
its width and forms the cylindrical proventriculus. This is a hard structure with a
number of sclerotized teeth on the intima, large circular muscles, and, outside these,
six longitudinal muscles arranged in pairs. The proventriculus functions as a grinding
organ and possibly as a straining device. It 6ccupies the entire metathorax.
The mid-gut extends from the posterior end of the metathorax to the sixth
abdominal segment. It is darker than the rest of the alimentary canal and lacks the
silvery tone of the fore-gut. The proventriculus pushes into the forward end of the
mesenteron, forming the stomodaeal invagination. The mid-gut is about one-third
as wide as the abdomen and is folded into transverse ridges which increase the assimila­
tive area. The longitudinal muscles break up to form a layer of muscles around the
tube. Beneath these muscles is a very thin layer of circular muscles. No distinct valve
is present between the mid- and hind-gut, but the latter is of narrower diameter.
At the junction of the mid- and hind-gut arises the circle of six Malpighian
tubules, two dorsal, two lateral, and two ventral. The dorsal tubules extend forward
through the abdominal cavity into the metathorax. The lateral pair coil forwards,
lying close to the alimentary canal as far as the third abdominal segment, and then
pass backwards, lying close to the body wall as far as the eighth abdominal segment.
The ventral pair also coil forwards, passing to the fourth abdominal segment, and
pass back in a zigzag fashion to the eighth abdominal segment. The tubules are
irregular in outline and light yellow to white, with patches of dark pigment.
The intestine is oval in outline. A constriction at the posterior end of the seventh
segment is the only indication of change from small to large intestine. At the posterior
end of the eighth segment the intestine is again constricted before the rectum. At this
THREE SPECIES OF CADDIS FLIES (TRICHOPTERA)
11
point the walls of the i ntestine are invaginated as folds which posteriorly become
longer and fewer to form the blood gills which lie in the rectum. The rectum extends
through segment nine; its diameter becomes narrower after its original swelling,
following the constriction in segment eight, and then dilates again to accommodate
the invaginations forming the blood gills. In C. modica th e rectum thus serves the
dual function of elimination of waste material and of resp iration . Glycerin mounts
show that the blood gills are not tracheated.
The anterior part of the intestine has a heavy musculature, being surrounded
by large circular and narrow longitudinal muscles. The musculature of the rectum,
however, is thin, and the walls are almost transparent.
In T. volda the oesophagus expands in the mesothorax into a short s ac-like crop.
At the posterior margin of the mesothorax, as in C. modica, the fore-gut constricts
to form the small proventriculus. The latter is like a posterior dilation of the crop,
as the heavy muscle coat and sclerotized teeth present in C. modica are lac king .
T. volda is a herbivorous species, and the grinding teeth of the semi-carnivore are
not necessary.
As in C. modica, the mid gut extends from the posterior end of the metathorax
to the sixth abdominal segmen�. In the second abdominal segment the mid-gut is
slightly constricted. The six Malpighian tubules have the same arrangement as in
C. modica but arc slightly longer. The dorsal pair coil forwards into the metathorax,
then turn back to the first abdominal segment. The lateral pair coil forwards to the
second abdominal segment, turn, and pass back to the eighth abdominal segment.
The ventral pair continue forward to segment three before turning back.
-
There is no constriction between small and large intestine, the intestine being a
wide tube, narrowing at the beginning of segment eight before the rectum.
In A. lat(fascia the oesophagus dilates slightly in the mesothorax to form the
crop, which is m a rked from the proventriculus at the anterior margin of the meta
thorax by a slight constriction. As in T. volda, the proventriculus lacks sclerotized
teeth .
­
The mid-gut is shorter than that of C. modica or T. volda, extending to the fifth
abdominal segment. It is in the form of an extremely depressed sac. 'rlle six Malpigh
ian tubules are arranged as in C. modica and T. volda. The dorsal tubules coil forward
to the second or third segment and back to the eighth The lateral t u bules follow a
zigzag path to the mesothorax, and the ventral pair pass to the first abdominal
segment and back to the fourth.
­
.
The intestine and rectum resemble those of T. volda, the rectum gradually
narrowing as it nears the anus.
Circulatory System
The dorsal blood vessel extends in tubular form from the middle of the head to
the middle of the ninth abdominal segment. The tip of the cephalic end bifurcates
to give two short aortic branches.
The nine pairs of alary mus cles occupy a ventral intersegmental position, the
first pair between the metathorax and the first abdominal segment, and the last
between the eighth and ninth abdominal segments
.
Reproductive System
As pointed out by Branch this system seems to have been given adequate atten·
tion by Zand er (1901), Liibben (1907), and Marshall (1907). 1 merely located the
organs in gross dissection. As to the period of appearance of the organs, there is
difference of opinion Klapalek (1889), Vorhies (1905), and Pictet (1834) state that
the organs do not appear until near the period of pupation. Liibben discusses condi­
tions in the transforming larva, while Marshall speaks of the condition of the organs
.
KATHERINE KORBOOT
12
in the youngest larva he had, but does not state the stage. 1 have observed the gonads
to be present in the last three larval instars in C. modica, T. volda, and A. latifascia.
[n over fifty specimens dissected the gonads appear to take two forms-narrow
elongate tubes and small oval bodies. The elongate type probably represents the
fut u re male organs and the oval ones the female organs. The gonads are paired and
occur in the fourth abdominal segment in the three species. From a compilation of
records, the position of the gonads in Trichopterous larvae seems to be in either the
fourth or fifth segment. Each gonad bears two attachments, one a thread-like tissue,
the other a duct. The former arises from the outer side of the gonad and extends to
the ventral body wall at the cephalic end of the third abdominal segment. The latter
arises from the inner side of the gonad, and the tubules of the gonad converge towards
the base of the duct. The duct extends posteriorly to the ventral body wall of the eighth
segment. The ducts of the two sides do not fuse and, in these three species, do not
appear to pass to the exterior as reported by LUbben (1907).
Nervous System
The nervous system of trichopterous larvae is generalized, with three thoracic
pairs and eight abdominal pairs of ganglia.
In C. modica the brain is near the front of the head. The optic nerves branch on
leaving the ganglion. From the small frontal ganglion a branched nerve proceeds
forwards, the outer branch supplying the labrum and the inner branch the dorsal
region of the buccal cavity.
An oesophageal ring of the tritocerebrum encircles the oesophagus.
Of the three pairs of nerves from the sub-oesophageal ganglion, the most dorsal
extends forwards and upwards and branches in front of the frontal ganglion. One
branch innervates the base of the labrum and the other the mandible. The second
pair of nerves also branches, the outer branch supplying the musculature of the
maxilla, and the inner dividing again to supply the maxillary sclerite and the labium.
The third pair of nerves is ventral in position and innervates the labium.
Each ganglion of the thorax and abdomen represents a fused pair of ganglia.
A pair of connectives passes from the sub-oesophageal ganglion to the first thoracic
ganglion in the prothorax. The pro- and mesothoracic ganglia are of about the same
size as the sub-oesophageal ganglion and are situated in the middle of the segment
which they innervate. The metathoracic ganglion is larger than those of the preceding
segments, and is situated at the posterior border of the metathorax and incompletely
fused with the first abdominal ganglion. The ganglia of abdominal segments two and
three are situated in the posterior halves of segments one and two respectively.
A bdominal ganglion four is situated in the anterior half of its segment, and abdominal
ganglion five in the posterior half of segment five. The sixth, seventh, and eighth
abdominal ganglia are closely united and lie in the sixth abdominal segment.
The thoracic ganglia and abdominal ganglia one to six innervate their respective
segments and appendages. The seve nth abdominal ganglion bears a single pair of
fine nerves which extend backward into segment seven. The eighth abdominal ganglion
innervates segments eight and nine and the anal appendages.
The ganglia and nerves of the head of T. volda and A. lat!fascia do not differ
materially from those of C. modica. However the three species differ considerably
as to the relation of the thoracic and abdominal ganglia to their respective segments.
A ll have three thoracic and eight abdominal ganglia; but in A. latifascia there are
apparently only seven abdominal ganglia, due to the complete fusion of the first
abdominal and metathoracic ganglia, the enlarged composite ganglion occupying a
central position in the metathorax. In C. modica the first abdominal ganglion has
incompletely united with the ganglion of the metathorax and come to lie in the
posterior half of the metathorax. In T. volda the first abdominal ganglion is distinctly
separated from the metathoracic, lying in the middle of its own segment.
THREE SPECIES OF CADDIS FLIES (TRICHOPTERA)
13
In T. volda abdominal ganglia two, three, four, five, and six occupy central posi­
tions in their respective segments, while ganglia seven and eigllt lie closely united
as a large central ganglion in segment seven, indicating a forward migration of
ganglion eight. In A. lat�fascia abdominal ganglion two lies in the first abdominal
segment, segment two being void of a ganglion but being innervated by the nerve
branches from ganglion two. The ganglia of segments three, four, five, and six occur
in their respective segments near the posterior margins. Segment seven is void of a
ganglion, ganglion seven being closely nnited, but not fused, with ganglion eight in
the middle of segment eight.
Silk Glands
These are the most prominent glands of the trichopterous larva and have a
similar structure in the three species studied. They extend from the labial spinneret
to the sixth abdominal segment and fill that part of the body cavity not occupied by the
alimentary canal and fat body. They are twice bent and comprise two regions, the
glandular part and the duct. The glands lie ventral to the alimentary canal in the thorax
and lateral to it in the abdomen. In the sixth abdominal segment they narrow and lie
beneath the intestine.
In the centre of the anterior margin of the labium is the spinneret. It is connected
to a slender tube which divides; the two ducts pass under the nerves supplying
the mouthparts and the tentorium and, on reaching the sub-oesophageal ganglion,
run close together beneath the oesophagus and open into the silk glands. Close
behind the spinneret is a muscular silk press which controls the ±low of secretion.
Further details of the structure of the silk press are given by Gilson ( !894).
THE EXTERNAL ANATOMY OF THE PREPUPAE AND PUPAE
Method of Study
The information presented was obtained during the rearing of larvae to adults.
Pupae were fixed for four hours in Carnoy's fixative and preserved in 80 per cent
alcohol. Pupal skins were dehydrated in alcohol and mounted in Canada balsam.
Pupal Cocoon
A cocoon is characteristic of all triehopterous pupae. In C. modica the cocoon is
made of small stones cemented together into an oval-roofed chamber. The floor of
the chamber is a rock or submerged log. When the time of pupation draws near, the
mature larva leaves its silken retreat, wanders to the floor of the stream, collects
stones of about the same size into a heap, and then begins to construct the pupal
chamber. Many specimens of C. modica were observed in aquaria, and in all cases
the larvae left their original home and pupated elsewhere. The site chosen for pupation
may however be near the retreat of another larva. Between the stones forming the
pupal chamber small spaces occur, through which water passes to the pupa inside.
Undulations of the pupal abdomen keep the water circulating. The pupal cocoon of
C. modica differs from that of the case-bearing larva, where the cocoon is made from
the larval case by blocking in various ways the front and rear openings, so as to protect
the pupa from enemies and silt. In A . lat�fascia the posterior net is replaced by a s ilke n
plug, and anteriorly a silken lid is spun, the lid having a small slit-like opening. The
pupal gratings lie at the extreme ends of the leaf fragment which forms the floor of
the pupal shelter. The larval case ofT. volda is sealed posteriorly with a silken plug,
and anteriorly a grating of fine silken threads is spun. The pupal gratings are not
situated at the extreme ends of the case but lie a short distance within the case.
Prepupal Period
When the pupal case is completed changes occur in the larva. As described by
Hickin, it becomes stiff, the head and abdomen lose their usual flexibility, and the
KATH E R I N E K O R B OOT
14
inter-segmental grooves of the abdomen become very indistinct. The legs occupy
po sitions characteristic of the prepupal phase.
C. modica :
Fore legs. The coxa and trochanter point downwards and
forwards, the femur points up, and the tibia an d tars us point forwards, at an angle,
l ying on either side of the head.
Mid legs . The coxa and trochanter point down and back , the femur is vertical ,
and the tibia and tarsus lie in a horizontal position on either side of the abdomen .
Hi nd legs.
A s fo r mid legs.
T. v olda :
Fo re legs . The coxa and trochanter are directed down and forwards .
The femur, tibia, and tarsus are directed forward s and upwards.
Mid legs .
Held in the same position as the fore leg s .
Hind l egs. Coxa and trochanter are directed forwards and upwards. Femur,
tibia, and tarsus follow the dorsal surface of the thorax in a forward position.
A.
latifascia :
The fo re and mid legs are pressed close to the sides of the body.
Fore legs . The coxa and trochanter are directed upward and forward. The
femur, tibia, and tarsus are pressed cl ose to the sides of the head.
Mid legs. The coxa, trochanter, and femur are directed upward s and for wards .
The tibia and tars us lie c lose t o the head and are parallel to those o f the fore legs .
Hind legs . The coxa and trochanter are directed posteriorly, fem ur up and
back, and the tibia and tarsus foll ow the abdomen on the dors al s urface .
Pupa
All Trichoptera have exarate pupae with functional mandibles (pupae liberae of
Hickin ( 1 949) , decticous pupae of Hinton ( 1 946) ) . The pupal integum ent is colourles s
and loo sely envelops the forming imago lying within. In external appearance the
pupa has many of the characteristics of the adult . However the man d ibles and dorsal
hoo k-bearing plates provide features of exceptional interest. The dorsal hook-bearing
plates are a series of horny scle rites used for gripping the sides of the case when the
pupa is emerging, and the mandibl es are used fo r cutting through the case at
emergence.
Head
The head resembles very closely that of the adult, but the mouthp arts ditler
greatly. The imago feeds very little , if at all, and when it does feed the nutrient is of a
l iquid n ature . The pupal mandibles however carry out the important function of
cutting the exit hole in the pupal case and are well developed. The labrum is very
difterent from that of the larva and adult. The anten nae are straight and lie close
along the sides of the pupa. They possess the same number of segments as the
antennae of the imago and are of the s ame length and shape. In all cases the antennae
pass in front of the eyes and along the anterior margin of the wing pads.
In C. modica the antennae end at the ventral aspect of the eighth segment, after
rolling twice around that segment. In T. v olda they extend to the nin th segment,
around which they cud twelve times , the tip of the antenn a being tucked down
ventrally. The antennae of A. latifascia lie straight along the sides of the body and
extend ab out 5 . 6 mm . beyond the tips of the anal appendages.
In the three species studied the colouration of the p upal eyes followe d the s ame
pattern. The eyes were colourless in the newly fo r med pupa, and passed through brown
a n d red before reaching the black colour of the mature pupal eye.
The labrum is armed with stout bristles . In C. modica it i s fiat and plate-like, and
lies in the same plane as the fronto-clypeus . A gro up of l arge bristles is present distally,
TH R E E S PECI ES
OF
CADDIS FLI ES (TRICHO PTE RA)
15
and a pair of promixal groups is present on each side. The anterior mar gin bears a
double indentation. In T. volda the l ab r um is a fiat sub-rect angular plate lying in th e
same pl ane as the fr onto-clypeus. It is covered with l ong stout bri stl es and be ars a
slight indentati on along the posterior margin, whil e the anterior margin is slightly
pointed in the middl e . The labrum of A. latifascia is smal l , sub-rectangul ar, and
proj ects outwards from the head. It bears anteriorl y a gr oup of stout b ristles and
p o steri orly two l arge bristles .
The man d ibles are l o n g and heavil y scl erotized . In C. modica they are sickle­
shaped and have three la rge an d two small apical teeth . A t th e base are two ventral
group s each of six stout b lack bri stles . In T. volda the apices of the m a n d i bles are
s ickle- shaped , and a smalJ tooth is presen t in the middle. Tw o l on g bristles are b orn e
on the outer margin near the base. Tn A . latifascia t h e apices are very s harp b ut have
n o teeth . The re are two small b ristles on the ou ter side near the b ase.
The maxil lary p alp s are well developed and five- segmented . The l abial palps
are three segmented .
Thoracic Segments
These are m uch the same as in the a d ult, each bearing a pair of j o inted l egs, and
the second and third segments having extern al wing pads. The win g pads are clo sely
p ressed to the pleural region of the th orax. 1 n C. modica and T. vo lda the wing pads
extend as far as the fourth abdominal segment, and in A. latifascia to the fifth
abd ominal segment.
The pro- and mesothoracic legs are entirely free, and the metathoracic
Legs:
legs have the tibi a and tarsus fre e . The pupal segments are similar to those of th e adult
except for th e occurrence of an extra tarsal segmen t , m aking six . The legs posses s
l on g swimming hairs . My observations with C. m o dica uphold Hickin ' s statement
that on ly the middle legs are used for swimming, when the pupa swim s to the surface
of the water for the final metamorphosis . The swimmi ng hairs are best devel oped
in the midd le legs , forming a d oubl e fringe of hairs along the length of the tibia and
tarsus.
Abdomen
Nine s egments are present which are similar to those of the im ago but are lo nger
and mo re flexi ble.
In C. modica, sm all, bunched tracheal gills are present on ab dominal segments
three to eight in clusive. As the time for emergence draws near the gen italia of th e
adult may be seen beneath the pupal skin.
On the d orsum of the abdomen are the sclerotized hook-bearing plates . In
C . modica these pl ates are prese nt on segments one to eight inclusive. Segme nt three
has an anterior and a posterior set of plates. On the thi r d anterior and the fourth
segmental plates the hooks point anteri orly ; on all o ther pl ates they p o i nt posterio rl y .
In T. volda hook-bearing plates are present on the po sterior ma rg ins o f segments
two to six inclus ive . The hooks of segment five p oint anteriorl y, those of the
other segm ents b eing directed posteriorly. A . latij'ascia has pl ates only on segments
one and five, and all the ho oks point p osteriorly.
The n i nth ab domin al segment bears processes armed with stout spine s . There
seems to be general agreement as to the fu nction of the anal app end age s . They are
use d , like the spines on the l abrum , to keep the p upal case free fro m silt.
The newl y fo rmed pupa of T. volda i s cream , of C. modica cream w ith green ish
ab d omen , while in A. latifascia the thorax , hea d , l eg s , and antennae are cream , and
the abd omen is orange with black l ateral lin e a n d po sterior ventral fringe.
KATH E R I N E K O RBOOT
16
Sho rtly before emergence , T. vo lda is dark brown, C. m odica ha s dark brown
wings and abdomen and a rich cream head, thorax , and legs, while A. latifascia
has the head , thorax , legs , and abd omen pale yell ow and the wings and antenn ae
black.
THE
EXTERNAL ANATOMY OF THE ADULT
OF Cheumatopsyche modica
Head
The head is wider than lon g , is hyp ognathous, and bears a number of setae .
The compound eyes are comparatively l arge and ocelli are absent. The frons is large
and bears two areas of sens ory spots , and the clypeus is well scleroti zed and bulges
slightly. The anterior tentorial pits are present at the lateral margins of the clypeus .
The frons is a sub-rectangular area lying between the compound eyes and fo nn s the
anterior part o f the face. The genae, which meet the lateral margins of the clypeus,
are al so stro ngly sclerotized . They lie below the compo und eyes and are drawn down
ventrally i nto a hinge where the card o articulates with the cranium. The labrum lies
in the anterior arch of the clypeus , and the maxillae lie alongside the labrum . Three
areas of sensory spots are present in the parietal regio n. Occipital and po st- occipital
sutures are present . The gul ar region is memb ranous and lies in loose folds near the
cervix.
The tentorium consists of anterior, d orsal, and p osterior arms which meet the
cranium at the sides of the clypeus, at the inner angles of the ante n n a] sockets , and
near the base of the postoccipital suture respectively . The tentorial body consists
of a tran sverse bar bel ow the phary n x .
An tennae : When at rest t h e antennae a r e held porrected in front of t h e head .
They are inserted in the antenna! sockets on the inner side of the comp ound eyes . The
anten nifer artic u lates with the outer side of the scape and is relatively promi nent.
The scap e is short, thick, and stumpy. Deo ras ( 1 940) i s foll owed in calling the articula­
tion at the distal end of the scape and the proximal end of the pedicle, which might
be confused with t he organ of J ohns o n , th e " scapular peg" . A projection is present
on the inner side of the scape, and the anten nifer and scapular peg give separate
movements to the scape and flagellum. The pedicle is a small segment, about o ne-third
the length and half the width of the scape. The scape and pedicle are richly covered
with hairs, and the s cape bears small setae. The flagellum is filiform . The first flagellar
seg ment is sl ightly sh orter than the others. The flagellar segments bear regular rows
of hair s , and a dark band is present at each flagellar j oint. The black curved bands
which are p resent on the inner side of the first eight o r nine flagellar s egments i n the
gen us Hydropsyche are absent in this genus. The flagellum has fo rty-three segm ents
in the mal e and thirty-eight segments in the female .
Mou thparts: The m outhparts are reduced in correl ation with the non-feeding
habits of the adults . The palp s however are wel l devel oped . The labrum is short and
broad and the mandibles vestigial and non-functio nal , consisting o nly of a smal l
mandib ula r piece . The cardo o f the maxil la i s reduced and covered b y the stipes .
The stipes articulates with a downward hinge-like projection of th e gen a. The stipes
carries a l obe on the inner side and the palp o n the outer side. The pal p s are five­
segmented and c overed with hairs and setae. The first segment is sto ut and glo bular,
th e next three segments are m ore elongate , and the distal s egment is elongate, flexible,
and tap ering. The galea and lacinia are absent.
Labium. Th e ligula is absen t. The tip of th e labium is a roun ded sclerotized
area which, according t o D eoras ( 1 940) , represents the reduced mentum and sub­
mentum. The labial palp is three-segmented , the distal segment being elongate.
Hyp ophary nx. The hyp opharynx of Imm s and Tillyard is the haustellum o f
Deoras. The proximal r i m of the hypopharynx is bord ered by two curved sclerotized
TH R E E S PECI ES OF CAD DIS FLIES (TR I C H O PTERA)
17
hooks. The upp er surface i s covered by minute hairs, and the sal ivary receptacle
open s on the un derside. According to Deoras, the " haustel lum" is the modified
gl ossae and paragl ossae of the ligula.
Thorax
The prothorax is small and rin g-like, and the mesoth o rax is slightly la rger than
the m etath orax. The meso scutum is divided mid-d orsally and is large and bulgi n g ,
while t h e metascutum i s smaller , triangular, and partly obscured b y the first abd ominal
tergum . Th e thor acic sterna are membrano u s . The propleur on is largely m embranous,
and the episternum is a sm all sub-triang ular sclerite. The epimeron is a l a rger sclerite
behind which lies the spiracl e . The meso- and metapleura p ossess cle arly defined
episterna a nd epi mera, the l atter being l arge rectan gul ar sclerites, sep a rated from the
epistern a by the ple ural sutures, which ari se fr om the b asal coxal s uture and end n e ar
the win g sclerites. The m esepisternum is divi d ed by a suture into an upper anepi­
stern um and lower kat e p i s tern um . A large mero n i s p res e nt b eh i n d the m eso- and
metacoxae.
Wings : The anteri or wings are 7- 8 . 5 mm. l o n g , relatively narrow, and are pale
yellow, mottled with d arker yel l ow an d b r own . They are e xtremely hairy, d ue to the
presence of large microtrich ia on the wing memb rane and on the veins. The hi nd
wing is 4 . 5 - 5 . 5 mm. long, creamish sub-hyaline, and has a red uced cl othing of hair s,
but a frin ge of l o ng white hairs is pres ent along the p o steri or m argin. An amplexiform
type o f coupling apparatus i s used in flight, a fold wh ich runs the full len gth o f th e
anal m argin of the fore wing en gaging the co sta of the hind wi ng. The thyridium may
be seen on bo t h wings as a smal l whitish spot d evoid of hairs in the angle o f the
fork of RH s· The di scoidal, med ian, and thyridial ce l ls are present in the fore wing,
whi l e the median and thyri dial cel l s are ab sent i n the hind wing.
Venation of Fore Wing . The win g venati on is the same i n the mal e an d female.
The l ength of the fore wing is e i ght mm. , and the length of the hi nd win g is five m m .
The anterior margin of t h e win g i s formed by the costal vei n . M o re or less paral l e l to it
runs the subcosta, l inked to the costa at the base by the humeral cro s s vein , and
terminati n g in the c osta well b efore the apex of the wing. The radius bifurcates near
its base fo rming R1 and the r adial sector, w hich also bifurcate s , the t wo branches
being j oined by a cr os s vein to fo rm the d iscoidal cel l . B oth branches of the radial
sector bifurcate to give R2 to R 5 .
The main stem o f the media fo rks near the midd le of the wing, the branches being
by a cross vein t o enclose the median cell. Each branch of the media d ivides
again before reaching the wing margi n to give M1 to M4• The large thyridial cell is
cl osed by a medio-cubital cross vein. This cross vein connects the main posterio r
branch of the media to the main stem of the cubitus . The c ubitus forks near the wing
margin to give Cu1 a and Cu1 b . C u 2 is a strong vei n j oined to Cu1 by a cross vein.
lA runs almost the full length of the anal margin of the wing. 2A and 3 A are small
veins meeting l A ne ar the base of the win g.
j oined
Venation of the Po steri or Wing.
In the po sterior wing a sim ilar arr angement of
veins occurs . The su bco sta meets R1 before the wing margin. The fir st b ranch of the
radius and the second b ranch of the media are not fo rked. The three anal veins reach
the wing margin, l A being the lo ngest a n d 3A the shortest.
Wing Articu lation.
In the fore wing the hu meral sc!erite is a small subt riangu l ar
sclerite on the anterior margi n of the wing nea r the base. T he base of the co sta arises
fro m this sclerite. The first axillary sclerite is bro ad po sterio rl y and narr o w s towards
the apex as i t approaches the subcosta . The first a xil lary scl erite is associated with
the anterio r notal p r o cess and is in close proximity to the b ase of the s ubcosta.
The second axillary sclerite arti culates pa rtly with the b ase of the radius and is
closely ass ociated with the first axillary sclerite a n d the p o steri o r m e d i a n p l a t e .
18
KATH E R I N E K O R B OOT
The third a x illary sclerite articulate s with the posterior n otal process and is a lon g
rel atively thin sclerite. It is associated with the a n al vein s . The median plate s are
large li ght l y sclerotized areas . The tegul ae are sm all , scale like l1a iry sclerites carried
at the extreme base o f the costa of each fore wing.
-
,
In the hind wing the articular sclerites a re m uch the s a me as in the fo re win g
but the m e dian plates lie behind and not beside each other
,
.
Legs : The legs are lon g and used for r u nning The co x ae are relativel y
el o n gate and the m id coxa has a partiall y scl erotized posterior mer o n . The tro
chanter is small and bears a sm al l ch aracteristic black dot. The femur and tibia are
lon g and s lender. The fo re tib i a bears o n e pair of ap i cal spurs, th e mid and hind
tibiae bear one p air of a p ical and one pair of mid d l e spurs . Th e tarsi are five­
segm en ted and end in a pair of very small claws. Between the claws is a small
cush i on l ik e empo d i um
.
­
,
-
.
A b domen
The abdom en is more o r less cylind rical and is t en s egmen ted Each s egment
bears a p ai r of spiracles , tho se of segments three to eight inclusive bein g readily
fo und in the mal e , and of three to seven inclusive in the femal e. Wide p l eural
mem branes separate the tergites and sternites of the first seven s egments in the
female and the first eight segments in the male. Th e rudiments of the tracheal gill s
are seen as dark p urpl e masses on eithe r side of segm ents three to eight inclusive
-
.
.
Male External Gen italia : An adeq uate descripti on of the m ale external genital i a
is given by M osely and K im m in s ( 1 9 5 3 ) .
Female External Genitalia : The eighth tergum d o e s n o t differ greatl y from
the o t h er terga but it bears a li near median d ivision , the posterior m argin being lobe­
like. A sub genital pl ate is absent. The eighth sternum is comp l ete l y divi ded, forming
two large sclerotized valvular structures, the posterio r margins of which b e a r l o ng
hairs. The ninth tergum is small , wit h the l ateral m argi n s produced downwards,
and the n inth sternum form s a small m edian plate. The gen it al ope ni n g is between the
eighth and ninth s ter na, and is both egg l ayi n g and copulatory in fu nction. The
tenth segment is s m al l , fleshy, and l o b e-like and bears six di git-like , chitinous appen­
dage s Two bristles and numerous hairs are pre sent on the tenth seg m ent
-
-
.
.
SOME POINTS OF COMPARISON BETWEEN THE EXTERNAL MORPHOLOGY OF
Ch eumatopsyche modica , Triplec tides volda , AND Aniso cen tropus lat(fascia
In the three species the head is wider t h an long , and ocell i are ab sent .
In re l ation to the size of the head the frons is largest in A . lat(fasc ia where i t
occupies most of t h e posterio r part of t h e head . Th e fro ns of T. vo lda bears o n e patch
of sensory spots, such spots bein g absent in A . /atifas cia. The occiput m ay be seen in
all cases, but t he po st occiput i s not broad ly visible in C. modica a n d A. lat ifas cia
as it i s in T. volda , where it o ccupies the whole of the back of the head . The clypeus
is arched p osteri orly but in T. volda lateral poster i o r expansions extend at the s i des
of the antennae. The clype us is smallest in C. modica. In the three species the gen al
region is a large scl erotized a rea below the eyes and forms a h inge where the m axil la
articulates with the c ran i um . The gul ar regio n is membranous .
,
,
The a n ten n a of T. volda is more than twice as l on g as the fore wing, with one
h u ndre d Jl agellar segments in the female and one hundred an d six in the male. l n
A . lat ifascia the antenna h a s fo rty fi ve fl agellar segments i n both sexes a n d i s nearl y
twice the len gt h of th e fore win g . I n T. volda the scape is l arge thick basally, and taper
i n g di stally The ped icle is small , an d the fl agell a r segme nts lon g and narrow. A r i ng
-
,
.
­
T H R E E S P ECI ES OF CADDIS FLI ES (T RIC H O PT E RA )
19
of white hairs is pres ent distally o n each flagellar s egmen t . The scapul ar p e g i s ill­
defin ed . In A . latifascia the scape is elongate , the pedicl e small an d globular, and the
flagellar segments elongate. The head and antennae are c overed with yellow hair s .
The labrum of T. volda is elongate distally and bulged proximally. There i s a
more prominent constriction between the proximal and d istal ends than in the case of
C. modica , but as in C. modica and A . latifascia the labrum is well scl erotize d . In
A . lat(fascia the constriction d ivides the labrum into two rectangular halves , the dis tal
being the smaller of the two .
In the three species the mandibles are vestigial and in A . lat(fascia app ear to be
totally lacking. In T. volda the maxillary palps are five- segmented in both s exes as in
C. modica, but in A. latifascia th ey are six-segmente d, the sixth segment b ei n g very
short. The last segment of the palp in T. volda an d A. lattfascia is not elon gate and
flexibl e . T. volda and A . latifascia are alike but d i ffer from C. modica in th at the stip es
is redu ced to a small band-l i ke sclerite and the small car d o articulate s with the hin ge
of the gen a . The lobe of the maxilla is largest i n T. volda and in T. volda an d
A . latifascia bears stout bristles and sensory spots .
The tip of the m embranous labium area is sclerotized an d i s ro unded in C. modica
and T. volda, b u t po inted and triangular i n A . latifascia. Th e proximal segment o f the
three-segmented labial p alp s in the three species is situated on a rais ed n od e-like
sclerite . In C. modica these nodes are j oined at th e base, but i n T. vo lda and A. latifascia
th ey are is olated from each other on eithe r sid e of the scl erotized tip of the labium .
The hypopharynx is gre atly red uced in C. mo di ca and A . la tifascia. In T. volda
it is a well-developed , po u ch-like, holl ow lobe , the u pper su rface of which is covered
with minute hairs and regular radiating chann els which b i fu r cate distally.
In the three species th e prothor ax is small , narrower th an the head , and r in g-like•
and in T. volda an d A . latifascia it bears a m edian d o rsal s uture as in C. modica.
In T. volda and A . latifascia the mesoscutum is not divid ed mid -d orsally, as in
C. modica, but i s l a rge and bul ging and forms the largest thoracic sclerite . ln
A. latifascia two l ongitudinal impre s s ions mark off a central p orti on from two later al
portion s . The m eso scutellum i s the largest in T. volda, whil e the meso-post notal
sclerite is t he largest i n A. lat(fascia, wh ere the p l eural membranes are not visib le
dorsally in this region. Th e metascutum and scutellum are s imil ar i n the three species.
The meso- and metap l e u ral sclerites are large and sub- rectang ular in all three, b ut in
T. volda a n d A. latifascia the mesepi stern um is not divid ed . In A. latifascia the
metep isternum is d ivided i nto an upper anepisternum an d a l ower katepisternum.
The mesopl eu ral suture of A. latifascia is a membranou s area separating the meso­
pleural sclerites.
The arrangement of the tibial spurs of A. latifascia d iffers from that of C. modica
and T. volda. The fore tibiae bear two smal l spu rs at the apex ; the mid tib iae bear
two spurs at the apex and two in the mid dle, the outer spur of each pair bei n g l ong ;
the hind tibiae have o ne long spur i n the mid dle and two u n e q u a l ones at the a pex.
In T. volda and A . latifascia, as in C. modica, a small cushion- l ike empodium is
pres ent between the claws of the pretars u s .
No g i l l r u d iments a r e pre sent o n t h e abdomens of T .
as they are in C. modica.
vo
lda
and A.
lat(fascia
In T. volda abd ominal spiracles are visi ble on s e gments three to e ight in the
pleu ral membranes. A . latifascia d i ffers from T. volda and C. modica in that the
spiracl es are vi sible on segments one to eight in the pleural me m br ane s . The abd omen
of A. latifascia i s black in colour and bears a ch aracteristic patte rn on terga two to
eight .
In A . latifascia the win gs are colo ured grey-black and yellow. No clear colour
change is vi s i ble between the base and apex of the wing, yell ow me rging into black
20
KATH E R I N E KORBOOT
at the base. (It is intere sting io n ote that the yellow band which occupies the basal
half of the fore wing of A. elegans does not develop fully until twenty-four hours
after emergence .) The hind wings are 6-7 mm. in len gth, and the fore wings are broad ,
obliquely rounded at the apex , and 7-8! mm. in length. The hind wing shows a striking
character which according to Mosely and Kimmins ( 1 9 5 3) may be generic. The area
immediately po sterior to vein Cu1 a is clear, the veins Cu 1 b and Cu2, which normally
occupy this area, being virtual ly obliterated . The venation is the same in the male
and the female .
The wings of T. vo lda are a pale brown covered with short white and brown hairs ·
The fore wings are l l - 1 2 . 5 mm. long, and the hin d wings 7-8 mm. long. The venation
of the fore win g of the mal e and female d i ffers slightly. The discoidal cell is lon ger in
the fem ale , and veins M 1 and M 2 are not fused as they are in the male.
THE INTERNAL A NATOMY OJ< THE ADl.JLT OF Cheumatopsyche modica
Dissection Technique
The specimens to be d i s s ected were treated in one of the following fixatives ­
Carn ey, Bouin, or Mosely' s ( 1 9 3 9) collecti ng fluid . Fixation in Carnoy gave the most
sati sfactory general results , and was suitab l e for the dissections of the reprod uctive
system and microtome work by paraffi n embed ding. Bouin' s fixative was s uitable
for d i ssection of the n ervous and digestive system s . Mosely' s coll ecti ng fluid was not
so efficient. After fixation the ins ects w ere preserved in 70 per cent alcohol .
The an atomical studies were carried out by diss ections unde r high power magni­
fication assisted by 8 to I 0 f-L microtome sections. The figures were drawn either from
microscopical preparations or d irect dis sections . In the former they are drawn to
scale, while in the latter they are semi-diagrammatic.
Digestive System
Salivary glands. The salivary glands are well developed and consist of a number
of irregularly arranged tubules which lie on either side of the oesophagus in the
first and second thoracic segments . The main d uct lies within the h eap of tubules
in th e first thoracic segment and is alongside the ventral nerve cord, which supplies
the duct with a smal l nerve . The two ducts unite in th e gular region and pass into a
smal l sal ivary reservoir which opens on the underside of the hypo pharynx. The main
salivary duct is slightly shorter than the oesophagus .
Alimen tary Canal. Within the mouth is a chitinous ring, which is supported
by the proxim al part of the hypopharynx and the lower part of the labrum. It leads
into a wide muscular pharynx. The oesophagus is a very thin, semi-tran sparent tube
and is surrounded by the pale yellow fat bodies. The oes ophagus l eads into the
membranous crop, which is very large and sac-like and extends to the third abdomin al
segment. In a fre shly killed specimen the crop is d ilated with air and probably
functions as an aerostatic organ .
The prove ntriculus is very short and consists m ainly of th e anterior sphincter
muscl e s , followed by a number of long fine teeth which proj ect i nto the lum en of the
mid -gut. The mid-gut is m ore thickly walled than the crop and is darker in colour.
It begins in abdominal segment five. The dark colouration, accordin g to Deoras,
is due to the presence of pigmented matter enclosed in a membrane . The mi d-gut is
smaller than the crop but is again sac-like, and gastric caeca are wanting (as is to be
expected in adults which feed little and th en o n l y on a liquid diet) . The mid-gut is
fold ed on itself, so that its posterior end lies cl ose above its anterior end.
At the junction of the mid- an d hind-gut are six Malpighian tubules arranged
i rregu larly around the gut. The length of the tubules varies from nine to fourteen rom . ,
and their colourati on i s greyish gree n . Th e hind-gut i s almost straight, longer than
TH R E E S PECI E S
O F CADDIS FLI ES (TRICHOPTERA)
21
the mid-gut, and i s again thicker and more darkly coloured than the o esophagu s .
The rectum however i s membranou s , wider than the rest of the hind-gut , and gl obular
in shape. Six opaque patches, the rectal papillae , are arranged in a row round the
circumference of the rectum . Gl asgow ( 1 9 3 6) describes these papillae in Hydropsyche
colonica as being large swellings , alm ost filling the gut lumen, each being sub­
hemi spherical with fo ur o r five big n uclei.
The alimentary canals of adults which had been bred fr om pupae and kept alive
fo r a number of days in a breeding cage were found to be free from fo od contents ,
b u t in all cases the crop was dil ated with air. The alimentary canal s of specimen s
caught in the field often contained liquid nutrients , and the rectum of such specimens
often contained small amo unts of faecal material .
Cen tral Nervous System
The cerebral gan gl ion is con spicuous by the presence of the large op tic l obes at
its side s . The protocerebrum is bilobed and gives off a small median nerve an d a pair
of very fine nerves which run out lateral ly. From the deutocere brum ari ses a pair of
thick antenna! nerves. The deutocerebrum ru n s forward to meet the frontal ganglion
in front of the arch of the brain . Po sterior l y the deutocerebrum give s off a pair of
nerves to the occipital ganglion . The tritocerebrum is contin ued ventro-l aterally as
thick circum- oesophageal connectives to join the large sub-oesophageal ganglion .
A transverse nerve j oins th e connectives.
A large number of nerve fibres arise from each side of the pyriform sub­
oesophageal ganglion . A short nerve runs anteriorly to the redu ced m andible. The
large second nerve fibre, which arises ventro-laterally and bifurcates shortly after
leaving the sub-oesophageal ganglio n, innervates the maxillary palp . Three more
pairs of nerves may be traced from the sub-oesophageal ganglion. The first is long
and supplie s the labial region. The second is short and supplies the hypopharynx,
and the third the cervical region . Dorsall y, a short tine nerve supplies the oesophagu s .
The connectives between the sub-oesophageal ganglion and the first thoracic gan glion
are p aired and give off a pair of nerves to the main s alivary duct.
The mesothoracic ganglion is the l argest of the thoracic ganglia, but in Plate 1 3 ,
Fig. 1 , it appears smaller than that of the prothorax a s it i s laterally compressed
between the leg s , so that the nerve branches issue ventro-l aterally . The connective s
between the pro- and me sothoracic ganglia are paired, but those between the meso­
and metathoracic ganglia are fused.
Three main pairs of nerves arise from the prothoracic gangl ion . One pair supply
the firs t pair of legs, one pair the tubules of the salivary gl an d , and one pair the general
musc ulature of the segment . Three main pairs of nerves al so arise from the meso­
thoracic gangli on, one pair supplying the legs, one the wi n g sclerites , and one the
general musculature of the segment. Two pairs of nerves arise from the metatho racic
ganglion, one pair supplying the legs and one the general musc ulatu re of the segment .
The first to fourth abd ominal gangli a are sm all and lie in th e anterior part of their
respective segm ents. The fifth and sixth ganglia lie close together in the fifth segment.
The sixth ganglion i s large, and probably represents a fusion of the ganglia of the
sixth, seventh, and eighth segments. All the abdominal ganglia are connected by paired
lo ngitudinal connectives an d giv e off n erves to the body wall and viscera . The nerves
from the sixth ganglion are the l ongest and thickest, and extend to the last abdomin al
segment.
Oesophageal Sympathetic Nervous System
The fr ontal ganglion is a narrow band-like ganglion and lies below the clypeu s .
Fine nerves are given o ff anteriorly to the labrum , a n d short stout nerves connect the
fron tal ganglion to the deut ocerebrum . Posteriorly the rec urrent nerve runs along the
22
KATH E R I N E K O R BOOT
side of the pharynx until it meets the occipital ganglion behind the deutocereb rum .
The occipital ganglion als o receives fine nerves from the deutocereb rum and gives o ff
the two fi n e recurrent nerves po steriorly. The latter meet the small corpora cardiaca
on the oes ophagus and ramify over the crop . The nerve connections b etween the
corpora cardiaca and the occipital ganglion could not be determined. The occipital
gangl i o n is co nn ected by short thick con nectives to the co rpus all atum of e ach side.
The corpora allata are do uble stru ctures lying on either s i de of the aorta, and
con nected to the corp o r a cardiac a b y fmc nerves. The edges of the lobes of th e
corpora allata are sl ightly convoluted.
Male Reproductive System
The testes are comp act lobulated bodies lyi n g in the seventh ab dominal segment.
Each testis has a s ac-like co vering and each lobe is j oined by a short vas efferens to
a smal l central chamber of the testis. The vas d eferens is a lon g coiled t u b e o f gre ater
width but less transpare ncy than the Malpighi an tubu les. The accessory gl ands are
membranous pyrifo rm s acs and occupy much of the seventh and eighth ab dominal
segments. They were found to be full of the amber coloured crystals that are mentioned
by Deoras. The access ory gland s lie next to the testis of their side and open without a
d uct into the vas deferen s . Beyo n d its j u nction with the accessory gl and the vas
deferen s ope ns into a creamish-coloured unp aired accessory gland which enl arges
into a stout seminal reservoir (ves icula seminalis) .The median ej acul atory duct
(ductus ej aculatorius) is covered by a m u sc ular s ac and lead s into t he penis duct
which is directed downwards. The penis is thick and fleshy and co vered proxim ally
by a chitinous sheath.
ln this species there seems to be a tendency to ward s shorteni ng of the vas deferens
and simplific ati o n of the male reproductive organs.
Female Reproduc tive System
The ovaries are situated in the ftfth abdominal segment and look like two large
cream r aspberrie s. They consist of a l arge number of smal l acrotro phic ovari oles
grouped together i nto a calyx. The ovaries open into narrow, p aired oviducts which
fuse in the midl ine to fo rm a stout median o viduct (oviductus communis) . The
pear - shaped gland is a small, ro und membranous sac lyi ng beside the median ovi duct
and opening into it by a slender duct. The pear-shaped gland was found to contain a
tran sparent fluid . It was considered by Stitz ( 1 904) to be the receptacu lum seminis ,
but according to Cholod kovs ky ( 1 9 1 3) it is a gland of unknown function.
The b ursa copulatrix is als o a membranous sac but is larger than the pear­
shaped gland . The narro w duct (ductus b u rsae) , from the bursa copu latrix, j o i n s the
duct from the pear-shaped gland b efore the latter opens into the median o viduct .
The bursa copulatrix was a deep cream in colour and in a number of cases was found
to contain a small amount of viscous materia l . The bursa copulatrix bears a long
tubular structure at its proxim al end. This struct ure was called the "flagellum" by
Stitz , b ut it i s shown by Cholodkovs ky that it functions as a receptaculum seminis.
Behind the opening of the pear-shaped gland d uct and the d uctus b u rsae, opens
the common duct of the colleteri al glands. The col leterial glan d s are lo ng, wide
tubes j oined at the base b y a broad t ransverse connective . These glands were full of a
clear mucilaginous material . The terminal part of the genital chamber is relatively
long an d muscular.
SOME POINTS OF COM PARISON BETWEEN THE INTERNAL ANATOMY
OF THE A D U LTS OF Cheumatopsyche modica, Triplec tides volda ,
AND Anisocen tropus latifascia
Digestive Sys tem
Salivary Glands. In T. volda the structure o f the s alivary glands is s imil ar to
that o f C. modica, but the tubules are extremely fine, and the main duct is almost
T H R E E SPECIES OF CADDIS FLIES (TRI C H O PTERA)
23
indistingui shable. In A . latifascia the tubules are absent altogether, but the salivary
duct is a p rominent structure .
Alimen tary Canal. In T. volda the oeso phagus is sho rter than that of C. modica
but of ab o ut the same width . I n A. latifascia the oesophagus is very long and extremely
narrow. In T. volda the crop is sac-like an d i s s maller than that of C. mo dica even when
fully dil ated . A . !a tifascia has a cylind rical crop which is the smallest of the three
specie s . Jn all cases the p rovent ricul us is very short and h ardly d istingu ishable. The
mid-gut of T. vo lda tapers p o steriorly a n d is slightly l arge r than the crop . The mi d-gut
of A. latifascia is smal ler than that of T. volda, but its surface is folded . In T. volda
the hind gut and rectum do n ot differ from th ose o f C. m o di ca but in A . latisfacia
the hind-gut is a coiled tube and the rectum is mo re exte nsive. 1 n all species th ere
are six Malpighian tubules and six rectal papil lae.
-
,
Nervous System
The cerebral ganglion is similar in the three species. The optic lo bes are the l argest
in T. vo lda and the smallest in C. modica . T. volda has five ab dominal ganglia, the
fi fth being fused with the sixth . In A . latifascia there are six ab do minal ganglia as in
C. m odica the fifth and sixth being more equal in size than in C. m o dica . In all
species the last abdominal gangl ion gives off nerves which reach the last abdominal
segm ent. In T. volda and A . latifascia th e con n ectives between the meso- and meta­
thoracic ganglia are not fused as they are in C. modica , but in T. volda the posteri or
l o n gitudinal connectives have coal esced.
,
There are few outstan ding peculiarities in the oesophageal symp athetic nervo us
system of the different species, except for d ifferences i n shape and size of the corpora
all ata. These are relatively the largest i n C. modica and much reduced in T. volda.
In C. modica and A . la tifascia they are s imilar in size but in A . latifasc ia they are more
l obulated.
Male R eproductiv e System
In T. vo!da the testes consist each of three sm a ll separate lobes, the p aire d
accessory gland b e i n g larger than the testis . The vas deferens is lo nge r and more
convoluted than that of C. modica. The u npaired acces sory glan d and vesicul a
seminalis are similar in C. modica, T. volda and A . latifascia. In T. volda the ej acul ato ry
d uct is long. In A. lat(lascia the testes are small , simpl e, round ed bodies, the -p aired
accessory gland is a large pyrifo rm membranous sac, a n d the vas deferens and
ej acul atory duct are very long.
,
Female Reproductive System
In T. vo lda the ovaries are much smaller than in C . modica and consist of about
fifteen acrotrophic ovario les. The p aired oviducts are narrow. The pe ar- shap ed gland
and b ursa cop ulatrix are similar to those of C. modica, but the tubular structure of
the bursa was not found. The colleterial glands are very long and narrow. I n
A . latifascia the ovaries co nsist of a large number o f polytrop hic ov arioles grouped
together on a lo n g calyx, the calices opening onto very short, p aired oviducts. The
terminal filaments meet to fo rm a suspensory ligament. The pe ar-shap ed gland is
similar to that of T. vo!da and C. modica, but the bursa copulatrix is the l a rgest of the
three s pecies . Again the tub ul ar structure of the bursa was not fo und . The coll eterial
glands are l arge and tubular.
KATH E RI N E K O R BOOT
24
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DAs, G . M . (1 937). The musculature of the mouth-parts of insect larvae. Q uart, J. micr. Sci. 80 : 39-80.
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GILSON, G . (1 894). Recherches sur l es cellules secretantes. La s o i e et les appareils sericigen es . I I .
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HICKIN, N. E. (1 946). Larvae of British Trichoptera (key to families). Trans. roy. ent. Soc. 97: 1 8 6-2 1 2 .
HICKIN, N. E. ( 1 949) . Pupae of Bri tish Trichopte ra and some other insects. Trans. roy. ent. So c .
1 00 : 2 7 5- 89.
HINTON, H . E. ( 1 946) . A new classification of i nsect p u pae. Proc. zoo/. So c. Lond. 116: 282- 3 2 8 .
TMMS, A . D . ( 1 9 57) . A Ge n e ral Textbook of Entomology . Lond o n : Methuen .
KLAPALEK, F. ( 1 889). The metamo rphosis of Apatoenia m uliebris McLachlan . A chapter in p artheno­
genes i s . Ent. mon. Mag . 24 : 24 1 -42.
KRAFKA, J. ( 1 923). Morp hol ogy of the head of Trichopterous larvae as a basis for the revision of
family relationships. J. N. Y. ent. Soc. 3 1 : 3 1 -52.
LESTAGE, J . A. ( 1 9 2 1 ) . Chapter in Rousseau , E. ( 1 92 1 ) . Larves et Nymphes A quatiques des In s ec te s
d Europe . Brussels.
'
LLOYD, J. T. ( 1 92 1 ) . North American caddis fly larvae. Bull. Lloyd Libr. 21 : 3 - 1 24 .
Li.iBBEN, H. ( 1 907). Ueber d i e innere Metamorphose d e r Tr ich opt eren. Zoo/. Jb. 24 : 7 1 - 1 2 8 .
MAcDoNALD, N. W. ( 1 9 50) . The larvae of Mys tacides azurea L. , Cyrnus flavidus McLachlan and
Oxyethria simplex Ris ( Trichoptera) . Proc. roy. ent. So c. Lond. Series A. 25 : 1 9 -28.
M A R SHALL, W. S . (1 907) . The early history of the cellular elements of the ovary of a Phryganid,
Platyphylax designatus Walk. Z. wiss. Zoo!. 86 : 2 1 4-37.
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Routledge.
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'
SILTALA (SILFVENIUS) , A . J. ( 1 906) . U ber die Nahmng der Trichopteren. Helsinfors A cta So c. Fauna
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.
VoRHIES, C. T. (1 905) . Hab its and anatomy of the l arvae of the caddis fly Platyphylax designatus
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Z. w iss . Zoo!. 70 : 1 92-2 3 5 .
.
THREE SPECI ES OF CADDIS FLIES (T RICHOPTERA)
KEY TO FIGURES
LARVAL EXTERNAL ANATOMY
(Pl ates
1 , 2, 3, 1 0, 1 1)
labrum
man dible
maxilla
labium
coxa
tibia
trochanter
pretarsa l c l aw
femu r
tarsus
eye
fronto-clypeus
pronotum
mesonotum
metanotum
dorsal tubercle
subdorsal gill
episternum
epimeron
pleural suture
lateral tubercle
a
b
c
d
e
f
g
h
i
j
k
I
m
n
0
p
q
r
s
t
u
lateral line
su bventral gi l l
lateral gill
anal appendage
claw
vertex
gu Jar s uture
gu 1 ar sc ler i te
m o u th parts
max illary palp
ligula and spinneret o n prementum
inner lobe
stipes
car do
post mentum
T-shaped anus
abdominal segment nine
stout brist les
subdorsal gi l l
epicranial s u ture
an te-cl ypeus
v
w
X
y
z
a'
e'
g'
h'
i'
j'
k'
I'
m
n
0
p'
q
'
r'
s'
t'
LARVAL INTERNAL ANATOMY
(Plates
a
b
c
d
e
f
g
h
i
j
k
1
m
n
0
p
q
r
u
v
w
X
y
-----
3, 4, 5, 6, 1 6)
proventriculus
stomo daeal invagination
mid-gut
lateral Malpighian tubule
cro p
ven tral M a l pighian tubule
oesophagus
sil k gland
d o rsal Malp ighian tubule
pharynx
small intestine
buccal cavity
large i ntestine
rectum
silk gland d uct
sub-oesop hageal ganglion
silk gland p roper
Gi lson 's gland
al i mentary can a l
aorta
dorsal blood vessel
alary muscle 1 .
alary muscle 9 .
filament
gonad
z
a'
b'
c'
d'
c
'
f'
g'
h'
i'
j'
k'
1'
m'
n'
o'
p'
q
r
'
'
s'
t'
u'
v'
w'
x
'
duct
s u pra- oeso phageal gan g l i o n
prothoracic ganglion
mesothoracic gangl ion
metathoracic ganglion
first abdominal ganglion
fourth abdominal ganglion
sixth abdominal gangl ion
eighth abdominal ganglion
o ptic nerve
lateral nerve
anten na! nerve
nerve t o fr ont of head
mandibular nerve
fr ontal ganglion
l abial n erve
recurre n t nerve
intima
epithelium
nuc leus
pigment
oesophageal ring
labial nerve
= maxillary nerve
intestine
=
PUPAL A N ATOMY
(Plates
a
b
c
d
e
f
g
h
antenna
compound eye
pronotum
mesonotum
fore wing pad
metanotum
hind wing pad
anal process
5, 6, 7)
i
j
k
pretars al c l aw
tarsal segment six
tars al segment five
1
dorsal hook-beari n g p late
m
abdominal segment eight
abdomi nal segment nine
n
o
,=,
anal process
25
26
KATH E R I N E KO RBOOT
AD ULT EXTERNAL ANATOMY
(Plates
7, 8, 9, 10, 1 1 , 1 2)
-
antenn a
clypeus
compound eye
frons
pron otum
tegu la
mesoscutum
i
mesoscutellum
j
meta-postnotu m
]c
metanotum
1
abdomen
m
11
clasper
0
aedeagus
Rc = disco i d al cell
median cell
q
r
thyridial cell
thyr i d ium
apical fork
scape
u
v
maxillary palp
gena
w
X
labrum
y
lobe of maxilla
z
man d i bular piece
a'
h ypopharynx
labial palp
b'
occiput
c'
d'
post-occiput
e'
seco n d flagellar segment
f'
first flage l l ar segment
g'
pedicle
h'
antennifer
i'
proximal bulging of labrum
outer side of labrum
j'
k'
distal bulging of labrum
I'
base of lab ial palp
m l = reduced labium
n'
seco nd segment of maxillary palp
o'
l obe of maxilla
a
c
d
f
g
h
--
:::c=
p'
q'
r'
s'
t'
u'
v'
w'
x'
y'
'
z
a"
b"
c"
d"
e"
f"
g"
h"
i
ll
y�
k"
1"
Ill11 :=
n"
o"
p"
(
r
s"
t"
u
"
v"
w"
x"
y"
z
chitinous rod
median scuta! line
pleural membrane
metascutum
metascutellum
head
epimeron
episternum
pleural s utme
sensory h airs
outer side of mandible
inner side of man dible
base of mandible
ginglymus
femur
coxa
middle spurs
troch anter
tibia
fi ne hairs
apical spurs
tarsus
claws
abdominal tergu m 8
abdominal tergum 9
abdomin al segment 1 0
di gital processes
abd ominal sternum 8
abd ominal sternum 9
cervical sclerite
humeral pl ate
first axillary scler i tc
second axillary sclerite
anterior n otal process
anterior median plate
- ·
"
a ' )/ =
p osterior med ian p late
third axillary sclerite
posterior notal process
ADULT lNIERNAL ANATOMY
(Plates
a
b
c
d
e
f
g
h
i
j
k
l
M
n
0
p
q
r
s
mouth
sal ivary reservoir
pharynx
salivary duct
oesoph agus
salivary ductules
crop
tip of proventriculus
mid-gut
M a l p i g h ian tub ules
hin d -gut
rectum
rectal papilla
anus
anten n a! nerve
peduncle t o median oce l lus
arch of br ain
optic lobe
nerve connective from frontal ganglion
to d eutocerebrum
1 2, 1 3-1 5, 1 6)
u
v
w
X
y
z
a'
b'
c'
d'
e'
f'
g'
h'
i'
j'
k'
posterior connective
para-oesophageal connective
mandib ular n erve
maxillary nerve
sub-oesophageal ganglion
labial nerve
hypoph aryngeal nerve
nerve t o the salivary gland and gular
region
lateral ocel l ar nerve
occipital ga nglion
corpus a l l atLlm
aorta
recurrent nerve
nerve t o oes oph agus
upper lobe
convoluted margin
l ower lobe
nerve t o occipital ganglion from
deutocerebrum
TH R E E SPECIES OF CADDIS FLIES (TRICHO PTE RA)
m ' = cep halic ganglion
'
nerve to main salivary duct
first do uble lon gitudinal con nective
o'
prothoracic ganglion
p' .
mesothoracic ganglion
q'
fused con nectives between meso- and
r'
metathoracic ganglia
metathoracic ganglion
s'
fi fth abdominal gangli o n
t'
sixth abdominal ganglion
u'
nerves reach ing last abdominal segment
v'
anterior nerve
w'
x'
frontal gan glion
ventral lobe of frontal gangli o n
y'
testes
z'
vesicula seminalis
a"
paired accessory g land
b"
unpaired accessory glan d
c"
vas deferens
d"
ejaculatory duc t
e"
ovary
f"
n
g"
h"
i"
j"
k"
I"
m"
n"
o"
p"
q"
r"
t"
u"
v"
w"
x"
y"
=,
27
ovariole
paired oviduct
bursa copulatrix
col leterial gland
pear-sh aped gland
spermathecal duct
j unction of spermathecal du ct, shel I
gland duct, and median ovi d uct
t ransverse connection of co l l eterial
glands
gen i tal chamber
corpus cardiacum
circum-oesoph ageal comm iss ure
first ab d ominal gan glion
ductus bursae
cuticular calyx
tubular structure of bursa copulatrix
sperm sac
protein mass
termi nal ligament
LEGENDS To PLATES
PLATE 1 .--Larval external anatomy.
Figs. 1-3, dorsal and ventral aspects of heads : ( 1 ) C. modica ; (2) T. vo lda ; (3) A . latifascia .
Figs. 4-6, d orsal aspect of labrum : (4) C. modica ; (5) T. volda ; (6) A. latzfascia. Figs . 7-9, mandibles :
(7) C. mo dica ; (8) T. volda ; (9) A. latifascia . Figs . 1 0, 1 1 , head of C. mo dica : (10) ventral aspect ;
( 1 1 ) latera l aspect. Figs. 1 2, J 3 , maxilla and labiu m : ( 1 2) T. volda ; ( 1 3) A. latifascia. Figs. 1 4 - 1 6 ,
dorsal view o f a n a l clasper : ( 1 4) C . modica ; ( 1 5) T . volda ; ( 1 6) A . latifascia. Figs . 1 7 - 1 9 , ventral view
of anal clasper : (\ 7) C. modica ; ( 1 8) T. volda ; ( 1 9) A . latifascia.
PLATE 2.-Larval external anatomy.
Figs. 1 - 3 , dorsal aspect of thorax : (1) C. modica ; (2) T. volda ; (3) A. latifascia. Figs. 4-6, lateral
aspect of anal claspers : (4) C. modica ; (5) T. vo lda ; (6) A. lat!fascia. Figs. 7-9, fore, mid, and hind
legs of C. modica. Figs. 1 0-12, fore, mi d , and hind legs of T. volda . Figs. 1 3- 1 5, fore, mid, and hind
legs of A. latifascia. Fig. 1 6, fore leg of A. elegans.
PLATE 3 .-Larval external anatomy (Figs. 1 - 5 ,
1 1). Larval internal anatomy (Figs. 6- 10, 1 2, 1 3 ).
Figs. 1 - 5 , A . elegans : (1) mid leg ; (2) h i n d leg ; (3) dorsal aspec t of lab r um ; (4) mandi bles ;
(5) dorsal view of thorax . Figs. 6- 1 3 . C. modica : (6) lateral aspect of alimentary canal ; (7) ventral
aspect of alimentary canal ; (8) d orsal aspect of silk gl ands ; (9) position of gonad ; ( 1 0) cross section
of Malpigh ian tubule ; ( 1 1 ) gill branchin g ; ( 1 2) longitud inal section of Malpighian tubule ; ( 1 3)
relative position of Malpighian tubu les at divisi on between mid and hind gut.
PLATE 4.--Larval internal anatomy.
Figs . 1 -6, C. modica : ( 1 ) ventral aspect of circul atory syste m ; (2) d o rsal aspect of centra l nervous
system; (3) l ateral dissection of mature larva ; (4) dorsal aspect of supraoesophageal ganglion ;
(5) lateral aspect of supra- and sub oesophageal ganglia ; (6) ventral aspect of suboesophageal ganglion.
PLATE 5 . -Larval internal anatomy (Figs. 1 --4). Pupal external an atomy (Figs. 5 , 6) .
Figs. 1 -2 , dorsal aspect of central nervous system : ( 1 ) T. volda ; (2) A . latifascia. Fig. 3, dorsal
aspect of alimentary canal of A. latifascia. Fig. 4, lateral aspect of a limentary canal of T. volda.
Fig. 5, dorsal aspect of labrum of T. volda . Fig. 6, dorsal aspect of labrum of A . latifascia .
PLATE 6.--- -Larval internal anatomy (Fig.
1). Pupal external an atorny (Figs . 2, 3,
8).
Fig. I , d orsal aspect of al imentary canal of T. volda. Figs. 2, 3 , dorsal v iew : (2) C. modica ;
(3) T. volda. Figs. 4-6, prepupal stage : (4) C. modica ; (5) T. volda ; (6) A . lat(/ascia. Fig. 7, l id of p upal
case of A . latifascia. Fig. 8 , dorsal aspect of lahrum of C. modica.
28
KATH E R I N E KOR BOOT
PLATE 7 .-Pupal external anatomy (Figs . 1 -4, 8- 1 3). Prepupal anatomy (Figs. 5-7). Adult external
anatomy (Figs . 1 4- 1 8).
Fig. 1, dorsal aspect of pupa of A. latifascia. Figs . 2-4, mandibles : (2) C. modica ; (3) T. volda ;
(4) A. latifascia. Figs. 5-7, mesotarsal claw : (5) C. modica ; (6) T. volda ; (7) A . latifascia. Figs . 8 - 1 0 ,
C. modica : (8) dorsal aspect of ninth abdominal segmen t ; (9) ventral aspect o f ninth abdomin al
segment ; (10) ventral aspect of ninth abdominal segment showing curling of antennae. Fig. 1 1 ,
dorsal aspect of ninth abd ominal segment of A . latifascia. Figs. 1 2 , 1 3 , T. vo fda : ( 1 2) dorsal aspect of
ninth abd ominal segment ; ( 1 3) ventral aspect of ninth abdominal segmen t . Figs. 1 4- 1 8, C. modica :
( 1 4) front view of head ; ( 1 5) dorsal view of head ; (16) dorsal view of female terminalia ; ( 1 7) ventral
view of female terminalia ; ( 1 8) lateral view of female termin alia.
PLATE 8.-Pupal anatomy (Figs . 1 -3). Adult extern al anatomy (Figs . 4- 1 4) .
Figs . 1 - 3 , dorsal abdominal hook-bearing plates : (1) C . modica ; (2) T. vo fda ; ( 3 ) A . latzfascia.
Figs. 4-14, C. modica : (4) basal section of antenna ; (5) labium ; (6) labrum ; (7) pronotum ; (8) maxilla ;
(9) lateral view of abdomen ; (10) mes o- and metanota ; (1 1 ) propleuron ; ( 1 2) meso- and metapleura ;
( 1 3 ) fore leg ; ( 1 4) mandible.
PLATE 9.-Adult external anatom y.
Figs. 1, 2, T. volda ; (l) hind leg ; (2) dorsal view of head . Figs. 3 - 5 , C. m odica : (3) mid leg ;
( 4) lateral view of head ; (5) right fore wing.
PLATE 1 0 . --Adult external anatomy (Figs. 1 - 1 2, 1 5- 1 9) . Larval external anatomy (Figs . 1 3 , 14).
Fig. 1 , right hind wing of C. modica. Figs. 2, 3 , front view of head : (2) T. vo lda ; ( 3 ) A . latifascia
Fig. 4, dorsal view of head of A. latifascia. Figs. 5, 6, basal section of antenna : (5) A. latifascia ;
(6) T. vo lda . Figs. 7-9, l abrum : (7) A. latifascia ; (8) T. volda ; (9) T. vo lda. Fig. 10, l abium of
A. latifasc ia . Figs. 1 1 , 1 2, maxil lary palp : (1 1) T. vo lda ; ( 1 2) A. latifascia. Fig. 1 3 , lateral view of
prothorax of C. modica. Fig. 1 4 , lateral view of mesothorax of C. modica. Figs . 1 5, 1 6, meso- and
metaterga : (1 5) T. vofda ; ( 1 6) A. fa t ifasc ia Fig. 1 7 , l ateral view of abd omen of A. latifascia. Fig. 1 8 ,
dorsal view o f abd ominal tergites one t o fo ur of A . latifascia. Fig. 1 9 , meso- and metapleura o f
T. vo lda.
.
PLATE 1 1 .-Ad ull external anatomy (Figs. 1 , 7-1 6). Larval external anatomy (Figs. 2-6).
Fig. 1 , meso- and metapleura of A. latifascia. Figs. 2, 3, lateral view of pro th orax : (2) T. volda ;
(3) A. latifascia. Figs. 4, 5, lateral view of mesothorax : (4) A. latifascia ; (5) T. vo lda. Fig. 6, lateral
view of metathorax of A. laufascia. Figs . 7-9, T. volda : (7) fore leg ; (8) mid leg ; (9) hind leg. Figs.
1 0- 1 2, A. latifascia : ( 1 0) fore leg ; ( l l ) mid leg ; ( 1 2) hind leg. Figs. 1 3 , 14, propleuron : ( 1 3) C. modica ;
( 1 4) T. volda . Fig. 1 5, right fore and hind wing of T. volda (male). Fig. 1 6, dorsal view of right fore
wing of C. modica showing wing articu lation sclerites .
PLATE 1 2 .-Adult external anatomy (Figs. 1 , 2, 4). Ad ult internal anatomy (Figs. 3, 5).
Fig. 1 , right fore and hind wing of A. latzfascia. Fig. 2, rigl1t fore wing of T. volda (female) .
Fig. 3 , position of spermatophore in bursa copulatrix of C. modica. Fig. 4, dorsal view of ri ght hind
wing of C. modica showing wing articulation sclerites. Fig. 5 , lateral dissection of C. modica (male) .
PLATE 1 3 .-Adult in tern al anatomy.
Figs . 1 -4 , C. modica : (1) front view or cerebral and sub-oesophageal ganglia ; (2) digestive
system ; (3) lateral view of cerebral and sub-oesophageal gan glia ; (4) frontal ganglion dorsally .
PLATE 14.---A dult internal anatomy.
Figs . 1 , 2, C. modica : ( 1 ) the nerve chain ; (2) corpora allata.
PLATE 1 5 .--Adult internal anatomy.
Fig. 1 , d orsal view of oesophageal sympathetic n ervous system of C. modica. Fig. 2 , corpora
allata of A. latifascia. Figs . 3, 4 , digestive system : (3) T. volda ; (4) A . latifascia. Figs . 5, 6, male repro­
d uctive system : (5) A . latifascia ; (6) T. volda . Fig. 7, corpora allata of T. volda.
PLATE 1 6. --Adult internal anatomy (Figs. 1 -5). Larval i nternal anatomy (Fig. 6).
Fig. 1 , female reprod uctive system of T. volda . Fig. 2, female reproductive system of A . latifascia.
Figs. 3-5, C. modica : (3) corpora allata laterally ; (4) fe male reproductive system ; (5) male repro­
d uctive system. Fig. 6, lateral aspect of alimentary canal of A . latzfascia.
TH R E E SPEC IES O F CADDIS FLIES (TRICHO PTERA)
3
29
s
�--� ��
12
18
·�
14
16 �
PLATE 1
30
KAT H E R I N E K O R BOOT
-
--
-"
0
2
I m. rn .
6
4
PLATE 2
TH R E E S P E C I E S
3
5
31
O F C A D D I S F L I E S (T R I C H O PT E RA)
4
I rn.m.
32
KATH E R I N E KORBOOT
v=-----1
)
4
PLATE 4
33
T H R E E S PE C I ES OF CAD D I S F L I ES (T RIC H O P T E RA)
a
'
·--g
-- b
'
-b
--- C
c
d
d'
-- ·
Il
'
I
I
l
'
c
---- h
rr-+------ g
·------ •'
6
t mm
PLATE 5
1
KATH E R I N E K O R BOOT
34
7
6
PLATE 6
TH R E E S P ECIES OF CADDIS FLI ES (T R I C H O PT E RA)
35
6
�- � I
_m
9
I S
18
PL ATE 7
KAT H E R I N E KO R BOOT
36
�
u
wu
O CJ
'� �
9
�
�N
e;
�
�
�
)j
C)
�
v
(l) � b:J
� '�
u
8
6
�
2 -3
�
3
EJ
�
e'
3-4
4-5
5
4
6
5
()== '
-:·
---1< '
@[§
J m rn_-i
PLATE 8
TH REE
S P E C I E S OF CAD D I S
FLI ES (TR I C H O PTE RA)
111-------"'��-=;;;;;o-"-=��::::-=-=-=-=- 7 "
1/--- ---------"-.:::--1- f :
_
______ (
PLATE
9
�
�
37
38
KATH E R I N E K O R BOOT
:tf'- y '
w
'
I5
()/
19
18
--coxa
PLATE 1 0
39
TH RE E SP ECI E S OF
CADD IS
FUES
(iRICHOPTERA)
7
IS
P LA TE
11
40
KATH E R I N E KO R BOOT
PLATE 1 2
TH R E E SPECIES
OF
CADDIS F L I ES (TRICH OPTERA)
41
-
-
I.
.·
- g
rh
:}--,
--
-- --j
a ' -----··- -- -
0
2
----------�---
)
�
:·.==--=-----��
--- �:--==---===- -
q"
g'
-
-� �-
-- ------ -
------
��---- -
---��
--- �
�-�
X ------------
P LATE 1 3
4
--�-- 1 '
42
KAT H E R I N E KORBOOT
m'
s'
--
:l .
r·�----
t' ----
P LATE 1 4
TH REE SPEC I ES OF CADDIS FLIES (T RIC H O PTERA)
\ )
,=;;eD
'/( �--f '..� · -... � - -
'\ - - · \'"
.. ·
. ., , _
.. �
.. H
'" - - w ..
d'�--- ---+-�
p''-----'ll
f ' ---
I.
2
·.-/------- '
�----- m
----+-- z '
--T-j------- b"
--- 0
"
PLATE 1 5
43
KATH E R I N E KOR BOOT
44
�"
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PLATE 1 6