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.
[Illustration: Fig. 78.--Cicada (Male).]
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.
[Illustration: Fig. 79.--Musical Apparatus of the Male Cicada.]
"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.
[Illustration: Fig. 80.--Female Cicada laying her eggs in the groove
she has bored in the branch of a tree.]
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.
[Illustration: Fig. 81.--Larva of the Cicada.]
[Illustration: Fig. 82.--Pupa of the Cicada.]
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,"
never dreamt of such victuals, for it lives entirely on the sap of
large vegetables. The fables of the poet, who is called in France, one
never knows why, "Le bon La Fontaine," teem with errors of the same
kind as those we have just pointed out. The habits of animals are
nearly always represented as exactly the contrary to what they really
are. To initiate himself into the mysteries of the habits of animals,
La Fontaine certainly had neither the works of Buffon nor the memoirs
of Réaumur, which had not then been written; but had he not the book
of Nature?
But it is time to mention the principal species of the Cicada. We will
describe two: that of the Ash, which lives on those trees in the south
of France; and that of the Manna Ash, which is very common in the
south-east of France. It is particularly plentiful in the forests of
pines which abound between Bayonne and Bordeaux. It is on these two
species of Cicada that Réaumur made the beautiful observations of
which we gave a summary above.
The _Cicada plebeia_ or _Tettigonia fraxini_, very common in Provence,
is found, though rarely, in the forest of Fontainebleau, occasionally
in La Brie. It is of a grey yellow below, black above; the head and
thorax are marked or striped with black.
M. Solier, in a Memoir inserted in the "Annales de la Société
Entomologique de France," says that its song, very loud and very
piercing, seems to consist of one single note, repeated with rapidity,
which insensibly grows weaker after a certain time, and terminates in
a kind of whistle, which can be partly imitated by pronouncing the two
consonants _st_, and which resembles the noise of the air coming out
of a little opening in a compressed bladder. When the Cicada sings, it
moves its abdomen violently, in such a manner as alternately to move
it away from, and to bring it near to, the little covers of the
sonorous cavities; to this movement is added a slight trembling of the
mesothorax.
The same entomologist relates a very interesting observation made on
this species of Cicada by his friend, M. Boyer, a chemist at Aix, and
which he himself verified. The Cicadas, in general, are very timid,
and fly away at the least noise. However, when a Cicada is singing,
one can approach it, whistling the while in a quavering manner, and
imitating as nearly as possible, its cry, but in such a manner as to
predominate over it. The insect then descends a small space down the
tree, as if to approach the whistler; then it stops. But if one
presents a stick to it, continuing to whistle, the Cicada settles on
it and begins again to descend backwards. From time to time it stops,
as if to listen. At last, attracted, and, as it were, fascinated by
the harmony of the whistle, it comes to the observer himself.
M. Boyer managed thus to make a Cicada, which continued to sing as
long as he whistled in harmony with it, settle on his nose. Charmed by
this concert, the insect seemed to have lost its natural timidity.
The _Cicada orni_ is of a greenish yellow, spotted with black. The
abdomen is encircled by the same colours. The elytra and the wings are
hyaline, or glassy, and their veins alternately yellow and brown. The
legs are yellow throughout. The song of this species is hoarse, and
cannot be heard at any great distance.
M. Solier, in the work we quoted just now, says that the song of this
Cicada is of a deeper intonation, but that it is quick and is sooner
over. It does not terminate in the manner which characterises that of
the other species.
Next the genus _Cicada_ comes _Fulgora_, whose type is the _Fulgora
lanternaria_, or Lantern Fly (Fig. 83).
Belonging to South America, these insects are above all remarkable and
easy to recognise, by their very large elongated head, which nearly
equals three-quarters of the rest of the body. This prolongation is
horizontal, vesiculous, enlarged to about the same breadth as the
head, and presents above a very great gibbosity. The antennæ are
short, with a globular second articulation, and a small terminal hair.
The species represented in Fig. 83 is yellow varied with black. The
elytra are of a greenish yellow, sprinkled with black; the wings, of
the same colour, have at the extremity a large spot resembling an eye,
which is surrounded by a brown circle very broad in front. It inhabits
Guyana. This remarkable insect enjoys a great renown with the vulgar,
by a peculiarity which might be called its speciality--the property of
shining by night or in the dark. Hence its name of _Fulgora
lanternaria_.
The knowledge of the _Fulgora lanternaria_ has been spread and
popularised in Europe by a celebrated book, which has for its
title, "Métamorphoses des Insectes de Surinam." This book, which
contains the result of patient study of the natural history of Dutch
Guyana (Government of Surinam), was written and published in three
languages, by a woman whose name this work has rendered immortal--Mlle.
Sybille de Mérian--and who won the admiration and respect of her
contemporaries by her love of the beauties of Nature, and her
perseverance in making them known and admired. Sybille de Mérian was
born at Bâle. Daughter, sister, and mother of celebrated engravers,
herself an excellent flower-painter, she had worked a long time at
Frankfort and at Nuremburg; and had read with the greatest attention
the "Théologie des Insectes,"[25] and with admiration Malpighi's book
on the silkworm. Full of enthusiasm for the study of natural history,
she left Germany, to visit the magnificent collection of plants which
were kept in the hot-houses of Holland, and made admirable
reproductions of them with her pencil.
[25] "Théologie des Insectes, ou Démonstration des Perfections
de Dieu dans tout ce qui concerne les Insectes, par Lesser,
traduit en Français." La Haye, 1742.
[Illustration: Fig. 83.--Lantern Fly (_Fulgora lanternaria_).]
This attentive study of the vegetable world suggested to her the idea,
which soon became an ardent desire, of observing these marvels of
Nature in those parts of the globe in which they display themselves
with the greatest magnificence and splendour. At the age of
fifty-four, Sybille de Mérian set out for equatorial America. From the
very first days of her arrival she hazarded her life, sometimes
without a guide, in the swampy plains or burning valleys of Guyana.
During the two years she sojourned in those dangerous parts, she made
a large collection of drawings and paintings, which were destined to
inaugurate in Europe the introduction of art into natural history.
In the plates to her work, Sybille de Mérian represents always the
insects she wishes to describe under its three forms of larva, pupa,
and perfect insect. With this drawing she gives another of the plants
which serves the insect for food, as also of the animals which prey on
it. Each plate is a little drama. Near the insect is seen the greedy
lizard opening its dreadful mouth, or the ferocious spider watching
for it. The short life of insects is shown here in its entirety, with
its continual struggles, its infinite artifices, its rapid end, and
all the episodes of its existence, for which life, as in the case of
the moral man, is but a long and painful struggle.
Such was the work, such was the noble devotion and the worthy career
of Sybille de Mérian. Let women, let young girls, who are martyrs to
the ennui of a life devoid of occupation, peruse her beautiful books,
and learn from it how much a woman may do with the time which is now
either utterly unoccupied or only devoted to useless employments. To
study Nature in any of its phases ought, it seems to us, to give more
satisfaction to the soul, more strength to the mind, and cause more
admiration of and gratitude to the supreme Author of Nature than doing
a little embroidery.
It is, as we have already said, in the work of Sybille de Mérian,
"Métamorphoses des Insectes de Surinam," that one finds mentioned, for
the first time, the luminous properties of the _Fulgora lanternaria_.
The author thus relates her observations, which were the result of
chance:--
"Some Indians having one day brought me a great number of the Lantern
Flies, I shut them up in a large box, not knowing then that they gave
light at night. Hearing a noise, I sprang out of bed and had a candle
brought. I very soon discovered that the noise proceeded from the box,
which I hurriedly opened; but, alarmed at seeing emerging from it a
flame, or, to speak more correctly, as many flames as there were
insects, I at first let it fall. Having recovered from my astonishment,
or rather from my fright, I caught all my insects again, and admired
this singular property of theirs."
Since the time when Mlle. de Mérian visited Guyana, different
travellers have said that they could not observe, as she did, this
phosphorescent phenomenon. It is, then, probable that this property
only exists in the male or female insect, and then only at certain
seasons.
What a marvellous spectacle must the rich valleys of Guyana present,
when, in the stillness of the night, the air is filled with living
torches; when, the _Fulgoræ_ flying about in space, the flashes of
fire cross each other, go out and blaze up again, shine brightly and
then die out, and present, on a calm evening, the appearance of those
lightning flashes which are usually seen only in the midst of a
tempest!
Let us now go on to another interesting insect of the order of which
we are treating, the Aphrophora, without being frightened by its
disagreeable name, for there are many other names we may give it if we
choose among those by which it is popularly known. In the months of
June and July one sees on nearly every tree, and on plants of the most
different kinds, a sort of white froth, composed of air bubbles,
deposited on the leaves and branches. It is produced by an insect
which the peasants in France call _Crachat de Coucou_, or _Ecume
printanière_ (spring froth), and which is called in England, Cuckoo's
spittle. De Geer carefully studied the metamorphoses of this insect.
The Aphrophora (from [Greek: aphros], foam, and [Greek: pherô], I bear
or carry) is lodged in the froth of which we have just been speaking.
It lives in it, only leaving it when it has its wings. De Geer
wondered why this insect confines itself during the whole of its life
in liquid, and concludes that the froth has the effect of protecting
the insect from the burning heat of the sun. This covering seems also
to protect it from the attacks of carnivorous insects and spiders. On
the other hand, its skin is without doubt so constituted that it would
perspire too freely if it were exposed to the air, and the insect
would very soon die dried up. Whatever explanation may be given of the
necessity for this semi-aërial, semi-liquid medium, it is easy to
verify the fact that the larva of the Aphrophora cannot live long out
of its frothy envelope. If withdrawn from it, the volume of its body
diminishes perceptibly, and the poor animal dies, like a fish taken
out of its natural element.
The insects which live in this froth are six-legged grubs (Fig. 84),
which, when the froth is cleared from them, walk quickly enough on the
stalks and leaves of plants. They are green, with the belly yellow.
[Illustration: Fig. 84.--Larva of the Aphrophora (_Aphrophora
spumaria_).]
De Geer wished to know how they produced this singular froth, and
found out in the following manner:--He took one of them out of its
frothy dwelling, wiped it dry with a camel's-hair pencil, and placed
it on a young stalk, recently cut from the honeysuckle, which he put
into water in a glass, in order to preserve its freshness, and this is
what he observed:--
"It begins," says the Swedish naturalist, "by fixing itself on a
certain part of the stalk, in which it inserts the end of its trunk,
and remains thus for a long time in the same attitude, occupied in
sucking and filling itself with the sap. Having then withdrawn its
trunk, it remains there, or else places itself on a leaf, where, after
different reiterated movements of its abdomen, which it raises or
lowers and turns on all sides, one may see coming out of the hinder
part of its body a little ball of liquid, which it causes to slip
along, bending it under its body. Beginning the same movements again,
it is not long in producing a second globule of liquid, filled with
air like the first, which it places side by side with, and close to,
the preceding one, and continues the same operation as long as there
remains any sap in its body. It is very soon covered with a number of
small globules, which, coming out of its body one after the other,
tend towards the front part, aided in this by the movement of the
abdomen. It is all these globules collected together which form a
white and extremely fine froth whose viscosity keeps the air shut up
in the globules, and prevents its froth from easily evaporating. If
the sap which the larva has drawn from the plant is exhausted before
it feels itself sufficiently covered with froth, it begins to suck
afresh, until it has got a new and sufficient quantity of froth,
which it takes care to add to its first stock."[26]
[26] "Mémoires pour servir à l'Histoire des Insectes,"
tome iii.
It is in the froth that the larvæ change into pupæ, and they do not
leave their habitation to undergo their final metamorphosis. They have
then, says De Geer, the art of causing the froth inside to evaporate
and dry up, in such a manner as to form a space inside the mass of
froth, in which their bodies are entirely free. The exterior froth
forms a roof closed in on all sides, under which the insect lies quite
dry.
In this vaulted cell the pupa disengages itself little by little from
its skin, which first splits up along the head, and then on the
thorax. This opening is sufficiently large to enable it to come out of
its envelope. It is in the month of September that these insects are
particularly abundant, and then the trees and plants are covered with
them. Sometimes the froth drips off, like a sort of small rain, from
branches which are covered with it. Towards the autumn the females are
pregnant. They are then so heavy that they can hardly jump or fly. The
males, on the contrary, make prodigious bounds; they throw themselves
forward to a distance of more than two yards. They are very difficult
to catch, and still more difficult to find again when one has once let
them escape. And so Swammerdam calls these insects _Sauterelles-Puces_
(Flea-Grasshoppers), because they jump like fleas.
All that we have said relates to the _Aphrophora spumaria_, or
Froghopper (Fig. 85), an insect common all over Europe, and which
Geoffroy calls the _Cigale bedeaude_.
[Illustration: Fig. 85.--The Froghopper (_Aphrophora spumaria_).]
"It is of a brown colour," says Geoffroy, "often rather greenish. Its
head, its thorax, and its elytra, are finely dotted; on these last one
sees two white oblong spots. The lower part of the insect is light
brown."[27]
[27] "Histoire abrégée des Insectes, dans laquelle ces animaux
sont rangés dans un ordre méthodique." In 4to. Tome i., p. 416.
An VII. de la République.
We will mention, as it belongs to the group with which we are now
occupied, a noxious insect, _Iassus devastans_, which since 1844 seems
to have taken up its quarters in the commune of Saint Paul, in the
department of the Basses-Alpes. It sucks the leaves and stalks of
cereals, causing them to wither, and may be found even in winter
on young corn, but principally in the spring. According to M.
Guérin-Méneville, its head is of an ochrey yellow, with the apex
marked with black spots; the forehead yellow, elongated, striped with
black, as are the legs. The elytra are straw-coloured and spotted with
brown. The wings are transparent, and slightly blackened at the
extremities. This remarkable insect, which is not more than the
twelfth of an inch in length, jumps and flies with great ease.
[Illustration: Fig. 86.--1. Hypsauchenia balista. 2. Membracis foliata.
3. Centrotus cornutus. 4. Umbonia Spinosa. 5. Bocydium globulare.
6. Cyphonia furcata.]
A small brownish insect, whose strange appearance struck Geoffroy, the
historian of the insects of the environs of Paris, may be seen
springing over the fern stalks and thistles, in the damp parts of most
of the woods of Europe.
Geoffroy calls this insect "le Petit Diable." "Le Petit Diable," he
writes, "is of a dark blackish-brown. Its head is flat, projecting but
slightly, and, as it were, bent downwards. Its thorax, which is rather
broad, has two sharp horns, which terminate in pretty long points on
the sides. In the middle of the thorax is a crest or comb, which,
prolonged into a sort of sinuous and crooked horn, terminates in a
very sharp point, reaching to within one quarter of the extremity
of the wing-cases. These--viz., the wing-cases--are dark, with
brown veins; and the wings, shorter than their cases, are rather
transparent. The insect jumps very well, and is not readily
caught."[28]
[28] "Histoire abrégée des Insectes, dans laquelle ces animaux
sont rangés dans un ordre méthodique." In 4to. Tome i., p. 423.
An VII. de la République.
The Petit Diable of Geoffroy is the _Centrotus cornutus_ of modern
naturalists. This curious little insect belongs to a strange and
remarkable group, whose thorax takes the most extraordinary and most
varied forms, as may be seen in Fig. 86, which represents somewhat
magnified, many of these insects. Nearly all inhabit Guyana, the
Brazils, and Florida.
We will now proceed to examine one of the most interesting groups of
insects--that of the Plant-lice. These insects have for a long time
attracted the attention of naturalists. They are so abundant that all
our readers have seen them, and there are few plants in our fields or
gardens which do not nourish some species. How often does one hesitate
in gathering a rose or a bit of honeysuckle, for fear of touching the
unattractive guest of those charming flowers!
During the whole of the summer one sees on the branches, on the
leaves, but principally on the young shoots of the rose-tree, large
companies of green plant-lice, which subsist on the sap of the tree.
Some are provided with wings (Figs. 87, 88), others are wingless
(Figs. 89, 90). The last-named are the largest, and are a line and a
half long. They are entirely green, except two parts, of which we will
speak immediately. The body is oval; the head is small, and furnished
with two brown eyes. The skin is smooth, and tightly drawn over the
body. The antennæ, which are very long and slender, almost equal the
body in length. The six legs are long and slim, and the short feet
terminate in two hooks. On the upper part of the body are two small
cylindrical horns, surmounted by a small knob. The antennæ and these
horns are black.
The winged individuals are of the same size as these, but are of a
dark green colour, mixed with black. The wings are transparent, and
the upper ones are as long again as the body. The young shoots of the
elder-tree, all round their circumference for the length of from a
foot to a foot and a half, are often covered with black plant-lice, or
with those of a greenish-black colour. They are crowded one against
the other, and sometimes there are two layers of them.
[Illustration: Fig. 87, 88.--Winged Aphides, or Plant-lice (magnified).]
If observed without moving the plant about, they appear to be tranquil
and inactive. They are, however, then absorbing from the plant the
nourishment it should have; piercing with the point of their trunks
the epidermis of the leaves or stalks, and drawing from them a
nourishing liquid.
But this occupation is confined to those which are on the plant
itself. Those which, on account of the enormous agglomeration of these
insects, walk, not on the branch, but on other plant-lice, and cannot
therefore suck the sap of the plant, are employed entirely in
preserving and multiplying their species.
[Illustration: Fig. 89, 90.--Wingless Aphides, or Plant-lice (magnified).]
Réaumur often saw the latter, easily recognised by their great size,
giving birth to little plant-lice, which are quite alive when they
leave their mother. The young ones set off and mount or descend till
they reach one end of the crowd, and there each takes up its position,
like a cardboard capuchin (_capucin de carte_), in such a manner that
the head is just behind the plant-louse which precedes it. There they
bury their trunks in the vegetable tissue, and set to work to imbibe
the sap.
Small as is the trunk of the plant-louse, yet when there are thousands
of those little beings fixed to the stalk or the leaves of a plant, it
is evident that it must suffer. And so the plant-louse is, in truth,
one of the most terrible enemies of our agricultural and horticultural
productions, and the exact list of the ravages which it occasions
would be indeed interminable. We will confine ourselves to a few
examples. For some years the lime-tree aphis has seriously attacked
the lime-trees of the public promenades of Paris. The peach-tree
plant-louse causes the blight of the leaves of that tree. It is to
these prolific little parasites that are due, in a great number of
cases, the contortions of leaves and of the young shoots of trees of
all sorts.
These insatiable depredators cause sometimes a still more remarkable
alteration. On the leaves of elms are often seen bladders round and
rosy, like little apples. On opening these bladders one finds that
they are inhabited by a species of aphis. On the black poplar galls of
different kinds grow, some from the leaf stalks, and others from the
young stems. They are rounded, oblong, horned, and twisted into a
spiral. Other galls show themselves on the leaf itself. They are all
inhabited by plant-lice, differing from those of which we have given a
description above, in the extremity of their abdomen not presenting
the two remarkable horns to which we shall have later to call the
attention of the reader. The body is generally covered with a long and
thick down.
Of this genus, the species, alas! so unfortunately celebrated is the
Apple-tree Aphis (_Myzoxyle mali_), which attacks that tree. This
insect is of a dark russet brown, with the upper part of the abdomen
covered with very long white down. Its presence was announced for the
first time in England in 1789, and in France, in the department of the
Côtes du Nord, in 1812. In 1818 it was found in Paris, in the garden
of the École de Pharmacie. It had become common in 1822 in the
departments of the Seine, the Somme, and the Aisne. In 1827 its
presence in Belgium was announced.
The apple-tree aphis, according to M. Blot, can only exist on that
tree. Carried away and placed on any other, it very soon perishes. It
does not attack the blossom, the fruit, nor the leaves, but fixes
itself on the lower part of the trunk, whence it propagates itself
downwards as far as the roots, underneath the graftings, &c. It also
likes to lodge in cracks of the trunk and large branches. But it
always looks out for a southern, and avoids a northern aspect. It is
not active, walks very little, and its dissemination from one place to
another can only be explained by the facility with which so small an
insect can be transported by the wind, its lightness being still more
increased by the down which covers it.
The _Myzoxyle mali_ renders the wood knotty, dry, hard, brittle, and
brings on rapidly all the symptoms which characterise old age and
decay in attacked trees. M. Blot recommends the following means for
preserving the apple-tree from this insect: Employ for the seed-beds
the pips of bitter apples only; give to the nursery and to the plants
only as much shelter as is absolutely necessary; avoid those sites
which are too low and too damp; encourage the circulation of air, and
the desiccation of the soil; surround the foot of each apple-tree with
a mixture of soot or of tobacco and fine sand.
As for the manner of freeing a tree once invaded by this insect, the
most simple plan is to rub the trunk and the branches, in order to
crush the insects, or to employ a brush or broom.
We spoke above of the reproduction of the aphis, but without entering
into any particular details; we will now touch upon this question, one
of the most interesting in natural history.
It was at the time when Réaumur was writing his immortal "Histoire des
Insectes," when Trembley was publishing his admirable researches on
the freshwater Hydra, whose wonderful vitality we have mentioned in
our work on Zoophytes and Molluscs,[29] that another naturalist
astonished the learned world by his experiments on the reproductions
of plant-lice. This naturalist, whose name will live quite as long as
those of Réaumur and of Trembley, was Charles Bonnet, of Geneva.
[29] "The Ocean World."
Charles Bonnet made the extraordinary discovery that aphides can
increase and multiply without the intervention of the sexes. An
isolated specimen can produce a series of generations of its kind. We
will relate the curious experiments of the Genevese naturalist. He
placed in a flower-pot, filled with mould, a phial full of water, and
put into this phial a little branch of spindle, having only five or
six leaves, and perfectly free from any insect. On one of these leaves
he placed a plant-louse, which was born under his own eyes, of a
wingless mother. He then covered the branch with a glass shade, whose
rim fitted exactly into the top of the flower-pot. Having taken these
precautions, Charles Bonnet was perfectly certain of being able to
observe his prisoner at his ease. He could keep it under his eye and
under his hand, with more certitude and security than was the
mythological Danaë, shut up, by order of Acrisius, in a tower of
bronze.
"I took care," says Charles Bonnet, "to keep a correct journal of the
life of my insect. I noted down its least movements; nothing it did
seemed to me indifferent. Not only did I observe it every day from
hour to hour, beginning generally at four or five o'clock in the
morning, and only leaving off at about nine or ten at night; but I
even looked many times in the same hour, and always with the
magnifying glass, to render my observation more exact, and to learn
the most secret actions of my little lonely one. But if this continual
application cost me some trouble, and bored me not a little, in amends
I had some cause for self-applause and for having subjected myself to
all this trouble.... My plant-louse changed its skin four times: on
the 23rd, in the evening; on the 26th, at two in the afternoon; on the
29th, at seven o'clock in the morning; and on the 31st, at about seven
o'clock in the evening.... Happily delivered from these four illnesses
through which it was obliged to pass, it at last reached that point to
which, by my care, I had been trying to bring it. It had become a
perfect plant-louse. On the 1st of June, at about seven o'clock in the
evening, I saw, with great satisfaction, that it had given birth to
another; from that time I thought I ought to look upon it as a female.
From that day up to the 20th inclusive, she produced ninety-five
little ones, all alive and doing well, the greatest number of which
were born under my own eyes!"[30]
[30] "Traité d'Insectologie, ou Observations sur les Pucerons,"
pp. 28-38. 1re partie, 18mo. Paris, 1745.
He very soon made some other experiments on the aphis of the
elder-tree, so as to assure himself if the generations of plant-lice,
reared successively in solitude, preserved the same property of
procreating without copulation.
"On the 12th of July," says he, "about three o'clock in the afternoon,
I shut up a plant-louse that had just been born under my eyes. On the
20th of the same month, at six o'clock in the morning, it had already
produced three little ones. But I waited till the 22nd towards noon
before I shut up a plant-louse of the second generation, because I
could not manage earlier to be present at the birth of one of those
produced by the mother I had condemned to live in solitude. I always
continued to observe the same precaution. I shut up only those
plant-lice which were born under my very eyes. A third generation
began on the 1st of August; it was on this day that the plant-louse I
had shut up on the 22nd of July gave birth to this generation. On the
4th of August, about one o'clock in the afternoon, I put into solitary
confinement a plant-louse of the third generation. On the ninth of the
same month, at six in the evening, a fourth generation, due to this
last one, had already seen the light: it had given birth to four
little ones. On the same day, towards midnight, all intercourse with
its own species was forbidden to the plant-louse of the fourth
generation born at that hour. On the 18th, between six and seven
o'clock in the morning, I found this last in the company of four
little ones to which it had given birth."[31]
[31] "Traité d'Insectologie," &c., pp. 67-69.
In this case, the want of food caused the death of the isolated
individual of the fifth generation, and the experiment was brought to
a close.
Bonnet then tried experiments on the plantain aphis, following them up
during five consecutive generations, which succeeded each other
without interruption, in the space of three months.
After having stated the extraordinary facts, which he relates with the
most perfect simplicity, Charles Bonnet, examining at the end of the
fine season specimens of the winged oak-tree aphis, was able to be
present at their nuptials. He preserved the females with great care,
and saw, not without profound astonishment, that they gave birth, not
to small living insects, as was the case in the first experiments, but
to eggs of a reddish colour, which were stuck fast to each other, on
the stem or stalk of the plant.
A short time afterwards, this illustrious observer was able to
convince himself that the oak-tree plant-lice, whose nuptials he had
witnessed in the autumn, present the same phenomena of solitary and
viviparous propagation, already so often mentioned by him.
At last some new observations permitted him to establish beyond all
doubt the connection of these facts, in appearance so contradictory.
He discovered that, during the whole of the fine season, the
plant-lice are solitary and viviparous, but that towards the autumn
these creatures return to the ordinary course of things, and are
propagated by eggs, whose development requires the co-operation of a
male and female individual. These eggs are hatched in Spring, and
produce only viviparous plant-lice. In the autumn the males and
females show themselves, and from that moment ovipositing recommences.
These curious facts, seen and published more than a century ago, have
been verified many times since. In 1866 M. Balbiani asserted that the
plant-lice are hermaphrodite, or of both sexes at the same time, which
would explain the facts observed by Charles Bonnet. But the anatomical
proofs appealed to by Balbiani in support of this idea are far from
establishing the existence of this arrangement of sexes among them.
The observations of Charles Bonnet produced profound astonishment
among naturalists, and, in this respect, 1743 may be considered as a
memorable year.
The simple statement of the few experiments which he made, and which
we have cited, has sufficed to show how rapid is the multiplication of
aphides. A single female produced generally 90 young ones; at the
second generation these 90 produce 8,100; these give a third
generation, which amounts to 729,000 insects; these, in their turn,
become 65,610,000; the fifth generation, consisting of 590,490,000,
will yield a progeny of 53,142,100,000; at the seventh, we shall thus
have 4,782,789,000,000; and the eighth will give 441,461,010,000,000.
This immense number increases immeasurably when there are eleven
generations in the space of a year. Fortunately a great many
carnivorous insects wage fierce war against the plant-lice, and
destroy immense numbers of them. Thus they are kept in check, and
prevented from multiplying inordinately. To show with what prodigious
abundance the reproduction of these little but formidable parasites
must go on, we will relate a fact which was made known to us by M.
Morren, Professor in the University of Liége.
The winter of 1833-34 had been extremely warm and dry; whole months
had passed without any rain. A well-known _savant_, Van Mons, had
foretold, as early as the 12th of May, that all the vegetables would
be devoured by plant-lice. On the 28th of September, 1834, at the
moment when the cholera had began to spread its ravages over Belgium,
all of a sudden a swarm of plant-lice showed themselves between Bruges
and Ghent. They were to be seen the next day at Ghent, hovering about
in troops, in such quantities that the daylight was obscured. Standing
on the ramparts, one could no longer distinguish the walls of the
houses in the town, so covered were they with plant-lice. The whole
road from Antwerp to Ghent was rendered black by innumerable legions
of them. They appeared everywhere quite suddenly. People were
obliged to protect their eyes with spectacles and their faces with
handkerchiefs, to keep off the painful and disagreeable tickling
caused by them. The progress of these insects was interrupted by
mountains, hills, even by undulations of land of very slight
elevation, but sufficient to have an influence on the wind. M. Morren
thinks that they came from a great distance, and that they arrived in
Belgium by the sea-coast. Whatever be the explanation of the
phenomenon, it establishes sufficiently the prodigious multiplication
of these little insects.
There is another trait, and without doubt the most curious in the
history of the aphides, to which we have still to call the attention
of the reader: we mean the relations which exist between them and the
ants.
No one can have failed to observe ants frequenting those places where
plant-lice are gathered together in great numbers. Are ants simply
friends of the plant-lice, as thought the ancients? or have their
visits some selfish object?
Linnæus, Bonnet, and Pierre Huber thought that the ants did not pay
these visits for nothing, and that they had some object in view. But
what could they want of the plant-lice? It is to Pierre Huber we owe
the solution of this mystery. This naturalist has made the most
beautiful observations on the relations which exist between plant-lice
and ants. They are detailed in a chapter of his admirable work,
entitled "Recherches sur les Moeurs des Fourmis Indigènes."
The plant-lice have, as we have said, at the extremity of their
abdomen, two small movable horns. These are in communication with a
little gland which produces a sugary liquid. When one carefully
observes plant-lice attached to the stem of a plant, one sees a little
syrup droplet oozing out of the extremity of these tubes.
M. Morren, who has made some interesting observations on the anatomy
and generation of the aphis, says that, having shut up females in
wide-mouthed glass bottles, he saw the young, a little time after
their birth, suck the sweet juice which exudes from the little tubes
at the extremity of the mother's abdomen. This secretion seems, then,
destined for the nourishment of the young in the first moments of
their existence, before they are able to nourish themselves on
vegetable juices. The saccharine fluid produced by the mother must be,
then, a sort of milk intended for the nourishment of her young. This
being settled, attend to what follows. In all places where plant-lice
are assembled in great numbers it is easy to observe how excessively
fond ants are of the sugary liquid destined for suckling the young.
But how do the ants manage to get the plant-lice to allow themselves
to be, as we may say, milked?
"It had been already noticed," says this celebrated observer, "that
the ants waited for the moment at which the plant-lice caused this
precious manna to come out of their abdomen, which they immediately
seized. But I discovered that this was the least of their talents, and
that they also knew how to manage to be served with this liquid at
will. This is their secret. A branch of a thistle was covered with
brown ants and plant-lice. I observed the latter for some time, so as
to discover, if possible, the moment when they caused this secretion
to issue from their bodies; but I remarked that it very rarely came
out of its own accord, and that the plant-lice, which were at some
distance from the ants, squirted it out with a movement resembling a
kick.
"How did it happen, then, that the ants wandering about on the thistle
were nearly all remarkable for the size of their abdomens, and were
evidently full of some liquid? This I discovered by narrowly watching
one ant, whose proceedings I am going to describe minutely. I saw it
at first passing, without stopping, over some plant-lice, which did
not seem in the least disturbed by its walking over them; but it soon
stopped close to one of the smallest, which it seemed to coax with its
antennæ, touching the extremity of its abdomen very rapidly, first
with one of its antennæ and then with the other. I saw with surprise
the liquid come out of the body of the plant-louse, and the ant
forthwith seize upon the droplet and convey it to its mouth. It then
brought its antennæ to bear upon another plant-louse, much larger
than the first; this one, caressed in the same manner, yielded the
nourishing fluid from its body in a much larger dose. The ant advanced
and took possession of it. It then passed to a third, which it cajoled
as it had the preceding ones, giving it many little strokes with its
antennæ near the hinder extremity of its body; the liquid came out
immediately, and the ant picked it up.... A small number of these
repasts are sufficient to satisfy the ant's appetite. (See Fig. 91.)
"It does not appear that it is out of importunity that these insects
obtain their nourishment from the plant-lice.
"The neighbourhood of ants is agreeable to plant-lice, since those
which could get out of the way of their visits, viz., the winged
plant-lice, prefer to remain amongst them, and to lavish upon them the
superabundance of their nourishment."[32]
[32] "Recherches sur les Moeurs des Fourmis Indigènes," pp.
181-186. 8vo. Paris, 1810.
What we have just related applies not only to the brown (_Formica
brunnea_), but also to the tawny ant (_Formica flava_), to the ashy
black (_Formica nigra_), to the fuliginous (_Formica fuliginosa_), and
to a great many more.
The Red Ant (_Formica rufa_) is singularly adroit in seizing the
droplet left it by the plant-louse. According to Pierre Huber, it
employs its antennæ, which swell somewhat towards their extremities,
in conveying this droplet to its mouth, and causes it to enter it by
pressing it first on one side, then on the other, using its antennæ as
if they were fingers. The greater number of ants seek them on those
plants on which they usually fix themselves--the lowest herbs, as well
as the highest trees. There are some, however, which never leave their
place of abode, and never go out to the chase. These are the little
ants, of a pale yellow colour, rather transparent, and covered with
hairs, and which are extremely numerous in our meadows and orchards.
These subterranean creatures are very noxious to the farmer. Pierre
Huber often wondered how they subsisted, and with what food they could
provision themselves, without quitting their gloomy habitations.
Having one day turned up the earth of which a habitation was composed,
in order to discover if any treasure were to be found stowed away
there, he found nothing but plant-lice. Of these the greater number
were fixed to the roots of the trees which hung down from the roof of
their subterranean nest; others were wandering about among the ants.
These latter, moreover, set about milking their nurses, as usual, and
with the same success. To verify his discovery, he dug up a great
number of nests of the yellow ant, and invariably found aphides in
them. So as to study the relations which must exist between these
insects, he shut up ants with their friends, the plant-lice, in a
glazed box, placing at the bottom of the box, earth, mixed with the
roots of some plants, whose branches vegetated outside the box. He
watered this ant-hill from time to time, and thus both the animals and
the plants found in his apparatus sufficient nourishment.
"The ants," he says, "did not endeavour in the least to make their
escape. They seemed to want for nothing, and to be quite content. They
tended their larvæ and females with the same affection they would have
shown in their usual ant-hill; they took great care of the plant-lice,
and never did them any harm. These, on the other hand, did not seem to
fear the ants; they allowed themselves to be moved about from one
place to another, and when they were set down they remained in the
place chosen for them by their guardians. When the ants wished to move
them to a fresh place, they began by caressing them with their
antennæ, as if to request them to abandon their roots or to withdraw
their trunk from the cavity in which it was inserted; then they took
them gently above or below the abdomen with their jaws, and carried
them with the same care they would have bestowed on the larvæ of their
own species. I saw the same ant take three plant-lice in succession,
each bigger than itself, and carry them away into a dark place....
However, the ants do not always act so gently towards them. When they
fear that they may be carried off by ants of another kind, and living
near their habitation, or when one opens up too suddenly the turf
under which they are hidden, they seize them up in haste and carry
them off to the bottom of their little cavern. I have seen the ants of
two different ant-hills fighting for their plant-lice. When those
belonging to one ants' nest could enter the nest of the others, they
took them away from their rightful owners, and often these took
possession of them again in their turn; for the ants know well the
value of these little animals, which seem made on purpose for
them,--they are the ants' treasures. An ants' nest is more or less
rich, according as it is more or less stocked with plant-lice. The
plant-lice are its cattle, its cows, its goats. One would never have
thought that the ants were a pastoral people!"[33]
[33] "Recherches," &c., pp. 192-194.
Their hiding in the ants' nest is not voluntary; they are prisoners of
war. The ants, after having hollowed out galleries in the midst of
roots, make a foray upon the turf, and seize upon plant-lice scattered
about here and there, bringing them with them, and collect them
together in their nests. The captive insects take their wrongs with
patience, and behave like philosophers under this new kind of life.
They lavish on their masters, with the best grace in the world, the
nutritious juices with which their bodies superabound. Charles Bonnet
has stated some real wonders of the cleverness and industry of other
ants which also make a provision of plant-lice.
"I discovered one day," says he, "a Euphorbia, which supported in the
middle of its stem a small sphere, to which it served as the axis. It
was a case which the ants had constructed of earth. They issued forth
from this by a very narrow opening made in its base, descended the
stem, and passed into a neighbouring ants' nest. I destroyed one part
of this pavilion, built almost in the air, so that I might study the
interior. It was a little room, the vault-shaped walls of which were
smooth and even. The ants had profited by the form of the plant to
sustain their edifice. The stalk passed up the centre of the
apartment, and for its timber-work it had the leaves. This retreat
contained a numerous family of plant-lice, to which the brown ants
came peacefully, to make their harvest, sheltered from the rain, the
sun, and from other ants. No insect could disturb them; and the
plant-lice were not exposed to the attacks of their numerous enemies.
I admired this trait of industry; and I was not long in finding it
again, in a more interesting character, in ants of different species.
"Some red ants had built round the foot of a thistle a tube of earth,
two inches and a half long by one and a half broad. The ants' nest was
below, and communicated directly with the cylinder. I took the stalk,
with what surrounded it, and all that the cylinder contained. That
portion of the stem which was inside the earthen tube was covered with
plant-lice. I very soon saw the ants coming out at the opening I had
made at the base; they were very much astonished to see daylight at
that place, and I saw that they lived there with their larvæ. They
carried these with great haste to the highest part of the cylinder
which had not been altered. In this retreat they were within reach of
their plant-lice, and here they fed their young.
"In other places many stalks of the Euphorbia laden with plant-lice
rose in the very centre of an ant-hill belonging to the brown ants.
These insects, profiting by the peculiar arrangement of the leaves of
this plant, had constructed round each branch as many little elongated
cases; and it was here they came to get their food. Having destroyed
one of these cells, the ants forthwith carried off into their nests
their precious animals; a few days afterwards it was repaired under my
eyes by these insects, and the herd were taken back to their pens.
"These cases are not always at a few inches from the ground. I saw one
five feet above the soil, and this one deserves also to be described.
It consisted of a blackish, rather short tube, which was built round a
small branch of the poplar at the point where it left the trunk. The
ants reached it by the interior of the tree, which was excavated, and
without showing themselves, they were able to reach their plant-lice
by an opening which they had made in the base of this branch. This
tube was formed of rotten wood, of the vegetable earth of this very
tree, and I saw many a time the ants bringing little bits in their
mouths to repair the breaches I had made in their pavilion. These are
not very common traits, and are not of the number of those which can
be attributed to an habitual routine."[34]
[34] "Traité d'Insectologie," &c., pp. 198-201.
One day, Pierre Huber discovered in a nest of yellow ants a cell
containing a mass of eggs having the appearance of ebony. They were
surrounded by a number of ants, which appeared to be guarding them,
and endeavouring to carry them off.
Huber took possession of the cell, its inhabitants, and of the little
treasure it contained, and placed the whole in a box lid, covered with
a piece of glass, so as to be more easily observed. He saw the ants
approach the eggs, pass their tongues in between them, depositing on
them a liquid. They seemed to treat these eggs exactly as they would
have treated those of their own species; they felt them with their
antennæ, gathered them together, raised them frequently to their
mouths, and did not leave them for an instant. They took them up, and
turned them over, and after having examined them with care, they
carried them with extreme delicacy into the little box of earth placed
near them.[35]
[35] "Recherches," &c., pp. 205, 206.
[Illustration: Fig. 91.--Aphides and Ant (magnified).]
These were not, however, ants' eggs. They were the eggs of aphides.
The young which were soon to be hatched were to give to the provident
ants a reward for the attentions they had lavished upon them. How
wonderful are the life and the habits of the plant-lice, and their
relations to ants! But we should be led on too far, if we were to
pursue these attractive details.
We pass on now to the history of another family--namely, the
_Gallinsecta_, as Réaumur calls them, or _Cocci_. They pass the
greatest part of their lives--that is to say, many months--entirely
motionless, sticking to the stalks or branches of shrubs; remaining
thus as devoid of movement as the plant to which they are attached.
One would say that they were part and parcel of it. Their form is so
simple, that nothing in their exterior would make one guess them to be
insects. The larger they become the less they resemble living things.
When the coccus is in a state for multiplying its species, when it is
engaged in laying its thousands of eggs, it resembles only an
excrescence of the tree.
The Gallinsecta are found on the elm, the oak, the lime, the alder,
the holly, the orange-tree, and the oleander. Some of the species are
remarkable for the beautiful red colouring matter which they furnish.
Such are the _Coccus cacti_, the _Chermes variegatus_, or Oak Tree
Cochineal, and the _Coccus polonicus_.
The Common Cochineal, _Coccus cacti_, is found in Mexico, on the
Nopal, or prickly pear (_Opuntia_), particularly on the _Opuntia
vulgaris_, the _Opuntia coccifera_, and the _Opuntia una_, plants
which belong to the family of the Cactaceæ.
These insects are rather remarkable, in that the male and female are
so unlike, that one would take them for animals of different genera.
The male presents an elongated, depressed body, of a dark-brown red.
Its head small, furnished with two long feathery antennæ, has only a
rudimentary beak. The abdomen is terminated by two fine hairs, longer
than its body. The wings, perfectly transparent, reach beyond the
extremity of its abdomen, and cross each other horizontally over its
back. It is lively and active. The female presents quite a different
appearance. It is in the first place twice as large as the male (Fig.
92), convex above, flat below. It resembles a larva, and has no wings.
Its body is formed of a dozen segments, covered with a glaucous dust.
The beak is very fully developed, and the two hairs or bristles on the
abdomen are much shorter than in the male.
[Illustration: Fig. 92.--Cochineal insects, (_Coccus cacti_) male and
female.]
The weight of the body, combined with the shortness of the legs,
prevents these creatures from being active. The legs only serve, in
fact, for clinging to the vegetable from which they draw their
nourishment. The circumstances attending the birth of the cochineal
insect are very curious. The larvæ are born in the dried-up body of
their dead mother, the skeleton of their mother serving them as a
cradle. This happens thus:--The eggs are attached to the lower part of
the mother's body. When the abdomen of the mother is empty, its lower
side draws up towards the upper side, and the two together form a
pretty large cavity. When the mother dies, which is not long in
happening, her abdomen dries up, her skin becomes horny, and forms a
sort of shell. It is in this membranous cradle that the larvæ of the
cochineal insect are born. The cochineal insect in its wild state
lives in the woods. But it can without difficulty be reared
artificially.
Every one knows that the little insect called the cochineal,
furnishes, when its body has been dried and reduced to powder, a
colouring matter of a beautiful red, peculiar to itself. This
circumstance has saved the cochineal from the persecution to which so
many other kinds of insects have been devoted by the hand of man. In
hot climates, in which the cochineal insect delights, it has been
preserved, and is cultivated as an article of commerce. This is how
the cochineal is reared in Mexico:--An open piece of land is chosen,
protected against the west wind, and of about one or two acres in
extent. This is surrounded with a hedge of reeds, planted in lines,
distant from each other about a yard, with cuttings of cactus at most
about two feet apart. The cactus garden made, the next thing is to
establish in it cochineals. With this object in view they are sought
in the woods, or else the females of the cochineal insect which are
pregnant are taken off plants which have been sheltered during the
winter, and placed in dozens, in nests made of cocoa-nut fibres, or in
little plaited baskets made of the leaves of the dwarf palm, and hung
on the prickles of the cactus. These are very soon covered with young
larvæ. The only thing now required to be done is to shelter them from
wind and rain. (PLATE IV.)
[Illustration: IV. Gathering Cochineal in Algeria.]
The larvæ are changed into perfect insects, which take up their abode
permanently on the branches of the cacti, as Fig. 93 represents. The
Mexicans gather them as soon as they have reached the perfect state.
The harvest cannot be difficult, considering the immobility of these
little creatures. When collected, the cochineals are killed, packed in
wooden boxes, and sent to Europe, to be used in dyeing.
Such is the method, very simple, as we see, of rearing the
cochineal--a method which has been followed for centuries in Mexico.
Towards the end of the year 1700, a Frenchman named Thierry de
Menouville, formed the project of taking this precious insect away
from the Spaniards, and of bestowing it upon the French colonies. He
landed in Mexico, and concealed so well the object of his voyage, that
he managed to embark and carry to St. Domingo several cases containing
plants covered with living cochineals. Unfortunately, a revolution
which had broken out at St. Domingo prevented him from succeeding in
his praiseworthy endeavours. The cochineals died, and the Spaniards
preserved their monopoly in the rearing of this insect.
In 1806 M. Souceylier, a surgeon in the French navy, succeeded in
bringing from Mexico into Europe some live cochineals. He gave them to
the professor of botany at Toulon; but this attempt to preserve them
was unsuccessful.
In 1827 the naturalisation of the cochineal was attempted in Corsica,
but without success. During the same year the cochineal was introduced
into the Canary Islands, but the inhabitants did not understand the
importance of the experiment. They counted the cochineal among the
number of noxious insects, and tried in all ways to rid themselves of
it. It was only after results obtained by some more intelligent
farmers, that the inhabitants of the Canary Islands perceived the
profits they might derive. From that time its cultivation was
extended, and after the year 1831 it increased rapidly. Thus, the
cochineal imported from the Canary Isles in that year amounted to
only 4 kilogrammes. In 1832 the amount was 60 kilogrammes, in 1833
it was 660 kilogrammes, in 1838, 9,000 kilogrammes, and in 1850,
400,000 kilogrammes. The French colonists in Algeria also tried to
raise it. In 1831, M. Limonnet, a chemist of Algiers, collected some
cochineals, and had the merit of first introducing the insect into the
colony. On account of bad weather these first essays were fruitless,
but it was not long before they were repeated.
[Illustration: Fig. 93.--Branch of the Cactus, with Cochineal Insects on.]
M. Loze, surgeon in the navy, undertook to introduce the insect again,
and, with M. Hardy, director of the central garden of Algiers, gave
himself up, with great intelligence, to the naturalisation and rearing
of the cochineal in Algeria.
In 1847 the French Minister of War, for the purpose of having the
value of the Algerian cochineal fixed by commerce, caused to be sold
publicly on the market-place of Marseilles a case of cochineal, the
produce of the harvests of 1845 and 1846, from the experimental garden
of Algiers, and which contained 17 kilogrammes of this commodity.
Since that time the cultivation of this insect, the beginning of which
was due to M. Limonnet, has rapidly developed. In 1853, in the
province of Algiers alone, there were fourteen _nopaleries_, or cactus
gardens, containing 61,500 plants. The Government at that time bought
the harvests for fifteen francs the kilogramme.
We have only pointed out in a general way how the cochineal harvest is
conducted. We will now enter into some details on the subject. These
insects are gathered when the females are about to lay, that is, when
a few young are hatched. It is when the females are pregnant that they
contain the greatest amount of colouring matter. When the harvest time
has arrived, the rearers stretch out on the ground pieces of linen at
the foot of the plants, and detach the cochineals from them, brushing
the plants with a rather hard brush, or scraping them off with the
blade of a blunt knife.
If the season is favourable, the operation may be repeated three times
in the course of a year in the same plantation. The insects thus
collected are killed, by dipping into boiling water, by being put into
an oven, or by being placed on a plate of hot iron. The cochineals,
when withdrawn from the boiling water, are placed upon drainers, first
in the sun, then in the shade, then in an airy place. During their
immersion in water they lose the white powder which covers them. In
this state they are called in Mexico _ronagridas_. Those which have
passed through the oven they call _jaspeadas_, and are of an ashy
grey; those that are torrefied are black, and are called _negras_. In
commerce three sorts of cochineal are recognised; first, the
_mastique_ (_mestèque_), of a reddish colour, with a more or less
abundant glaucous powder; secondly, the _noire_, which is large and of
a blackish brown; thirdly, the _sylvestre_, which is, on the contrary,
smaller and reddish. The latter is the least esteemed, and is gathered
on wild cacti.
Each year there are imported into France 200,000 kilogrammes of
cochineals, which represents a value of about three millions of
francs. Every one knows that it is from cochineal that carmine is
made, a magnificent red frequently employed by painters. Lake carmine
is another product obtained from the cochineal. And, lastly, scarlet
is the powder of the cochineal precipitated by a salt of tin.
Before the Mexican cochineal was known in Europe, the _kermes_, or
_Coccus ilicis_, known still in commerce and by chemists under the
names of _Animal kermes_, _Vegetable kermes_, and _Scarlet seed_, was
used for the preparation of the carmine employed in the arts. This
cochineal lives by preference (at least, so it is supposed) on the
evergreen oak (_Quercus ilex_), whence its specific name.
The _Coccus ilicis_ develops itself almost exclusively, not on the
evergreen oak, but on the _Quercus coccifera_, or kermes oak, a shrub
common in dry arid places on the Continent, and which vegetates on a
great number of spots in the Mediterranean, particularly on the
_garrigues_, or waste land, of Herault.
The females of this insect, which, dried, bear the name of _graines de
kermes_, are of the size of an ordinary currant, without any trace of
rings, nearly spherical, of a violet and glaucous colour. They adhere
to the boughs of the shrub _Quercus coccifera_, and form dry brittle
masses, which the peasants of the south of France collect, and sell at
a tolerably high price.
Before we possessed the cochineal of Mexico and of Algeria, this
cochineal was very much employed in the south of Europe, in the East,
and in Africa. It furnishes a beautiful red colour. This last named
and the Mexican cochineal are somewhat used in pharmacy. They enter
into alkermes, a sort of liquor served at dinner in Italy, chiefly at
Florence and Naples.
Another species of cochineal is the _Coccus polonicus_, which is met
with in Poland and Russia, more rarely in France, on the roots of a
small plant, the _Scleranthus perennis_. This cochineal is gathered in
the Ukraine towards the end of June, when the abdomen of the female is
swollen, and filled with a purple and sanguineous juice.
The Polish kermes (_Coccus polonicus_) was formerly used very much in
Europe. This product has not indeed lost all its importance in those
countries where it is met with in abundance.
We have now only to point out among the insects of this group the
_Coccus lacca_, which lives in India on many trees, among others on
the Indian fig-tree, the Pagoda fig-tree, the Jujube tree, on the
Croton, &c.
These last-mentioned insects produce a colouring matter known under
the name of Lac Dye. They fix themselves on the little branches,
getting together in great numbers, forming nearly straight lines. The
bodies of many fecundated females, united together by a resinous
exudation which is caused by the piercing of the bark, constitutes the
matter called in commerce and by dyers by the name of Lac Dye,
Shell-lac, Gum-lac, &c.
Resinous lac is found in commerce under four forms:--First, the
stick-lac, such as it is found concreted at the extremity of the
branches whence it exudes--it is an irregular brownish crust;
secondly, the seed-lac, picked off the branches and pounded; thirdly,
shell-lac in scales melted down and run into thin plates, which vary
in quality according to the proportion of colouring matter they
contain; fourthly, thread-lac, which resembles reddish threads, and is
prepared thus in India.
One more word about the cochineal. The _Coccus manniparus_, which
lives on the shrubs (_Tamarix mannifera_) on Mount Sinai, causes to
exude from the branches it has pierced a sort of manna. The _Coccus
sinensis_ produces a kind of wax which is employed in China in the
manufacture of candles.