A^COMPARATIVE MORPHOLOGICAL STUDl) OF THE
AXILLARY RSXJIO^ OP SOME PTERYGOT2 INSECTS
Rioh&rd M, Baranowakl, B.A.» M.S.
Utica College of Syracuse University, 1951
University of Connecticut, 195?
A Dissertation
Submitted in Partial Fulfillment of the
Requirements for the Degree of
Doctor of Philosophy
at
The University of Connecticut
1959 APPROVAL PAGE
Dootor of Hilloaophy Oiasertatlon
A COMPARATIVE MORPHOLOOICAL STUDY OP THE
AXILLARY REGION OP SOME PT2RYGOTE INSECTS
Proaontod by
Rlohard M. B&ranovalel, B.A.( M.S.
Major Advisor /] ///
Aaaoolato Advlaor
Aaaooiate Advlaor
The Univeraity of Oonnootieut
1959
f' f* f* O O
11 ACKK0WLSDQEU2HT3
In making aoknoviodgoments, th® author must first of all deolare his indobtness to Dr. Russoll H. DoOoursoy for his adrioe throughout the oourso of this work and for his constructive aid in editing the manuscript. Acknowledgement is also made to Dr. Edward
0. Boettiger for his Invaluable aid and advioe» especially in respect to obtaining and interpreting the oscillograph records. This portion of the work would not have been possible without his aid. In particular the author gratefully acknowledges the advice and encouragement of
Dr. Norman T. Davis» who was always willing to discuss the problem and offer valuable suggestions. The author also wishes to acknowledge the assistance of Dr. Ifeul V. Oman of the Entomology Research Divisionf
United States Department of Agriculture, and his staff for the identification of some of the insects used in this study.
ill TABLE OP CONTENTS
Aoknowladgeaents ••••••••••••••••••••• ill
List of Illuttratlon* •••••••••••••••••• v
Introduotlon ••••••••••••••••••••••• 1
Materials and Methods • ...... ••••* ...... •• $
Dlssostelra Carolina (L«) (Orthoptera) •••• ...... 9
Aoanthooephala tenalnalls (Dallas) (Henlptera) •••••• 1?
Magloloada septendeoln (L«) (Hoaoptera) ...... 18
Umbonla orassloornls (A* AS*) (Hoaoptera) •••••«•• 22
fhyllophaga drakll (Kirby) (Coleoptera) ••••••••• 26
Panorpa nebuloaa Westwood (Moooptera) ••«••••••• J2
Pyonopsyohe olroularls (Prov*) (Trlohoptera) ••••••• J6
Protoparoe aexta (Johan.) (Lepldoptera)* ...... •*•• 41
Vespula maoulata (L*) (Hymenoptera) ......
Discussion and Oonoluslon ••••••••■•••*••• $0
Literature Cited «•••*•••••••••••»•••• $7
List of Abbreviations ...... 59
Illustrations •»••••••••••••»•••*••• 60
Iv LIST OP ILLUSTRATIONS
Plat* X Intoot and elootrodo support.
Plat* II Axillary rorion, Dltsostelra Carolina (L«)»
Plat* III Axillary region. Aoanthooaphala terminalis (Dallas)
Plat* X? Axillary rerlent Uarloloada septendeela (L.).
Plato T Axillary region. Umbonla orastioomit (A. & 3.).
Plat* TX Axillary region. Riyllophaga drakll (Kirby).
Plat* YIX Axillary region. Ifenorpa nebulota Vestvood.
Plat* YXII Axillary region. IVenopsyeh* olroularls (ftrov.).
Plato XX Axillary region. Protoparoe aexta (Johan.).
Plato X Axillary region. Vespula maoulata (L.).
Plat* XX Otolllograph reoords showing wlngbeat frequency and
thoraolo potentials.
r INTRODUCTION
With the steady increase in the use of insects in physiological
research* there has developed an increasing need for studies of func
tional morphology* Work on the physiology of insect flight has* for
example* suggested the mechanical importance of exoskeletal structures
directly or indirectly Influencing the functioning of muscles (Boettiger
& Furshpan, 1952). Although the Diptera* as representatives of a group
of insects which move their wings at a seemingly impossible rate* have
been the subjects of considerable study in flight physiology* due in
large part to the ease of keeping cultures in the laboratory* work on
other groups is being undertaken*
The literature on the morphology of insects is immense* perhaps
second in volume only to the taxonomic literature* However* when the
literature is confined to the comparative studies and in particular to
the axillary region* one sees how meager our knowledge of this subject
is*
One of the earliest comparative studies of the axillary region
is that of Amans (1885)* This work* typical of the studies of the
period* is essentially descriptive morphology with little emphasis
on the mechanisms involved in flight movements* Ohabrler (1320) and
Straus-Durokheim (1823) made detailed morphological studies of
Melolontha vulgaris* These studies did include the axillary region*
Voss (1905) presents a very detailed description of a single species*
Oryllus domeatlcus and also reviews the wing articulations in other
orders* Two more recent studies are those of Snodgrass (1909* 1927).
These works are invaluable to the student of thoracic morphology*
According to Snodgrass* Jurine first described the scleritee of the
1 2 wing basa and gava thaa Individual naaaa in Xylooopa vlolaoaa« a aaabar of tha Hymanoptera.
Tha noaanclatura used for tha axillary ragion has changed a great deal* For example, Lowne (1890-92) rafera to tha masopleural wing prooaae as tha hamulua, while Ritter (1911) calls it tha processus ptaralis thoracis V* Undoubtedly tha nomenclature used in vartabrata morphology had a strong influence on early authors in naming arthropod structures* The nomenclature used by Snodgrass (1935) is followed in this study.
The axillary solerites are small plates located between the lateral margins of the noturn and the base of the wing-veins* It is believed that they are formed, in part, as detached portions of the lateral region of the notum, and in part as detached basal portions of the wing-veins, or as solerotized areas at the bases of the veins*
These articulatory solerites enable the wing to be flexed more readily and also take part in flight movements*
Studies by Pringle (19^9) and Boeder (1951) h**® shown that insect flight muscles must Include at least two types* The type found in insects such as roaches and dragonflies, ordinarily behaves as the muscles found in the legs of insects in that each contraction is the sequel of a single motor impulse, resulting in a single wing, beat* With the other type, found in flies and bees for example, each motor impulse results in a series of contractions, hence several wing- beats* For convenience the term synchronous flight is applied to those insects covered by the former condition and asynchronous flight for the latter*
In a short paper Boettiger and Furshpan (1950) describe the 5 effect of placing files in carbon tetrachloride fumes and later
(1951) presented evidence that the click phenomenon, described in the previous work, was a part of normal flight in these insects* In a study of the flight mechanics of Sarcophaga bullata Parker, Boettiger and Furshpan (1952) describe the axillary region and discuss the move, ments of the parts concerned in respect to this click phenomenon* The theory presented indicated that the mesopleural wing process moves in and out twice, once during the downstroke and once during the upstroke*
According to earlier accepted ideas, the mesopleural wing process merely acted as a fulcrum, possibly moving outward on the upstroke and inward on the downstroke as a result of the contraction of the vertical and
longitudinal muscles respectively. Later Boettiger (unpub*) by placing extremely minute mirrors on the mesopleural wing process and on the arm of the ecutellar lever of flies, was able to show that the mesopleural wing prooess does move in the manner described in the
earlier work*
Pipa (1955)i on the basis of a histological study of the flight muscles of several Insects, divided the flight muscles into three groups! the lamellar, fibrillar and microfibrillar* The insects which at that time were known to be asynchronous possessed the fibrillar
type.
Since the insects examined, in respect to flight, appeared to
fall into fairly definite categories from the histological point of
view and since the Diptera at least appear to have an unusual mechanism
in the click phenomenon, this work was undertaken* A study was made to
determine whether this mechanism, or a similar mechanism, is a morpho
logical characteristic of other insects exhibiting asynchronous flight* k
Oscillograph raoorda showing tha relationships betwoen the wing beat frequency and the nerve impulses have been obtained for only a few
inseots* For this reason it was necessary to obtain the oscillograph
flight records to determine into which category the various inseots
studied fell* MATERIALS AND METHODS
Tho specimens used for the morphological studies were, in most instances» preserved in "JOfi alcohol* In some oases the specimens were first placed in Xahle's Fixative and then kept in 7Q£ alcohol until used* For the study of the preserved material 70^ alcohol was used as a dissecting fluid and petrl dishes or metal pillboxes) vere used as dissecting pans* Some of the pillboxes had beeswax on the bottom and others had black dissecting pan wax. It was found advantageous to use both light and dark backgrounds* The petri dishes were used when transmitted light was desired. As an aid to examination some of the
specimens were placed in hot potassium hydroxide (10^) for a short
time to facilitate the removal of the tissuest but usually this was not necessary* At no time were specimens treated in this way used
for the determination of movements of the various parts* Stains were
at times used to differentiate certain structures* Thickened regions
in the membranous areas are at times present and the stain served to
define these ligaments more clearly* Mallory's Triple Stain and merourochrome were used* Of the two* mercurochrome proved to be more
convenient to use and more satisfactory* The length of time in the
stain was not critical and ten to fifteen minutes was sufficient*
Drawings were first made on tracing paper under which graph
paper had been placed to serve as a guide. An ocular grid ruled
into 0*5 millimeter squares was an invaluable aid for this work*
The structures seen in each square of the grid were drawn into a
corresponding square of the graph paper* thus enabling an accurate
reproduction of the relationships* The drawings were then transferred
to bristol board and inked*
5 6
A variety of dissecting instruments were used. It was found that Th* Dumont JO jewelers forceps vere very satisfactory for this type of work* needing only a small amount of grinding to fora fine points* Cuticle scissors* with the tips finely ground* proved satis factory for larger operations* Small scalpels were made from No* 0 pulp canal cleaners which vere obtained from a dental equipment distributor* The burred end is out off and discarded* The cut end of the remaining part is flattened and then shaped to size and form on a whetstone* This last prooess is best done with the aid of a dissect ing microscope* The blade is then placed in a convenient handle*
Probes and hooks were made from the same material*
Movements of various parts vere determined by a combination of methods* The intact thorax was held in such a way that there was little or no interference with movement and the wing was then manipu lated and the action observed* This method has limited use as the fixed* intact muscles limit or dampen the movements to some extent*
Saglttally and parasaglttally cut specimens' were used to determine the action of muscles on the region* Transverse sections were also used at times* By gently pulling on the muscles or imitating their action by pressure* one can to some extent determine the various movements of the related structures* Lastly by dissecting out individual articulations* or two associated parts* one can determine the limits of movement and the direction of possible movement of eaoh individual connection without the interference of other parts*
The method of obtaining flight records was patterned after that of Boettiger and Furehpan (19J2)* This method is based on inducing a charge on the wings of the specimen by means of a charged non-conductor placed next to it* The change in the charge caused by the moving 7 wings between the piclc-up electrodes can then be amplified and photo-
graphed*
The equipment used consisted of a cathode ray oscillograph
(EtoMont, type 204h)» an electronio switch (Heathkit, model 3-1), two
preamplifiers (Grass Instrument Co*, model P-5), and an oscillograph
camera (DuMont, type 296)•
The animals used for the flight records were brought to the
laboratory as soon as possible after capture. The specimen was
attached by means of Tacky Vax to a support which consisted of a glass tube with a short length of wire taped to one end (fig*l,A)*
The point of attachment on the animal was as small as possible while
still holding the animal securely* This point was on the dorsum of
the thorax* Two wires pass through the glass support and were con nected to two fine copper electrodes (fig* 1»B). The plugs at the
other end were connected to one of the preamplifiers* The animal
support was clamped to a stand which also holds the static electrodes
(fig. 1,0) which pick up the wing beat frequency, and the charged non-conductor (fig* 1,D), in this case, a luolte rod* The plugs from
the second pair of electrodes, termed the static electrodes were con nected to the second preamplifier* The preamplifiers were connected
to the electronio switch which in turm fed into the oscillograph*
The electronio switch splits the single beam into two separate beams
allowing the wing beat frequency and the thoraolo potentials to be
recorded simultaneously*
The static electrodes were positioned in such a way that one was just above the highest point of the wing cycle and the other just
out of reach of the legs of the animal* Two small punctures were cade
in the thorax and the pair of copper electrodes inserted to record the 6 thoracis potentials. To facilitate mounting and handling of the
specimens, these electrodes were connected to plugs which were in*
sorted into the leads to the preamplifiers. This allowed the support
and the electrodes to be removed easily for changing animals.
The complete unit, holding the specimen and the electrodes,
was placed in a grounded screen box that acted as an a.c. shield.
The time scale was provided with a stimulator (Grass Instrument
Co., model S^A), or by using a 60 cycle wave. DISSOSTSIRA CAROLINA (L.) (0RTH0PT2RA)
DESORIPTION
Tho first axillary solorite can bo oonsidorod as having two parts, a flat somowhat triangular body that narrows antoriorly into a uniformly slender nook region (fig* 2, I)* As the neck extends an. terlorly it bends sharply ventrad under itself, forming a hook. The neok of the first axillary rides on top of the anterior notal wing prooess (fig* 2, ANP). The distal tip of the anterior notal wing process curves up, preventing the first axillary from disengaging from the wing process* The extreme tip of the neok is connected to the edge of the anterior notal wing process by means of a thick liga ment. Just posterior to the wing process, the proximal edge of the first axillary body is quite olosely connected to the tergum by mem. brane, but there is no interlocking* The distal side of the first axillary neck is closely connected to the anterior part of the second axillary sclerite. The anterior part of tho first axillary body ex tends under the second axillary and the posterior half of the distal edge is on top of the second (fig* 2)* This essentially forms a groove in the distal edge of the first axillary in which tho edge of the second articulates*
Just anterior to the first axillary sclerite, the presoutum forms a bifurcated projection (fig* 2, prao) that extends posteriorly*
When the wing is in the resting position the head of the suboosta fits into the notch* Also, when tho wing is unfolded, the suboosta remains in the notch, so that the prescutum acts as a type of universal joint for the wing during flight*
Dorsally the second axillary sclerite appears as an elongate sclerite (fig* 2, II) that is fused directly to the radius by a 9 10 elender bridge. Just posterior to this the distal edge of the second axillary is connected to the edge of the median plate (fig. 2, m).
The posterior tip of the second axillary articulates with the anterior projection that arises at about the center of the third axillary sclerite.
The ventral portion of the second axillary consists of a heavy blunt projection on the proximal side of the sclerite, that articulates vlth the mesopleural wing process (fig. 5, II, MVP).
A heavy wide ligament extends from the inside of the top edge of the mesopleural wing process to the ventral part of the second axillary solerlte (fig. !)• This connection is such that the second axillary essentially hinges in and out on top of the mesopleural wing prooess, but yet does not articulate directly with it* The ligament connecting the two solerites is flexible, allowing free movement of the second axillary, but because of its width, the movement is primarily in one plane. When all solerites are dissected away, leaving only the second axillary connected to the mesopleural wing process, the second axillary always springs back to its initial position when moved. In this way the ligament connecting the two solerites is much the same as a leather strap. Just posterior to the connection of tho second axillary to the mesopleural wing process, the posterior end of the second axillary extends toward tha subalare. The membrane between the two solerites is stronger than most membranous areas, but a definite ligament does not occur. The mesopleural wing prooess is also connected to the ventral surface of the head of the suboosta (fig. 5). This connection is also by means of a heavy ligament.
The third axillary (fig. 2, III) is an elongate sclerite fused to the base of the anal veins and connected to the second and fourth 11 axillary eoleritsB and to tho median plate* The eonneotion to the oeoond axillary probably serves as another pivot point for this solerite. There is no dlreot articulation between the third and fourth axillary solerites*
The fourth axillary solerite (fig* 2, IV) is a small solerite with the distal end formed into a hook* This solerite articulates directly with the tergpm and is connected by membrane to the third axillary* A dorsal projection of the second phragma (fig* 2, ph) can be observed in the hook of the fourth axillary and oonneoted by membrane to this solerite* Contraction of tho longitudinal muscles would pull the phragma forward causing the fourth axillary to hinge upward*
M0V£H£NTS
When the wing is in the up position* the dorsal surface of the first axillary is toward the thorax and the solerite is nearly vertical*
The second axillary is oonneoted to the first in suoh a way that its dorsal surface is nearly horizontal* but slightly tilted toward the thorax* From the pleural area* the second axillary is now mesad of the mesopleural wing prooess and the part of the second axillary oon neoted to the wing prooess is in about the same plane as the top of the wing prooess* The top portion of the mesopleural wing process Is inclined nasally at about a thirty degree angle* As the wing starts downward the first axillary swings ventrally until at the end of the downstroke its dorsal surface is nearly horizontal and the dorsal surface of the second is nearly vertioal* The seoond axillary is now above the mesopleural wing prooess and the part of the seoond oonneoted to it is inclined slightly away from the body* No movement is evident 12 betvaen tho first and second axillary solerites when the wing ie manipulated* The only movement possible would be an extension of the position of the eeoond axillary at the end of the upstroke and at the end of the downstroke*
When the wing is at rest* the position of the first and seoond axillaries is approximately the same as when the wing is in the up
position. At this time the third axillary ie vertical* When the wing
is up» tho third axillary is inolined about fifteen degrees away from
the body and at the end of the downstroke* it is horizontal* No movement of the fourth axillary is noted during the manipulation of
the wing* Since this solerite is so small and not intimately asso
ciated with the wing* it probably is Insignificant in any wing move
ments* including folding the wings into the resting position*
As tho wing goes down* the presoutum is noted to rise* It is
possible that this solerite* through its eonneotion to tho suboosta*
aids in bringing the wing back to the up position by acting as a
spring. AOAHTHOOEPHALA TERMIMALI3 DALLAS (H^IFTERA)
DESCRIPTION
Tha first axillary is a rather szall, simplo, L-shapad solerite (fig* 4, I)* One ara of the solerite extends dorsally and anteriorly} the other arm extends ventrally and somewhat toward the thorax* The anterior ara is strongly oonneoted to the anterior notal wing prooess and slightly overlaps the posterior edge of this process*
The anterior notal wing prooess extends dorsally from the tergal mar gin rather than laterally as is the case in most other groups of inseots*
The posterior ara of the first axillary articulates with the anterior end of the aoutellar lever* Instead of the usual typo of oonnsotion found between these structures in which the ara of the first axillary is against the side of the ecutellar lover, the reverse is true; the end of the soutellar lever is against the first axillary ara* Tho edge of the first axillary that articulates with the second axillary is grooved, aore prominently along the anterior portion where the first axillary extends under the second* The edge of the seoond whioh ar ticulates with the first axillary is straight* The eonneotion of these solerites is firm and movement between the two solerites can only occur in one plane*
The second axillary (fig* 4, II) is a largo Irregular solerite that probably should be considered as a fusion of the second axillary, the humeral plate and a median plate to the head of the radius* This seoond axillary complex artioulates with tho first axillary, the third axillary and the mesopleural wing prooess* There is also a small, slender solerite, a median plate, on the distal side of the second axillary that is almost obscured by the latter solerite*
15 The anterior portion of the eeoond axillary oomplex extends over tho leading edge of the wing. The posterior edge dips ventrally so that the solerite may be considered as having three surfaces! the anterior* the dorsal and the posterior. The distal end also dips ventrally and is attached by membrane to the slender median plate and to the third axillary sclerite.
Two processes extend ventrally from the seoond axillary complex! one from the humeral plate area and the other from the seoond axillary proper (fig. He* a1)• Both of these processes are in close asso ciation with the mesopleural wing process. The anterior is more closely associated with the basalare (fig. 5» ba) which extends upward
Just anterior to the mesopleural wing process. The ventral prooese from the seoond axillary proper has two arms* one extends anterior to the head of the mesopleural wing process and the other posterior to
It (fig. He)* Neither of the two processes from the seoond axillary oomplex articulate directly with the pleural struoturea* but are oonneoted to them by heavy ligaments.
The third axillary (fig. 4* III) is an elongate* slender sclerite.
This solerite artioulates vlth the fourth axillary and the vannal section of the wing. The portion of this solerite articulating with the vannal section also has an arm that extends anteriorly to the second axillary. The third axillary is strongly oonneoted to the vannal section of the wing and ie connected to the fourth axillary solerite by a ligament-like band.
The fourth axillary appears as a slender solerite extending from the third axillary to the posterior notal wing process. The fourth axillary is very broadly connected to the posterior notal wing prooess* almost appearing as an integral part of this structure and at 15 ona point a fusion does oacur between the two solerites* When exanined from the pleural region, a larger portion of the fourth axillary be. oomes apparent ( fig* 5, IV). The fourth axillary extends under the third (fig* A, IV), widens considerably and is connected by means of a ligament to the posterior, inner edge of the mesopleural wing pro cess*
HOVfiMSNTS.
The first axillary shows little movement when the wing is manipulated. When the wing is in the up position the dorsal surface of the first axillary is appressed to the thorax. The edge oonneoted to the second axillary is dorsal and oriented in an anterior-posterior direction and is horizontal* When the wing is in the down position, the surface considered as dorsal is facing posteriorly and the edge connected to the second axillary is now oriented transversely and is at a forty-five degree angle rather than horizontal*
The movement of the second axillary, since it is a composite structure in this insect is difficult to describe* Essentially this structure hinges downward and anteriorly as the wing moves from the up position to the down position* The movement of the ventral portion of the second axillary reflects the movement of the dorsal portion* The posterior of the two processes comes down over the mesopleural wing process until the two solerites come in contact with each other* At this point the ventral part of the second axillary fits over the meso- pleural wing process*
Movement between the first and seoond axillary solerites seems to occur only on the upstroke* As the wing goes up the two solerites move as one, but near the top of the stroke, the first axillary reaches 16 the limit of its movement* Prom this point on* to the completion of the stroke* the second axillary hinges on the first* As the wing goes down* the first and seoond axillary solerites regain their relative positions and again move as a unit* When the two solerites are dis«
sooted apart from the remaining structures and the first axillary held firm* the seoond axillary oan be moved through an aro of about twenty
degrees*
The basal portion of the meso-wing is rigid except for two areas. The first is a narrow flexible area separating the clavus from
the remainder of the wing (fig. A, x). The second Is the membranous
area of the axillary region whioh also extends around the head of the
radius (fig* y)« This flexible area essentially separates the head
of the radius from the remainder of the wing* Since the head of the
radius is separated from the remaining wing veins* the wing is capable
of rotation on its longitudinal axis independently of the head of the
radius and the axillary solerites* The third axillary* being asso
ciated with the vannal region* can probably control this part of the
wing* In as much as this part of the wing is separated from the re
maining part of the wing, apparently the anterior portion can rotate
or hinge up and down somewhat independently* There does not appear
to be any evident advantage to this type of condition* It appears
that having a leading edge capable of independent movement might even
be a disadvantage since it might tend to take the path of least re
sistance during the wing cycle, or offer more resistance to move
ment by hinging either up or down rather than presenting an edge to
cut the air oleanly. It should be pointed out that though these
movements oan easily be demonstrated on a preserved specimen* it is
not known whether or not in actual flight there is any independent 17 movement of these portions of the wing. Independently controlled movsnents of the posterior portion oan perhaps provide an additional
advantage in directional noveaents suoh as turning and rising,
functioning ntuoh the same as the wing flaps of an airplane. MAQIOXOADA 3EPTENDE0IH (L.) (HOMOPTERA)
DESCRIPTION
Tha first axillary is a cuneiform solerite, wider at tho anterior end (fig* 6, I)* This solerite is oonneoted in suoh a way
that the surface of the solerite faoes the thorax and an edge is pro.
sented dorsally* The upper corner of the anterior end of the first
axillary is oonneoted to the anterior notal wing prooess whioh extends
laterally from the thorax in front of the first axillary solerite
(fig* 6, ANP)* The lower corner of the anterior edge artioulates with
the lateral edge of the tergal margin somewhat posterior to the oon-
neotlon to the anterior notal wing process* Throughout the length of
its dorsal margin, the first axillary articulates with the second
axillary solerite except at the most anterior region where it is in
close association with the humeral plate (fig* 6, hp)* The dual oon~
nection of the first axillary to the thorax, through the anterior
notal wing process and the lateral margin of the tergum, forms a hinge-
like articulation so that movement of the solerite is only in one
plane. This movement is in an anterior-posterior direotlon. The
anterior movement is a few degrees below the longitudinal axis of the
thorax and the posterior movement a few degrees above the longitudinal
axis*
The second axillary is an Irregularly shaped solerite exhibiting
both a dorsal and ventral solerotizatlon in the wing base (fig* 6, II)*
Dorsally the inner margin of the solerite is attached to the first
axillary* The anterior margin artioulates with the base of the radius-
suboosta and is oonneoted to it by a very narrow solerotized bridge.
The ventral portion of the second axillary appears as a triangular
18 19 solerotized area in the aembrane of the wing base, looated posterior to the mesopleural wing prooess (fig* 7» II)* The anterior edge of this ventral part of the second axillary solerite is hollowed out* presenting the appearance of an elongate cavity*
The third axillary (fig* 6, HZ) is a narrow right-angled solerite associated with the trailing edge of the wing and artioulates with the seoond axillary solerite at its outer most point*
The fourth axillary (fig* 6, IV) is an elongate flat solerite articulating with the inner edge of the third axillary solerite and with the posterior notal wing prooess*
The humeral plate (fig* 6t hp) is a large solerite fused to the radlus-suboosta and separated from the costa by a membranous area*
Ventrally this solerite exhibits a fairly regular surface with two areas of apparently heavier solerotizatlon. The first is a oonoavo area situated at the posterior outer corner* The seoond and smaller area is looated at the posterior inner oorner*
MOVEMENTS
Oontraotlon of the longitudinal and oblique muscles appear to cause the anterior edge of the presoutum to be pulled in a posterior- ventral direction* This movement oauses the anterior notal wing pro cess and the lateral edge of the tergum to rise in an outward curving aro. The prealar bridges may also aid this upward movement of the lateral edges of the tergum to some extent by acting as fulcra. Along with this movement the mesopleural wing prooess moves inward slightly*
Extension of tha wing swings the first axillary out so that it is at right angles to the longitudinal axis of tho thorax* At this point the first axillary is probably at its limit of anterior movement as 20 the oonnsotlon to th« anterior notal wing prooeee la suoh that for ward noToment la atopped by the eolerite coning in oontaot with a part of the anterior notal wing prooeae* Extenaion of the wing alao plaoea the ventral portion of the humeral plate anterior to the meao- pleural wing prooeaa and the aecond axillary aolerlte juat posterior to it* Aa the wing entera the downatrokei it appeara that the meao- pleural wing prooeaa artloulatea with the poaterior area of the humeral plate and the anterior edge of the aeoond axillary* These two aolerltes apparently form a sooket-like area between them that elides over the wing prooeaa aa the wing approaohea the end of the downatroke. Al though the heavily solerotlzed convexity on the ventral surface of the humeral plate appeara more aultable aa an articulating surface for the wing process, it apparently is used only when the wings are folded in the rest position. It seems that the only possibility of its being used in flight would occur it the wings were only partly extended be fore flight movements were begunf rather than when they were fully ex. tended. That a condition suoh as this occurs in flight appears doubtful.
Bcaslbly this la a type of "look* that helps to hold the wings in the resting position.
The oontraotion of the vertical muscles appears to have a two fold effect. The anterior-lateral edge of the notum is pulled both downward and inward. Simultaneously the basiateraum la pulled dorsally.
The Inward movement of the baalaternum acta against the aneplaternum, which in turn forces the mesopleural wing process outward. The pre- alar bridges may possibly act as fulcra in effecting this outward movement of the mesopleural wing process. Aa the lateral edge of the notum moves in and downward, and the wing process outward, the wing la passing through the upstroke. Early in the oyole the oontaot 21 botvsen the wing prooeee and the humeral plate and the eecond axillary eolerite le probably broken and the only eonneotlon la by aeane of the membrane In thle area* The doreal surface of the aeoond axillary ro tates slightly posteriorly and the first axillary swings posteriorly until it is oppressed to the thorax* This may be assumed to be the peak of the upstroke* The oppression of the first axillary to the thorax may cause this area to bend inward slightly due to the inherent elasticity of the thorax, especially in this area, as there is a mem
branous area directly above the attachment of the first axillary to the anterior notal wing process (fig* 6t x). This would probably in
crease the flexibility of the thorax due to a decrease in the
solerotlzed area* If this bending does occur then the movement of the
edge of the thorax, in moving into its original position, would be an aid in initiating the downstroke* UMBONIA CRAS3IvORNI3 (A. & 3.)(H0M0PT2RA)
DESCRIPTION
Tho first axillary is a vory sinpla triangular aolarite
(fig* 8* I)* This aolarite is attached to the thorax in nearly a dorse-ventral plane* though the lower end of the solerite is slightly posterior to the upper or anterior end (fig* 9$ !)• The anterior part of the aeaal edge of the first axillary articulates with the posterior edge of the anterior notal wing process. The tip of the anterior notal wing process extends distally beyond the first axillary so that it is a limiting factor in the forward movement of this sclerite* An upward projection of the mesal edge of the first axillary articulates with the undersurface of the anterior notal wing process* The pos terior lower tip of the sclerite articulates in a concavity on an anterior projection of the tergum* This is a very firm connection enabling a rotation of the first axillary sclerite at this point.
From the standpoint of the first axillary connection to this structure* and its general shape* it is quite similar to the ecutellar lever found in the Diptera. However* this structure is not capable of the movement observed in the Diptera*
The anterior distal edge of the first axillary articulates with the second axillary sclerite* The articulating edges of the two solerites are quite straight* forming a hinge-like connection*
The second axillary solerite (fig* 8* II) is a comparatively large structure* The dorsal part of tho second axillary* in this insect* extends further into the wing that it does in the specimens examined in other orders* This sclerite may be the result of a fusion of the second axillary* the humeral plate and a median plate* The
22 25
Bocond axillary is asaoelatad with the third axlllaryf a median platef tho radius* tho mesopleural wing process and the first axillary as already discussed*
The second axillary has a small ventral projection on its distal end that articulates with the median plate* The median plate
(fig. 8* m) is a very small sclerite situated at the distal end of the second axillary and partially covered by it*
The end of the second axillary closest to the thorax is fused to the head of the radius so that both structures move together* Both of these structures have a weakened area allowing the wing to fold at this point* This area is just distad of the head of the radius and approximately across the center of the second axillary where an in dentation of this sclerite occurs* The amount of folding that can occur is apparently governed by the size of this indentation or cleft
(fig* 8* x) on the posterior edge of the second axillary* As the wing is folded back* the two sides of this cleft come together* stopping further movement* When the wings are folded at rest* the second axillary is in the position described*
The second axillary solerite articulates with the third axillary only where the pointed anterior projection of the third axillary comes in oontaot with the posterior edge of the second axillary* There is no actual articulation of the two solerites*
The ventral part of the second axillary is quite unusual
(fig* 10* II). It is not a solid structure* extending through the wing from the dorsal part* as in other insects* but rather* it wraps around the anterior edge of the wing* just mesad of the head of the radius* Thus this dorsal portion of the second axillary appears more closely related to the radius than to the axillary sclerite itself* 2h
Tho edgo of the ventral part of tho aeoond axillary that artloulatea with the Deaopleural wing prooeaa la more heavily aolerotlzed than the remainder of thla portion of the aolerlte. The oonnootlon between the aeaopleural wing prooeaa and the aeoond axillary la by meana of a wide ligament. There la no direct articulation of the two aolerltea.
The aubalare (fig. 10» aa) appeara aa a amall narrow aolerlte and la oloaely aaaoolated with the poaterior border of the ventral part of
the aeoond axillary.
The third axillary (fig. 8» III) la a large Irregular aolerlte aaaoolated with the aeoond axlllaryt the poaterior notal wing prooeaa and with the vannal region of the wing. All of theae oonneotlona are meabranoue with no direct artloulatlona.
MOVEMENTS
Because of the location of the oonneotlona of the first axillary
to the thorax, thla aolerlte essentially moves anteriorly and posteriorly.
Since the lower connection la slightly poaterior to the upper, the
aolerlte does awing up slightly aa It moves posteriorly. Vhen the wing
la In the up position, the edge of the first axillary oonneoted to
the aeoond la dorsad and horlsontal with the dorsal surface of the
first axillary against the thorax. As the wing goes down, the first
axillary swings anteriorly until at the end of the downstroke the edge
oonneoted to the aeoond axillary la about forty-five degrees from the
horizontal and the dorsal surface la almost posterior. The aolerlte
la now In oontaot with the tip of the anterior notal wing prooeaa
whloh prevents farther movement. In the up position the aeoond axillary
and the head of the radius are horizontal with the widened end of the
radius being anterior. Thla portion of the radius eannot be appreaaed 25 to tho thorax or rotated In any way so that it faces the thorax. This aay have some significance in the remaining portion of the wing being able to move somewhat Independently of it. Since the second axillary appears to continue around the leading edge of the wing to form the ventral part* it is understandable that the second axillary-radius head does not appear to move very much. This can be interpreted as
being due to the connection of the second axillary to the mesopleural
wing process. At the end of the downstroke the widened end of the
radius faces dorsally and anteriorly*
The apparent movement of the ventral part of the second axillary
is simple. At the top of the upstroke the ventral part of the second
axillary is directly above the mesopleural wing process and is in a
dorso-ventral plane. As the wing goes down it hinges downward on its
connection to the mesopleural wing process and actually swings below
the top of the wing process. The conformity of the ventral part of
the second axillary is suoh that it appears to fit over the external
surface of the mesopleural wing process at the end of the downstroke.
The wing membrane surrounding the head of the radius is very
flexible in comparison with the remainder of the wing membrane. In
figure 8 this flexible membrane is the only membrane designated by
stippling. This Is the same type of situation as discussed* for this
arsa* In the section on Acanthooephala termlnalls. The discussion of
the movements concerned with this area also apply to Umbonla orassl-
oornls. PHTLLOFHAQA DRAKII (KIRBY) (OOLEOPTERA)
DESCRIPTION
Tho first axillary solerlto can bo conaldorod as having a fairly flat posterior body portion and an anterior head and nook
region ( fig* 11, I). The more heavily solerotlzed head and nook
region Is turned toward the wing and Is bifurcated dorso-ventrally en
gaging a oorrespondlng bifurcation at the base of the oosta to provide
a looking msohanlea for flight (fig* 11, 0)* The head and nook region
of the first axillary Is oonneoted to the anterior notal wing process
(fig* 11, ANP) In a hinge-like fashion, with the first axillary over
lapping the edge of the anterior notal wing prooess* The body of the
first axillary Is oonneoted to a posterior projeotion of the lateral
edge of the tergum* This projection begins just posterior to the an
terior notal wing prooess* The eonneotlon of the first axillary Is to
the ventral edge of this projeotion (fig* 11, y)* At the point where
the change In the dorso-ventral relationship between the first axillary
solerite and the edge of the tergum oocurs,the edge of the first
axillary la groovedi the groove being formed by the nook region rising upward somewhat and the edge of the body of the solerite extending
under the neck* This groove fits over the alar margin of the tergum
at the point where the anterior notal wing prooess ends and the post
erior projection begins* It appears that this type of oonneotlon would
be much stronger than would be the ease if the anterior notal wing pro
oess and the first axillary solerite were oozmeoted edge to edge* The
outer edge of the first axillary solerite Is oonneoted to the second
axillary (fig. 11, II).
26 27
The second axillary eolerite Is roughly diamond-shaped vlth the aoute points being anterior and posterior* Nearly half of this solerite Is covered by the first axillary and a part of it is also oovered by the median plate* The anterior part of the second axillary
Is narrower than the posterior part and is raised above the arm of the solerite that is under the first axillary* This raised portion forms a ridge that the first axillary abuts against* It Is here that the two solerites are oonneoted* The extreme anterior tip of the second axillary extends slightly under the head of the first axillary but is not direotly oonneoted to it in terms of an articulation* The pos terior distal side of the aeoond axillary is oonneoted to the median plate (fig* lit a) in what appears to be an edge to edge oonneotlon, but an arm of the aeoond axillary extends under it so that this oon neotlon is quite similar to the oonneotlon of the aeoond to the first axillary* The posterior tip of the second axillary is oonneoted to an anterior projeotion of the third axillary solerite by a thickened area in the membrane between the two solerites* This ligament Is flexible, i ! but no to the extent of membrane, exhibiting a tendency to retain the I | same relationship between the two solerites when they are dissected out* [ | The part of jbhej second axillary that is under the body of the first axillary solerite is oozmeoted to the metapleural wing prooess*
The oonneotlon of this solerite to the wing prooess is not at the dorsal tip of the prooess, but rather, slightly ventrad of it* At this point there is an enlarged area or projeotion* Extending ventrally from this projeotion is a heavy ligament that is oozmeoted to the second axillary so that in this ease the cozmeotlon is not a direct artioulation of the two solerites* Instead, the ligament appears to form a sling-like connection that would allow a fair amount of move- 28 meat between the two solerites (fig* 12, 1)*
Located in the membrane posterior to the metapleural wing pro
oess is a small solerotlzed area, the subalare solerite. Attaohed to
the internal surface of this solerite is a small solerotlzed musole
diso* A slender ligament runs from this solerite to the posterior
end of the second axillary solerite (fig* 12, 1)* This ligament ex
tends posteriorly from the musole diso to a small apodeme at the lateral
edge of the phragma*
The third axillary solerite is nearly rectangular in shape and
has a small projeotion in the center of the anterior edge (fig* 11, III)*
The distal end is highly convex dorsally, gradually flattening out to
wards the proximal end* The third axillary artloulatea with the pos
terior notal wing prooess in a hinge-like manner* Due to the angle
at which the posterior notal wing prooess projects from the thorax, and
the angle of the edge of the third axillary that articulates with it,
the distal end of this third axillary moves forward as it moves up* } Vhen the wings are folded the dorsal surface of the third axillary is
quite closely oppressed to the thorax and quite closely associated
with a small solerite that is anterior and mesad of the projeotion of
the third axillary* This small solerite may be a aeoond part of the
third axillary* The third axillary is also oonneoted by a very narrow
solerotlzed bridge to the same portion of the median plate that is
aseooiatsd with the seoond axillary solerite.
MOVEMENTS
The first step in flight movements would be the unfolding of
the wings and the looking of the head of the costa to the first
axillary* Vhen the wing is in a down position, the body of the first 29 axillary is a few dagreea below a horizontal plane* The part of the aeoond axillary that ia under the first axillary la now at its oloaeat point to the ventral surface of the first axillary* The angle of the up and down strokes seems to bear direotly on the angle of the head of the first axillary at the point where the costa artloulatea with it*
This type of eonneotlon seems to indicate that the anterior edge of the wing moves in a straight linef i«e*, does not prescribe a figure eight or loop* etc. Movement other than this doss not seem possible due to the connection of the first axillary to the anterior notal wing pro. oess limiting the movement of the first axillary to one plane* This would seem to limit the movement of the vlng( as any deviation from a straight line would tend to unlock the first axillary-costa coupling.
At the bottom of the downstroke the costa is about fifteen degrees posterior to a transverse plane through the anterior notal wing process area* As the wing comes up* this angle increases due to the angle of the first axillary head and due to the posterior connection of the first axillary being lower than the anterior connection. Also during the upstroke* the part of the seoond axillary that is under the first axillary is moving away from the first axillary as the first axillary is moving into a vertical position and the metapleural wing prooess is moving outward. At the peak of the upstroke the first axillary is about fifteen degress from the vertical with its ventral surface now facing distally* The seoond axillary projection is now at its maximum distance from the ventral surface of the first axillary solerite. The extreme movement of the projeotion of the seoond axillary away from the first axillary could be no greater than about eighty degrees due to the morphological limitations of the connection of the two solerites. In all species of Ooleoptera examined* the basalare 50 and aubalara busolas have tha sana appaaranco as tha indiraot musolas*
Tha basalara isusola, at laast, has tho saaa histological struoturo aa tha Indiraot ausoles* The subalare solerite Is reduced to a small solerotlzed area direotly ventrad of the posterior notal wing prooess*
It Is completely surrounded by membrane* The subalare musole as well as the basalare musole Inserts on a solerotlzed diso that Is attaohed to the respective solerites* The subalare musole la the smaller of the two*
The dlreot aotlon of the subalare musole is on the subalare solerltei but indirectly on the second axillary solerite via the ligament mentioned previously* It would appear that this would be the main aotlon of the musole* The aotlon could be of two types} It oould pivot the seoond axillary solerite down or, since the foroe is also In a posterior direotlon( it may tend to pull the wing back to some extent or it may be a combination of the two* It Is doubtful that there is any appreciable movement of the apodeme to whloh the posterior ligament Is attached*
The dlreot aotlon of the basalare musole is oonoernad with rotation of the dorsal head region of the basalare solerite* Upon oontraotion* the head of the basalare rotates inward* The aotlon of this muscle oan be duplicated by either pulling on the musole direotly or by pushing down on the musole diso attaohed to the basalare* It does not appear that this musole has any appreciable effect on the meta~ pleural wing prooess even though the two solerites are quite olose*
If the wing Is manipulated so that it is extended outward* nearly at a right angle to the body* and the head of the basalare is pushed inward in about the same way as the basalare musole would pull it* the wing is pulled down* Also* if the wing is elevated* the head 51 of tho basalare Is rotated outvard* It does not appear that the function of this ousole is solely concerned vlth the rotation of the costal re gion or with bringing the wing forward to change the direction of flight, but rather, considering the size of the muscle, its histological similarity to the indirect flight muscles and the action indicated by manipulation, it appears more reasonable that its function is concerned primarily with depression of the wing. It may be possible that the basalare muscle is also concerned vlth holding the oosta looked to the first axillary, since the holding in of the basalare, after the ving is extended, does seem to serve this purpose* PANORPA NSBUL03A WESTWOOD (MECOPTBRA)
DESCRIPTION
The first axillary solerite (fig* 15, I) is analogous to an irregular right triangle, the right angle being at the inner end of the posterior aargin* The anterior end of the first axillary is rounded and curved ventrally with the innermost edge of this portion extending ventrally and then slightly anteriorly to form a blunt pro jection* This projection extends under the head of the subeosta*
This probably is an aid in forming a rigid mechanical linkage between the first axillary and the wing proper* The posterior inner corner of the first axillary extends under the lateral margin of the tergum*
The first axillary muscle inserts on this arm of the aolerlte* The anterior neck-like portion of the first axillary lies over the anterior notal wing prooess though there is no direct articulation between the two, in the sense of two closely united solerites. The first axillary can be easily separated from the anterior notal wing process by gentle pulling to reveal the membranous connection at this point* The pos terior distal arm of the first axillary articulates with the posterior end of the dorsal part of the seoond axillary solerite* At this oon neotlon, the first axillary extends over the seoond. This is the only point where the two solerites are direotly oonneoted (fig* 15, *)•
The seoond axillary solerite (fig* 15* II) le fairly narrow anteriorly and expands somewhat toward tho posterior end where it ex tends under the arm of the first axillary* The anterior end of the second axillary is in contact with the head of the suboosta (fig* 15, y)*
Interposed between the anterior portion of the first axillary and the seoond axillary is a small triangular solerite (fig* 15, z) in very
52 55 olos# ataoclation with the seoond axillary* This solerite appears to
be a part of the suboostai apparently a etruoture whose funotion is to
increase the rigidity of the seoond axillary - wing oonneotion*
The seoond axillary solerite presents a rather small dorsal
appearance* Dorsally it is oonneoted to the head of the suboosta* the median plate (fig* 1?* m) and to the first axillary* The posterior end
of the aeoond axillary extends under the posterior distal end of the
first axillary* The anterior portion of this solerite is olosely con-
neoted to the suboosta along its inner margin* The outer margin is
associated with the median plate along most of its length* more olosely
at the posterior end* The ventral portion of the seoond axillary oomes
off the posterior end of the solerite just below the point where the
first and seoond axillary solerites articulate* The ventral portion of
the seoond axillary ourves under the first axillary and extends
anteriorly slightly* more or less forming a hook* This ventral portion
articulates with the mesopleural wing prooess* The ventral hook of
the second axillary is quite heavy* Tho faoe that articulates with
the mesopleural wing process is slightly oonoave. It is oonneoted
to the mesopleural wing prooess by a heavy ligament in suoh a way
that the two solerites are not in dlreot oontaot.
The third axillary eolerite (fig* 12* III) is a narrow elongate
solerite. The anterior distal end of this solerite articulates with
the median plate and the posterior end articulates with the fourth
axillary solerite* Both of the oonneotlons are membranous with no
direct oontaot of the solerites existing* except for an extremely
small part of the third that does articulate direotly with the median
plate.
The fourth axillary solerite (fig* 15* IV) is found direotly & antorior to tho axillary oord* Thla solerlto la alao a slender elongate atruoture* In addition to Ita oonneotlon with the third axillary( It artloulatea with the poaterior notal wing prooeaa* The anterior of the two connections fits Into a notched area of the poaterior notal wing prooeaa* Poaterior to thla connection, a slender am of the fourth axillary goes under the axillary oord and la alao oonneoted to the poa« terior notal wing prooeaa* This seoond oonneotlon appears to be a fusion of the two atruoturea*
MOVEMENTS
The first axillary la attaohed to the anterior notal wing process in suoh a way that all of the movement of thla aolerlte la In a dorso- ventral are* It appeara that this movement la limited to a ninety degree are* When the wing la at the top of the upstroke, the first axillary ia
In a nearly vertical position, slightly inclined toward the tergum* At the end of the downatroke the position of the aolerlte la about hori zontal* Since the posterior oonneotion of the first axillary to the tergum la lover than the oonneotlon of the head of the first axillary to tha anterior notal wing prooesa, the first axillary ewinga forward aa It moves ventrally*
Tha only movement of the aeoond axillary that ia disoernable dorsally la a possible movement of the dorsal aspect of the second axillary away from the first* As the first axillary undergoes a hinging movement ventrally on ita oonneotion to the anterior notal wing prooeaa, the aeoond axillary undergoes a similar movement at its oonneotion to the first, but to a smaller extent* Thla ia the only movement observable between the two solerites* The oonneotlon of the aeoond axillary to the mesopleural ving prooesa may be considered as a pivot point of the aolerlte* Viewed from the pleural region, it oan 35 bo aeon that at the top of the upstroke) the seoond axillary is mesad of the aeaopleural wing prooess* As the ving goes down) the relative position of the seoond axillary and the mesopleural wing prooess ohangeS) so that at the end of the downstroke) the ventral part of the seoond is nearly in line with the aeaopleural wing process*
The head of the suboosta has an angular projeotion on its ventral surface* It appears that this projeotion fits into a concavity at the top of the basalare* This structure appears to funotion as a looking asohanlsa when the wings are held at rest* PY0N0P3I0H3 CIRCULAR13 (PROY.) (TRIOHOPTERA)
DESCRIPTION
Tho first axillary oolerito confoma to tho genoral outline of thio solerite in other groups in that it oan be divided into a body and a head and nook region (fig* 15» I). The body consists essentially of two arms, the larger being the proximal arm which articulates with the thorax* The tip of this arm ourves up slightly* This modifioation helps to make this articulation more rigid by providing a more positive
looking meohaniem*
The neok region of the first axillary is very slender, especially at the point where it arises from the body* As it extends anteriorly,
it widens gradually until the anterior end is about twioe as wide as the
base of the neok* This portion of the solerite ourves ventrally*
The first axillary has two eonneotions to the tergum* The an terior part or neok region is oonneoted to the anterior notal wing pro oess (fig* 15, ANP)* The anterior notal wing prooess is quite prominent and braoed along its anterior edge by a thickened ridge* The lateral edge of the anterior notal wing prooess is gently curved upward so that a shallow groove is formed in whloh the neok of the first axillary articulates* The oonneotlon of the first axillary to the anterior notal wing prooess is olose to the base of the neok, so that a large part of the head and neok region is anterior to the prooess* This is a mem branous oonneotion with the first axillary overlapping the anterior notal wing process*
The lateral edge of the tergum is heavily solerotlsed and forms an anterior projeotion just posterior to the anterior notal wing pro oess* The proximal arm of the first axillary projeots under this and 57 artloulatea with It, forming the seoond artioulation with the tergum*
The head of the first axillary also artloulatea with a small
projeotion that oomes off the leading edge of the head of the radius
(fig* l%x). The head of the first axillary extends under this pro~
jeotion and is olosely oonneoted to it* Because of the flexibility
of the neok of the first axillary due to its length and slender
structure, this oonneotlon appeara to be a pivot point*
The remaining oonneotion of the first axillary is to tha seoond
axillary solerite* This oonneotion is a double overlapping type* At
the anterior end of this eonneotlon the seoond axillary overlaps the
first and at the poaterior end, the distal arm of the first axillary
overlaps the second*
The seoond axillary (fig* 15, II) is a very irregular solerite*
Dorsally the seoond axillary is oonneoted to the first axillary, as
already mentioned, to the median plate (fig* 15, ») and also to the
radius* The only olear artioulation is that between the first and
seoond axillary solerites* The remaining oonneotlons, between the
seoond axillary and the median plate, and between the seoond axillary and the radius are actually fusions and the boundaries of the solerites are not olearly disoernable* The "fold* (fig* 15, f) between the
seoond axillary solerite and the median plate may be considered as the
boundary between the two solerites*
Tho ventral expression of the seoond axillary is also more com
plicated than in other groups (fig* 16, II)* The ventral part has an anterior arm that is oonneoted to the posterior edge of the mesopleural wing prooess (fig* 16, MVP) and also a posterior arm that is associated with the subalare* Just above the posterior arm is a slender process
that extends back to the third axillary (fig* 16, III)* The dual 58 oonneotion of the ventral part of the eeoond axillary appeara to fora a limitation to the type of movement Involved that would not ooour in a aingle oonneotion*
The third axillary (fig* 1?» XXI) la an elongate eolerite of
Irregular ehape articulating vlth tho eeoond axillary and with tho poaterior notal wing prooeee* Although the oonneotlon of the third axillary to the poaterior notal wing prooeee appeara to be a direct articulation, the two eolerltea oan be pulled apart revealing a menu branoue area between them*
The poaterior notal wing prooeee (fig* 15* HIP) hae two dletinot arms, but the poaterior playa no apparent part in the wing articulation*
MOVEMENTS
When the wing ia in an up poeitlon, the doreal aurfaoe of the firet axillary la appreaaed to the thorax and the proximal aide of the neok of the firat axillary liea on the anterior notal wing prooeaa*
At thia time the doreal aurfaoe of the aeoond axillary ia alao toward the thorax* Viewed from the pleural region, moat of the aeoond axillary ia now meaad of the meeopleural wing prooeaa* The only part of the aeoond axillary not meaal of the mesopleural wing prooeaa la the amall portion that artloulatea with the wing prooeaa and the aubalare*
As the wing ie brought down, the first axillary hinges downward until its dorsal aurfaoe ia nearly in a horizontal position* Aa the wing continues down, the slender neck and head region twists ao that the head moves meaally; A amall flexible area ooours on the radius just distad of the head. During the last part of the downstroke the wing bends slightly at this point; Probably the inertia of the moving ving, in normal flight, oauaea the bending at this point'* 59 During tho coursa of tha downstrolca tha aaoond axillary ia alao changing poaltion. It ia evinglng outward on ita two pivot points* tha maaoplaural wing prooaaa and tha aubalara* Sinoa tha oonnaotlon of tha aeoond axillary to the aubalara is lower than tho oonnaotlon of tha aaoond axillary to tha maaoplaural wing prooesa* the aaoond axillary alao swings anteriorly during ita downward oourso* It ia quite evident that tha aubalara muaolo plays an important part in tha direotlon of tha wing movement in thia speoies* Tha aotlon of tha aubalara musole oauaea tha posterior part of tha aaoond axillary to move in a dorso-ventral direotlon* The change in position of tha aaoond axillary relative to ita oonneotlon to tha maaoplaural wing prooeaa* governs tha degree of anterior movement of tha wing during tha downatroke* A» tha subalare musole oontraota* tha portion of tho aubalara that ia oonneoted to tho aaoond axillary is pulled downward* Thla also pulls tha posterior portion of tha aaoond axillary in tha same direotlon* Tha lower thla portion of tho aaoond axillary la* relative to ita antorior oonnaotlon to tha maaoplaural wing prooaaa* tho greater tha anterior movement during tha downatroke*
At tha bottom of tho downatroke* all of tha seoond axillary ex cept tha part between tha aubalara and tha maaoplaural wing prooaaa* la distal of tho pleural region*
Meohanioal manipulation of tha wing does not show any apparent movement between tha firat and seoond axillary solerites whan the wing and associated solerites are intaot* If the wing and associated aolerltea are removed* ao that only the firat and aeoond axlllaries remain oonneoted to the anterior notal wing prooess and mesopleural wing prooesa respectively*, some.movement between the two aolerltea la evident* This movement would soem to oocur at the ends of the up and dovnatrokea* Whan tho wing ia nearly at the end of the upatroke and the doreal aurfaoe of the firat axillary ia appreaaed to tho tergum( or nearly ao( tho aeoond axillary* along ita oonneotion to tho firat axillary aolerito* hingea alightly toward the tergum* Just before tho end of tho downatroke la reached* the oppoaite movement oocura* tho aeoond axillary* along the aame oonneotion* hingea ventrally and at the aamo time alightly anteriorly* Apparently during moat of tho wing oyole the two aolerltea aot essentially aa one* The movementa of tho aeoond axillary in relation to the firat* at the end of eaoh etroke* may poaaibly aerve to inoreaae the amplitude of the wing oyole in both direotlona*
The third axillary* having a simple oonneotion* merely ewinga up and down on its hinge-like artioulation to the posterior notal wing prooeaa*
The relative anterlor-poaterlor position between the mesopleural wing prooeaa and the anterior notal wing prooeaa also changes during the oourae of the wing oyole* Aa the wing goea down* the mesopleural wing prooeaa moves forward slightly* Thus the mesopleural wing prooesa stoves inward and posteriorly as the wing goea up* and it moves outward and anteriorly as the wing returns to the down position* Thio type of movement also inoreases the amount of anterior movement of the wing during the downatroke* FROTOPAROS 3EXTA (JOHAN.) (LSPIDOPTSRA)
DESCRIPTION
Th« axillary region of Protoparoe sexta (Johan.) la somewhat different from inaeota in other orders examined In that it Is situated more posterior in relation to the thorax.
The first axillary solerite (fig. 17* I) is a fairly large* elongate aolerlte. Its longest axis runs from the thorax to the wing rather than anterior and posterior. At about the oenter of its anterior edge* it abruptly narrows and dips ventrally sharply. Immediately this anterior portion rises as sharply as it dropped. It then very gradually curves ventrally and widens slightly. This erratic shape of the solerite results in a sharp* deep*elongate oleft running aoross the solerite differentiating it into the larger body region and the slender neok and head region (fig* 17* *)•
The flattened anterior edge of the head articulates with the sub oosta* The edge of the first axillary head ie bent upward* interlooking with the downward bent edge of the suboosta* Tho narrow anterior part of the first axillary body is olosely oonneoted to the posterior end of the anterior notal wing prooess (fig* 17* ANP)* The curved neok is oonneoted to the anterior notal wing prooess by a wide heavy ligament* but the two solerites are not olosely assooiated* The mesal edge of the first axillary body is oonnsoted intimately to an anteriorly facing tergal projeotion (fig* 17* y) that arises just anterior to the posterior notal wing process* The anterior half of this edge extends under the tergal projeotion in zsuoh the same manner as the first axillary head is oonneoted to the suboosta* The posterior portion of the edge ex tends over the projeotion and is very olosely oonneoted to it* 42
Tho distal and of tho first axillary and tho anterior edge distad of tho neok artioulate with the seoond axillary solerite* This is a
Tory tight oonneotion, not allowing any play between the two solerites*
The proximal end of the seoond axillary overlaps the anterior part of
the first axillary body at the point where the sharp concavity is
located* The remaining assooiated edges of the two solerites are so
formed that they fit together though they do not Interlook*
Dorsally the seoond axillary (fig* 17» II) appears as a small
slender solerite with a median posterior blunt projeotion* This solerite
is situated along the anterior distal edge of the first axillary*
Dorsally the seoond articulates with the first axillary, the radius and
the third axillary* The proximal end of the seoond is fused to the radius
by a slender bridge. The entire anterior edge of the seoond is mem.
branoualy oonneoted to the radius* The distal end of the aeoond axillary
is very Intimately assooiated with the third axillary* The anterior
oorner of the upraised edge of the third axillary forms a deep socket
in which the end of the seoond artloulatea*
From the pleural region, the seoond axillary (fig* 18, II)
appears as a large solerite situated just posterior to the head of the
mesopleural wing prooess (fig* 18, MVP)* Outwardly there appears to be
only a membranous eonneotlon between the two solerites* Examination of
the internal surface of these solerites reveals that the anterior edge
of the second axillary extends mesally into the thorax and then an.
terlorly so that it essentially forms a socket around the posteriorly
projeoting head of the mesopleural wing prooess* The upper posterior
oorner of the ventral part of the seoond axillary is strongly connect
ed to the bottom of the ventral fold of the third axillary by a heavy
ligament* The membrane between the second and the subalare (fig* 18« sa) is also quite heavy* Also noted from the pleural region is the heavy
ligament that connects the head region of the leading edgo of the wing
to the basalara (fig* 18, ba). There is also a lighter ligament ex.
tending from the anterior oorner of the basalare to the same wing region.
The third axillary (fig* 17, HZ) is a large, highly irregular
solerite* It consists of a large, flat median region, a more slender mesal part that is at a right angle to the main body and articulates
with the posterior notal wing prooess (fig* 17* FHP)* This is a strong
oonneotion but it still allows a great deal of movement sinoe there Is no interlooking* The distal edge of the third consists of the fold
assooiated with the second axillary* A small arm arises from this same
side, but from the posterior oorner of the fold and extends to tho vannal
region of the wing*
M0Y2MSHTS
Host of the movement of tho first axillary appears to be assoo.
iated with its connection to the tergal projeotion rather than with the f anterior notal wing prooess* The first axillary goes through about a ninety degree oyole* At the top of the upstroke it is nearly vertical, with the dorsal surfaoe toward the tergum* As the wing goes down, the
first axillary swings down until it is horlsontal at the end of the
stroke* Oontraotion of the longitudinal muscles cause the tergal pro.
jeotion to move anteriorly and at the same time tilt upward* This move, ment of the tergal projeotion would tend to oause the first axillary to
rotate so that the posterior edge would be dropping in respect to the anterior edge during the downstroke* This results in an anterior move, ment of the first axillary and the wing during this part of the wing oyole* hh
Booaus* of tho fusion of tho seoond axillary to the radius* thio
solerite eannot rotate or move independently of the radiua to any ex.
tent and due to its olose oonneotlon to the first axillary* it follova
the movement of thle aolarite* The only movement evident in this re
lationship is that observed during the downstroke* During thla part of
the oyole the point of fusion between the radius and the second axillary
aots aa a hinge and the radius ewinga away from the seoond axillary*
Thla movement is very small and allows the leading edge of the wing to move forward a little more than would be the ease if there was a com
plete fusion*
At the top of the upatroke all of the ventral portion of the
second axillary la mesad of the mesopleural wing prooess exoept for the
ventral edge of the aeoond* Aa the wing goea down* the solerite rotates
downward on an axis that would pass through the head of the mesopleural
wing prooess head and the ventral edge of the seoond axillary* The
large membranous expanse surrounding the subalare and the etrong con
nection to the seoond axillary would indicate that the subalare musole
plays a large part in the downstroke of this insect* Manipulation of the
wing and also pulling on the subalare musole does result in a sub
stantial movement of this solerite* Sinoe moot of the ventral portion
of the seoond axillary is tilted inward at the top of the upstroke* the upper edge of this portion of the solerite* where the ligament from the
subalare is attaohed* must move upward slightly before it rotates down
ward* This would indicate that the subalare musole exerts its effect on
the seoond axillary during the latter part of the downstroke or that in
actual flight the second axillary is not tilted inward as mueh as it
appears to be during meohanioal manipulation* VE3RJLA MAOULATA (LINN.) (HIUSNOPTSRA)
D230RIPTI0N
Tha axillary region of V. naoulata ia ahieldad dorsally by the large seale-like tegula. The first axillary (fig. 19> I) is a large, elongate solerlte, irregular in shape and oriented primarily in a dorso-ventral direction. The anterior end of the solerlte is formed into a slender neok, terminating in an expanded, flattened head region.
Extending from the anterior edge of the flattened head region is a narrow hook-like projection that oomes up under the suboosta resulting in a very close articulation. The edge of the suboosta, under which this projection extends, bends sharply ventrad so that an interlooking oon- neotion is formed. The anterior head and neok region of the first axillary is set off from the remaining part of the solerlte by a mem branous cleft. This probably allows for a greater flexibility of the anterior portion. The body of the eolerite can be divided, for pur poses of discussion, into a posterior and a distal arm. The anterior faoe of the distal arm is oonoave. When the wing is at rest, a part of the second axillary fits into this concavity. The posterior arm of the first axillary solerlte is a blunt elongate projection. The first ax illary articulates with the suboosta, as previously mentioned, the anterior notal wing process, the second axillary and with the soutellar lever (fig. 19, si). The anterior notal wing prooess (fig. 19» ANP) projeots laterally from the tergum and la heavily solerotised. It Is deeply notched, dividing it into two approximately equal lobes. The anterior lobe curves slightly upward and the posterior lobe, downward.
The anterior edge of the anterior notal wing prooess is bent sharply dorsal so that this part is nearly at a right angle to the body of the prooess* This part of the anterior notal ving prooess is quite thin in
respeot to the remaining part* The first axillary fits into the deep notch of the anterior notal wing prooess* The side of the first ax.
illary that artioulatos with the anterior notal wing prooess also has a notoh that interlooks with the wing prooess* resulting is a very firm
connection. One that allows only a limited amount of movement*
The heavy posterior arm of the first axillary articulates with
the end of the soutellar lever* The end of the soulellar lever is mesad
of the first axillary arm* The extreme tip of the lever curves out*
forming a concavity in whioh the first axillary arm rides* The two
solerltes are strongly oonneoted by heavy membrane* This connection
of the first axillary to the soutellar lever ooours under the posterior
lobe of the anterior notal wing prooess*
The second axillary (fig* 19* II) appears as a small Irregular
solerlte from the dorsal surface* The larger part of this solerlte Is
hidden or covered by the assooiated structures. The anterior tip of
the second axillary is fused to the suboosta by a very narrow solerotised
bridge* The anterior part of the solerlte is oonneoted by membrane to
the head and neck region of the first axillary* The distal arm of the
first axillary overlaps the second axillary and is firmly oonneoted to
it* The lower anterior oorner of the seoond axillary (fig* 20* II)
is oonneoted to the mesopleural wing prooess (fig* 20* KWP)* The upper
posterior corner of the mesopleural wing prooess forms a blunt pro.
jeotlon that extends posteriorly* A heavy ligament (fig* 20* 1) ex.
tends ventrally from this projection to the seoond axillary*
The third axillary (fig* 19* III) is a bulbous solerlte situated posterior to the seoond axillary solerlte* Its ventral edge articulates 47 with the postorior edge of tho saoond axillary* The third axillary ia also in oloae aesooiatlon with the base of tha anal raina* Vhen viewed from tha doraal aurfaoe, tha oloea connection of tha third axillary to the second ia not evident* however* tha association ia quite evident froa the pleural area (fig* 20* II* III)*
The third axillary ia oonneoted directly to the posterior notal wing prooess* no fourth axillary solerlte being present*
M0VHHSNT3
Because of the ooapaotneea of the axillary region and the snail area involved* it is diffioult to determine the moveaenta on an intaot ppeoinen* All movements discussed for this insect are baaed on partially dissected specimens*
By dissecting out* as a unit* the lateral edge of the tergua bearing the anterior notal wing process* the scutellar lever* the first axillary and the seoond axillary* one can determine the limits of move*, ment of the first axillary and the effect of the soutellar lever on this solerlte*
The flret axillary* aa. previously discussed* is an elongate solerlte* oriented dorso-ventrally and articulates in a notch of the anterior notal wing prooess* Prom the morphology alone* one can deduce that any moveaent of the first axillary that ooours is limited by the notoh and by the scutellar lever* Since the connection of the first axillary to the scutellar lever is below the connection to the anterior notal wing prooess* it oannot hinge dorso-ventrally to any extent* but
rather* uses the anterior notal wing prooess as a fulcrum* Thus when one half of the solerlte moves in one direction* the other half moves
in tho opposite direction* 48 If tha tergum is held stationary and the soutellua raised, the soutellar lexer swings downward and posteriorly. At this stage the surface of the first axillary considered as dorsal is oppressed to the thorax and the solerlte is tilted so that the upper half, the head and neok region, is anterior to the lower half. Vhen the seutellum is pushed down, the scutellar lever swings upward and anteriorly* This causes the head and neok region to move posteriorly and outward and the lower half to move anteriorly and inward until the first axillary assumes a vertical position*
During the oyole of the first axillary, the movement of the end of the seoond axillary normally oonneoted to the mesopleural wing pro. oess oan be ascertained* It must be remembered that the seoond axillary is moving freely and not oonneoted to the mesopleural wing prooess*
The anterior tip of the ventral margin of the seoond axillary, the point oonneoted to the mesopleural wing prooess, is in line with the part of the first axillary articulating with the anterior notal wing process*
Because of this relationship and slnoe this part of the first axillary does not move very muoh, the part of the second axillary oonneoted to the mesopleural wing prooess shows little movement* Vhen the soutellar lever is baek, the part of the seoond axillary oonneoted to the meso- pleural wing prooess moves up and in* Vhen the lever swings forward, this movement is reversed* If the wing veins are removed froa a spool. I men, leaving the axillary solerltes attached to the thorax, the same type of movements are observed*
The movements of the axillary solerltes oan now be applied to the wing oyole* At the top of the upstroke the first axillary is j against the thorax and the part of the seoond axillary oonneoted to the mesopleural wing prooess is at its highest point* The seutellum is up at this tlmsi the lever being down and baolc* Ae the wing starts, on the downstrokef the first axillary starts pivoting on its oonneotion to the anterior notal ving prooess* The upper part of the first axillary moves posteriorly and outward and the part of the seoond axillary con nected to the mesopleural ving process moves downward and slightly outward* At the end of the dovnstrolee the first axillary is in its vertical position, the second axillary is at its lowest point and tha soutellua is down* DI3CU39I0I1 AUD C01i3LU3X0U
Although tho axillary oolarltoa aro epeoifioally dovolopad only in ving-floxing inaooto (3nodgraaa» 1S55)» 1^ 1» apparent that thia ia not thair only function* but that they are alao important in driving tha winga* For thia purpoae it appaara that tha flrat and aeeond axillary aoleritea are tha aclaritaa of major importance in that they have a direct action on ving movement and are moat intimately aseo- eiated with tha doraal and pleural atruoturaa reaponalble for wing movement*
While the muaclea that move the winga of Inaeete are activated by the central nervoua eyeten* the individual ving moveaenta of aoma inaeota are not* Frlngle (1949) found that in acme Inaeota the action potentiala of the flight muaclea bore no relation to the vingbeat fre quency* Roeder (1991) preaented additional evidence eupportlng the work of Pringle* Thia phenomenon la commonly referred to aa aeyn- ohronoua flight* Iho typa of flight exhibited by Inaeota shoving tha usual Itl relationship between stimulus and reaponse is referred to aa synchronous flight*
Very few inaeota have been classified according to the physio logical type of flight that they exhibit* Roeder (1991) preaented evidence that Parlplaneta (Orthoptera) and Agrotie (Lepidoptora) vers synchronous and that various Olptera and Hymenoptera were asynchronous*
Boettiger (personal communication) has obtained records shoving that a epeolea of Fhyllophaga (Ooleoptera) la alao asynchronous*
In view of the difficulties in getting specimens to fly after being mounted and the recording eleotrodea inserted* the scarcity of information concerning the physiological typos ie understandable. Tha
90 51
majority of Imoota tried by the author would not fly after being
mounted* Of thoee that did* only a rery email number would fly after
the eleotrodea were inserted* However, records have been obtained
that show J>* Carolina (Aorididas, Orthoptera), (fig* 21), Tibloen
canioularls (Oioadidae, Homoptera), (fig* 22), a member of the
Oeroopidae (Homoptera), (fig* 25), fhnorpa nebulosa (ftmorpidae,
Heooptera), (fig* 24), Platyoentrows vadiatus (Limnophilidae*
Triohoptera), (fig* 25), and a member of the Sphingidae (Lepidoptera),
(fig* 26) are synchronous, all showing a direct relationship between
the action potentials and the wingbeat frequency* Hagaiotonus
qulnquesplnosus (Coreldas. Henlptera), (fig* 27), Monobla quadrldens
(Vespidae, Hymenoptera), (fig* 28), Telamona sp* (Hembraoidae,
Homoptera), (fig* 29) and Fonana rublda (Oioadellldae, Homoptera),
(fig* 50) are asynchronous*
In figure 21 through figure 50, the upper traoe is the wing,
beat frequency and the lower traoe is the notion potentials* Ihe
record of the sphlngid (fig* 26) appears to show three distinct i peaks to eaoh wing oyole* This specimen is still synchronous slnoe
there is a direct relationship between the wingbeat frequency and the
notion potentials* All other records in the first group (fig* 21.25)
show a single potential for eaoh oyole*
Thus members of the Orthoptera, Heooptera, Triohoptera and
Lepidoptera are synohronous and members of the Hemiptera, Hymenoptera, 2.39309 Ooleoptera and Diptera are asynohronous* The Homoptera contains
groups that fall into both physiological types* Tho Oioadidae and
Oeroopidae are synohronous and the Oioadellldae and Hembraoidae are
asynohronous* 52 In addition to tho reoordo figured, records have been obtained
for Arphla eulphurea (F.) (Aorididae, Orthoptera), Ophidema flavloephala
Oody, Oyrtolobue ep»» Qphlderna ep»> Stlotoeephala lutea (Wlk.) and
OloBeonotue turrloulatua (Emm.) all Membraoldae (Homoptera)* These
reoordB agree with those in the same groups figured*
Hpa (1955) classified several inseots as either synohronous or
asynohronous on the basis of the size of the flight muscle fibrils*
If the fibril diameter of fixed musole was in the range of 2*? to
4,6 mlora, the physiological type was considered to be asynohronous)
if the fibril diameter was between 0*9 and 2*2 nlora, the physio
logical type was synchronous* The olassifioation presented by Pipe,
in respeot to the groups considered by him and the author are in
agreement exoept for the Oeroopidae whioh Hpa oonsldered as asyn- ! ohronous* Although there is a possibility of both physiologies! types ( occurring in the same family, it is not probable* More probably in
this case, it is an error of determination. Pipa lists Oampylenohla
sp* as a representative of the Oeroopidae. This genus is, in fact, a
member of the Membraoldae* Thus, if the specimen used by Pipa was a member of the Oeroopidae and wrongly determined, the size of the
fibrils is not related to the physiological type in all eases* But,
if the specimen was identified correctly and inadvertantly used as a
member of the Oeroopidae, rather than the Membraoldae, the relation
ship between fibril size and physiological type is consistent* It
seems more probable that the error occurred in placing the specimen
in the proper family.
Boettiger and Furshpan (1920), in a short paper, described the
effect of placing flies in carbon tetrachloride fumes* Briefly, when
a fly is placed in the fumes, there are first violent muscular spasms, 55 often followed by anaesthetic flight* As the effeot of the fumes in creases, the wingbeat frequenoy increases, then decreases and becomes irregular* Abruptly the wings stop in either the up or down position*
Pressure applied to the soutellua will cause tho wings to snap rapidly froa the up to the down position* The authors also present evidence
(1951) that this click phenomenon is a part of normal flight* Later
Boettiger and Furshpan (1952) described the action of the principal parts of the flight aeohanisa of Saroophaga bullata Parker and related this to the click meohanlsa*
This click phenomenon described by Boettiger and Furshpan and considered as an integral part of normal flight is dependant upon certain morphological or mechanical relationships* Briefly this aeohanisa, in 3* bullata* consists of four components, the lateral edge of the tergua, the anterior notal wing prooess, the first axillary- second axillary complex and the mesopleural wing process* Mechanically there are two parts, the mesopleural wing prooess and the lateral edge of the tergua, that basically move in and out and between them two parts, the anterior notal wing prooess and the first axillary-second axillary complex that move up and down* This oan best be illustrated by holding the forearms vertically and parallel with the index fingers horizon tally and the tips touching* In this way the left arm simulates the mesopleural wing prooess, the left index finger the first axillary- second axillary complex, the right index finger the anterior notal wing process and the right ara the tergua* Vhen the arms are moved toward eaoh other, a force is exerted against the fingers, causing them to flip down forming a V or, flip up forming an inverted V*
The former position ooours on the upstroke and the latter on the downstroke* The greatest resistance to movement occurs at the point 54 wher* tha dlstano® batveen the mesopleural wing prooess and tha edge of tha tergum is tha greatest* This would occur about at tha point where the fingers would be horizontal* Vhen they ara moved in either direotion beyond this point, they rapidly move to the end of the stroke*
This type of meohanism necessitates the mesopleural wing prooess moving in end out twioe during the wing oyole rather than move in during the downstroke and out during the upstroke ae considered previously*
Boettiger (personal conmmioation), by placing minute mirrors, made by removing the silver from plate mirrors, on the mesopleural wing prooess of flies and reoording the movements, has been able to show that the mesopleural wing prooess does move in and out twioe during eaoh wing oyole.
The morphological parts necessary for the click meohanism found in the Diptera are present in all of the inseots examined*
However, Boettiger and Furshpan state that a flexible hinge oonneotion ocours between the anterior notal wing prooess and the lateral edge of the tergum in S* bullata* Baranowski (1955) in a study of Tabanus species t was not able to show thia flexible hinge oonneotion in the members of this genus or, in representatives of several other families* Hone of the inseots examined here had such a oonneotion* Strlotly from a mechanical viewpoint, this type of struoture is not necessary* Slnoe the baslo structural oomponents consist of two units oapable of
} hinging up and down between two relatively rigid structures, the first and seoond axillary solerltes oould conceivably act as the links between tho mesopleural wing prooess and an anterior notal wing pro oess that is rigidly oonneoted to the tergum* This is the condition found in the inseots examined* Zt is also possible that the oliok phenomenon is not related to asynohronous flight* 55 lh« axillary region in all of the ineeote examined, regardless of the number or shape of the axillary aolerites present, performs some common functions in connecting the ving to the thorax* Although the base of the ving is quite narrov, it le oonneoted to the tergua at tvo points* Mechanically, two points of contact establish more strength than a single connection, provide more control over rotating movements of the ving and finally, provide more flexibility* Since the insect ving is an expansion of the body vail, it is also oonneoted to the pleural region* In all oases this is accomplished by the seoond axillary articulating with the pleural ving process* Thus, there are three points of contact betveen the ving and the thorax common to all of the insects studied! an anterior connection through the first axillary to the tergua, a posterior oonneotion through the third or fourth axillary and a ventral connection through the seoond axillary to the pleural ving process*
Theories proposed by Jbringle (19^9) and Boettiger and Furshpan
(1950) la regard to the asynohronous physiological type found in flies, both suggest that the physiological response of the musole is controlled by the mechanical action of the thorax* According to Arlngle, nerve impulses produce an alteration in the flight muscles causing them to be excited vhen stretched* By means of the thoracic skeletal connections betveen them, the shortening of one set of musolee stretches and thus excites the antagonistic muscles* Boettiger and Furshpan considered the antagonistic muscles to be under constant tetanic stimulation during flight, the mechanical action of the articulation altering the musole load so as to produce oscillation*
The axillary solerltes of the Inseots examined are remarkably uniform* As already stated the primary connections of the ving to tha thorax ara quite similar* In aoma inaeota tha first axillary may be oonneoted to tha thorax only through the anterior notal wing pro oess while in others it la also oonneoted to an arm arising from tha lateral edge of the tergum, but yet not forming a soutellar lever*
The second axillary is always oonneoted to the pleural wing prooess, but the oonneotion may be restriotive in respeot to the amount of movement or it may be more or less loosely oonneoted so that it does not limit any movements*
If a speoial type of morphological relationship of the axillary region was peculiar to the asynohronous physiological type, one would suspect that it would be most evident in the Homoptera, since both types occur in this order* However no morphological peculiarity has been noted in the asynohronous specimens examined in this group or in any other representative of an aeynohronous type*
Thus, if the mechanical action of the thorax does control the physiological response of the flight muscles in the asynohronous types, it is not due to any specific modification of the thorax to accomplish this, but rather the thorax of all insects appear to have the capabilities of responding to the higher frequencies usually assooiated with insects of the asynohronous type* LITERATURE CITED
Amans, P.O. 1885* Qompariaons das organes du vol dans la serie
anloalo. Ann, Sol, Hat., ear. 6, Zool. XIXI 9-222.
Baranowski, R.M. 1955* A morphological study of tho axillary solerltos
of Tabanus, Unpublished Master's thesis, Univ, of Conn,
Boettiger, S.Q. and S. furshpan, 19^0. Observations on the flight
motor of Diptera, Biol. Bull., 99i
. 1951* Observations on tho flight motor of Diptera. Fed.
Aroa., 10il7.
... - . 1952. Meohanlos of flight in Diptera. Biol. Bull., 1021
200.211
1952* The reoording of flight movements. Science, II61
60-51.
Ohabrier, J. 1820. Essal sur level des inseotes. Mem. du Mus.
d'Hist. Hat., VI. 410-472.
Loans, T. 1890-92, The anatomy, physiology, morphology and develop
ment of the blow-fly. R.H. Barter, London.
Pipa, R.L. 1955* A comparative hletologloal study of the indirect
flight musolee of various insect orders. Unpublished Master's
thesis, Unlv. of Conn.
Pringle, J.V.9. 1949. The excitation and contraction of the flight
musolee of inseots. Jour. Jhyslol., 1081 226-222;
Ritter, V. 1911. The flying apparatus of the blow.fly. Smiths';
Mi so. Coll., 56(12)i 1-76,
Roeder, K.D. 1921* Movements of the thorax and potential changes in
the thoraolo musolee of inseots during flight. Biol. Bull.,
lOOt 95-106.
57 53
Snodgrass* H.S. 1909* Ths thorax of insoots and the articulations
of the wings* Proo* U.3. Nat* Mus*» }6t ^11.95*
1927* Morphology and neohanism of the insect thorax*
Smiths* Miso* Coll,, 80(1)t 108 pp*
1955* ftrinciples of insect morphology* McGraw-Hill Book
Oo** New York*
Straus-Durokheim* H* 1828* Oonsiderationes generales sur 1'anatorn!e
compares des animaus artieules* Royal Institute of Prance*
Voss* P* 190$* Uber den Thorax won Qryllus domestlcue* mit besonderer
Berucksiohtigung des flugelgelenks und dessen Bewegung* Zeit* P*
Viss. Zool.* LXXYIIt 268-521, 654-759. LIST 07 ABBREVIATIONS
Z«*«..««••••••••. first axillary aolerita
IZ ...... •••••• seoond axillary solerito
ZIZ ••••• ...... third axillary solerito
IV...... fourth axillary solerlte
ANP •••••»••••••••* anterior notal wing process ba ...... basalare
0 •••••••••• ...... costa hp...... humeral plate l**************** ligament m ...... ••••••• median plate
MVP • ...... ••••••• mesopleural wing prooess
M'VP •••••••••••••• metapleural wing prooess ph ...... •••••• phragma
FNP posterior notal wing prooess prso ••••••«• ...... presoutum sa •••••••••••••»• subalare
So ••••••••••••••• suboosta si ...... ••••••••• soutellar lever
59 ILLUSTRATIONS
60 FLATS Z
Figure 1* Support to hold inseot and recording eleotrodea* D
FIG. I FLATS II
Piguro 2* Dorsal view of axillary region, Dlssostelra Carolina (L«)»
Figure J. Pleural view of axillary region, £• Carolina. FIG. 3 PLATS IV
Figure 6. Dorsal view of axillary region, Maglcicada aeptendecim (L.).
Figure 7* Pleural view of axillary region, M. aeptendecim. W % W!' \\ vi ' \ \N
FIG 5 FLATS III
Figaro h. Dorsal viov of axillary region, Aeanthooephala terminalIs
(Dallas).
Figaro *>• Pleural view of axillary region, terminal is. FIG 7 PLATE V
Figure 8* Dorsal view of axillary region, Umbonla orasaloorhle
(A. & SO*
Figure 9» Articulation of the first axillary solerlte to the
anterior notal wing prooess, U. oraasloornls.
Figure 10* Pleural view of axillary region, U. erassloornls# FIG 10 FLATS VI
Figure 11. Dorsal Yiew of axillary region, Fhyllophaga drakii (Kirby).
Figure 12. Pleural view of axillary region, P. drakii. c PUTS VII
Figaro IJ. Dorool view of axillary rogion* Panorpa nobuloaa
Wostwood.
Figure 14. Pleural view of axillary region, P. nebuloea. FIG. 13
G PLATS VIII
Pigur® 15» Dorsal Tie® of axillary region, pycnopsyoho olrcularlg (Proy«)»
Figure 16. Pleural view of axillary region, P. elreularls r--X
FIG. 15
MWP
_,G. 5 PUTS IX
Pigur* X?. Dorsal Yiew of axillary roglon, Protoparoe aexta (Johan,)•
Figure 18, Pleural.Yiew of axillary region, P. »exts_. ANP-- PLATS X
Figure 19* Dorsal view of axillary region, Veepuln naculata (L.).
Figure 20* Pleural view of axillary region, V* naoulcta. -Sc
FIG. 19
"C _j PLATE XI
Figures 21 > JO. Thoraolo potentials and wingbeat frequency.
Upper trace - wingbeat frequency, lover
trace - thoracio potentials.
Figure 21* D. Carolina.
Figure 22* Tiblcen oanloularis Harris*
Figure 22* Unknown species of Oeroopidae.
Figure 24. P. nebuloea.
Figure 25* Platycentropus vadlatus (Say).
Figure 26, Unknown species of Sphingidae.
Figure 2?. Megalotonus qulnquesplnosue Say.
Figure 23. Monobia quadridens (L.).
Figure 29. Telamona sp.
Figure ?0. Ponana rublda DeLong. * * ■ ' * * z' V 'V ^ ^ ^ V /V i V >^v*^ • '*v^• ^ »%
J ’*v
FIG. 21 FIG 22 FIG. 23
T~' vV FIG. 24 FIG 25 FIG. 26 vv J' FIG. 27 , />. , / .'■ srr. N/ V 'v v s. ^ V V ! ' y - '*' \ C- v^Vyv'. # ■ V FIG. 2 9 FIG. 30