THE CICADA: THE LAYING AND THE HATCHING OF THE EGGS
The Common Cicada entrusts her eggs to small dry branches. All those
which Réaumur examined and found to be thus tenanted were derived from
the mulberry-tree: a proof that the person commissioned to collect
these eggs in the Avignon district was very conservative in his methods
of search. In addition to the mulberry-tree, I, on the other hand, find
them on the peach, the cherry, the willow, the Japanese privet and
other trees. But these are exceptions. The Cicada really favours
something different. She wants, as far as possible, tiny stalks, which
may be anything from the thickness of a straw to that of a lead-pencil,
with a thin ring of wood and plenty of pith. So long as these
conditions are fulfilled, the actual plant matters little. I should
have to draw up a list of all the semiligneous flora of the district
were I to try and catalogue the different supports used by the Cicada
when laying her eggs. I shall content myself with naming a few of them
in a note, to show the variety of sites of which she avails herself.
[17]
The sprig occupied is never lying on the ground; it is in a position
more or less akin to the perpendicular, most often in its natural
place, sometimes detached, but in that case sticking upright by
accident. Preference is given to a good long stretch of smooth, even
stalk, capable of accommodating the entire laying. My best harvests are
made on the sprigs of Spartium junceum, which are like straws crammed
with pith, and especially on the tall stalks of Asphodelus cerasiferus,
which rise for nearly three feet before spreading into branches.
The rule is for the support, no matter what it is, to be dead and quite
dry. Nevertheless my notes record a few instances of eggs confided to
stalks that are still alive, with green leaves and flowers in bloom. It
is true that, in these highly exceptional cases, the stalk itself is of
a pretty dry variety. [18]
The work performed by the Cicada consists of a series of pricks such as
might be made with a pin if it were driven downwards on a slant and
made to tear the ligneous fibres and force them up slightly. Any one
seeing these dots without knowing what produced them would think first
of some cryptogamous vegetation, some Sphæriacea swelling and bursting
its skin under the growth of its half-emerging perithecia.
If the stalk be uneven, or if several Cicadæ have been working one
after the other at the same spot, the distribution of the punctures
becomes confused and the eye is apt to wander among them, unable to
perceive either the order in which they were made or the work of each
individual. One characteristic is never missing, that is the slanting
direction of the woody strip ploughed up, which shows that the Cicada
always works in an upright position and drives her implement downwards
into the twig, in a longitudinal direction.
If the stalk be smooth and even and also of a suitable length, the
punctures are nearly equidistant and are not far from being in a
straight line. Their number varies: it is small when the mother is
disturbed in her operation and goes off to continue her laying
elsewhere; it amounts to thirty or forty when the line of dots
represents the total amount of eggs laid. The actual length of the row
for the same number of thrusts likewise varies. A few examples will
enlighten us in this respect: a row of thirty measures 28 centimetres
[19] on the toad-flax, 30 [20] on the gum-succory and only 12 [21] on
the asphodel.
Do not imagine that these variations in length have to do with the
nature of the support: there are plenty of instances that prove the
contrary; and the asphodel, which in one case shows us the punctures
that are closest together, will in other cases show us those which are
farthest removed. The distance between the dots depends on
circumstances which cannot be explained, but especially on the caprice
of the mother, who concentrates her laying more at one spot and less at
another according to her fancy. I have found the average measurement
between one hole and the next to be 8 to 10 millimetres. [22]
Each of these abrasions is the entrance to a slanting cell, usually
bored in the pithy portion of the stalk. This entrance is not closed,
save by the bunch of ligneous fibres which are parted at the time of
the laying but which come together again when the double saw of the
ovipositor is withdrawn. At most, in certain cases, but not always, you
see gleaming through the threads of this barricade a tiny glistening
speck, looking like a glaze of dried albumen. This can be only an
insignificant trace of some albuminous secretion which accompanies the
eggs or else facilitates the play of the double boring-file.
Just under the prick lies the cell, a very narrow passage which
occupies almost the entire distance between its pin-hole and that of
the preceding cell. Sometimes even there is no partition separating the
two; the upper floor runs into the lower; and the eggs, though inserted
through several entrances, are arranged in an uninterrupted row.
Usually, however, the cells are distinct.
Their contents vary greatly. I count from six to fifteen eggs in each.
The average is ten. As the number of cells of a complete laying is
between thirty and forty, we see that the Cicada disposes of three to
four hundred eggs. Réaumur arrived at the same figures from his
examination of the ovaries.
A fine family truly, capable by sheer numbers of coping with very grave
risks of destruction. Yet I do not see that the adult Cicada is in
greater danger than any other insect: he has a vigilant eye, can get
started quickly, is a rapid flyer and inhabits heights at which the
cut-throats of the meadows are not to be feared. The Sparrow, it is
true, is very fond of him. From time to time, after careful strategy,
the enemy swoops upon the plane-trees from the neighbouring roof and
grabs the frenzied fiddler. A few pecks distributed right and left cut
him up into quarters, which form delicious morsels for the nestlings.
But how often does not the bird return with an empty bag! The wary
Cicada sees the attack coming, empties his bladder into his assailant’s
eyes and decamps.
No, it is not the Sparrow that makes it necessary for the Cicada to
give birth to so numerous a progeny. The danger lies elsewhere. We
shall see how terrible it can be at hatching- and also at laying-time.
Two or three weeks after the emergence from the ground, that is to say,
about the middle of July, the Cicada busies herself with her eggs. In
order to witness the laying without trusting too much to luck, I had
taken certain precautions which seemed to me to assure success. The
insect’s favourite support is the dry asphodel: I had learnt that from
earlier observations. This plant is also the one that lends itself best
to my plans, owing to its long, smooth stalk. Now, during the first
years of my residence here, I replaced the thistles in my enclosure by
other native plants, of a less forbidding character. The asphodel is
among the new occupants and is just what I want to-day. I therefore
leave last year’s dry stalks where they are; and, when the proper
season comes, I inspect them daily.
I have not long to wait. As early as the 15th of July, I find as many
Cicadæ as I could wish installed on the asphodels, busily laying. The
mother is always alone. Each has a stalk to herself, without fear of
any competition that might disturb the delicate process of inoculation.
When the first occupant is gone, another may come, followed by others
yet. There is ample room for all; but each in succession wishes to be
alone. For the rest, there is no quarrelling among them; things happen
most peacefully. If some mother appears and finds the place already
taken, she flies away so soon as she discovers her mistake and looks
around elsewhere.
The Cicada, when laying, always carries her head upwards, an attitude
which, for that matter, she adopts in other circumstances. She lets you
examine her quite closely, even under the magnifying-glass, so greatly
absorbed is she in her task. The ovipositor, which is about two-fifths
of an inch long, is buried in the stalk, slantwise. So perfect is the
tool that the boring does not seem to call for very laborious
operations. I see the mother give a jerk or two and dilate and contract
the tip of her abdomen with frequent palpitations. That is all. The
drill with its double gimlets working alternately digs and disappears
into the wood, with a gentle and almost imperceptible movement. Nothing
particular happens during the laying. The insect is motionless. Ten
minutes or so elapse between the first bite of the tool and the
complete filling of the cell.
The ovipositor is then withdrawn with deliberate slowness, so as not to
warp it. The boring-hole closes of itself, as the ligneous fibres come
together again, and the insect climbs a little higher, about as far as
the length of its instrument, in a straight line. Here we see a new
punch of the gimlet and a new chamber receiving its half-a-score of
eggs. In this fashion the laying works its way up from bottom to top.
Once we know these facts, we are in a position to understand the
remarkable arrangement controlling the work. The punctures, the
entrances to the cells, are almost equidistant, because each time the
Cicada ascends about the same height, roughly the length of her
ovipositor. Very rapid in flight, she is a very lazy walker. All that
you ever see her do on the live branch on which she drinks is to move
to a sunnier spot close by, with a grave and almost solemn step. On the
dead branch where the eggs are laid she retains her leisurely habits,
even exaggerating them, in view of the importance of the operation. She
moves as little as need be, shifting her place only just enough to
avoid letting two adjoining cells encroach upon each other. The measure
of the upward movement is provided approximately by the length of the
bore.
Also the holes are arranged in a straight line when their number is not
great. Why indeed should the laying mother veer to the left or right on
a stalk which has the same qualities all over? Loving the sun, she has
selected the side of the stalk that is most exposed to it. So long as
she feels on her back a douche of heat, her supreme joy, she will take
good care not to leave the situation which she considers so delightful
for another upon which the sun’s rays do not fall so directly.
But the laying takes a long time when it is all performed on the same
support. Allowing ten minutes to a cell, the series of forty which I
have sometimes seen represents a period of six to seven hours. The sun
therefore can alter its position considerably before the Cicada has
finished her work. In that case the rectilinear direction becomes bent
into a spiral curve. The mother turns around her stalk as the sun
itself turns; and her row of pricks suggests the course of the gnomon’s
shadow on a cylindrical sundial.
Very often, while the Cicada is absorbed in her work of motherhood, an
infinitesimal Gnat, herself the bearer of a boring-tool, labours to
exterminate the eggs as fast as they are placed. Réaumur knew her. In
nearly every bit of stick that he examined he found her grub, which
caused him to make a mistake at the beginning of his researches. But he
did not see, he could not see the impudent ravager at work. It is a
Chalcidid some four to five millimetres [23] in length, all black, with
knotty antennæ, thickening a little towards their tips. The unsheathed
boring-tool is planted in the under part of the abdomen, near the
middle, and sticks out at right angles to the body, as in the case of
the Leucospes, [24] the scourge of certain members of the Bee-tribe.
Having neglected to capture the insect, I do not know what name the
nomenclators have bestowed upon it, if indeed the dwarf that
exterminates Cicadæ has been catalogued at all.
What I do know something about is its calm temerity, its brazen
audacity in the immediate presence of the colossus who could crush it
by simply stepping on it. I have seen as many as three exploiting the
unhappy mother at the same time. They keep close behind each other,
either working their probes or awaiting the propitious moment.
The Cicada has just stocked a cell and is climbing a little higher to
bore the next. One of the brigands runs to the abandoned spot; and
here, almost under the claws of the giantess, without the least fear,
as though she were at home and accomplishing a meritorious act, she
unsheathes her probe and inserts it into the column of eggs, not
through the hole already made, which bristles with broken fibres, but
through some lateral crevice. The tool works slowly, because of the
resistance of the wood, which is almost intact. The Cicada has time to
stock the next floor above.
As soon as she has finished, a Gnat standing immediately behind her,
waiting to perform her task, takes her place and comes and introduces
her own exterminating germ. By the time that the mother has exhausted
her ovaries and flies away, most of her cells have, in this fashion,
received the alien egg which will be the ruin of their contents. A
small, quick-hatching grub, one only to each chamber, generously fed on
a round dozen raw eggs, will take the place of the Cicada’s family.
O deplorable mother, have centuries of experience taught you nothing?
Surely, with those excellent eyes of yours, you cannot fail to see the
terrible sappers, when they flutter around you, preparing their felon
stroke! You see them, you know that they are at your heels; and you
remain impassive and let yourself be victimized. Turn round, you
easy-going colossus, and crush the pigmies! But you will do nothing of
the sort: you are incapable of altering your instincts, even to lighten
your share of maternal sorrow.
The Common Cicada’s eggs are of a gleaming ivory-white. Elongated in
shape and conical at both ends, they might be compared with miniature
weavers’-shuttles. They are two millimetres and a half long by half a
millimetre wide. [25] They are arranged in a row, slightly overlapping.
The Ash Cicada’s, which are a trifle smaller, are packed in regular
parcels mimicking microscopic bundles of cigars. We will devote our
attention exclusively to the first; their story will tell us that of
the others.
September is not over before the gleaming ivory-white gives place to
straw-colour. In the early days of October there appear, in the front
part, two little dark-brown spots, round and clearly-defined, which are
the ocular specks of the tiny creature in course of formation. These
two shining eyes, which almost look at you, combined with the
cone-shaped fore-end, give the eggs an appearance of finless fishes,
the very tiniest of fishes, for which a walnut-shell would make a
suitable bowl.
About the same period, I often see on my asphodels and those on the
hills around indications of a recent hatching. These indications take
the form of certain discarded clothes, certain rags left on the
threshold by the new-born grubs moving their quarters and eager to
reach a new lodging. We shall learn in an instant what these cast skins
mean.
Nevertheless, in spite of my visits, which were assiduous enough to
deserve a better result, I have never succeeded in seeing the young
Cicadæ come out of their cells. My home breeding prospers no better.
For two years running, at the right time, I collect in boxes, tubes and
jars a hundred twigs of all sorts colonized with Cicada-eggs; not one
of them shows me what I am so anxious to see, the emergence of the
budding Cicadæ.
Réaumur experienced the same disappointment. He tells us how all the
eggs sent by his friends proved failures, even when he carried them in
a glass tube in his fob to give them a mild temperature. O my revered
master, neither the warm shelter of our studies nor the niggardly
heating-apparatus of our breeches is enough in this case! What is
needed is that supreme stimulant, the kisses of the sun; what is
needed, after the morning coolness, which already is sharp enough to
make us shiver, is the sudden glow of a glorious autumn day, summer’s
last farewell.
It was in such circumstances as these, when a bright sun supplied a
violent contrast to a cold night, that I used to find signs of
hatching; but I always came too late: the young Cicadæ were gone. At
most I sometimes happened to find one hanging by a thread from his
native stalk and struggling in mid-air. I thought him caught in some
shred of cobweb.
At last, on the 27th of October, despairing of success, I gathered the
asphodels in the enclosure and, taking the armful of dry stalks on
which the Cicada had laid, carried it up to my study. Before abandoning
all hope, I proposed once more to examine the cells and their contents.
It was a cold morning. The first fire of the season had been lit. I put
my little bundle on a chair in front the hearth, without any intention
of trying the effect of the hot flames upon the nests. The sticks which
I meant to split open one by one were within easier reach of my hand
there. That was the only consideration which made me choose that
particular spot.
Well, while I was passing my magnifying-glass over a split stem, the
hatching which I no longer hoped to see suddenly took place beside me.
My bundle became alive; the young larvæ emerged from their cells by the
dozen. Their number was so great that my professional instincts were
amply satisfied. The eggs were exactly ripe; and the blaze on the
hearth, bright and penetrating, produced the same effect as sunlight
out of doors. I lost no time in profiting by this unexpected stroke of
luck.
At the aperture of the egg-chamber, among the torn fibres, a tiny
cone-shaped body appears, with two large black eye-spots. To look at,
it is absolutely the fore-part of the egg, which, as I have said,
resembles the front of a very minute fish. One would think that the egg
had changed its position, climbing from the bottom of the basin to the
orifice of the little passage. But an egg to move! A germ to start
walking! Such a thing was impossible, had never been known; I must be
suffering from an illusion. I split open the stalk; and the mystery is
revealed. The real eggs, though a little disarranged, have not changed
their position. They are empty, reduced to transparent bags, torn
considerably at their fore-ends. From them has issued the very singular
organism whose salient characteristics I will now set forth.
In its general shape, the configuration of the head and the large black
eyes, the creature, even more than the egg, presents the appearance of
an extremely small fish. A mock ventral fin accentuates the likeness.
This sort of oar comes from the fore-legs, which, cased in a special
sheath, lie backwards, stretched against each other in a straight line.
Its feeble power of movement must help the grub to come out of the
egg-shell and—a more difficult matter—out of the fibrous passage.
Withdrawing a little way from the body and then returning, this lever
provides a purchase for progression by means of the terminal claws,
which are already well-developed. The four other legs are still wrapped
in the common envelope and are absolutely inert. This applies also to
the antennæ, which can hardly be perceived through the lens.
Altogether, the organism newly issued from the egg is an exceedingly
small, boat-shaped body, with a single oar pointing backwards on the
ventral surface and formed of the two fore-legs joined together. The
segmentation is very clearly marked, especially on the abdomen. Lastly,
the whole thing is quite smooth, with not a hair on it.
What name shall I give to this initial state of the Cicada, a state so
strange and unforeseen and hitherto unsuspected? Must I knock Greek
words together and fashion some uncouth expression? I shall do nothing
of the sort, convinced as I am that barbarous terms are only a cumbrous
impediment to science. I shall simply call it “the primary larva,” as I
did in the case of the Oil-beetles, the Leucospes and the Anthrax. [26]
The form of the primary larva in the Cicadæ is eminently well-suited
for the emergence. The passage in which the egg is hatched is very
narrow and leaves just room for one to go out. Besides, the eggs are
arranged in a row, not end to end, but partly overlapping. The creature
coming from the farther ranks has to make its way through the remains
of the eggs already hatched in front of it. To the narrowness of the
corridor is added the block caused by the empty shells.
In these conditions, the larva in the form which it will have
presently, when it has torn its temporary scabbard, would not be able
to clear the difficult pass. Irksome antennæ, long legs spreading far
from the axis of the body, picks with curved and pointed ends that
catch on the road: all these are in the way of a speedy deliverance.
The eggs in one cell hatch almost simultaneously. It is necessary that
the new-born grubs in front should move out as fast as they can and
make room for those behind. This necessitates the smooth, boatlike
form, devoid of all projections, which makes its way insinuatingly,
like a wedge. The primary larva, with its different appendages closely
fixed to its body inside a common sheath, with its boat shape and its
single oar possessing a certain power of movement, has its part to
play: its business is to emerge into daylight through a difficult
passage.
Its task is soon done. Here comes one of the emigrants, showing its
head with the great eyes and lifting the broken fibres of the aperture.
It works its way farther and farther out, with a progressive movement
so slow that the lens does not easily perceive it. In half an hour at
soonest, the boat-shaped object appears entirely; but it is still
caught by its hinder end in the exit-hole.
The emergence-jacket splits without further delay; and the creature
sheds its skin from front to back. It is now the normal larva, the only
one that Réaumur knew. The cast slough forms a suspensory thread,
expanding into a little cup at its free end. In this cup is contained
the tip of the abdomen of the larva, which, before dropping to the
ground, treats itself to a sun-bath, hardens itself, kicks about and
tries its strength, swinging indolently at the end of its life-line.
This “little Flea,” as Réaumur calls it, first white, then amber, is at
all points the larva that will dig into the ground. The antennæ, of
fair length, are free and wave about; the legs work their joints; those
in front open and shut their claws, which are the strongest part of
them. I know hardly any more curious sight than that of this miniature
gymnast hanging by its hinder-part, swinging at the least breath of
wind and making ready in the air for its somersault into the world. The
period of suspension varies. Some larvæ let themselves drop in half an
hour or so; others remain for hours in their long-stemmed cup; and some
even wait until the next day.
Whether quick or slow, the creature’s fall leaves the cord, the slough
of the primary larva, swinging. When the whole brood has disappeared,
the orifice of the cell is thus hung with a cluster of short, fine
threads, twisted and rumpled, like dried white of egg. Each opens into
a little cup at its free end. They are very delicate and ephemeral
relics, which you cannot touch without destroying them. The slightest
wind soon blows them away.
Let us return to the larva. Sooner or later, without losing much time,
it drops to the ground, either by accident or of its own accord. The
infinitesimal creature, no bigger than a Flea, has saved its tender,
budding flesh from the rough earth by swinging on its cord. It has
hardened itself in the air, that luxurious eiderdown. It now plunges
into the stern realities of life.
I see a thousand dangers ahead of it. The merest breath of wind can
blow the atom here, on the impenetrable rock, or there, on the ocean of
a rut where a little water stagnates, or elsewhere, on the sand, the
starvation region where nothing grows, or again on a clay soil, too
tough for digging. These fatal expanses are frequent; and so are the
gusts that blow one away in this windy season which has already set in
unpleasantly by the end of October.
The feeble creature needs very soft soil, easily entered, so as to
obtain shelter immediately. The cold days are drawing nigh; the frosts
are coming. To wander about on the surface of the ground for any length
of time would expose us to grave dangers. We had better descend into
the earth without delay; and that to a good depth. This one imperative
condition of safety is in many cases impossible to realize. What can
little Flea’s-claws do against rock, flint or hardened clay? The tiny
creature must perish unless it can find an underground refuge in time.
The first establishment, which is exposed to so many evil chances, is,
so everything shows us, a cause of great mortality in the Cicada’s
family. Already the little black parasite, the destroyer of the eggs,
has told us how expedient it is for the mothers to accomplish a long
and fertile laying; the difficulties attendant upon the initial
installation in their turn explain why the maintenance of the race at
its suitable strength requires three or four hundred eggs to be laid by
each of them. Subject to excessive spoliation, the Cicada is fertile to
excess. She averts by the richness of her ovaries the multitude of
dangers threatening her.
In the experiment which it remains for me to make, I will at least
spare the larva the difficulties of the first installation. I select
some very soft, very black heath-mould and pass it through a fine
sieve. Its dark colour will enable me more easily to find the little
yellow creature when I want to see what is happening; and its softness
will suit the feeble mattock. I heap it not too tightly in a glass pot;
I plant a little tuft of thyme in it; I sow a few grains of wheat.
There is no hole at the bottom of the pot, though there ought to be, if
the thyme and the wheat are to thrive; the captives, however, finding
the hole, would be certain to escape through it. The plantation will
suffer from this lack of drainage; but at least I am certain of finding
my animals with the aid of my magnifying-glass and plenty of patience.
Besides, I shall indulge in no excesses in the matter of irrigation,
supplying only enough water to prevent the plants from dying.
When everything is ready and the corn is beginning to put forth its
first shoots, I place six young Cicada-larvæ on the surface of the
soil. The puny grubs run about and explore the earthy bed pretty
nimbly; some make unsuccessful attempts to climb the side of the pot.
Not one seems inclined to bury itself, so much so that I anxiously
wonder what the object can be of these active and prolonged
investigations. Two hours pass and the restless roaming never ceases.
What is it that they want? Food? I offer them some little bulbs with
bundles of sprouting roots, a few bits of leaves and some fresh blades
of grass. Nothing tempts them nor induces them to stand still. They
appear to be selecting a favourable spot before descending underground.
These hesitating explorations are superfluous on the soil which I have
industriously prepared for them: the whole surface, so it seems to me,
lends itself capitally to the work which I expect to see them
accomplish. Apparently it is not enough.
Under natural conditions, a preliminary run round may well be
indispensable. There, sites as soft as my bed of heath-mould, purged of
all hard bodies and finely sifted, are rare. There, on the other hand,
coarse soils, on which the microscopic mattock can make no impression,
are frequent. The grub has to roam at random, to walk about for some
time before finding a suitable place. No doubt many even die, exhausted
by their fruitless search. A journey of exploration, in a country a few
inches across, forms part, therefore, of the young Cicada’s curriculum.
In my glass jar, so sumptuously furnished, the pilgrimage is uncalled
for. No matter: it has to be performed according to the time-honoured
rites.
My gadabouts at last grow calm. I see them attack the earth with the
hooked mattocks of their fore-feet, digging into it and making the sort
of excavation which the point of a thick needle would produce. Armed
with a magnifying-glass, I watch them wielding their pick-axes, watch
them raking an atom of earth to the surface. In a few minutes a well
has been scooped out. The little creature goes down it, buries itself
and is henceforth invisible.
Next day I turn out the contents of the pot, without breaking the clod
held together by the roots of the thyme and the wheat. I find all my
larvæ at the bottom, stopped from going farther by the glass. In
twenty-four hours they have traversed the entire thickness of the layer
of earth, about four inches. They would have gone even lower but for
the obstacle at the bottom.
On their way they probably came across my thyme- and wheat-roots. Did
they stop to take a little nourishment by driving in their suckers? It
is hardly probable. A few of these rootlets are trailing at the bottom
of the empty pot. Not one of my six prisoners is installed on them.
Perhaps in overturning the glass I have shaken them off.
It is clear that underground there can be no other food for them than
the juice of the roots. Whether full-grown or in the larval stage, the
Cicada lives on vegetables. As an adult, he drinks the sap of the
branches; as a larva, he sucks the sap of the roots. But at what moment
is the first sip taken? This I do not yet know. What goes before seems
to tell us that the newly-hatched grub is in a greater hurry to reach
the depths of the soil, sheltered from the coming colds of winter, than
to loiter at the drinking-bars encountered on the way.
I put back the clod of heath-mould and for the second time place the
six exhumed larvæ on the surface of the soil. Wells are dug without
delay. The grubs disappear down them. Finally I put the pot in my
study-window, where it will receive all the influences of the outer
air, good and bad alike.
A month later, at the end of November, I make a second inspection. The
young Cicadæ are crouching, each by itself, at the bottom of the clod
of earth. They are not clinging to the roots; they have not altered in
appearance or in size. I find them now just as I saw them at the
beginning of the experiment, only a little less active. Does not this
absence of growth during the interval of November, the mildest month of
winter, seem to show that no nourishment is taken throughout the cold
season?
The young Sitaris-beetles, [27] those other animated atoms, as soon as
they issue from the egg at the entrance to the Anthophora’s [28]
galleries, remain in motionless heaps and spend the winter in complete
abstinence. The little Cicadæ would appear to behave in much the same
manner. Once buried in depths where there is no fear of frosts, they
sleep, solitary, in their winter-quarters and await the return of
spring before broaching some root near by and taking their first
refreshment.
I have tried, but without success, to confirm by actual observation the
inferences to be drawn from the above results. In the spring, in April,
for the third time I unpot my plantation. I break up the clod and
scrutinize it under the magnifying-glass. I feel as if I were looking
for a needle in a haystack. At last I find my little Cicadæ. They are
dead, perhaps of cold, notwithstanding the bell-glass with which I had
covered the pot; perhaps of starvation, if the thyme did not suit them.
The problem is too difficult to solve; I give it up.
To succeed in this attempt at rearing one would need a very wide and
deep bed of earth, providing a shelter from the rigours of winter, and,
because I do not know which are the insect’s favourite roots, there
would also have to be a varied vegetation, in which the little larvæ
could choose according to their tastes. These conditions are quite
practicable; but how is one afterwards to find in that huge mass of
earth, measuring a cubic yard at least, the atom which I have so much
trouble in distinguishing in a handful of black mould? And, besides,
such conscientious digging would certainly detach the tiny creature
from the root that nourishes it.
The underground life of the early Cicada remains a secret. That of the
well-developed larva is no better-known. When digging in the fields, if
you turn up the soil to any depth, you are constantly finding the
fierce little burrower under your spade; but to find it fastened to the
roots from whose sap it undoubtedly derives its nourishment is quite
another matter. The upheaval occasioned by the spade warns it of its
danger. It releases its sucker and retreats to some gallery; and, when
discovered, it is no longer drinking.
If agricultural digging, with its inevitable disturbances, is unable to
tell us anything of the grub’s underground habits, it does at least
inform us how long the larval stage lasts. Some obliging husbandmen,
breaking up their land, in March, rather deeper than usual, were so
very good as to pick up for me all the larvæ, big and small, unearthed
by their labour. The harvest amounted to several hundreds. Marked
differences in bulk divided the total into three classes: the large
ones, with rudiments of wings similar to those possessed by the larvæ
leaving the ground, the medium-sized and the small. Each of these
classes must correspond with a different age. We will add to them the
larvæ of the last hatching, microscopic creatures that necessarily
escaped the eyes of my rustic collaborators; and we arrive at four
years as the probable duration of the underground life of the Cicadæ.
Their existence in the air is more easily calculated. I hear the first
Cicadæ at the approach of the summer solstice. The orchestra attains
its full strength a month later. A few laggards, very few and very far
between, continue to execute their faint solos until the middle of
September. That is the end of the concert. As they do not all come out
of the ground at the same period, it is obvious that the singers of
September are not contemporary with those of June. If we strike an
average between these two extreme dates, we shall have about five
weeks.
Four years of hard work underground and a month of revelry in the sun:
this then represents the Cicada’s life. Let us no longer blame the
adult for his delirious triumph. For four years, in the darkness, he
has worn a dirty parchment smock; for four years he has dug the earth
with his mattocks; and behold the mud-stained navvy suddenly attired in
exquisite raiment, possessed of wings that rival the bird’s, drunk with
the heat and inundated with light, the supreme joy of this world! What
cymbals could ever be loud enough to celebrate such felicity, so richly
earned and so ephemeral!