[Illustration: Fig. 207.--Fourth age.]
The first age lasts for five days. At the second (Fig. 205), the worm
is grey, almost without down, then of a yellowish white, and one sees
the crescents making their appearance on the second and fifth segment.
At the third age (Fig. 206), there is not a single hair remaining, and
the worm becomes whitish, and is always becoming lighter. The third
age lasts six days, as does also the fourth (Fig. 207). At the fifth
(Fig. 208), the worm has very nearly reached the end of its career in
the caterpillar state, and now is the time of its greatest voracity.
This age is the longest; it lasts nine days.
At each of these periods in the life of the silkworm may be remarked
a physiological fact to which has been given the name of _frèze_. When
the silkworm has just moulted it eats little, but the time very soon
arrives when it does so with extraordinary avidity. It is indeed
insatiable. The _frèze_ of the last age is called the _grande frèze_.
It takes place about the seventh day. During this day worms, the
produce of thirty grammes[61] of eggs, consume in weight as much as
four horses, and the noise which their little jaws make resembles that
of a very heavy shower of rain. It is at the end of this stage that
the insect prepares the shelter in which is to be brought about its
metamorphosis into a chrysalis.
[61] One gramme = 15·4325 gr. troy.
[Illustration: Fig. 208.--Fifth age.]
A little while before this it ceases to eat, turns yellow, and becomes
as transparent as a grape. It is now said to have reached its
_maturity_. Up to this moment the worm had never tried to leave its
litter. It lived a sedentary life, and never thought of wandering away
from its food. Now it is seized with an imperious desire for changing
its quarters. It gets up, it roams about, and moves its head in all
directions to find some place to cling on to. It walks over everything
within its reach, particularly over those obstacles which are placed
vertically. It aspires, not to descend, like the heroes of classic
tragedy, but to rise. It is for this reason that this period of the
silkworm's life has received the name of the _mounting_ or _ascending
season_. It now looks for a convenient place in which to establish its
cocoon. Every one has remarked how the animal sets to work to
accomplish its task. It begins by throwing from different sides
threads destined for fixing the cocoon; this is what we call _refuse
silk_. The proper space having been circumscribed by this means, the
worm begins to unwind its thread--a continuous thread of about a
thousand mètres long.
It has been calculated, let us say by the way, that forty thousand
cocoons would suffice to surround the earth at the equator with one
thread of silk. Folded on itself almost like a horse-shoe, its back
within, its legs without, the worm arranges its thread all round its
body, describing ovals with its head. It approximates gradually the
points of attachment of the thread. As long as the cocoon is not very
thick one can watch it through the meshes of the web applying and
fixing its thread, still to a certain degree soft, in such a manner as
to make it adhere closely to the parts already formed.
"We can state," says M. Robinet, "that the silkworm makes every second
a movement extending over about five millimètres. The length of the
threads being known, it follows that the worm moves its head three
hundred thousand times in making its cocoon. If it employs seventy-two
hours at its work, it is a hundred thousand movements every
twenty-four hours, four thousand one hundred and sixty-six an hour,
and sixty-nine a minute, that is to say, a little more than one a
second."
About the fourth day, after having expended all its silk,[62] the worm
shut up in the cocoon becomes of a waxy white colour, and swollen in
the middle of its body. The abdominal legs wither away; the six fore
legs approach each other and become black. The parts of the mouth tend
downwards; the skin wrinkles. Very soon it is detached and pushed down
towards the hinder part, and the chrysalis appears under the rents in
the skin. It is at first white, but speedily becomes of a brown red.
[62] "Manuel de l'Educateur du Ver à Soie," p. 37.
The silkworm remains in general from fifteen to seventeen days in the
pupa state. At the moment of hatching, the moth begins by breaking the
skin in which it is shut up, and which is pretty thin. But how can it
come out of the silky prison which it has itself built? To effect this
it makes use of a peculiar liquid contained in a little bladder with
which its head is provided, and which was discovered by M.
Guérin-Méneville. It moistens the cocoon with this liquid; which soaks
through and penetrates the whole thickness of the silken wall which
confines it. The threads of silk of which it is composed are moistened
and disunited, but not broken. The moth opens a passage for itself
through the threads thus separated, and makes its appearance in the
light of day. Its wings are folded back on themselves, and it is still
quite wet, but it seeks immediately for a good place in which to dry
itself, and in a little time assumes its final appearance (Figs. 209,
210). The female (Fig. 210) has whitish wings, the antennæ only
slightly developed and pale, the abdomen voluminous, cylindrical, and
well filled. It is quiet, heavy, and stationary. The male is smaller;
its wings are tinged with grey, its antennæ blackish; it moves about,
beats its wings together, and is lively and petulant.
Before laying her eggs, the female looks out for a place suitable for
this purpose. When she has found this place, she ejects an egg covered
with a viscous liquid, which causes it to adhere to the body upon
which it falls. Very soon she lays a second egg by the side of the
first, then a third by the side of the second, and so on. She very
rarely piles them up on each other. The laying lasts about three days;
the number of eggs is from 300 to 700 for each female. These eggs are
generally tentacular and flattened towards the centre. At the moment
at which they are laid they are of a bright yellow. In a week they
become brown. The colour changes then to a reddish grey; lastly it
becomes of a slaty grey, remaining this colour during the autumn,
winter, and a great part of the spring. Then as the temperature rises,
the colour of the eggs passes successively through bluish, violet,
ashy, and yellowish shades. And, lastly, they become more and more
whitish every day as the hatching time approaches.
[Illustration: Fig. 209.--Silkworm Moth (_Bombyx mori_), male.]
[Illustration: Fig. 210.--Silkworm Moth (_Bombyx mori_), female.]
If looked at closely, one remarks a black spot and a brownish crescent
extending along the circumference. The black spot is the head of the
worm, which closely touches the shell; the crescent is the body, which
is already covered with little hairs. When it leaves the egg, the
silkworm gnaws through the shell on its side, never on its flat
surface. When the opening is large enough, it breaks out through it,
head foremost, and immediately fixes a thread of silk to any object it
can reach, no doubt in order to prevent itself from falling. Sometimes
the opening is too small to allow of the head passing out, and
the larva is forced to come out backwards, that is to say, tail
foremost. At times, not being able to get its head free, the poor
animal very soon dies of fatigue and hunger.
[Illustration: VI. A Silkworm rearing Establishment.]
We will now give a summary of the rearing of the silkworm, that is
to say, of the attention which must be paid to this insect that it
may construct its cocoon advantageously. We will call to our aid
in this very rapid summary the works or notices of MM. Robinet,
Guérin-Méneville, Eugène Robert, and Louis Leclerc, and we must not
forget the excellent and classical Dandolo.[63]
[63] "L'Art d'élever des Vers à Soie, par le Comte de Dandolo,
traduit par Philibert Fontaneilles." In 8vo. Lyons, 1825.
Robinet, "Manuel de l'Education des Vers à Soie." In 8vo.
Paris. Guérin-Méneville et Eugène Robert, "Manuel de
l'Education des Vers à Soie." In 18mo. Paris. Louis Leclerc,
"Petite Magnanerie." In 18mo. Paris.
When it is desired to rear silkworms--_magnans_, as they were called
in old French, and as they are still called in the patois of
Languedoc--the first thing to do is to obtain good eggs, good _grain_,
to use the technical word, and then to choose suitable premises. The
essential, the fundamental point, in the rearing, is to possess
premises in which the air is easily renewed. The worms should have as
much air as possible given to them without ever being allowed to be
chilled. There is no better means of attaining this end than by
keeping a constant open fire in a room, and by letting air into the
room from another chamber which separates it from the open air. One
has, in this way, the best workroom for a small rearing.
In the workshop are arranged racks, by the aid of which are placed, at
the distance of 50 centimètres from each other, frames made of reeds.
These frames, or _canisses_, as they are called in the Cévennes, may
be from 1 mètre to 1-3/4 mètres in breadth. They should be placed in
such a manner that one can easily pass round them to place and remove
the worms, and to distribute their leaves to them uniformly. They
should be protected by a small border of a few centimètres in height,
to prevent the worms from falling. And lastly, they should be covered
at the bottom with large sheets of paper. (PLATE VI.) A provident
silkworm-rearer has always at his disposal a cellar or cool room, so
as to be able to stow away his leaves as soon as they are brought in
from the country.
What we have just said applies especially to a small rearing. In large
establishments, or even those of second-rate importance, everything is
in advance of this, and mathematically regulated: aspect and
arrangement of rooms, furniture of these rooms, warming, ventilation,
&c. So, for a rearing house for 300 grammes of eggs, the building
should be constructed in such a manner that its front and back look
east and west, to avoid any inequality in the heat derived from the
sun. It ought to consist of a ground-floor, a very lofty first-floor,
and of a rather low roof. The ground-floor comprises the chamber of
incubation, the store-room for leaves, and the air-chamber with the
grate intended for warmth and ventilation. The first-floor constitutes
the rearing-room properly so called.
But let us leave these grand industrial establishments, to return to
our rearing houses on a small scale, such as are found among the
peasants of the Cévennes. They generally receive the silkworms' eggs
before the end of the winter. In order to preserve them till the
hatching season, they are placed in thin layers, in a piece of folded
woollen stuff, which must be hung up in a cool, but not a damp place,
exposed to the north. As soon as the buds of the mulberry tree begin
to be partially open, they proceed to the incubation of the eggs. They
are spread out on sheets of paper, in very thin layers, placed on a
table in a room having a southern aspect, and left thus during three
or four days, taking care to prevent the rays of the sun from touching
them. It is necessary also, from time to time, to open the windows.
After three or four days, the fire is lighted, taking care not to have
more heat than 13° Centigrade round about the table which supports the
eggs, and which should be placed as far as possible from the fire.
Each day the room is warmed a little more, in such a way that the
temperature is raised 1° to 2° a day, until 25° Centigrade of heat
have been attained, at which temperature it is to be maintained when
the eggs have reached the last stage, and till the hatching is
terminated. On the first day few worms are hatched; but the hatching
of the second day is very abundant, as also that of the third. Of
these newly-born worms two divisions are made, separated by an
interval of twenty-four hours. The worms which are born afterwards are
thrown away, unless they are so abundant that they can be made a third
batch of, which is to be mixed up with the second at the period of the
moult.
In the large rearing houses there is a special chamber for the
incubation. Various simple, convenient, cheap apparatuses, whose main
object is to create a permanent warm and damp atmosphere, whose degree
of heat can be regulated at will, have been proposed. M. Louis
Leclerc, in his pamphlet entitled "Petite Magnanerie," has given a
description and drawing of a little box which is very useful for
facilitating the hatching of eggs. We refer those of our readers who
wish for further information on the subject to that work. As soon as
the worms are hatched, the eggs are covered with net, and over this
are placed mulberry boughs, covered with tender leaves, on which all
the little worms congregate. They are then lifted up with a hook made
of thin wire, and the worms are placed on a table covered with paper,
leaving a proper space between each. They are given, as their first
meal, tender leaves cut into little pieces with a knife. These are the
operations gone through for the two raisings of worms on the second
and third day of the hatching. During this first age they give them
from six to eight meals a day, taking care to distribute their food to
them as equally as possible. The first meal is given at five o'clock
in the morning; the last at eleven or twelve o'clock at night.
When the moult is approaching, the young ones are made to climb on to
boughs having tender leaves, so that they can be moved to litters as
thin and clean as possible, and there sleep in a good state of health.
When the mass of worms is well awake again, the next thing to do is to
take them off the litter on which they moulted, and to give them food.
If this problem were proposed to a person strange to the operation
which is now occupying our attention--to separate the worms from the
faded and withered food upon which they are reposing, without touching
them--he would certainly be very much at a loss what to answer. The
solution of this problem presented for a long time great difficulties,
and occasioned numerous reverses in the rearing. Now-a-days, thanks to
the employment of a net, the _délitement_, or taking them off their
bed, has become an easy operation.
Over the worms, placed on a table, is spread a net, the meshes of
which are broad enough to allow them to pass through. On this net are
spread the leaves which are to compose a meal. The worms immediately
leave the old food, and get on to the new leaves. They then lift the
litter with the worms, and throw away the old leaves, now unoccupied,
clean the table, and replace the net with the worms. At the next
_délitement_ the first net is found under the litter. Figs. 211 and
212 represent two forms of these nets made of thread.
Thread nets, which were of great use, have been supplanted lately,
with great advantage, by paper ones, which were invented by M. Eugène
Robert. These are leaves of paper, of a peculiar manufacture, pierced
with holes proportioned to the size of the worms which are to pass
through them. The paper net can be used advantageously also for
separating the worms that are too near together, or, as they say, for
the _dédoublement_. Formerly, the _délitement_ and the _dédoublement_
were done by hand--a tedious work, and one that presented serious
disadvantages. Now-a-days, as we have seen, the worms themselves
perform these two perilous operations.
At the second age they still cut the leaves for the worms, but into
larger pieces, and proportioned to their size. During the day the
temperature of the room ought to be kept to 21° Centigrade, but it may
be lowered by 1° or 2° during the night. Towards the end of this age
they have only four meals. When the worms are on the point of going to
sleep, their meals are decreased.
[Illustration: Fig. 211.--Lozenge-shaped net.]
[Illustration: Fig. 212.--Square net.]
During the third age the number of the meals is kept to four, the
first being given towards five o'clock in the morning, and the last
between ten and eleven o'clock at night. The leaf is cut into much
larger pieces, and distributed as equally as possible. The
_délitement_ and the _dédoublement_ are proceeded with as in the
preceding age. One begins to find pretty often during this period of
the life of worms, some _luisettes_--that is to say, worms which have
not strength enough to moult. They are larger than those just woke up,
and that have not as yet eaten, and are shiny. They must be carefully
removed, for they will not be long before they die, and infect the air
of the room.
During the fourth age they no longer cut the leaves, but give them a
great deal more at once. The result is that the litters increase in
thickness, and that the _délitement_ must be performed oftener; for
the rest, four meals are always necessary. Many _luisettes_ may be
seen during the fourth age. The moult which follows the fourth age is
the most critical phase in the life of the silkworm. During their
sleep they are a prey to acute suffering, and are plunged into a
state of lethargy which resembles death. The dryest and cleanest
litters diffuse very soon a sickly smell. This moult lasts from
thirty-six to forty-eight hours. During this time the room should be
kept to at least 22° Centigrade.
When they awake out of this last sleep the attendant should
continually be on his guard, as it is then that diseases break out.
The worms suffering from these different diseases have received
different names. There are besides the _luisettes_ the _arpians_--that
is to say, worms that have exhausted all their energy in the work of
the last moult, and have not even strength to eat--the _yellow_, or
_fat_ worms, which are swollen, of a yellowish colour, and which very
easily die; the _flats_ or _mous_, the soft or indolent ones which,
after having eaten a great deal and become very fat, die miserably,
and enter into a state of putrefaction. And lastly, it is at this age
that the _muscardine_, which hardly shows itself at any other age of
the insect, appears with great intensity.
The _muscardine_ is a terrible scourge to the rearers of silkworms.
The losses which result from this disease in France are estimated at
at least one-sixth of the profits. No particular symptom allows of our
recognising the existence of this disease in worms which, however,
contain its germ; only, the worm, which has eaten up to that time as
usual, appears almost in a moment to change to a duller white; its
movements become slower, it becomes soft, and is not long before it
dies. Seven or eight days after its death it becomes reddish and
completely rigid. Twenty four hours afterwards a white efflorescence
shows itself round the head and rings, and soon after the whole body
becomes floury. This flour is a fungus called _Botrytis bassiana_, of
which the _mycelium_ develops itself in the fatty tissue of the
caterpillar, attacks the intestines, and fructifies on the exterior.
This fungus has been considered as the immediate cause of the
_muscardine_, and has been also regarded as the last symptom or end of
the disease. The communication of the disease by contagion has
alternately been admitted and denied. As its true cause, and any
efficacious means of opposing it, are still unknown, the breeders of
silkworms must be content to apply--so as to prevent or struggle
against this dreadful scourge--the precepts of hygiene: good
ventilation, excessive cleanliness, frequent _délitements_, and good
food properly prepared.
After the _muscardine_, we must mention another epidemic disease still
more terrible, the _gattine_. This disease shows itself from the very
beginning of the rearing, and increases in intensity at each age, so
that the number of worms able to enter regularly into the moult
becomes smaller and smaller. We are still in a state of utter
ignorance as to the cause of this last affection, which has
occasioned, for the last ten years, incalculable losses in the rearing
houses, which threatens the silkworm with complete destruction, and
which in the meanwhile has ruined the unfortunate countries of the
Cévennes, the principal seat of sericulture in France.
During the fifth age, the worms become large so quickly that on the
fifth or sixth day they are obliged to be moved away from each other
on the litter. The _délitement_ must be made every two days, or
indeed, every day now, on account of the enormous amount of the
excrement; and, at the same time, a good ventilation must be
constantly maintained. The temperature of the room should now be kept
to 24°, without ever exceeding this degree of heat. When it is
perceived that the worms wish to ascend, or _mount_, there are placed
on the tables, at certain distances from each other, little sprigs of
heather or very dry branches of light wood.
[Illustration: Fig. 213.--Sprigs of heather arranged so that Silkworms
may mount into them.]
When the worms begin to mount into the heather, one must
_encabaner_--that is to say, form with these branches little hedges,
curved back like a hut or cradle, the openings of which are, on an
average, seventeen inches or so (Fig. 213). At the expiration of
twenty-four hours all the good worms have mounted. The laggards who
remain under the _cabanes_ are taken off by hand, and placed on a
table, which is immediately _encabanea_.
The cocoons spun on these branches of heather ought to be large,
heavy, and well-shaped. The good cocoons are regular; their ends are
rounded and not pierced; and they are hard, especially at their
extremities, and have a fine grain. They are cylindrical. The best are
drawn in towards the middle, or have a concavity on either side of it
(Fig. 215). Every one knows that there are white and yellow cocoons.
They are the produce of different races of worms.
Commerce recognises two kinds of white silk: the _first white_ and the
_second white_. The silk of the _first white_ is produced by the race
_Sina_, the cocoons of which are of a perfect and azured white. They
produce the most beautiful and most precious silk, and serve for the
fabrication of light and delicate coloured tissues. The silk of the
_second white_ is furnished by two races: the _Espagnolet_ and the
_Roquemaure_.
[Illustration: Fig. 214.--Spherical cocoon of the Bombyx mori.]
[Illustration: Fig. 215.--Cocoon of Bombyx mori, drawn in towards the
middle.]
The races that produce yellow cocoons are more numerous than the white
ones. The yellow races are divided into three groups: those that have
small, middle-sized, or large cocoons. The first and second are
stronger, and more esteemed than the last.
The greater number of the races of silkworms have, let us here
mention, white and yellow cocoons; there are some, however, whose
cocoons are of a greenish white, or even quite green, or of a reddish
green. One race, raised in Tuscany, near Pistoia, has cocoons of a
pale rose colour; and, lastly, mention has been made of cocoons of a
purple colour.
When the cocoons are completed, the people in charge of the rearing
establishments separate them from the heather and sell them to the
silk-spinners. But they must manage to get these cocoons into a state
in which they will remain entire during a long time. They must, in
other words, kill the chrysalis, to prevent the cocoons being pierced
by the moth. To kill the chrysalis so as to prevent the development
of the imago is an operation which is called the _étouffage_, or
stifling.
[Illustration: Fig. 216.--Larva, pupa, cocoon, and moth of Bombyx mori.]
To effect this stifling, the cocoons are exposed to a high
temperature. Formerly, in the Cévennes, the cocoons were placed in a
baker's oven, heated for baking bread. But they ran the risk thus of
being burnt, or of a certain number of chrysalides remaining alive.
Now, to kill the chrysalides, they make use of steam at 100°, produced
by water boiling in a vessel, and which passes through wicker baskets
filled with cocoons.
The rearer must also take care at the time he gathers them, to
separate the cocoons which are to provide eggs for the next year. As
the female cocoons are heavier than the male cocoons, they are easily
separated by weighing them in a pair of scales.
To obtain the eggs, or grain, the cocoons are fixed on sheets of brown
paper, covered with a slight coating of paste made of flour. They are
arranged in such a manner that the moths shall find no obstacle when
they come out of them, head foremost; and, moreover, so that they may
be able to reach with their legs the cocoon which is opposite them, so
as to hang on to it, and to facilitate their exit from their own
cocoon (Fig. 218). The male and female cocoons are pasted on separate
sheets.
[Illustration: Fig. 217.--Apparatus for stifling the chrysalides in
the cocoons.]
It is from fifteen to twenty days after the _montée_, or _mounting_,
and when the temperature of the rooms has been kept between 20° and
25°, that the moths begin to be hatched. As they appear, they are
seized by the wings and placed on cloths stretched out for the
purpose, where they are left for about an hour, till their wings have
fallen flat on their bodies. As soon as they have evacuated a red
liquor, the males and females, which up to that time have been apart,
are put together.
They then stick sheets of paper on to screens, putting from
twenty-five to thirty females on each sheet (Fig. 219). It is here the
moths lay their eggs. The sheets of paper, covered with eggs, are then
hung on wires, at a small distance from the ceiling of a room having
a northern aspect, which is never warmed. They remain thus, exposed to
all variations of temperature, till the return of the warm weather. We
will say a few words, to bring this subject to an end, on the winding
of cocoons and the spinning of silk.
[Illustration: Fig. 218.--Sheet of paper with rows of cocoons prepared
for the exit of the moths destined for laying eggs.]
The winding of cocoons is an operation which at first sight appears
very simple, but which is in reality a difficult and delicate process.
It requires unremitting attention, great experience, and a delicacy of
touch which can only be found in the fingers of woman, or rather, in
the fingers of certain women.
[Illustration: Fig. 219.--Sheets of paper stuck into screens, and
inclined for the reception of moths.]
The woman who is spinning, stands before a sort of loom which is
called _tour_ (Fig. 220). Under her hand is a copper containing water,
which she heats to the required degree by opening the tap of a tube,
which brings a current of steam. She plunges the cocoons into the hot
water, and moves them about in it, to soften the gummy substance which
sticks the silken threads of the cocoon together. Then she beats them,
with a light hand, with a small birch-broom. The threads of the
cocoons get caught in the extremities of the twigs of which the little
broom is made, and the workwoman seizes with her fingers the bundle of
threads, and shakes them about till she perceives that they are all
single, and in a fit state to be joined together.
[Illustration: Fig. 220.--Silk-winding Establishment.]
Let us suppose that it is wished now to make up a _brin_, or staple,
by uniting together the ends of five cocoons. She chooses five ends in
the mass, makes of these a bundle, and introduces it into the hole of
a _filière_. She makes two staples (_brins_) at once, one on her
right, the other on her left hand. She then brings them together, she
crosses them, rolls them, and twists them, the one on the other,
several times; after which, she separates them from above and keeps
them well apart, making each of them pass into a hook at a distance,
from which they are going to twist round into a hank, separately, on a
wheel. The two threads thus twisted are drawn close together,
compressed, and become one, getting round by rolling on each other,
and being kept in continual motion, drawn out as they are by the rapid
motion of the wheel.
The difficulty which the emptying the cocoon of its silk thread
presents, makes us understand what difficulties those manufacturers
must have met with who have lately attempted to extract from the
stalks of mulberry leaves a sort of silk. We will enter into no
details of the attempts which have been made to accomplish this object
in our time, attempts which have, however, been crowned with no
success whatever. We will confine ourselves to reminding the reader
that these attempts are far from being of recent origination, since
they date back to as far as Olivier de Serres, the father of French
sericulture.
In a little work published by Olivier de Serres, in 1603, under the
title of _Cueillette de la Soie_, "The Gathering of Silk," we find a
memoir entitled: _La second richesse du mûrier, qui se trouve en son
escorce, pour en faire des toiles de toute sorte, non moins utile que
la soie provenant d'icelui_, "The second wealth of the mulberry tree
which is found in its bark, how to make of it cloth of all sorts, not
less useful than the silk derived from this tree." Olivier de Serres
proves in this memoir that the second bark, or _liber_, of the
mulberry tree contains a fibre capable of replacing hemp or flax, and
he describes the processes by which this may be obtained. The
processes which had been proposed by Olivier de Serres in 1603, were
resumed in the Cévennes a dozen years ago by M. Duponchel on the one
hand, and on the other by M. Cabanis,[64] who operated on the bark
instead of taking the whole of the wood of the mulberry tree. But none
of these attempts have given any good results up to the present
moment.
[64] See the "Année scientifique," 7e année, p. 432.
The various diseases which for the last fifteen years have been so
fatal to the mulberry silkworm, have suggested the idea of
acclimatising in Europe other silk-producing Bombyces, if not with
the view of superseding, at least as auxiliaries to the mulberry
species. The genus _Attacus_ has furnished these auxiliaries. Among
the species which have, in this respect, the greatest claims to our
attention, we must place in the first rank those which feed upon the
leaves of the oak tree. Indeed, the trees which can be made use of for
their cultivation are very numerous in Europe, and, moreover, the silk
produced by these worms appears to possess superior qualities.
There are three oak-feeding species of the genus _Attacus_. They are
_Yama-Maï_, _Pernyi_, and _Mylitta_.
[Illustration: Fig. 221.--Larva of Attacus (Bombyx) Yama-Maï.]
The silk of _Yama-Maï_ is as bright as that of the mulberry silkworm,
but a little less fine and strong, and occupies the first rank after
it. If we could succeed in acclimatising this species it would supply
any deficiency there might be in our crops of ordinary silk.
The eggs of the _Attacus Yama-Maï_ were brought from Japan--where this
worm is reared--conjointly with the mulberry silkworm, in 1862. The
larvæ hatched at Paris, in 1863, were green, of a great size, remained
in that state eighty-two days, and were easily reared. Their cocoon
resembles that of the mulberry species. It is composed of a beautiful
silk of a silvery whiteness in the interior, and of a more or less
bright green on the exterior. The moth is very large and beautiful, of
a bright yellow colour, approaching orange.
We give a drawing of the _Attacus Yama-Maï_, taken from the plates
which accompany M. Guérin-Méneville's memoir.[65]
[65] Sur le Ver à Soie du Chêne, et son Introduction en Europe.
Extrait du Magasin de Zoologie, 1855, No. VI.
[For an account of experiments conducted in England by Dr.
Wallace, whichunfortunately were complete failures as far as
rearing the moth went, see an essay by that gentleman in _The
Transactions of the Entomological Society of London_, 3rd
series, vol. v., pt. 5; Longmans and Co. The results of an
experiment which give the greatest hopes of success, will be
found in "The Entomologist" for October, 1867.--ED.]
[Illustration: Fig. 222.--Cocoon of Attacus (Bombyx) Yama-Maï.]
[Illustration: Fig. 223.--Attacus (Bombyx) Yama-Maï.]
Fig. 221 represents the larva, or caterpillar, two-thirds natural
size; Fig. 222, the cocoon, drawn on the same scale; and Fig. 223, the
moth.
In 1866, M. Camille Personnat published a very interesting monograph
of _Yama-Maï_, which may be consulted with profit by both cultivators
of silk and naturalists.[66]
[66] Le Ver à Soie du Chêne (_Bombyx Yama Maï_), son histoire,
sa description, ses moeurs. 8vo., avec planches coloriées. A
Laval, à l'école de sériculture.
_Attacus pernyi_ yields a remarkably beautiful silk, fine, strong, and
brilliant, which can be spun and dyed with great ease. The tissues
obtained from it partake of the qualities of ordinary silk, of wool,
and of cotton. This species of _Attacus_, which is reared on the oak
in Mandchouria, has given rise to great hopes in France. The cocoons
and moths of this worm were exhibited for the first time at the
Universal Exhibition of 1855. They were reared by M. Jordan, of Lyons,
from some cocoons sent over from China by the missionaries. It is much
to be desired that this species may be acclimatised in Europe.
[Illustration: Fig. 224.--Cocoon of Attacus (Bombyx) pernyi.]
Figs. 224 and 225 represent, after drawings in the Memoir of M.
Guérin-Méneville, already referred to, the cocoon and moth of the
_Attacus pernyi_.
The silk which _Attacus Mylitta_ produces is perhaps superior to that
of _Pernyi_. When the cocoons are properly prepared, the silk can with
ease be wound off from one end of them to the other. This worm is
found in various parts of Bengal and of Calcutta, and also at Lahore,
and its silk is exported in considerable quantities under the name of
_tusseh_. Brownish stuffs are made of it in India of firm and bright
texture, which are used for summer clothing, or for covering
furniture.
[Illustration: Fig. 225.--Attacus (Bombyx) pernyi.]
Figs. 226 and 227 represent the moth and the cocoon of _Attacus
Mylitta_ after M. Guérin-Méneville.
[Illustration: Fig. 226.--Attacus (Bombyx) Mylitta.]
In 1855 M. de Chavannes reared this species in the open air, near
Lausanne, in Switzerland. This treatment succeeded perfectly, without
any degeneration, for many years. It, however, died out at last, from
the effects, perhaps, of too great a difference in the climate, or
from those accidents, still so little understood, to which even the
insects of our own country are subject. This was unfortunate, as this
species is one of those whose acclimatisation in Europe is the most to
be desired, for it would render great service to the cultivators of
silk.
It remains for us to speak of two other species, which are very
important, inasmuch as their domestication in Europe is now an
accomplished fact. We mean the _Attacus_ or _Bombyx_ of the Ailanthus,
and also that of the Castor-oil plant.
[Illustration: Fig. 227.--Cocoon of Attacus (Bombyx) Mylitta.]
Every one has heard of the Ailanthus silkworm (_Attacus_ [_Bombyx_]
_Cynthia_), whose acclimatisation in Europe has been materially
assisted by the admirable and persevering efforts of M.
Guérin-Méneville.
The Ailanthus worm is a native of Japan and of the north of China. It
was brought over in 1858 by Annibale Fantoni, and sent to M.
Guérin-Méneville by MM. Griseri and Colomba, of Turin. When it is
nearly full-grown it is emerald green, with the head, the feet, and
the last segment of a beautiful golden yellow, and has black spots on
each segment. This worm, in its full-grown state, is represented by
Fig. 228; in the same figure are also represented the eggs and the
cocoon. The moth has the abdomen yellowish underneath, with little
white tufts. Its wings are traversed by a white band, which is
followed exteriorly by a line of a bright rose; each wing is also
marked by a lunula or crescent-shaped spot.
In 1858 M. Guérin-Méneville presented to the Académie des Sciences of
Paris the first moths and the first eggs laid in France of the
_Attacus Cynthia_. This able entomologist demonstrated very soon
afterwards--1st, that the caterpillars of this insect can be reared in
the open air, and with scarcely any cost for management; 2ndly, that
it produces two crops a year in the climate of Paris and the north of
France; 3rdly, that the cultivation of the Ailanthus, or the false
Japan varnish tree, on which this insect lives, is easy even in the
most sterile soil.
[Illustration: Fig. 228.--Eggs, larvæ, and cocoons of Attacus (Bombyx)
Cynthia.]
M. Guérin-Méneville showed still further that _ailantine_, the textile
matter furnished by the cocoon of the Cynthia, is a sort of floss silk
holding a middle place between wool and the silk of the mulberry-tree
worm, and which, as it can be produced at scarcely any expense, would
be very cheap, and would serve for the fabrication of what are called
fancy stuffs, for which ordinary floss silk is now used. In 1862 M.
Guérin-Méneville sent in a Report to the Minister of Agriculture on
the progress of the cultivation of the Ailanthus, and of the breeding
of the silkworm, which was reared in the open air on this tree. He
mentions, in his Report, the rapid development of the cultivation of
the tree in France, the great number of eggs of the Ailanthus silkworm
sold, the foundation of a model silkworm nursery at Vincennes, and,
this one great point gained, that they had found out the way of
unwinding the silk from the cocoons of the _Cynthia_ in one unbroken
and continuous thread.
Till then European industry had only succeeded in drawing from the
cocoons of the Ailanthus silkworm a floss silk, composed of filaments
more or less short, obtained by carding, and unable to produce, when
twisted, anything better than floss, that is to say, refuse silk. It
is to the Countess de Vernéde de Corneillan, on the one hand, and to
Doctor Forgemot on the other, that the merit is due of having obtained
an unbroken thread of silk from the cocoon of _Attacus Cynthia_.
A monograph on the Ailanthus silkworm appeared in 1866 under the
title, "L'Ailante et son Bombyx, par Henri Givelet."[67] It is a
complete account of all the results obtained up to the time, both as
regards the rearing of the silkworm and also as regards the
cultivation on a large scale of the Ailanthus, or false Japan varnish
tree.[68]
[67] In 8vo, avec plans et planches coloriées. Paris, 1866.
[68] A work by M. Guérin-Méneville on the same subject,
entitled, "Education des Vers à Soie de l'Ailante et du Ricin,"
in 12mo., Paris, 1860, may also be consulted.
[For a full account of successful experiments carried on in
England, see Dr. Wallace's essay in _The Transactions of the
Entomological Society of London_, 3rd series, vol. v., pt. 2;
Longmans and Co.--ED.]
The Castor-oil Plant Silkworm (_Attacus_ [_Bombyx_] _ricini_) is a
species very nearly akin to the Ailanthus worm, perhaps only a
variety, and comes from India. The silk which it produces is very
similar in every respect to that of the _Cynthia_. The rearing of this
worm could never attain to any great importance in France, on account
of the necessity there is of renewing the plantations of the
castor-oil plant each year. It would, however, afford an additional
source of income to the farmers in the south of France, who cultivate
the castor-oil plant with a view to selling its seeds, which are much
used in pharmacy.
Nearly allied to the genus _Attacus_, which furnishes us with all
these precious auxiliaries to the mulberry silkworm, are a great
number of other species, both indigenous to Europe and exotic, mostly
remarkable for their great size, and a few of which are common in this
country.
Fig. 229 is the largest European moth, but never found farther north
than the latitude of Paris. Its wings are brown, waved, and variegated
with grey. Each of them has a large black eye-shaped spot, surrounded
by a tawny circle, surmounted by one white semicircle, and by another
of a reddish hue, the whole completely enclosed in a black circle.
"These moths," says Geoffroy, "are very large; they look as if they
were covered with fur, and, when they fly, one is inclined to take
them for birds."
[Illustration: Fig. 229.--Saturnia pavonia-major.]
_Saturnia pavonia-major_ comes from a very large caterpillar, which is
of a beautiful green, with tubercles of turquoise blue, each of which
is surmounted by seven stiff divergent hairs. This caterpillar lives
principally upon the elm, but it feeds also upon the leaves of the
pear, plum, and other trees. It spins a brown cocoon, formed of a
coarse silk of great strength. It is not until the following spring
that it becomes a moth.
The Emperor Moth (_Saturnia carpini_, Fig. 230) much resembles the
above, except in size. This species is common in England, and its
green larva, covered with black or pink warts, from which spring
hairs, as in the last, is by no means rare on heath in the autumn. It
also feeds on bramble and other plants.
[Illustration: Fig. 230.--Emperor Moth (_Saturnia carpini_).]
Among the _Attaci_ foreign to Europe, we must mention _Atlas_ (Fig.
231), the expanse of whose wings exceeds four and a quarter inches.
This magnificent moth, one of the largest known, comes from China.
The family _Bombycidæ_ comprises many species which we must not omit
to mention.
The Lackey (_Bombyx neustria_) derives its name from the colour of the
caterpillar, which has longitudinal lines of various colours, and a
blue head. These caterpillars live together on a great number of our
forest and garden trees, to which they do much damage. The moth (Fig.
232) has a brownish body, and wings of a more or less tawny yellow
colour, with two darker lines on the front wings.
The Procession Moth (_Bombyx processionea_) is a small greyish moth,
the caterpillars of which live in numerous troops on oak trees, and
devour the leaves at the moment of their development. In the evening
these caterpillars come out of their common nest, and form a sort of
procession; hence their name Procession Moth. "I kept some for a
little time in my house in the country," says Réaumur. "I brought an
oak branch which was covered with them into my study, where I could
much better follow the order and regularity of their march than I
could have done in the woods. I was very much amused and pleased at
watching them for many days. I hung the branch on which I had brought
them against one of my window shutters. When the leaves were dried up,
when they had become too hard for the jaws of the caterpillars, they
tried to go and seek better food elsewhere. One set himself in motion,
a second followed at his tail, a third followed this one, and so on.
They began to defile and march up the shutter, but being so near to
each other that the head of the second touched the tail of the first.
The single file was throughout continuous; it formed a perfect string
of caterpillars of about two feet in length, after which the line was
doubled. There two caterpillars marched abreast, but as near the one
which preceded them as those who were marching in single file were to
each other. After a few rows of our processionists who were two
abreast, came the rows of three abreast; after a few of these came
those which were four abreast; then there were those of five, others
of six, others of seven, others of eight caterpillars. This troop, so
well marshalled, was led by the first. Did it halt, all the others
halted; did it again begin to march, all the others set themselves in
motion, and followed with the greatest precision.... That which went
on in my study goes on every day in the woods where these caterpillars
live.... When it is near sunset you may see one caterpillar coming out
of any of the nests, by the opening which is at the top, which would
hardly afford space for two to come out abreast. As soon as it has
emerged from the nest, it is followed by many others in single file;
when it has got about two feet from the nest, it makes a pause, during
which those who are still in the nest continue to come out; they fall
into their ranks, the battalion is formed; at last the leader sets off
marching again, and all the others follow him. That which goes on in
this nest takes place in all the neighbouring nests; all are evacuated
at the same time."
[Illustration: Fig. 231.--Attacus (Bombyx) Atlas.]
[Illustration: Fig. 232.--The Lackey (_Bombyx neustria_).]
One part of Fig. 233 shows the arrangement of the caterpillars on
coming out of the nest. These caterpillars are furnished with long
hairs, slightly tufted, which come off with the greatest ease, and
which if they penetrate into the skin, cause violent itching. In 1865
a number of the alleys of the Bois de Boulogne were shut up from the
public in order to save them from this annoyance. These caterpillars
construct a covering common to them all, in which they live, and
transform themselves therein, each insect making for his own private
use a small cocoon. This insect is said to have been found in England,
but there is not sufficient evidence to admit it into our lists.
[Illustration: Fig. 233.--Larvæ of the Procession Moth (_Bombyx
processionea_).]
[Illustration: Fig. 234.--The Vapourer Moth (_Orgyia antiqua_), male
and female.]
The _Orgyias_ comprise a great number of small species, of a dark
colour, which do a great deal of damage to our forest trees. In
September and October the male of the _Orgyia antiqua_, with his
tawny wings, may often be seen flying about the streets of London. The
female (Fig. 234) is remarkable, as she has only the rudiments of
wings, and only goes as far as the side of her cocoon. The caterpillar
of the _Orgyia pudibunda_, called also the Hop Dog, attacks almost
every sort of tree. When the state of the atmosphere favours their
propagation, they appear in fearful quantities, and cause the greatest
havoc. During the autumn of 1828, in the environs of Phalsbourg, they
were to be counted by millions. The extent of the woods laid waste was
calculated at about fifteen hundred hectares. It is common in this
country.
[Illustration: Fig. 235.--Orgyia pudibunda.]
Among the genus _Liparis_, the species of which are also very
destructive to trees, we must mention the Brown-tailed Moth (_Liparis
chrysorrhoea_, Fig. 236), a species by no means rare in England.
The caterpillars live in quantities, on apple, pear, and elm trees,
and destroy the plantations of the promenades of Paris.
[Illustration: Fig. 236.--Liparis chrysorrhoea.]
The females of this genus tear off the fur from the extremity of their
abdomens to make a soft bed for their eggs, and to preserve them from
the cold. And yet they are never to see their young, for they die
after they have laid their eggs. Another tribe of _Bombycina_ contains
species of a small size, which are remarkable from the habits of their
caterpillars, which make, with foreign bodies, cases, in the interior
of which they live and undergo their metamorphoses.
The caterpillars of the genus _Psyche_ live in a case composed of
fragments of leaves, of bits of grass and straw, of small sticks of
wood, or of little stones, stuck together, and intermixed with silky
threads.
[Illustration: Fig. 237.--Case of Psyche muscella.]
[Illustration: Fig. 238.--Psyche muscella.]
[Illustration: Fig. 239.--Case of Pysche rubicolella.]
[Illustration: Fig. 240.--Case of Psyche graminella.]
[Illustration: Fig. 241.--Larva of Psyche graminella.]
[Illustration: Fig. 242.--Psyche graminella.]
[Illustration: VII. The Goat-moth (_Cossus ligniperda_). Larva, pupa,
and perfect insect. 1, 2. Perfect insect. 3. Pupa. 4. Larva.]
We give a representation (in Figs. 237, 239, and 240) of the cases of
the caterpillars of three different kinds. The females of these moths
are completely destitute of wings, and resemble caterpillars. As a
general rule they hardly ever leave their case. The males (Figs. 238,
242) are of a blackish grey, and fly very swiftly.
The caterpillars of the genus _Hepialus_ are difficult to observe, as
they live in the interior of the roots of various vegetables. Such is
the common Ghost Moth (_Hepialus humuli_), which sometimes causes the
greatest damage.
[Illustration: Fig. 243.--Zeuzera æsculi.]
The type of the genus _Zeuzera_ is _Zeuzera æsculi_, or Wood Leopard
(Fig. 243). It has white wings with large blackish blue spots on the
anterior, and small black spots on the posterior wings. The
caterpillar, of a vivid yellow, spotted with black, lives in the
interior of the trunks of a great many trees, principally the
chestnut, the elm, the lime, and the pear tree. This moth, which is
known also by the name of Coquette, is to be seen in the evening
flying about the public gardens of Paris, and is not rare in England.
The most celebrated species of the allied genus _Cossus_ is the
Wood-boring Goat Moth (_Cossus ligniperda_), figured in the opposite
plate. The moth has a heavy brownish body and greyish wings streaked
with black. It is found in most parts of Europe. The caterpillar is of
a reddish colour, as if it had on a leathern jerkin, and disgorges a
liquid which is believed to soften ligneous fibres, and it lives in
the interior of willows and other trees. It was on this caterpillar
that Lyonnet made his admirable anatomical researches.
[Illustration: Fig. 244.--Larva of Dicranura vinula.]
[Illustration: Fig. 245.--Dicranura vinula.]
Another tribe of _Bombycina_ comprises some very strange caterpillars,
whose hindermost feet are changed into forked prolongations, which
they move about in a threatening manner. These sort of fly-traps
are perhaps meant to keep at a distance those insects which would
lay their eggs upon the caterpillar's body. The caterpillars of
_Dicranura_ are of this kind. We give a representation of the
caterpillar and the moth of the Puss Moth (_Dicranura vinula_, Figs.
244, 245), as also the moth of the _Dicranura verbasci_, the former of
which is common in England, and the larva may be found during the late
summer and early autumn feeding on poplars and willows; and of the
caterpillar of _Stauropus fagi_, the Lobster Moth (Fig. 247), rare in
France, whose appearance is strange indeed. The moths, on the
contrary, have nothing about them remarkable.
[Illustration: Fig. 246.--Dicranura verbasci.]
[Illustration: Fig. 247.--Larva of the Lobster Moth (_Stauropus fagi_).]
The _Noctuina_ are a group of Lepidoptera of middling size, and
generally found in woods, meadows, and gardens, where their
caterpillars have lived. They seldom fly till about sunset, or during
the night. Their upper wings are of a dark colour, with spots in the
middle of a particular shape. Their lower wings are of various
colours, often whitish, sometimes red or yellow.
[Illustration: Fig. 248.--Noctua tegamon.]
[Illustration: Fig. 249.--Noctua nebulosa.]
We give representations of some of the species of this group.[69]
_Noctua tegamon_, Fig. 248; _Noctua nebulosa_, Fig. 249; _Noctua
musiva_, Fig. 250; _Noctua brunnea_, Fig. 251; _Catocala fraxini_,
Fig. 252; _Catocala Americana_, Fig. 253; _Catocala paranympha_, Fig.
254; _Catocala nupta_, Fig. 255, the Red Underwing; and _Erebus
strix_, Fig. 256.
[69] In England it numbers about three hundred species. The
larvæ are of diverse habits, but the majority feed on low
plants; the moths are provided with a trunk, and are very
partial to sweets.--ED.
[Illustration: Fig. 250.--Noctua musiva.]
[Illustration: Fig. 251.--Noctua brunnea.]
The bodies of these moths are robust and sometimes massive, and are
scaly rather than woolly. The thorax is sometimes bristling with hairy
tufts.
This genus includes 800 species, of which there are about 300 in
France. The caterpillars of the _Noctuina_ are smooth or very
slightly covered with hair, usually of a pale colour, and live on low
plants, of which they devour, some the leaves, others the roots; then
it is they are most destructive to agriculture. There are some of them
which eat any caterpillars they may chance to meet, and even those of
their own species, leaving nothing but the skin. Some of them surround
themselves with a light cocoon before becoming chrysalides; others
bury themselves in soft, well-pulverised soil.
[Illustration: Fig. 252.--Catocala fraxini.]
[Illustration: Fig. 253.--Catocala Americana.]
[Illustration: Fig. 254.--Catocala paranympha.]
[Illustration: Fig. 255.--Catocala nupta.]
[Illustration: Fig. 256.--Erebus strix.]
The family of _Geometrinæ_, or Geometers, comprises moths of a
middling size, and usually flying after sunset and during the
night.[70] They frequent the alleys of damp woods, where they become
the prey of the _Libellulæ_[71] and other carnivorous insects. Their
bodies and abdomens are slender, their wings large, thin, fragile,
often of a dark colour, with brilliant markings.
[70] few species fly in bright sunshine.--ED.
[71] Dragon-flies.--ED.
The caterpillars of the _Geometrinæ_ are known by the name of
loopers or geometers. We have previously described their singular
organisation. They are continually spinning a silken thread, which
keeps them attached to the plant on which they live. If you touch the
leaf which supports them they immediately let themselves fall.
[Illustration: Fig. 257.--Looper hanging by its thread.]
[Illustration: Fig. 258.--Seen at the side.]
[Illustration: Fig. 259.--Front view.]
[Illustration: Figs. 260 and 261.--Remounting its thread.]
"Nevertheless, they do not generally fall to the ground," says
Réaumur; "there is a cord ready to support them in the air (Fig. 257),
and a cord which they can lengthen as they will; this cord is only a
very thin thread, but has nevertheless strength enough to support the
caterpillar (Figs. 258, 259). All that there seems to fear is, that
the thread may lengthen too quickly and the caterpillar fall, rather
than descend gently, to the ground. But what we must first remark and
admire is, that the caterpillar is mistress of its movements, and is
not obliged to descend too quickly; it descends by stages; it stops in
the air when it pleases. Generally it only descends at most about one
foot at a time, and sometimes only half a foot or a few inches, after
which it makes a pause more or less long, as it pleases." It is in
this way that the caterpillars let themselves fall from the top of the
highest trees: they remount again with no less ease.
Let us listen to Réaumur's description of the means employed by this
caterpillar to ascend these heights. Figs. 260 and 261, drawn, as the
three preceding ones, from the plates in Réaumur's Memoir, help us to
follow the explanation given by the illustrious naturalist of the
evolutions of our little acrobat:--"To remount," says Réaumur, "the
caterpillar seizes the thread between its jaws, as high up as it can;
as soon as it has done this it twists its head round, lays it over on
one side, and continues to do so more and more every moment. Its head
seems to descend below the last of the scaly legs which are on the
same side as that to which it is inclined. The truth is, however, that
it is not its head which descends, the part of the thread which it
holds between its jaws is a fixed point for its head and for the rest
of its body; it is that portion of the back corresponding with its
scaly legs which the caterpillar twists upwards; the consequence is
that the scaly legs and that part of the body to which they belong
then ascend. When the last pair of legs is just over the jaws of the
caterpillar, one leg, viz., that which is on the side towards which
the head is inclined, seizes the thread and brings it over to the
corresponding leg on the other side, which is advanced to receive it.
If the head is then raised, which is done immediately, it is in order
that it may seize the thread at a higher point than that at which it
was caught at first; or, which is the same thing, the head, and
consequently the whole body of the caterpillar, is found to have
ascended to a height equal to the length of the thread which is
between the place where its jaws seized it the first time and that
where they seized it the second time. The first move in the upward
direction is thus made, and the second soon follows.... If you were to
seize the caterpillar on its arrival at the end of its upward journey,
you would see a packet of threads huddled together between the four
hindmost of the scaly legs. The greater the height ascended the
greater is the size of this packet. All the turns of the thread which
compose it are entangled. So the caterpillar does not consider it of
any value. As soon as the insect can walk it gets rid of the mass,
sets its legs free, and leaves it behind before one or at most two
steps have been taken. The cord is wasted on each ascent, but the
caterpillar can afford to lose as many as it likes, for it has in
itself the source of the matter necessary for the composition of the
thread, and it is a source from which that which was drawn off is
being continually re-supplied. Moreover, spinning the thread costs the
caterpillars but little; indeed, the loopers economise this thread so
badly that most of them leave it behind them wherever they go."
They are found on many trees, but particularly on the oak, the foliage
of which they often entirely devour. They burrow into the ground to
change into chrysalides, and undergo all their metamorphoses in the
course of the year. Others do not become perfect insects till the
autumn, or sometimes not even till the following spring. A few assume
the perfect state in winter. There are, indeed, some of these, such as
the males of the _Hybernias_, which fly about on the foggy evenings of
November. The females of this genus have either no wings at all, or
else only rudimentary ones. Two species, the _Hybernia defoliaria_, or
Winter Moth, and the _Chimatobia brumata_, abundant here, are very
common in the environs of Paris.
[Illustration: Fig. 262.--Hybernia leucophearia, male.]
M. Maurice Girard says, in his work on the metamorphoses of insects,
that the females of these moths can easily be found at the beginning
of November, in a very strange place, namely, on the gas lamps of the
public promenades; for instance, along the roads in the Bois de
Boulogne. No doubt they had climbed up to this height, attracted by
the light, or perhaps had been carried thither by the males, which
fly, having wings.
[Illustration: Fig. 263.--Winter Moth (_Hybernia defoliaria_), male.]
[Illustration: Fig. 264.--Winter Moth (_Hybernia defoliaria_), female.]
In February and March appear other analogous species. "We may find,"
says M. Maurice Girard, "near Paris, in the meadows which surround the
confluence of the Seine and the Marne, at the end of the month of
March, the _Nyssia zonaria_ (Fig. 267), the males of which insect
remain during the day motionless on the grass."[72]
[72] With us this insect has a very limited range, being only
found at New Brighton, near Birkenhead, where it is most
abundant.--ED.
[Illustration: Fig. 265.--Chimatobia brumata, male.]
[Illustration: Fig. 266.--Chimatobia brumata, female.]
There are some species of this family in which the wings of the
females are developed like those of the males.[73] Such are the
Peppered Moth (_Amphidasis betularia_) and the Currant Moth (_Abraxas
grossulariata_), whose caterpillar lives on the red currant and
gooseberry, and an immense number known as Thorns, Carpets, Waves, &c.
[73] The exception is with those in which the wings are _not_
developed in both cases, and in England this peculiarity is
confined to species appearing during the winter and early
spring.--ED.
[Illustration: Fig. 267.--Nyssia zonaria, male and female.]
The section of the _Pyralina_ contains the smallest nocturnal
Lepidoptera, and nearly all those tiny species which flutter round our
lights in the evening.
[Illustration: Fig. 268.--Penthina pruniana.]
Here are some drawings of a few of the numerous species of this
section, remarkable for their small size and beauty:--_Penthina
pruniana_, _Ædia pusiella_, _Xylopoda fabriciana_, _Poedisca
autumnana_, _Tortrix roborana_, _Philobacera fagana_, _Tortrix
sorbiana_, _Antithesia salicana_, _Poedisca occultana_, _Argyrolepia
æneana_, _Sericoris Zinkenana_, _Sarrothripa revayana_, _Cochylis
francilana_, _Choreutes dolosana_ (Figs. 268 to 281).[74]
[74] Many of these are placed by some authors among the
Pyralina, and by others among the Tortricina.--ED.
[Illustration: Fig. 269.--Ædia pusiella.]
[Illustration: Fig. 270.--Xylopoda fabriciana.]
In a book of this kind we can only mention some types among these
last insects, which claim our attention in what we might almost call a
tyrannical manner. We will, therefore, content ourselves by saying a
few words about the Green Tortrix, the Pyralis of the Vine, the
Bee-hive Moth, some species of the Clothes Moth family (_Tineina_),
and finally of the _OEcophoræ_.
[Illustration: Fig. 271.--Poedisca autumnana.]
[Illustration: Fig. 272.--Tortrix roborana.]
[Illustration: Fig. 273.--Philobacera fagana.]
[Illustration: Fig. 274.--Tortrix sorbiana.]
The Green Tortrix (_Tortrix viridana_) has wings of a green colour,
with the margin and fringe whitish on the anterior, and of an ashy
grey on the posterior wings. The under-side of the four wings is of a
bright white, as if it had been silvered. This pretty moth comes out
in the month of May. It is so common everywhere, that at this season
it is only necessary to shake the branches of the oaks which border
the alleys of the woods to set in motion hundreds of them. The
caterpillar is green, with black warty spots, each having a hair of
the same colour. They are wonderfully lively, the moment they are
disturbed taking refuge in a rolled leaf, which serves them as a
dwelling-place. If they are pursued, they let themselves fall by the
aid of a thread, and do not re-ascend till they think they can count
on repose and security. This, and many kindred species, do a great
deal of damage to our trees. They strip them of their leaves, and
sometimes give them, during the first days of summer, the sad and
melancholy appearance which they present in the middle of winter.
[Illustration: Fig. 275.--Antithesia salicana.]
[Illustration: Fig. 276.--Poedisca occultana.]
[Illustration: Fig. 277.--Argyrolepia æneana.]
[Illustration: Fig. 278.--Sericoris Zinkenana.]
[Illustration: Fig. 279.--Sarrothripa revayana.]
[Illustration: Fig. 280.--Cochylis francilana.]
[Illustration: Fig. 281.--Choreutes dolosana.]
We have just alluded to the tube formed of a rolled leaf, in which the
caterpillar takes refuge, and in which it lives. This tube it
constructs itself. Réaumur has devoted a magnificent chapter of his
Memoirs to observations on the skill with which divers species of
caterpillars fold, roll, and bind the leaves of plants and trees,
especially those of the oak. Let us listen to the great observer:--"If
one looks attentively at the leaves of the oak tree towards the middle
of the spring, many of them will be seen to be rolled in different
ways. The exterior surface of the end of one of these leaves has, it
appears, been rolled back towards the interior surface, in order to
describe the first turn of a spiral, which is then covered by many
other turns (Fig. 282). Some leaves are rolled towards their exterior
surfaces, others are rolled towards their interior surfaces, but in a
totally different direction. The length or axis of the first roll is
perpendicular to the principal rib and to the stalk of the leaf, the
axis of the latter parallel to the same rib (Fig. 283). Work of this
kind would not be very difficult to perform for those who had fingers;
but caterpillars have neither fingers nor anything equivalent to
fingers. Moreover, to have rolled the leaves is only to have done half
the work: they must be retained in a position from which their natural
spring tends constantly to draw them. The mechanism to which the
caterpillars have recourse for this second part of their work is
easily perceived. We see packets of threads attached by one end to the
surface of the roll, and by the other to the flat surface of the
leaf. They are so many bands, so many little cords which hold out
against the spring of the leaf. There are sometimes more than from ten
to twelve of these bands arranged nearly in the self-same straight
line. Each band is a packet of threads of white silk, pressed one
against the other, and yet we must remember all are separate."[75]
[75] Mémoires pour servir à l'Histoire des Insectes, tome ii.,
page 210 (5e Mémoire).
[Illustration: Fig. 282.--Oak leaf rolled perpendicularly.]
[Illustration: Fig. 283.--Oak leaf rolled sideways.]
Réaumur made the oak-leaf rollers work in his house. He has admirably
described all their little manoeuvres, but we lack the space to
convey to the reader the result of his minute observations. In fact,
the leaf-rollers construct for themselves a sort of cylindrical cell,
which receives light only through the two extremities. The convenience
of this green fresh habitation is, that its walls furnish food to the
animal which inhabits it. The caterpillar, thus sheltered, sets to
work to gnaw away at the end of the leaf which it rolled first; it
then eats all the rolls it has made, up to the very last.
[Illustration: Fig. 284.--Leaf of sorrel, a portion of which is cut
and rolled perpendicularly to the leaf.]
Réaumur found also rolls which had been formed of two or three leaves
rolled lengthwise, and he saw that the leaves which had occupied the
centre had been almost entirely eaten. He saw also caterpillars which
continued to eat while they were making their habitation. Let us add
that one of the ends of the roll is the opening through which the
caterpillar casts its excrement; that the caterpillar can prepare
itself a fresh roll if it is turned out of the first; and, lastly,
that it is in a rolled leaf that the caterpillar undergoes its
metamorphoses into a chrysalis and into a moth.
Réaumur studied other leaf-rollers; for instance, those which roll the
leaves of nettles and of sorrel. The last one works in a manner which
deserves to be mentioned. Its roll is of no particular shape, but it
is its position which is remarkable. It is set upon the leaf like a
ninepin (Fig. 284). The caterpillar has not only to twist it up into a
roll, but also to place it perpendicularly on the leaf.
[Illustration: Figs. 285 and 286.--Willow leaves rolled by a
caterpillar, and section of a bundle of leaves drawn together by a
caterpillar.]
Next to the rolling caterpillars, let us mention those which are
contented with folding the leaves. These caterpillars then lie in a
sort of flat box. Besides the rolling and folding caterpillars, there
are still those which bind up a good many leaves in one packet. These
packets are to be found on nearly every tree and shrub, and the
caterpillar, lying nearly in the middle of the packet, is well
sheltered, and surrounded by a good supply of food. We will content
ourselves by giving a drawing, after Réaumur, of the pretty
arrangement of the leaves of a species of willow (Figs. 285, 286). In
the figures we see the parcel bound together by the caterpillar. In
that to the right we see the transverse section of the packet of
leaves magnified. At the two edges are seen the threads which keep the
leaves together, and the cavity occupied by the caterpillar.
The Vine Pyralis is produced from a leaf-rolling caterpillar, which
deserves our attention on account of the ravages which it has for some
time committed, and which it still commits in vineyards. It was at the
end of the sixteenth century that this pyralis first showed itself in
the environs of Paris, in the territory of Argenteuil. "The
inhabitants of this commune," writes the Abbé Leboeuf, "looked on
the insects which spoiled their vines in the spring of 1562 as a
visitation of God. The Bishop of Paris gave orders that they should
offer up public prayers for the diminution of these insects, and that
they should join to their prayers, exorcisms, without leaving the
church." Prayers, processions, exorcisms, were again had recourse to
in 1629, in 1717, and in 1733, to stop the ravages of this insect
among the vines of Colombes, in the territory of Aï.
The country of the Mâconnais and the Beaujolais became in their turn
the theatre of the ravages of the pyralis. These ravages very soon
increased and spread. In 1836, 1837, 1838, this plague raged in the
departments of the Saône-et-Loire, of the Rhône, of the Côte-d'Or, of
the Marne, of the Seine-et-Oise, of the Charente-Inférieure, of the
Haute-Garonne, of the Pyrénées-Orientales, and of the Hérault.
To give an idea of the losses which may be occasioned by the pyralis,
in a period of ten years (1828-1837), twenty-three communes comprised
in the two departments of the Saône-et-Loire and of the Rhône lost
75,000 hectolitres of wine a year, which may be valued at 1,500,000
francs. If we were to calculate the supply of articles of all sorts
which this great number of casks of wine would have necessitated, the
imposts on their transport, the duty, the taxes levied on their sale,
the carriage by land and water, which would have brought receipts into
the treasury, and lastly the diminution of taxes which had to be
granted for seven years to the vine proprietors in the department of
the Saône-et-Loire, and in 1837 in the department of the Rhône, and
which amounted to a total of more than 100,000 francs, we shall find
that the ravages of the pyralis caused in these two departments an
annual loss of 3,408,000 francs, and as the visitation lasted ten
years, we get the enormous sum total of 34,000,000 destroyed by the
ravages of one species of insect. The moth of the pyralis (Fig. 287)
shows itself from the 10th to the 20th of June. It is yellowish, more
or less shot with gold. When at rest, its wings are folded back one
over the other like a roof. Its flight is of short duration; it
contents itself with going from one vine stock to another.
[Illustration: Fig. 287.--The Vine Pyralis.]
[Illustration: Fig. 288.--Caterpillar of the Vine Pyralis.]
It is at sunset mostly that you see the moths of the pyralis
fluttering about. They remain quiet during the day, particularly when
the sun is at its hottest. They live on an average for ten days. The
females lay their eggs--which are at first green, then yellowish, then
brown--on the lower surface of the leaves.
[Illustration: Fig. 289.--Chrysalis of the Vine Pyralis.]
The caterpillar of the pyralis (Fig. 288) is called, in vulgar
parlance, according to the different places in which it occurs, vine
worm, summer worm, vintage worm, shell. In the south of France it is
called, in the patois of Languedoc, _babota_. Almost immediately after
they leave the eggs, the little caterpillars hide themselves in the
fissures of the vine stocks or the props which support them. They spin
a small cocoon of a greyish silk, in which they remain curled up till
the month of May. From the moment the leaves begin to develop they
throw out threads here and there, entangling all the young shoots of
the vine, which gives a desolate appearance to the vineyards. The
leaves of the vine are their favourite food, but they attack the seeds
of the grape also. As they increase in size every day, the damage they
do goes on increasing, and has not reached the maximum of intensity
till the moment when the caterpillars are about to change into
chrysalides. They are then three-quarters of an inch long and of a
yellowish green colour.
[Illustration: Fig. 290.--The Vine Pyralis in its three states. 1.
Leaf with batches of eggs laid upon it. 2. Batches of recently laid
eggs. 3. Eggs in which caterpillars can be perceived. 4. Batch of eggs
from which the caterpillars have already emerged. 5. Small
caterpillars hanging by threads. 6. Leaf with the chrysalis. 7.
Caterpillar. 8. Moth.]
From the 20th of June to the 10th of July they seek shelter in the dry
and interlaced leaves which have already served them for places of
refuge and partly also for food, or else they make themselves a fresh
nest.
At the end of two or three days, the caterpillar has become a
chrysalis (Fig. 289), which in a short time assumes a brown colour.
Shut up in the interior of the cocoon which the caterpillar had spun
before undergoing its metamorphosis, it changes into a moth at the end
of from fourteen to sixteen days.
The best way to diminish the ravages of the pyralis is to pluck off
the leaves which are laden with eggs, and burn them, or bury them in
deep holes.
Fig. 290, which we devote to the conspicuous insect whose destructive
history we have been here able to sketch only slightly, gives all the
particulars relating to this dangerous guest of the vineyards. On a
branch of the vine may be perceived the pyralis in the caterpillar
state, the eggs which have been laid by the moths, the chrysalides,
and perfect insects. The eggs are shown at two periods of their
development.
The Bee-hive or Wax Galleria is to be met with in all countries where
bees are reared.
The moth (Fig. 291) hides itself during the day round about the
bee-hives, and endeavours to make its way into them after sunset. The
caterpillar is of a dirty white, with brown warty spots, each
surmounted by a fine hair. It lives on wax, twines its threads round
the honeycomb, and very soon causes the larvæ contained in it to
perish.
[Illustration: Fig. 291.--Galleria cerella.]
When it emerges from the egg, which the female has laid in the
honeycomb, the caterpillar makes for itself with the wax a round tube,
in which it is safe against the stings of the bees. This tube, at
first very small, is lengthened and enlarged as the caterpillar
increases in size. It is generally from three to five inches in
length. It is in the interior of this that the caterpillar constructs
itself a hard cocoon, resembling leather, and it changes into a
brownish chrysalis.
A species of the genus _Butalis_, the _Butalis_ or _Alucita granella_,
is, in certain cantons of France, one of the greatest pests to
agriculture. The caterpillar of the _Tinea granella_ undergoes its
metamorphosis in the interior of grains of barley and of wheat, which
it devours without being perceived from without. The female lays her
eggs on the grains of corn before they are ripe. From four to six days
after, the eggs are hatched, and the young caterpillars are hardly as
thick as a hair. Each one takes possession of a grain of corn, and
penetrates into it by an imperceptible opening. They eat the flower
without injuring the teguments of the grain.
[Illustration: Fig. 292.--Tinea granella.]
When it has attained its full size it spins itself a cocoon of white
silk in the interior of the grain, which, after having been its
lodging and its larder, becomes for some time its tomb. It has,
however, taken care beforehand to make at the extremity of the grain a
circular opening, through which the moth may come out when the grains
have been threshed and stored up in the granary.
It is important to mention the _Tineina_, not because these little
moths are beautiful--they are, on the contrary, very dingy--but
because it is in this group that are found those insects which do the
greatest damage to our crops. The moths of the genus _Tinea_ are very
small. Their wings, which are greyish or brownish, are generally
marked with whitish and yellowish spots or lines. These are the little
moths which, in our houses, burn themselves so frequently in the
flames of the candles.
Their caterpillars are small, voracious, and deserve, on account of
the damage which they cause, to be compared to rats and mice.
Furnished with powerful jaws, they destroy everything they find in
their way, such as woollen stuffs, hair, furs, feathers, grain, &c.
The _Tineina_ are divisible into three groups: 1st, the species
hurtful to our stuffs and furs; 2ndly, the species which destroy our
corn crops; 3rdly, the _phytophagous_ species, that is to say, those
which feed on plants.
In the first subdivision must be classed the Fur Moth, the Woollen
Moth, and the Hair Moth.
The Woollen Moth is represented in the figure on next page. Its
caterpillar has the form of a worm, and is of a glossy whiteness, with
a few hairs thinly sprinkled over it and a grey line on its back. It
is enclosed in a tube, or sheath, open at both ends, in the interior
of which is a sort of tissue of wool, sometimes blue, sometimes
green, sometimes red, according to the colour of the stuff to which
the insect attaches itself and which it despoils. The exterior of this
sheath is, on the contrary, formed of silk made by the insect itself,
of a whitish colour.
The caterpillars are hardly hatched before they begin to clothe
themselves. Réaumur observed one of these worms during the operation
of enlarging its case. To do this it put its head out of one of the
extremities of its sheath, and looked about eagerly, to the right and
to the left, for those bits of wool which suited it best for weaving
in. In Fig. 294, we see two larvæ occupied in eating a piece of cloth.
[Illustration: Fig. 293.--The Woollen Moth (_Tinea tapezella_).]
[Illustration: Fig. 294.--Larvæ of the Woollen Moth (_Tinea tapezella_).]
"The larva changes its place continually and very quickly," says
Réaumur. "If the threads of wool which are near it are not such as it
desires, it draws sometimes more than half its body out of its case to
go and look for better ones farther off. If it finds a bit that
pleases, the head remains fixed for an instant; it then seizes the
thread with the two mandibles which are below its head, tears the bit
out after redoubled efforts, and immediately carries it to the end of
the tube against which it attaches it. It repeats many times in
succession a similar manoeuvre, sometimes coming partly out of its
tube, and then again re-entering it to fix against one of its sides a
new piece of wool."
After having worked for about a minute at one end of its tube, it
thinks of lengthening the other. It turns itself round in its tube
with such quickness, that you would imagine it could not have had time
to do so, and would think that its tail was formed in the same way as
its head, and possessed the same address in choosing and tearing out
the bits of wool.
Furthermore, when the moth which is working at elongating its case
does not find the threads or hairs of wool to its taste within reach
of its head, it changes its place. Réaumur saw this insect walking, at
some speed even, carrying with it its case. It walks on its six front
legs (Fig. 295). With the middle and hind legs it clings to the
interior of its case.
[Illustration: Fig. 295.--Larva of a Tinea walking.]
At the same time that the larva becomes longer it becomes stouter.
Very soon its garment will be too narrow for it. Will it enlarge its
old coat, or will it make itself a new one? Réaumur discovered that it
preferred to widen its old coat.
That is what our naturalist saw when he placed larvæ with blue cases,
for instance, upon stuff of a red colour. The bands which extended in
straight lines from one end of the case to the other, showed the part
that had been added.
"From watching them at different times," says this admirable observer,
"I find that the means which they employ is precisely that to which we
should have had recourse in a similar case. We know of no other way of
widening a sheath, a case of any stuff that we find too narrow, than
to split it right up and to let in a piece of the proper size between
the parts which we have thus divided; we should let in a piece on each
side if the shape of the tube seemed to require it. This is also
exactly what our larvæ do, with an extra, and which with them is a
necessary, precaution, so as not to remain exposed while they are
working at the enlargement of their garment. Instead of two pieces,
which should each be as long as their case, they let in four, each of
which is not longer than half the length of their case; and so they
never split up more than half the length of the case at the same time,
which has enough stuff left in it to keep it together while this
opening is being filled up."
The wools of our stuffs furnish the moths not only with clothing, but
also with food. Their excrements are little grains, which are the same
colour as the wool they have eaten.
When they are full grown, and the time approaches for their
metamorphosis, the larvæ abandon their food, and establish themselves
in the angles of walls. They creep up to the ceilings and suspend
themselves to them by one extremity of their tube. The two ends of the
tube are now closed by a silken tissue (Fig. 296). The larva thus
enclosed very soon changes its form; it becomes a chrysalis; then at
the end of about three weeks it is set free as a moth.
The Fur or Skin Moth works like the carpet moth: it makes itself a
case of the same form, and constructs it in the same manner. Only in
this case its covering is made of a sort of felt resembling that of
which our hats are made.
[Illustration: Fig. 296.--Case of the Moth attached to a piece of cloth.]
While the Carpet Moth only detaches from the various stuffs the wool
it requires for clothing and nourishment, the Fur Moth causes much
more considerable and more rapid damage. It cuts off all the hairs
which are in its way right down to the skin; it seems as if it took a
delight in cutting them off. That which is necessary for its wants is
nothing in comparison to the great quantity of hair one sees fall off
a skin on which it has established itself, when it is shaken. As it
advances it cuts more thoroughly than a razor could all the hairs
which are in its way.
The Hair Moth (Fig. 297) shows itself in great numbers in the perfect
state, from the end of April till the beginning of June. They appear
again in September, and generally stay behind cabinets and other
pieces of furniture.
[Illustration: Fig. 297.--Hair Moth.]
The caterpillar, which is cylindrical, white, destitute of hair, and
striped with brown, lives principally in the hair with which furniture
is stuffed, and sometimes in hair mattresses. When it has reached its
full size, it abandons its abode, pierces through the stuff which
covers the hair, and constructs for itself with this stuff a case of
silk, open only towards the end where the head is. At the beginning of
April it shuts its case, and changes itself into a chrysalis.
We can only here mention some of the phytophagous species, as the
Cherry-tree Moth (_Tinea cerasiella_), the Hawthorn Moth (_Tinea
cratægella_), the Burdock Moth (_Tinea lapella_), and the Rustic Moth
(_Tinea rusticella_).
The caterpillars of the _OEcophoræ_ resemble whitish worms. They
attack the leaves, the blossoms, the bark, and certain parts of the
fruit of trees. Some of these hollow out for themselves galleries in
eating the fleshy part; others also make galleries, but only in the
cuticle of the tree, or in the tenderest part of its bark. Some,
again, shut themselves up in one or many leaves rolled like a trumpet,
while others keep at the summits of plants, whose leaves they bind
together in a parcel with threads. And, lastly, some devour the stones
of fruits, such as that of the olive.
The moths of these caterpillars are very small, and generally of
brilliant metallic colours, they are to be found in the woods, and
still more in the orchards, from the beginning of June till the month
of September.
The _OEcophoræ_ are very slim and elegantly formed. Their anterior
wings, which are very narrow, are often ornamented with silvery
longitudinal lines, the posterior wings exactly resembling two
feathers.
The caterpillars live and metamorphose themselves in portable cases,
which they manufacture from the membranous portions of leaves, whose
flesh alone they eat. These cases are generally of a brown colour,
resembling a dead leaf. They are attached perpendicularly under the
leaves of many trees, but often under those of fruit trees.
Certain species of _OEcophoræ_ have cases partly covered with loose
pieces only slightly attached, formed of portions of leaves, and
arranged in such a way that Réaumur compares them to the furbelows
which ladies used formerly to attach to the bottom of their dresses.