THE CICADA: HIS MUSIC
By his own confession, Réaumur never heard the Cicada sing; he never
saw the insect alive. It reached him from the country round Avignon
preserved in spirits and a goodly supply of sugar. These conditions
were enough to enable the anatomist to give an exact description of the
organ of sound; nor did the master fail to do so: his penetrating eye
clearly discerned the construction of the strange musical-box, so much
so that his treatise upon it has become the fountain-head for any one
who wants to say a few words about the Cicada’s song.
With him the harvest was gathered; it but remains to glean a few ears
which the disciple hopes to make into a sheaf. I have more than enough
of what Réaumur lacked: I hear rather more of these deafening
symphonists than I could wish; and so I shall perhaps obtain a little
fresh light on a subject that seems exhausted. Let us therefore go back
to the question of the Cicada’s song, repeating only so much of the
data acquired as may be necessary to make my explanation clear.
In my neighbourhood I can capture five species of Cicadæ, namely,
Cicada plebeia, Lin.; C. orni, Lin.; C. hematodes, Lin.; C. atra,
Oliv.; and C. pygmæa, Oliv. The first two are extremely common; the
three others are rarities, almost unknown to the country-folk.
The Common Cicada is the biggest of the five, the most popular and the
one whose musical apparatus is usually described. Under the male’s
chest, immediately behind the hind-legs, are two large semicircular
plates, overlapping each other slightly, the right plate being on the
top of the left. These are the shutters, the lids, the dampers, in
short the opercula of the organ of sound. Lift them up. You then see
opening, on either side, a roomy cavity, known in Provence by the name
of the chapel (li capello). The two together form the church (la
glèiso). They are bounded in front by a soft, thin, creamy-yellow
membrane; at the back by a dry pellicle, iridescent as a soap-bubble
and called the mirror (mirau) in the Provençal tongue.
The church, the mirrors and the lids are commonly regarded as the
sound-producing organs. Of a singer short of breath it is said that he
has cracked his mirrors (a li mirau creba). Picturesque language says
the same thing of an uninspired poet. Acoustics give the lie to the
popular belief. You can break the mirrors, remove the lids with a cut
of the scissors, tear the yellow front membrane and these mutilations
will not do away with the Cicada’s song: they simply modify it, weaken
it slightly. The chapels are resonators. They do not produce sound,
they increase it by the vibrations of their front and back membranes;
they change it as their shutters are opened more or less wide.
The real organ of sound is seated elsewhere and is not easy to find,
for a novice. On the other side of each chapel, at the ridge joining
the belly to the back, is a slit bounded by horny walls and masked by
the lowered lid. Let us call it the window. This opening leads to a
cavity or sound-chamber deeper than the adjacent chapel, but much less
wide. Immediately behind the attachment of the rear wings is a slight,
almost oval protuberance, which is distinguished by its dull-black
colour from the silvery down of the surrounding skin. This protuberance
is the outer wall of the sound-chamber.
Let us make a large cut in it. We now lay bare the sound-producing
apparatus, the cymbal. This is a little dry, white membrane,
oval-shaped, convex on the outside, crossed from end to end of its
longer diameter by a bundle of three or four brown nervures, which give
it elasticity, and fixed all round in a stiff frame. Imagine this
bulging scale to be pulled out of shape from within, flattening
slightly and then quickly recovering its original convexity owing to
the spring of its nervures. The drawing in and blowing out will produce
a clicking sound.
Twenty years ago, all Paris went mad over a silly toy called the
Cricket, or Cri-cri, if I remember rightly. It consisted of a short
blade of steel, fastened at one end to a metallic base. Alternately
pressed out of shape with the thumb and then released, the said blade,
though possessing no other merit, gave out a very irritating click; and
nothing more was needed to make it popular. The Cricket’s vogue is
over. Oblivion has done justice to it so drastically that I doubt if I
shall be understood when I recall the once famous apparatus.
The membranous cymbal and steel Cricket are similar instruments. Both
are made to rattle by pushing an elastic blade out of shape and
restoring it to its original condition. The Cricket was bent out of
shape with the thumb. How is the convexity of the cymbals modified? Let
us go back to the church and break the yellow curtain that marks the
boundary of each chapel in front. Two thick muscular columns come in
sight, of a pale orange colour, joined together in the form of a V,
with its point standing on the insect’s median line, on the lower
surface. Each of these fleshy columns ends abruptly at the top, as
though lopped off; and from the truncated stump rises a short, slender
cord which is fastened to the side of the corresponding cymbal.
There you have the whole mechanism, which is no less simple than that
of the metal Cricket. The two muscular columns contract and relax,
shorten and lengthen. By means of the terminal thread each tugs at its
cymbal, pulling it down and forthwith letting it spring back of itself.
Thus are the two sound-plates made to vibrate.
Would you convince yourself of the efficacy of this mechanism? Would
you make a dead but still fresh Cicada sing? Nothing could be simpler.
Seize one of the muscular columns with the pincers and jerk it gently.
The dead Cri-cri comes to life again; each jerk produces the clash of
the cymbal. The sound is very feeble, I admit, deprived of the fulness
which the living virtuoso obtains with the aid of his sound-chambers;
nevertheless the fundamental element of the song is produced by this
anatomical trick.
Would you on the other hand silence a live Cicada, that obstinate
melomaniac who, when you hold him prisoner in your fingers, bewails his
sad lot as garrulously as, just now, he sang his joys in the tree? It
is no use to break open his chapels, to crack his mirrors: the shameful
mutilation would not check him. But insert a pin through the side slit
which we have called the window and touch the cymbal at the bottom of
the sound-chamber. A tiny prick; and the perforated cymbal is silent. A
similar operation on the other side renders the insect mute, though it
remains as vigorous as before, showing no perceptible wound. Any one
unacquainted with the method of procedure stands amazed at the result
of my pin-prick, when the utter destruction of the mirrors and the
other accessories of the church does not produce silence. A tiny and in
no way serious stab has an effect which is not caused even by
evisceration.
The lids, those firmly fitted plates, are stationary. It is the abdomen
itself which, by rising and falling, causes the church to open and
shut. When the abdomen is lowered, the lids cover the chapels exactly,
together with the windows of the sound-chambers. The sound is then
weakened, muffled, stifled. When the abdomen rises, the chapels open,
the windows are unobstructed and the sound acquires its full strength.
The rapid oscillations of the belly, therefore, synchronizing with the
contractions of the motor-muscles of the cymbals, determine the varying
volume of the sound, which seems to come from hurried strokes of a bow.
When the weather is calm and warm, about the middle of the day, the
Cicada’s song is divided into strophes of a few seconds’ duration,
separated by short pauses. The strophe begins abruptly. In a rapid
crescendo, the abdomen oscillating faster and faster, it acquires its
maximum volume; it keeps up the same degree of strength for a few
seconds and then becomes gradually weaker and degenerates into a
tremolo which decreases as the belly relapses into rest. With the last
pulsations of the abdomen comes silence, which lasts for a longer or
shorter time according to the condition of the atmosphere. Then
suddenly we hear a new strophe, a monotonous repetition of the first;
and so on indefinitely.
It often happens, especially during the sultry evening hours, that the
insect, drunk with sunshine, shortens and even entirely suppresses the
pauses. The song is then continuous, but always with alternations of
crescendo and decrescendo. The first strokes of the bow are given at
about seven or eight o’clock in the morning; and the orchestra ceases
only with the dying gleams of the twilight, at about eight o’clock in
the evening. Altogether the concert lasts the whole round of the clock.
But, if the sky be overcast, if the wind blow cold, the Cicada is dumb.
The second species is only half the size of the Common Cicada and is
known in the district by the name of the Cacan, a fairly accurate
imitation of his peculiar rattle. This is the Ash Cicada of the
naturalists; and he is far more alert and more suspicious than the
first. His harsh loud song consists of a series of Can! Can! Can! Can!
with not a pause to divide the ode into strophes. Its monotony and its
harsh shrillness make it a most unpleasant ditty, especially when the
orchestra is composed of some hundreds of executants, as happens in my
two plane-trees during the dog-days. At such times it is as though a
heap of dry walnuts were being shaken in a bag until the shells
cracked. This irritating concert, a veritable torment, has only one
slight advantage about it: the Ash Cicada does not start quite so early
in the morning as the Common Cicada and does not sit up so late at
night.
Although constructed on the same fundamental principles, the vocal
apparatus displays numerous peculiarities which give the song its
special character. The sound-chamber is entirely lacking, which means
that there is no entrance-window either. The cymbal is uncovered, just
behind the insertion of the hind-wing. It again is a dry, white scale,
convex on the outside and crossed by a bundle of five red-brown
nervures.
The first segment of the abdomen thrusts forward a short, wide tongue,
which is quite rigid and of which the free end rests on the cymbal.
This tongue may be compared with the blade of a rattle which, instead
of fitting into the teeth of a revolving wheel, touches the nervures of
the vibrating cymbal more or less closely. The harsh, grating sound
must, I think, be partly due to this. It is hardly possible to verify
the fact when holding the creature in our fingers: the startled Cacan
does anything at such times rather than emit his normal song.
The lids do not overlap; on the contrary, they are separated by a
rather wide interval. With the rigid tongues, those appendages of the
abdomen, they shelter one half of the cymbals, the other half of which
is quite bare. The abdomen, when pressed with the finger, does not open
to any great extent where it joins the thorax. For the rest, the insect
keeps still when it sings; it knows nothing of the rapid quivering of
the belly that modulates the song of the Common Cicada. The chapels are
very small and almost negligible as sounding-boards. There are mirrors,
it is true, but insignificant ones, measuring scarcely a twenty-fifth
of an inch. In short, the mechanism of sound, which is so highly
developed in the Common Cicada, is very rudimentary here. How then does
the thin clash of the cymbals manage to gain in volume until it becomes
intolerable?
The Ash Cicada is a ventriloquist. If we examine the abdomen by holding
it up to the light, we see that the front two thirds are translucent.
Let us snip off the opaque third part that retains, reduced to the
strictly indispensable, the organs essential to the propagation of the
species and the preservation of the individual. The rest of the belly
is wide open and presents a spacious cavity, with nothing but its
tegumentary walls, except in the case of the dorsal surface, which is
lined with a thin layer of muscle and serves as a support to the
slender digestive tube, which is little more than a thread. The large
receptacle, forming nearly half of the insect’s total bulk, is
therefore empty, or nearly so. At the back are seen the two motor
pillars of the cymbals, the two muscular columns arranged in a V. To
the right and left of the point of this V gleam the two tiny mirrors;
and the empty space is continued between the two branches into the
depths of the thorax.
This hollow belly and its thoracic complement form an enormous
resonator, unapproached by that of any other performer in our district.
If I close with my finger the orifice in the abdomen which I have just
clipped, the sound becomes lower, in conformity with the laws affecting
organ-pipes; if I fit a cylinder, a screw of paper, to the mouth of the
open belly, the sound becomes louder as well as deeper. With a paper
funnel properly adjusted, its wide end thrust into the mouth of a
test-tube acting as a sounding-board, we have no longer the shrilling
of the Cicada but something very near the bellowing of a Bull. My small
children, happening to be there at the moment when I am making my
acoustic experiments, run away scared. The familiar insect inspires
them with terror.
The harshness of the sound appears to be due to the tongue of the
rattle rasping the nervures of the vibrating cymbals; its intensity may
no doubt be ascribed to the spacious sounding-board of the belly.
Assuredly one must be passionately enamoured of song thus to empty
one’s belly and chest in order to make room for a musical-box. The
essential vital organs are reduced to the minimum, are confined to a
tiny corner, so as to leave a greater space for the sounding-cavity.
Song comes first; all the rest takes second place.
It is a good thing that the Ash Cicada does not follow the teaching of
the evolutionists. If, becoming more enthusiastic from generation to
generation, he were able by progressive stages to acquire a ventral
sounding-board fit to compare with that which my paper screws give him,
my Provence, peopled as it is with Cacans, would one day become
uninhabitable.
After the details which I have already given concerning the Common
Cicada, it seems hardly necessary to say how the insupportable
chatterbox of the Ash is rendered dumb. The cymbals are clearly visible
on the outside. You prick them with the point of a needle. Complete
silence follows instantly. Why are there not in my plane-trees, among
the dagger-wearing insects, auxiliaries who, like myself, love quiet
and who would devote themselves to that task! A mad wish! A note would
then be lacking in the majestic harvest symphony.
The Red Cicada (C. hematodes) is a little smaller than the Common
Cicada. He owes his name to the blood-red colour that takes the place
of the other’s brown on the veins of the wings and some other
lineaments of the body. He is rare. I come upon him occasionally in the
hawthorn-bushes. As regards his musical apparatus, he stands half-way
between the Common Cicada and the Ash Cicada. He has the former’s
oscillation of the belly, which increases or reduces the strength of
the sound by opening or closing the church; he possesses the latter’s
exposed cymbals, unaccompanied by any sound-chamber or window.
The cymbals therefore are bare, immediately after the attachment of the
hind-wings. They are white, fairly regular in their convexity and boast
eight long, parallel nervures of a ruddy brown and seven others which
are much shorter and which are inserted singly in the intervals between
the first. The lids are small and scolloped at their inner edge so as
to cover only half of the corresponding chapel. The opening left by the
hollow in the lid has as a shutter a little pallet fixed to the base of
the hind-leg, which, by folding itself against the body or lifting
slightly, keeps the aperture either shut or open. The other Cicadæ have
each a similar appendage, but in their case it is narrower and more
pointed.
Moreover, as with the Common Cicada, the belly moves freely up and
down. This heaving movement, combined with the play of the femoral
pallets, opens and closes the chapels to varying extents.
The mirrors, though not so large as the Common Cicada’s, have the same
appearance. The membrane that faces them on the thorax side is white,
oval and very delicate and is tight-stretched when the abdomen is
raised and flabby and wrinkled when the abdomen is lowered. In its
tense state it seems capable of vibration and of increasing the sound.
The song, modulated and subdivided into strophes, suggests that of the
Common Cicada, but is much less objectionable. Its lack of shrillness
may well be due to the absence of any sound-chambers. Other things
being equal, cymbals vibrating uncovered cannot possess the same
intensity of sound as those vibrating at the far end of an echoing
vestibule. The noisy Ash Cicada also, it is true, lacks that vestibule;
but he amply makes up for its absence by the enormous resonator of his
belly.
I have never seen the third Cicada, sketched by Réaumur and described
by Olivier [16] under the name of C. tomentosa. The species is known in
Provence, so this and that one tells me, by the name of the Cigalon, or
rather Cigaloun, the Little Cigale or Cicada. This designation is
unknown in my neighbourhood.
I possess two other specimens which Réaumur probably confused with the
one of which he gives us a drawing. One is the Black Cicada (C. atra,
Oliv.), whom I came across only once; the other is the Pigmy Cicada (C.
pygmæa, Oliv.), whom I have picked up pretty often. I will say a few
words about this last one.
He is the smallest member of the genus in my district, the size of an
average Gad-fly, and measures about three-quarters of an inch in
length. His cymbals are transparent, with three opaque veins, are
scarcely sheltered by a fold in the skin and are in full view, without
any sort of entrance-lobby or sound-chamber. I may remark, in
terminating our survey, that the entrance-lobby exists only in the
Common Cicada; all the others are without it.
The dampers are separated by a wide interval and allow the chapels to
open wide. The mirrors are comparatively large. Their shape suggests
the outline of a kidney-bean. The abdomen does not heave when the
insect sings; it remains stationary, like the Ash Cicada’s. Hence a
lack of variety in the melody of both.
The Pigmy Cicada’s song is a monotonous rattle, pitched in a shrill
key, but faint and hardly perceptible a few steps away in the calm of
our enervating July afternoons. If ever a fancy seized him to forsake
his sun-scorched bushes and to come and settle down in force in my cool
plane-trees—and I wish that he would, for I should much like to study
him more closely—this pretty little Cicada would not disturb my
solitude as the frenzied Cacan does.
We have now ploughed our way through the descriptive part; we know the
instrument of sound so far as its structure is concerned. In
conclusion, let us ask ourselves the object of these musical orgies.
What is the use of all this noise? One reply is bound to come: it is
the call of the males summoning their mates; it is the lovers’ cantata.
I will allow myself to discuss this answer, which is certainly a very
natural one. For fifteen years the Common Cicada and his shrill
associate, the Cacan, have thrust their society upon me. Every summer
for two months I have them before my eyes, I have them in my ears.
Though I may not listen to them gladly, I observe them with a certain
zeal. I see them ranged in rows on the smooth bark of the plane-trees,
all with their heads upwards, both sexes interspersed with a few inches
between them.
With their suckers driven into the tree, they drink, motionless. As the
sun turns and moves the shadow, they also turn around the branch with
slow lateral steps and make for the best-lighted and hottest surface.
Whether they be working their suckers or moving their quarters, they
never cease singing.
Are we to take the endless cantilena for a passionate call? I am not
sure. In the assembly the two sexes are side by side; and you do not
spend months on end in calling to some one who is at your elbow. Then
again, I never see a female come rushing into the midst of the very
noisiest orchestra. Sight is enough as a prelude to marriage here, for
it is excellent; the wooer has no use for an everlasting declaration:
the wooed is his next-door neighbour.
Could it be a means then of charming, of touching the indifferent one?
I still have my doubts. I notice no signs of satisfaction in the
females; I do not see them give the least flutter nor sway from side to
side, though the lovers clash their cymbals never so loudly.
My neighbours the peasants say that, at harvest-time, the Cicada sings,
“Sego, sego, sego! Reap, reap, reap!” to encourage them to work.
Whether harvesters of wheat or harvesters of thought, we follow the
same occupation, one for the bread of the stomach, the other for the
bread of the mind. I can understand their explanation, therefore; and I
accept it as an instance of charming simplicity.
Science asks for something better; but she finds in the insect a world
that is closed to us. There is no possibility of divining or even
suspecting the impression produced by the clash of the cymbals upon
those who inspire it. All that I can say is that their impassive
exterior seems to denote complete indifference. Let us not insist too
much: the private feelings of animals are an unfathomable mystery.
Another reason for doubt is this: those who are sensitive to music
always have delicate hearing; and this hearing, a watchful sentinel,
should give warning of any danger at the least sound. The birds, those
skilled songsters, have an exquisitely fine sense of hearing. Should a
leaf stir in the branches, should two wayfarers exchange a word, they
will be suddenly silent, anxious, on their guard. How far the Cicada is
from such sensibility!
He has very clear sight. His large faceted eyes inform him of what
happens on the right and what happens on the left; his three stemmata,
like little ruby telescopes, explore the expanse above his head. The
moment he sees us coming, he is silent and flies away. But place
yourself behind the branch on which he is singing, arrange so that you
are not within reach of the five visual organs; and then talk, whistle,
clap your hands, knock two stones together. For much less than this, a
bird, though it would not see you, would interrupt its singing and fly
away terrified. The imperturbable Cicada goes on rattling as though
nothing were afoot.
Of my experiments in this matter, I will mention only one, the most
memorable. I borrow the municipal artillery, that is to say, the
mortars which are made to thunder forth on the feast of the
patron-saint. The gunner is delighted to load them for the benefit of
the Cicadæ and to come and fire them off at my place. There are two of
them, crammed as though for the most solemn rejoicings. No politician
making the circuit of his constituency in search of re-election was
ever honoured with so much powder. We are careful to leave the windows
open, to save the panes from breaking. The two thundering engines are
set at the foot of the plane-trees in front of my door. No precautions
are taken to mask them: the Cicadæ singing in the branches overhead
cannot see what is happening below.
We are an audience of six. We wait for a moment of comparative quiet.
The number of singers is checked by each of us, as are the depth and
rhythm of the song. We are now ready, with ears pricked up to hear what
will happen in the aerial orchestra. The mortar is let off, with a
noise like a genuine thunder-clap.
There is no excitement whatever up above. The number of executants is
the same, the rhythm is the same, the volume of sound the same. The six
witnesses are unanimous: the mighty explosion has in no way affected
the song of the Cicadæ. And the second mortar gives an exactly similar
result.
What conclusion are we to draw from this persistence of the orchestra,
which is not at all surprised or put out by the firing of a gun? Am I
to infer from it that the Cicada is deaf? I will certainly not venture
so far as that; but, if any one else, more daring than I, were to make
the assertion, I should really not know what arguments to employ in
contradicting him. I should be obliged at least to concede that the
Cicada is extremely hard of hearing and that we may apply to him the
familiar saying, to bawl like a deaf man.
When the Blue-winged Locust takes his luxurious fill of sunshine on a
gravelly path and with his great hind-shanks rubs the rough edge of his
wing-cases; when the Green Tree-frog, suffering from as chronic a cold
as the Cacan, swells his throat among the leaves and distends it into a
resounding bladder at the approach of a storm, are they both calling to
their absent mates? By no means. The bow-strokes of the first produce
hardly a perceptible stridulation; the throaty exuberance of the second
is no more effective: the object of their desire does not come.
Does the insect need these sonorous outbursts, these loquacious
avowals, to declare its flame? Consult the vast majority, whom the
meeting of the two sexes leaves silent. I see in the Grasshopper’s
fiddle, the Tree-frog’s bagpipes and the cymbals of the Cacan but so
many methods of expressing the joy of living, the universal joy which
every animal species celebrates after its kind.
If any one were to tell me that the Cicadæ strum on their noisy
instruments without giving a thought to the sound produced and for the
sheer pleasure of feeling themselves alive, just as we rub our hands in
a moment of satisfaction, I should not be greatly shocked. That there
may be also a secondary object in their concert, an object in which the
dumb sex is interested, is quite possible, quite natural, though this
has not yet been proved.