Part 9
It is with this rostrum, which resembles a case of surgical instruments, that the _Nepa_ pierces and sucks little aquatic insects, not even sparing its own species. Its wound is painful to man, but not in the least dangerous. With its four hind legs the _Nepa_ swims, but at a very slow pace. It generally drags itself along the bottom of the water, on the mud, and does not avoid the hand put out to seize it. Its body is terminated by a tail, composed of two grooved threads, which, when applied together, form a tube, capable of being moved from side to side. Through this canal it breathes the outer air; it puts the end of it out of the water, and the air enters it by inspiration. Some very small hairs, with which the interiors of the grooves are lined, interlace each other, and prevent the water from penetrating into the canal. It is probable that this same canal serves also for depositing the eggs. These last resemble small seeds, covered with points, and are buried in the stalks of aquatic plants.
Next to the _Nepa_ comes the _Ranatra_, with a cylindrical, elongated, linear body, with very long and very thin hind legs, and of which one species, which Geoffroy calls the "aquatic scorpion with an elongated body," is common everywhere in stagnant waters in spring. It is brownish, carnivorous, and very voracious.
We must now mention the genus _Corixa_, of which one species, the _Corixa striata_, is very common. This insect walks badly and slowly on land, but swims and cuts through the water with a prodigious rapidity.
However, it is not to delay over this last species that we have here mentioned the name of this genus. Some insects which belong to it, and which are found in Mexico, deserve to be alluded to, on account of certain peculiarities which their eggs present. A naturalist, M. Virlet d'Aoust, has published the following details on this subject:--
"Thousands of small amphibious flies," he says, "flit about in the air on the surface of lakes, and diving down into the water many feet, and even many fathoms, go to the bottom to lay their eggs, and only emerge from the water probably to die close by. We were fortunate enough to be present at a great fishing or harvest of the eggs, which, under the Mexican name of _hautle_ (_haoutle_), serve for food to the Indians, who seem to be no less fond of them than the Chinese are of their swallows' nests, which they resemble somewhat in taste; only the _hautle_ is far from commanding such high prices as the Chinese pay for their birds' nests, which for that reason are reserved entirely for the tables of the rich; while, for a few small coins, we were able to carry away with us about a bushel of the _hautle_, a portion of which, at our request, Mme. B---- was kind enough to prepare for us.
"They dress these in different ways, but generally make a sort of cake, which is served up with a sauce, to which the Mexicans give a zest, as they do indeed to all their dishes, by adding to it _chilié_, which is composed of green pimento crushed. This is how the natives proceed when they are fishing for _hautle_: they form with reeds bent together a sort of fasces, which they place vertically in the lake at some distance from the bank, and as these are bound together by one of the reeds, the ends of which are so arranged as to form an indicating buoy, it is easy to draw them out at will. Twelve to fifteen days suffice for each reed in these fasces to be entirely covered with eggs, which they thus fish up by millions. The former are then left to dry in the sun, on a cloth, for an hour or more; the grains are then easily detached. After this operation, they are replaced in the water for the next hautle harvest."
M. Virlet had attributed to flies the eggs of which we have been speaking. But in 1851 M. Guérin-Méneville having received, transmitted to him by M. Ghiliani, eggs of which _hautle_ is made, and some of the insects said to produce them, stated that the latter belonged to two different species. The one had been known a long time since under the name of _Corixa mercenaria_; M. Guérin-Méneville called the other _Corixa femorata_.
The same entomologist discovered, among the eggs of these two species, other eggs of a more considerable size, and which he attributed to a new species of the genus _Notonecta_, about which we are now going to say a few words.
The _Notonecta glauca_, which Geoffroy calls the Large Bug with Oars ("Grande punaise à avirons"), is very common in ditches, reservoirs, and stagnant waters. Its body is oblong, narrow, contracted posteriorly, convex above, flat below, having, at its sides and its extremities, hairs which, when spread out, support the animal on the water. Its head is large and of a slightly greenish grey, and has on each of its sides a very large eye of a pale brown colour. Its thorax is greyish, the hemelytra of a greenish grey, the membranous wings white. Of its legs, the front four are short; but the hind legs, almost twice as long, are furnished with long hairs, and resemble oars. It is with the aid of these that the animal moves through the water; and it does so in a singular manner, placing itself on its back, and generally in an inclined position, as in Fig. 77.
When this insect, on the contrary, drags itself along on the mud, the front legs are those which it employs, the hind legs being idle, and merely drawn along behind it. It is generally towards the evening or during the night that it comes out of the water, to walk and to fly, if it wishes to pass from one marsh to another.
This bloodthirsty insect lives entirely by rapine; it is one of the most carnivorous of insects. Those which it attacks die very soon after they have been hurt by it. De Geer thinks that the water bug drops into the wound a poisonous humour. It seizes upon insects much bigger, and apparently much stronger, than itself, and does not spare its own species.
The instrument with which the _Notonecta_ attacks its prey is composed of a very strong and very long conical beak, formed of four joints. The sucker is composed of an upper piece, short and pointed, and of four fine pointed hairs.
The female of the _Notonecta glauca_ lays a great number of eggs, white, and of elongated shape, which it deposits on the stems and leaves of aquatic plants. The eggs are hatched at the beginning of spring, or in May, and the young ones at once begin to swim about like their mother, on their backs, belly upwards. M. Léon Dufour says on this subject:--
"A dorsal region, raised like a donkey's back, or like the rounded keel of a boat, and covered with a velvety substance, which renders it impermeable, numerous fine fringes which garnish either the hind legs, or the borders of the abdomen and thorax, or lastly in a double row form a crest or comb running down the surface of the belly, and which spread themselves out or fold themselves in at the will of the insect, just like fins, favour both this supine attitude and the accuracy of the swimming movements of the _Notonectæ_. Since Nature--which seems often to delight in producing extraordinary exceptions to her ordinary rules, thus bearing witness to the immensity of her resources--had condemned this animal to pass its life in an inverted position, it was necessary, for the maintenance of its existence, that it should provide it with an organisation in harmony with this attitude. It is also for this object that its head is bent over its chest; that its eyes, of an oval shape, can see below from above; that the front as well as the middle legs, agile and curved, solely destined for prehension, can to a certain extent become unbent by means of the elongated haunches which fix them to the body, and clutch firm hold of their prey with the strong claws which terminate the tarsi."
HOMOPTERA.
We come now to the second group of the order Hemiptera, namely, Homoptera.
The insects which compose this division are numerous. They may be arranged into three great families, of the most remarkable members of which we shall give some account. These are the _Cicadæ_, the _Aphidæ_ or Plant Lice, and the _Coccidæ_.
The Cicada is the type of the first of these families. It has a deafening and monotonous song; as Bilboquet says, in the "Saltimbanques," "those who like that note have enough of it for their money." Virgil pronounced a just criticism on the song of the Cicada: he saw in it nothing better than a hoarse and disagreeable sound:--
"At mecum raucis, tua dum vestigia lustro, Sole sub ardenti resonant arbusta cicadis,"
says the Latin poet in his "Eclogues," and repeats the same opinion in a verse in his "Georgics:"--
"Et cantu querulæ rumpent arbusta cicadæ."
The song of the Cicada, so sharp, so discordant, was, however, the delight of the Greeks.
Listen to Plato in the first lines of "Phædo:" "By Hera," cries the philosopher-poet, "what a charming place for repose!... It might well be consecrated to some nymphs and to the river Achelöu, to judge by these figures and statues. Taste a little the good air one breathes. How charming, how sweet! One hears as a summer noise an harmonious murmur accompanying the chorus of the Cicada."
The Greeks, then, had quite a peculiar taste for the song of the Cicada. They liked to hear its screeching notes, sharp as a point of steel. To enjoy it quite at their ease they shut them up in open wicker-work cages, pretty much in the same way as children shut up the cricket, so as to hear its joyous _cri-cri_. They carried their love for this insect with the screaming voice so far as to make it the symbol of music. We see, in drawings emblematical of the musical art, a Cicada resting on strings of a cythera. A Grecian legend relates that one day two cythera players, Eunomos and Aristo, contending on this sonorous instrument, one of the strings of the former's cythera having broken, a Cicada settled on it, and sang so well in place of the broken cord, that Eunomos gained the victory, thanks to this unexpected assistant. Anacreon composed an ode in honour of the Cicada. "Happy Cicada, that on the highest branches of the trees, having drank a little dew, singest like a queen! Thy realm is all thou seest in the fields, all which grows in the forests. Thou art beloved by the labourer; no one harms thee; the mortals respect thee as the sweet harbinger of summer. Thou art cherished by the muses, cherished by Phoebus himself, who has given thee thy harmonious song. Old age does not oppress thee. O good little animal, sprung from the bosom of the earth, loving song, free from suffering, that hast neither blood nor flesh, what is there prevents thee from being a god?"
It was in virtue of the false ideas of the Greeks on natural history in general, and on the Cicada in particular, that this little animal symbolised, among the Athenians, nobility of race. They imagined that the Cicada was formed at the expense of the earth, and in its bosom, on which account those who pretended to an ancient and high origin, wore in their hair a golden Cicada. The Locrians had on their coins the image of a Cicada. This is the origin which fable assigns to the custom:--
The bank of the river upon which Locris was built was covered with screeching legions of Cicadas; whereas they were never heard (so says the legend) on the opposite bank, on which stood the town Rhegium. In explanation of this circumstance, they pretend that Hercules, wishing one day to sleep on this bank, was so tormented by the "sweet eloquence" of the Cicadas, that, furious at their concert, he asked of the gods that they should never sing there for evermore, and his prayer was immediately granted! This is why the Locrians adopted the Cicada as the arms of their city.
The Greeks did not only delight, as poets and musicians, in the song of the Cicada; they were not content with addressing to it poems, with adoring it, and striking medals bearing its image; obedient to their grosser appetites, they ate it. They thus satisfied at the same time both the mind, the spirit, and the body.
The Cicadas are easily to be recognised by their heavy, very robust, and rather thick-set bodies, by their broad head, unprolonged, having very large and prominent _ocelli_, or simple eyes, three in number, arranged in a triangle on the top of the forehead, and short antennæ. The immature anterior and posterior wings have the shape of a sheath, or case, enveloping the body when the insect is at rest; these are transparent and destitute of colour, or sometimes adorned with bright and varied hues. The legs are not in the least suited for jumping. The female is provided with an auger, with which she makes holes in the bark of trees in which to lay her eggs. The male (Fig. 78) is provided with an organ, not of song, but of stridulation or screeching, which is very rudimentary in the female. We will stop a moment to consider the apparatus for producing the song, or rather the noise, of the male Cicada, and the structure of the female's auger. We are indebted to Réaumur for the discovery of the mechanism by the aid of which the Cicada produces the sharp noise which announces its whereabouts from afar. We will give a summary of the celebrated Memoir in which the French naturalist has so admirably described the musical apparatus of the Cicada.[24]
[24] "Mémoires," tome v. 4to.
It is not in the throat that the Cicada's organ of sound is placed, but on the abdomen. On examining the abdomen of the male of a large species of Cicada, one remarks on it two horny plates, of pretty good size, which are not found on the females. Each plate has one side straight; the rest of its outline is rounded. It is by the side which is rectilinear that the plate is fixed immediately underneath the third pair of legs. It can be slightly raised, with an effort, by two spine-like processes, each of which presses upon one of the plates, and when it is raised, prevents it from being raised too much, and causes it to fall back again immediately.
If the two plates are removed and turned over on the thorax, and the parts which they hide laid bare, one is struck by the appearance which is presented. "One cannot doubt that all one sees has been made to enable the Cicada to sing," says Réaumur. "When one compares the parts which have been arranged so that it may be able to sing, as we may say, from its belly, with the organs of our throat, one finds that ours have not been made with more care than those by means of which the Cicada gives forth sounds which are not always agreeable."
We here perceive a cavity in the anterior portion of the abdomen and which is divided into two principal cells by a horny triangle.
"The bottom of each cell offers to children who catch the Cicada a spectacle which amuses them, and which may be admired by men who know how to make the best use of their reason. The children think they see a little mirror of the thinnest and most transparent glass, or that a little blade of the most beautiful talc is set in the bottom of each of these little cells. That which one might see if this were the case would in no way differ from what one actually sees; the membrane which is stretched out at the bottom of the cells does not yield in transparency either to glass or to talc; and if one looks at it obliquely, one sees in it all the beautiful colours of the rainbow. It seems as if the Cicada has two glazed windows through which one can see into the interior of its body."
The horny triangle of which we spoke above only separates in two the lower part of the cavity. The upper part is filled by a white, thin, but strong membrane. This membrane is only drawn tight when the body of the Cicada is raised. But with all this, where is the organ of song? What parts produce the sound? Réaumur will enlighten us on this point.
He opened the back of a Cicada, and laid bare the portion of the interior which corresponds with the cavity where the mirrors are, and was immediately struck with the size of the two muscles which meet and are attached to the back of the horny triangle, and to that one of its angles from which start the sides which form the cavities in which are both the mirrors.
"Muscles of such strength, placed in the belly of the Cicada, and in that part of the belly in which they are found, seem to be only so placed in order that they may move quickly backwards and forwards those parts which, being set in motion, produce the noise or song. And indeed, whilst I was examining one of these muscles, in moving it about gently with a pin, slightly displacing it, and then letting it return to its proper place, it so happened that I made a Cicada that had been dead for many months sing. The song, as might be expected, was not loud; but it was strong enough to lead me on to the discovery of the part to which it was due. I had only to follow the muscle I had been moving, to search for the part on which it abutted."
In the large cavity, in which are the mirrors and the other parts mentioned above, there are besides two equal and similar compartments, two cells, in which are placed the instrument of sound. This is a membrane in the shape of a kettledrum, not smooth, but, on the contrary, crumpled and full of wrinkles (Fig. 79). When it is touched it is more sonorous than the driest parchment. If the furrows on its convex surface are rubbed with a small body, such as a piece of rolled-up paper, incapable of piercing or tearing it, it is easily made to sound; and the sound is occasioned by the portions of the kettledrum which are depressed by the friction of the small body, returning to their former position as soon as it has ceased to act upon them. It is here that the two strong muscles act whose existence and use were discovered by Réaumur.
"It is clear," says this naturalist, "that when the muscle is alternately contracted and expanded with rapidity, one convex portion of the kettledrum will be rendered concave, and will then resume its convex form by the force of its own spring. Then this noise will be made, this song of which we have been so long seeking an explanation, because we wished to find out all the parts by means of which He, who never makes anything without its use, willed that it should be produced."
Let us add, to complete what we have already said on this subject, that if the kettledrums are the essential organs of the insect's song, the mirrors, the white and wrinkled membranes, and the exterior shutters which cover in the whole apparatus, contribute largely, as Réaumur pointed out, to modify and strengthen the sound.
We have said above that the female Cicada does not sing; and so her singing organs are quite rudimentary. This fact, moreover, has been known for ages. Xenarchus, a poet of Rhodes, says, with little gallantry:--
"Happy Cicadas! thy females are deprived of voice!"
Nature has indemnified the female Cicada for this privation, by giving her an instrument less noisy indeed, but more useful. This is a sort of auger, destined to penetrate the bark of the branches of trees, and lodged in the last segment of the abdomen, which, for this purpose, is hollowed out groove-wise. By the aid of a system of muscles the auger can be protruded or retracted at pleasure. It is furnished with three implements. In the middle there is a piercer, or bodkin, which when run into a branch supports the insect, and two _stylets_, whose upper edges, having teeth like a saw, resting back to back, on the middle implement, move up and down it. With this admirable instrument the female Cicada incises obliquely the bark and wood until she has almost reached the pith (Fig. 80). The male sings while she is at work. When the cell is sufficiently deep and properly prepared, the female lays at the bottom of it from five to eight eggs.
From these eggs come very small white grubs (Fig. 81), which leave their nest, descend by the trunk, and bury themselves in the ground, where they devour the roots of the tree. They then become pupæ, and hollowing out the earth with their front legs, which are very much developed, continue to live at the expense of the roots. At the end of spring these pupæ (Fig. 82) come out of the earth, hook themselves on to the trunks of trees, and strip themselves one fine evening of their skin, which remains whole and dried. Very weak at first, these metamorphosed insects drag themselves along with difficulty. But next day, warmed by the first rays of the sun, having had, no doubt, time to reflect on their new social position, and less astonished than they were on the preceding evening, they agitate their wings, they fly, and the males send forth into the air the first notes of their screeching concert. The Cicadas remain on trees, whose sap they suck by means of their sharp-pointed beak. It is difficult enough to catch them, for owing to their large, highly-developed wings, they fly rapidly away on the slightest noise.
They inhabit the south of Europe, the whole of Africa from north to south, America in the same latitudes as Europe, the whole of the centre and south of Asia, New Holland, and the islands of Oceania. The Cicada, which in hot climates always exposes itself to the ardour of the most scorching sun, is not found in temperate or cold regions. The consequence is that the southern nations know it very well, whilst in the north the large grasshopper, which is so common in those regions, and whose song closely resembles that of the Cicada, is commonly taken for it. There was to be seen at the Exhibition of Fine Arts in 1866 a picture by M. Aussandon, "La Cigale et la Fourmi," which showed, under an allegorical shape, the subject of La Fontaine's fable. The painter here represented the Cigale, or Cicada, under the form of a magnificent apple-green grasshopper. The artist materialised here, as we may say, the common mistake of the inhabitants of the north, which makes them confound the Cicada with the great green grasshopper.
For the rest, we may, by-the-by, say that La Fontaine's fable of "La Cigale et la Fourmi" is full of errors in natural history. Nothing is easier than to prove the truth of this assertion. From the very first verses, the author shows that he has never observed the animal of which he speaks.
"La Cigale ayant chanté Tout l'été."
No Cicada could sing "tout l'été," since it lives at the utmost for a few weeks only.
"Se trouva fort dépourvue Quand la bise fut venue."
"Quand la bise fut venue" means without doubt the month of November or December. But at this season of the year the Cicada has a long time since passed from life to death. When one wanders along the outskirts of woods as early as the month of October, in the south of France, one finds the soil covered with dead Cicadas. La Fontaine's _Cigale_ then could not have found itself "fort dépourvue," for the simple reason that it was already dead.
"Elle alla crier famine Chez la Fourmi, sa voisine, La priant de lui preter Quelque grain pour subsister."
The ant is carnivorous, and although it likes honey, it has nothing to do with grains of wheat, nor with any other grain, of which, according to the fabulist, it had laid up a stock. On the other hand, the Cicada, which he blames for having
"Pas un seul petit morceau De mouche ou de vermisseau,"