Transcriber's Note
Italicized text is represented as _Text_.
THE
LIFE OF AN INSECT;
BEING
A HISTORY OF THE CHANGES OF INSECTS FROM THE
EGG TO THE PERFECT BEING.
PUBLISHED UNDER THE DIRECTION OF
THE COMMITTEE OF GENERAL LITERATURE AND EDUCATION,
APPOINTED BY THE SOCIETY FOR PROMOTING
CHRISTIAN KNOWLEDGE.
LONDON:
PRINTED FOR THE
SOCIETY FOR PROMOTING CHRISTIAN KNOWLEDGE;
SOLD AT THE DEPOSITORY,
GREAT QUEEN STREET, LINCOLN'S INN FIELDS,
AND 4, ROYAL EXCHANGE;
AND BY ALL BOOKSELLERS.
LONDON:
R. CLAY, PRINTER, BREAD STREET HILL.
CONTENTS.
PART I.--THE EGG.
PAGE
Chapter I.--_The Nest._--The Microscope and Telescope--Terror
caused by Insects--Death-watch--Life-boat of Eggs--The
Water Beetle--Floating Ark of Eggs--The Gnat--her
difficulties--her Egg-raft--The Sand-boring Wasp--Towers
of rubbish--Captive Caterpillars--Wood-boring Bee--An
Insect Nursery--Escape of the young--Tapestry Bee--A Nest
lined with Poppy-flower Petals--Enchanted Leaf-tubes--The
spell broken--The Insect Sorcerer--Nest of Down made by a
Moth--The Lackey Moth--The Ichneumons--Their usefulness 1
Chapter II.--_Structure and contents of the Egg._--Its
Shape--Remarkable mistake about an Insect--The
Lace-wing Fly--Eggs carved on their surface--Colours of
Eggs--Changes of Colour--Eggs of the Garden Spider--Pretty
Nests--Anatomy of the Egg--Contents of the Egg 43
Chapter III.--_Life begins in the Egg._--Spring
Time--Influence of Heat and Cold--Eggs resist great
Cold--The time of Hatching--Escape of the new
Creature--Connexion between Plants and Insects--Changes
in the Egg--A Spider's Mother's love--Experiment with two
Spiders--Anecdote of an Earwig--Enormous number of Eggs of
different Insects 57
PART II.--THE LARVA.
Chapter I.--_The Young Larva._--Affection of a Field-Bug--An
Earwig Mother--Anecdote of a Spider--Ant-Nurses--Varieties
of Larvæ--The Larva born--Forms of Larvæ--Larvæ of
Butterflies--Structure of a Larva 79
Chapter II.--_Habits of the Larva._--The Lion of the
Aphides--its Courage--The Ant-Lion--The "Giant Grim" of
Insects--Formation of its Trap--An Insect Excavator--The
Den--A Stone in it--A captive Ant--Principle of
Compensation--The Sand-Wasp's Den--A Warrior-Wasp--An
Insect Duel--The Kakerlac and the Bandit Wasp--The
Corpse carried home--A Wasp clad in the Wings and
Limbs of Insects--The Tiger Beetle Larva--Dragon-Fly
Larva--its curious Mask--a ferocious creature--Ravages of
Cockchafer Larvæ--Lamp Oil got from Larvæ--"Old Father
Long-legs"--The Gamma Moth and its Larva--Magical Origin
of--The excessive numbers of the Larvæ--Destruction of
Trees by Larvæ--Killed by rain--The Weevil--Insects on
board Ship--Appetite of Larvæ--Silk-Worm Larva--Larvæ
enormous Eaters--Growth of Larvæ 93
Chapter III.--_Moulting of the Larva._--Escape of Larva
from its old Skin--Arrangement of the Hairs--Danger
attending the Moult--Colours of Larvæ--Influence of
Sun-light--Curious appearance of the Coats of Larvæ--Larvæ
like Twigs--Singularly coated Larva 146
Chapter IV.--_Respiration of the Larva._--Experiment
with Larvæ--Insects do not breathe by their
Mouths--Breathing Mechanism of Larvæ--Spiracles--Aquatic
Larvæ--Inhabitants of the Ditch and Pool--Rat-tailed
Larvæ--Remarkable Organ--Chameleon-Fly Larva--Larva of
the May-Fly--Their under-water Cells--Singular organs of
Respiration--Complete Armour of Dragon-Ely Larva 157
Chapter V.--_Means of Defence of the Larva._--Leaf-dwelling
Larvæ--Larva clad in Rags--"Hickory-horned Devil"--Larva
with a Squirt--Shaggy-coated Larvæ--Frozen
Larvæ--Dwellings of Larvæ--Remarkable Australian Larva
cases--Larvæ in Winter 178
Chapter VI.--_Preparation for a Change._--Age of the
Larva--its attempts at concealment--Cocoons of
Larvæ--Silk-Worm Cocoon--Extraordinary precaution of a
Larva--Case of Bark-skin--Anecdote of a Larva--Suspension
of the Larva, horizontally and perpendicularly--Larva of
Meat-Fly--Last action of the Larva 194
PART III.--THE PUPA.
Chapter I.--_The Transformation._--Meaning of the word
_Pupa_--Various names of Pupæ--Process of the
change--Remarkable feat of a Pupa--Time occupied in the
Change 213
Chapter II.--_What is a Pupa?_--Characters of a Pupa--Active
and Inactive--Dissection of a Pupa--Contents
of Pupa-case--Singular Pupa--Goedart's strange
Representations of Pupæ--Pupæ from Surinam--Colours of
Pupæ--Aurelia and Chrysalis--Ground Pearl 225
Chapter III.--_Respiration of the Pupa._--Spiracles
of Pupæ--Anecdote from De Geer--Air-Cell under
Water--Difficulty of the task--Pupæ with an Air-tube 239
Chapter IV.--_Varieties and Age of the Pupa._--Different
kinds of Pupæ--Age of the Pupa--Pupæ hatched in a
Hot-house--Butterflies in Winter--Pupæ hatched by a
Hen--Glass Eggs--Influence of Warmth and Cold--Dreams
of Immortality--Réaumur's mistake--Varnishing
Pupæ--Preservation of Eggs--Falling of the "Manna"--Final
changes of the Pupa 251
Chapter V.--_The Great Change._--An Insect Prisoner--Escape
of the Cossus--Escape of a Fly--A guide-line
to the Captive--Cocoon of Emperor Moth--Escape
backwards--Chemical solvent--Escape of Ants--Huber's
Ant-hill--Assistant Ants--Aquatic Insects--The
Caddis-worm--Singular escape--The Gnat--A time
of Peril--Blood-Worms--A curious spectacle--The
Dragon-Fly--Phenomena of the Change--The Insect
new-horn--Curious facts about Pupæ 273
PART IV.--THE IMAGO.
Chapter I.--_The New-born Perfect Insect._--The
Resurrection--Meaning of the word Imago--Curious aspect
of New-born Insect--Conclusion of the Dragon-Fly's
History--Structure of a Wing--how expanded--Deformed
Wings--Exception in the Ephemeræ--Dance of the
Ephemeræ--Insects without Wings--Showers and Stains of
Blood--Aphis-Lion Fly--Insects in the Imago state do not
increase in size 309
Chapter II.--_The Structure and Organs of the Imago._--Anatomy
and Physiology--Insects have not Bones--Leather-coated
Jack--The Head and Thorax--The Eyes--simple and
compound--Wonders of an Eye--Anatomy of the Eye--Immense
number of Eyes--Remarkable Provision--Experiments on the
Eyes of Bees--Beauty of the Eyes--The _Antennæ_--their
Function, perhaps the Nose--Insects Weather-wise--Insects
in Rain--Organs of Speech--Anecdote of Bees--Various
Functions of Antennæ--The Mouth in Insects--Parts of
the Mouth--Spiral Tube of the Butterfly--Taste and
Smell in Insects--The Trunk--Wings--Membranous--Scale
covered--Wing-Cases--Experiments on Flying--Painted
Wings--The glory of the Butterfly--The Legs
of Insects--Cleanliness of Insects--The Water
Boatman--Kangaroo Beetle--The Abdomen--The Sting of the
Bee--Insect with a Leg in its Tail 335
Chapter III.--_Respiration of the Imago._--Experiments upon
the Breathing of Insects--Chloroform--Coal-gas--their
Effects--Contest between a Spider and a Blue-Bottle
Fly--Air-Pipes of Insects--Multitude of Air-Tubes--
Circulation of Blood in Insects--An Insect's Pulse 398
Chapter IV.--_Food and Death of the Imago._--Vegetable
Eaters--Carnivorous Insects--The Tigers to Insects--Fasts
of Insects--The Last Duty--Insect Forethought--The
Creator's Wisdom and Love--God does not despise Little
Things 408
ILLUSTRATIONS.--DIRECTIONS TO BINDER.
Egg-rafts of the Gnat 1
Ferocious Larvæ of Dragon-Fly 79
Insects escaping from the Pupa condition 213
Evening Flight of Ephemeræ 307
THE LIFE OF AN INSECT.
PART I.--THE EGG.
CHAPTER I.
THE NEST
To look at a house-fly as it performs its figure-of-eight dances
in the air of our rooms, or as it buzzes against the window-pane,
vainly endeavouring to dash its tender body through the firm and
clear glassy wall--to mark how soon it comes into existence, and how
soon its little day of life is gone--one would say it is a foolish
and trifling thing to write the history of an insect's life; but any
one who would thus speak must be ignorant of that which he declares
to be folly and trifling. He cannot know the miracles of skill that
insects, insignificant as they seem, are capable of performing; nor
the astonishing lessons of wisdom which even man may learn from these
minute and short-lived beings. So long as we are ignorant of any part
of God's creation, we may very probably think light of it; but when
we come to inquire into the things we have formerly despised, and
will give a patient attention to what we before thought beneath our
notice, the tone of our remarks will greatly alter. Now, we shall find
in the meanest things formed by the Divine hand inexhaustible themes
for wonder and praise, and innumerable proofs that the great Almighty
power which built our round world, and countless worlds besides, which
fixed them with a firm decree in an appointed course, has not been less
displayed even in the formation of a tiny insect, which is this hour
alive, and the next lost to being.
The telescope shows us what God has created in the innumerable millions
of stars and suns which every clear night look down with gentle beams
upon the earth; it shows us that the earth on which we dwell, compared
to the worlds by which it is surrounded, is as a grain of sand to a
mighty mountain. But the microscope, on the contrary, shows us what
is almost more wonderful even than this; for it shows us that though
the High and Lofty One who inhabits eternity has created all these vast
systems of suns and stars, yet he has not thought it beneath Him to
chisel the egg of an insect or to adorn the coat of a tiny caterpillar.
Well might we pause and ask as we look now through the wonder-revealing
tube of the microscope and then through that of the telescope--Was it
not a greater evidence of power and wisdom to create, clothe, organize,
and endow with the powers of life, a little atom which we can detect
only by means of a powerful microscope, than to form even a great and
mighty world? For our part, then, we think an insect's history as
much a display of the wisdom and infinite power of the Creator as the
history of such an enormous body as is the sun, or any of the large
planets belonging to our system. However humble be the object which
God has seen fit to create, let not any one think it beneath _him_ to
examine. The poet Thomson has written some pretty lines which we shall
venture to transcribe, which, with far greater beauty of language than
we can pretend to, set before us the same train of thought:--
"Let no presuming impious railer tax
Creative wisdom, as if aught was formed
In vain, or not for admirable ends.
Shall little haughty ignorance pronounce
His works unwise, of which the smallest part
Exceeds the narrow vision of her mind?"
Animals, birds, reptiles, fish, and plants, have had their biographers,
and ponderous books have been written to give us an introduction to
their various families: so also have insects; although despised by
many, they have been highly esteemed by a few; and if honours went by
the size of books written about them, it might perhaps be shown that
the insects can boast of great and closely-printed books taken up with
nothing else but an account of them and their doings.
Perhaps there is another feeling about insects which ought to be
mentioned beside the feeling of contempt; that is, the feeling of
aversion. A great many people, ought we to write? a great many ladies
and children, are ready to scream, and take to their heels if they see
a poor "black beetle," racing in terror of his life for fear of _them_,
and as both parties are equally frightened of one another it becomes
very difficult to manage a reconciliation between them. At the sight
of spiders some people are ready to faint away, and to see a little
caterpillar creeping along with his magnificent coat of parti-coloured
hairs, and with that funny gait which it is quite ludicrous to behold
as he binds himself into a loop and walks after a fashion like no other
earthly being, is enough to make their hair stand on end and their
flesh to creep!
[Illustration: _Death's-head Moth._]
Sometimes insects are the innocent causes of alarm even to nations.
Thus there is a peculiar kind of moth, upon the back of which there
is very distinctly marked the appearance of what is vulgarly called a
"death's head," its name being the death's-head hawk moth, represented
in the adjoining cut, which was once the cause of the greatest terror
to a number of persons. It was in Bretagne that a large flight of them
suddenly made their appearance; at the same time a dangerous epidemic
disease fell upon the inhabitants; the awful look of the poor insect,
together with its strange supernatural noise, filled the ignorant
people with alarm, and the disease was considered to be actually caused
by the moths. Another insect, the church-yard beetle, which is of a jet
black colour, is related by the great Linnæus as producing the most
alarming feelings upon the minds of the superstitious and ignorant
among the peasantry of Sweden.
The death-tick beetle has also a terrible reputation for frightening
people. This little creature takes up its abode in decayed wood, and
thus frequently makes the bed-post its dwelling-place, or ensconces
itself in the wainscot of an old room. Now, when, as some entomologists
tell us, it wants to give a signal to its mate, the insect begins
hammering with all its might at the side of the wall, or knocks upon
its little floor until the noise is heard, and the mate then begins to
hammer, both producing for their size a tremendous noise, but in human
ears not sounding louder than the tick of a large watch. The poor
invalid, as he lies in bed perhaps very nervous and unable to bear loud
conversation, hears the noisy insects knocking one to the other, and
immediately his mind is filled with fears of the most groundless kind,
which the nurse, if she is one of the old school, is sure to confirm by
telling him that this ticking is the death-watch.
[Illustration: _Death-watch Beetle._]
All this is not only very weak and foolish, but when it reaches the
degree to which we have here referred, it is also very wrong. As to
the death's head hawk moth producing disease or foretelling death
and famine, as it has been said to do, how weak and credulous must
they be who draw such omens from a mark on an insect's head; and how
dishonouring is it to the all-wise providence of God to imagine that
he would suffer such a ridiculous emblem to have any such actual
signification! The little beetle which produces the ticking sounds was
caught by Dr. Derham one fine sunshiny day, tapping as loudly as it
could on a piece of paper in a window; he examined the little creatures
and kept them carefully, and he states that during the whole of one
summer they scarcely ever ceased tapping night and day. Birds have
their calls to their companions, and animals have theirs, yet we do
not draw from these the wild supposition that they foretell death or
such like disasters. Why, then, should the love-tap of an insignificant
beetle have received such an interpretation? It is hard indeed to tell.
Now all these feelings about insects, contempt, abhorrence, and
terror, arise in one common cause, and that is ignorance. A very
small acquaintance with the contents of the little work upon which
we are now entering, would suffice to dispel them all. It may be,
perhaps, difficult to overcome what is called a "natural aversion"
to any object, especially to an unfortunate insect; but when it is
overcome, and when we learn, for the first time, all the extraordinary
actions, habits, and instincts, of this portion of the great creation,
admiration will take the place of contempt, and even a humble sort of
affection that of the terror and aversion produced by them before.
With the reader's permission, then, we will proceed to take him with
us as we describe the various stages of the Life of an Insect, from
the egg up to the perfect being. It may be, however, just necessary to
premise that in so doing we shall not give anything like the history of
an individual insect, such, for example, as a fly or a bee; but shall
describe in order some of the most interesting phenomena connected with
insect-history and transformations generally. Whither, then, must we go
to watch the awakening of life in the insect? We might ask the reader's
company to
----"where the pool
Stands mantled o'er with green, invisible
Amid the floating verdure, millions stray."
Here might we point to him that wondrous and exquisite structure, the
life-boat of eggs, floating[A] securely on its silent surface, or
anchored, perhaps, to the side of some pond-plant's slimy stem; and
lingering here we might in a few days see the little eggs become burst
and give exit to a number of minute creatures of great activity. Some
of them would be seen twisting themselves about in a most extraordinary
manner, and swimming here and there through the still waters. Or we
might take him to the depths of the forest, and now, under the bark of
some of the trees, now upon their branches, now in little tents of
leaves, we could point out many a colony of eggs only waiting for the
life-giving influence of spring to burst into life and activity.
But it is better for us to proceed more systematically, and to notice
shortly the interesting facts which the science of entomology reveals
to us as to the egg-cradles, so to speak, of insects, by which is meant
the various localities selected by them for the deposition of their
eggs, some of them, as we have mentioned, in the water, some in the
earth, some upon plants and trees, and some in mansions made by the
insects themselves for the purpose of hatching their eggs.
Let us come, then, and watch the great water-beetle, at the time when
the mother-insect is about to commit her future offspring to the
care of the waters. She is to be found on fine days, when the sun is
going down into a bed of gold, enjoying herself and delighting in
the pleasant air of the evening, as she sits upon a plant close by
the water's edge; or she may even have taken up her position on a
floating leaf of the plant, the clear waters flowing gently beneath
her. She has been in the water all day long, and is now just emerged.
On other evenings she will take wing, and speed her way whither no
eye can follow; but now, she has another and the most important duty
of her existence to perform, and her customary evening ramble is not
permitted to interfere with its fulfilment. On watching her closely we
find her busy at some self-imposed occupation; what is its nature? To
discover that, she must be closely and patiently watched. At her tail
are a couple of spinning organs, which move from right to left and up
and down with great swiftness, all the while a glutinous fluid, which
hardens into a thread, being discharged from each of them. With this
apparatus the industrious insect is spinning a pouch not unlike the
purses which were in fashion before the long ones that ladies knit
came to be adopted. This purse is three quarters of an inch long; it
consists outside of a tissue, like parchment, which is quite impervious
to water, but is lined inside with the most beautiful, light, downy
material possible, which is as white as snow. There is a sort of little
horn to this pouch, which admits the air, but the opening to which
is protected by a layer of cross threads, which excludes the wet. In
three hours of patient toil this beautiful cradle is completed. The
water-beetle then safely secures it from being carried away by the
waters on which it floats so buoyantly, by fastening it by cables to
the neighbouring plants. Here safely moored it rests until the eggs are
hatched, soon after which the little creatures within escape into the
waters out of the ark, which has, during the period of their infancy,
safely preserved them from every danger, both of water and wind.
The proceedings of the common gnat, our summer tormentor, are no less
interesting and instructive. Her actions have been closely watched by
the great Réaumur, and are detailed by him with very striking accuracy.
They require, perhaps, sharper scrutiny than most of our readers
are in the habit of bestowing upon the actions of insects, but they
well repay a patient and attentive observation, and subjects for the
examination may easily be found at the side of any pool in summer.
The following is an outline of the difficulties the insect has to
contend with in depositing her eggs. First, they must be hatched on the
water; but, 2d, her eggs are heavier than water, and will therefore
sink if dropped into it one by one; and, 3d, the eggs are so small
and of so peculiar a shape that it would be difficult to make them
stand upright on a solid surface; far more so then, on the water. A
human ship-builder would be probably sorely puzzled to find out how to
overcome these difficulties, and of such materials how to construct a
floating raft; nay, a raft which cannot by any means be made to sink.
The insect has, however, been instructed by a Greater and Wiser than
man, and she solves the problem in a manner well calculated to excite
our admiration and praise. Fixing herself by her four front legs upon
a leaf or twig floating on the surface of the water, she stretches
out behind her the two hind legs, and crosses them over one another
somewhat in this manner [Illustration]. In the triangular space thus
formed she purposes to construct her boat of eggs. Now, all things
being ready, just where the crossed legs meet she places her first
egg, which is covered over with a thick glue. By the side of this she
places another, and again another, so that the three are, by means of
the glue which covers them, united together, and will, consequently,
preserve the upright position, as there is now a sufficiently broad
base of support for them to rest upon. To these she diligently adds egg
to egg until she has sufficiently formed the shape of her boat; after
which she uncrosses her legs and places them quite straight, so as to
shape the sides of the boat. When a sufficient number of eggs have been
thus glued together, the number varying from two to three hundred, the
gnat considers her task as ended, and wings her way from the pool,
abandoning her ingenious structure to the mercy of wind and wave,
although not without the security of knowing that neither wind nor wave
could commit serious injury upon it.
"In shape," write Messrs. Kirby and Spence, "this little boat pretty
accurately resembles a London wherry, being sharper and higher, to use
a nautical phrase, _fore_ and _aft_; convex below and concave above;
floating, moreover, constantly on the keel or convex part. But this,"
they add, "is not all; it is, besides, a _life-boat_, more buoyant
than even Mr. Greathead's. The most violent agitation of the water
cannot sink it; and what is more extraordinary, and a property still a
desideratum in our life-boats, though hollow it never becomes filled
with water, even though exposed to the torrents that often accompany a
thunder-storm. To put this to the test I yesterday placed half a dozen
of these boats upon the surface of a tumbler half full of water. I
then poured upon them a stream of that element from the mouth of a
great bottle held a foot above them, yet, after this treatment, which
was so rough as actually to project one out of the glass, I found them
floating as before upon their bottoms, and not a drop of water within
their cavity."
[Illustration: _Rubbish Towers of the Sand-Wasp._]
Some insects make the homes of their young in the earth. Of these,
the insect called the sand-wasp forms, perhaps, one of the most
interesting examples. This insect selects generally a hard sunny
sand-bank for the excavation it is about to accomplish. Armed with
a pair of powerful jaws, by means of which the insect can break off
good-sized fragments of the rock she is about to mine, she sets to
her arduous undertaking with a bold heart, and it is not long before
a tolerable cavity is scooped out. Many of our readers have seen the
manner in which human miners proceed when they are forming a hole
in a lime or other rock, for the purpose of blasting, and must have
noticed that they are in the habit of using a little water, in order
to facilitate the boring operation. We are all, also, familiar with
the tale of Hannibal chemically softening the Alpine rocks by means
of vinegar. The little insect in question has been instructed by the
great Creator also to adopt a means of shortening her labour, for it
has been observed that she moistens the rock by letting fall a drop or
two of fluid upon it from her mouth. By this means her work goes on
rapidly. The rubbish soon begins to accumulate. It will be scarcely
conjectured what this patient labourer does with it. Were we to look
narrowly at the sand-bank which such wasps frequent, we should find on
its surface a number of curious little projections like horns, rising
from the surface. These are towers built by the sand-wasp of the
pieces of rubbish which she scoops out of her mine. She cements them
together, and, instead of throwing them away, she lays the masses in
regular order until they have assumed the appearance here shown. It
has been supposed she does this with a view to keep out enemies and
to keep her progeny cool; just as in a tall house the cellar is its
coolest apartment, so the height of the tower in question seems to be
an additional protection against the rays of the scorching sun. After
it has deposited its egg at the bottom of the excavation, the sand-wasp
sets out on a foraging expedition, and hunts about until she finds
certain green caterpillars. Seizing upon one of these she flies with it
to her mine, and then returns for more prey. After collecting about a
dozen of these helpless beings, fixing them so that they are hopeless
captives inside her dark prison, she bids farewell to the egg, for the
future well-being of which she has thus assiduously provided. She takes
down her tower of stones, and, with the materials which composed it,
fills up the entrance to the cell, thus shutting in both the prisoners
and their future devourer in a common dungeon, there to await the
changes which time will inevitably bring about.
Let us speak now of eggs carefully deposited by other insects in
galleries and excavations made into timber. The insects which thus act
have been called by the fanciful title of carpenter-bees, in allusion
to the drilling process by which they penetrate the wood. A highly
interesting spectacle it is, in truth, to see one of these pigmy
carpenters at her work, and, fortunately, some of the species are not
very uncommon in our gardens. Spring is the season when she commences
her labours. She reconnoitres about for a proper piece of timber for
some time, and exhibits great discrimination in the selection of a
suitable place for establishing herself and for the nurture of her
progeny. Strange to say, she will not select living wood, such as the
trunk of a tree, but generally prefers wood which has already begun
to decay, as if fully aware that such wood was likely to give her
much less trouble in boring than any other. She also selects a piece
of wood placed in some sunny and genial position, with a view to the
development and comfort of her progeny. This important point being
settled to her mind, she next sets about the work. Well may Réaumur
exclaim, "Truly the labour she has undertaken demands strength,
courage, and patience!"
[Illustration: _Carpenter-Bee._]
[Illustration: _Mandibles of the Carpenter-Bee._]
The violet carpenter-bee is, perhaps, the most interesting example
we can select. She begins by cutting out with her strong jaws small
portions of the timber, and soon forms a little hole, which looks
downwards and inwards into the wood. She then alters the direction of
her drilling, and now perforates the timber perpendicularly downwards,
and in a parallel direction to the sides of the wood. Long and hard
does she thus labour, until she has actually scooped out a tunnel
in the timber a foot or so in length, and half an inch in diameter.
Sometimes she will drill several of these beautiful galleries in the
wood. The task, however arduous, never seems to weary her; impelled by
a heaven-bestowed influence, she works strenuously and cheerfully for
weeks, or even sometimes for months. Our readers may be interested
to know what she does with the saw-dust. If they can but get an
opportunity of watching her they will soon see her mode of dealing with
it. Standing by the side of the wood she is drilling, and keeping our
eyes stedfastly fixed on the hole, we shall presently observe her head
emerging from it, and immediately after she is seen to shovel out a
little heap of the dust, which accumulates on the ground beneath into
a pile. When her galleries are finished her labour is yet far from
accomplished. She has now to deposit her eggs, and make provision for
the prospective wants of her young ones. Now, her eggs must not be
piled together, nor be scattered about in the same cavity. The larvæ
which are to be produced by them must each live in separation from
the others. How is this fresh difficulty to be overcome? The insect
soon supplies us with the answer. She has not forgotten her heap of
saw-dust. She first deposits an egg at the bottom of the tunnel, and
then away she flies to the fields for a load of the fine yellow dust of
flowers, called _pollen_, and also for honey. She mixes these up into
a nice little mass of pollen-bread, or cake, which is intended for the
food of the larva, when it comes out of the egg, and then piles it up
in the gallery just over the first egg. She then, at a height of about
three quarters of an inch, plasters a layer or ring of saw-dust made by
her into a sort of mortar, and adds to this another and another ring
of the same material until the ceiling is quite complete, and the cell
thus formed is shut off from the rest of the excavation by a circular
plate of this substance, which effectually excludes all intercourse
between the occupants of this wooden nursery. Having completed this
cell she proceeds in the same way to lay an egg, and to provide a
store of food, and, finally, to close in the rest of the gallery,
until she has subdivided it into ten or twelve separate apartments.
The appearance of the circular ceilings formed on these ingenious
principles is exhibited in the engraving annexed.
[Illustration: _Cells of Carpenter-Bee._]
[Illustration: _Ceiling-plate._]
[Illustration: _Section of Cells, showing the ways of escape._]
One of the most striking facts in connexion with the proceedings of
this little creature has yet to be brought under our notice. It will
be readily admitted that the first egg deposited at the bottom of the
gallery will be the first, in point of time, that will be hatched, and,
consequently, the first to require to make its escape from the wooden
prison-house of its birth. How is it possible for this to take place,
when above the poor prisoner's head are ten or twelve cells full of
other occupants, and each shut in with a hard ceiling and floor? By
referring to the figure, we obtain a clue to this enigma. It is here
seen that there are holes which communicate with the tunnel within.
The uppermost of these holes was the one by means of which the tunnel
was first formed, but the two lower ones have been expressly formed by
the carpenter-bee to provide against the dilemma in which her young
would otherwise have been placed. They form as it were posterns or back
doors by which, when the insect is perfected, it is easily enabled to
make its escape. Singular, indeed, it is, that the insects, previous to
passing into their last transformation, arrange themselves with their
heads downwards, so that every one of them generally emerges at the
so-called back-door of the mansion.
There are many similar instances in natural history of the manifest
wisdom and forethought of the Creator of all things, visible and
invisible, but we may safely say there are not many which show it in
so clear and striking a point of view as this. It is to be remembered
this industrious insect in the arrangements in question does not act
from past experience. She never saw her young brood, nor could learn of
herself their wants and dispositions, yet her plans for their welfare
are as admirably contrived as if she had brought up generation after
generation under her own eye, and had learnt wisdom by the lapse of
years. Plainly, therefore, her actions are all directed by an impulse
given her from God, and we may well exclaim with the wise king of
old, it is God who "doth instruct her to discretion, and doth teach
her." Altogether, what an example of patience and cheerfulness in her
labours, and of admirable wisdom in their performance, is presented to
us by this little sketch of the history of the carpenter-bee's nest!
Among the birds discovered in Australia, is one called the Bower-bird,
from its fondness for making a bower, which it ornaments in a very
pretty manner. Other instances of a somewhat similar kind could be
mentioned, tending to show that some of the lower animals are as fond
of decorating their dwellings as we are ourselves. There is, however,
in the insect world, a little creature which has been called the
tapestry-bee, which adorns the place where its progeny is to be born
with a tapestry as novel as it is elegant. The great entomologist whom
we have before quoted, thus describes his first discovery of this
interesting fact:--"In one of my rambles, which had led me through
several lanes, and in the course of which I had frequently stopped to
examine the little tunnels pierced in the earth by various insects, my
companions began to engage in the same occupation with myself; one of
them at length perceived, and pointed out to my notice, a tunnel which
had some peculiarities of appearance not possessed by the others we had
seen; its interior seemed to be painted with vermilion. A small twig
was immediately gently pushed into it, and with a knife we carefully
removed the earth which surrounded it, taking great care not to injure
the walls of the tunnel. When we had uncovered it sufficiently, it was
found that the little stick was buried in a tube made of the leaves of
the field poppy.
[Illustration: _The Tapestry-Bee and its Cell._]
"I need scarcely say, that during the remainder of our ramble we were
exclusively occupied in searching for similar holes. It is a common
observation, that when a fact, which has not hitherto been recognised
among those presented to us in nature, is once caught sight of, we are
almost sure to see it again and again, until we wonder how it could
have been that it was never noticed before. We therefore now found
other holes, leading to similar tubes, formed in the same manner of the
flowers of the red poppy. Altogether, before returning home, we found
seven or eight of them; and since that time, I have found them in all
their different stages." These elegantly decorated apartments were
subsequently found to belong to the tapestry-bee.
[Illustration: _Poppy-flower cut by the Bee._]
This bee, in forming the future abode of her young, begins by scooping
out a burrow in some pathway, which she bores to the depth of two
or three inches. She then smooths the walls of this cavity, and all
being now ready for putting up the hangings, she betakes herself to
the fields, and alights upon some fresh-expanded poppy flower, just
displaying its crimson cheeks to the light of day. Here she quickly
plies the scissors which she has been armed with for this purpose,
and in a very short time cuts out of the bright petal on which she
rests, a smooth portion of a definite size. She then returns home,
and, by means of the scissors and her legs, she cuts and smooths the
piece until it lays quite flat upon the bottom of her cell. This done,
she flies for more, and in a short time, could we peep in, we might
find her mansion all over-spread with tapestry, more bright in colour,
and more delicate in point of finish and texture, than human art can
by possibility produce. The apartment being thus not only decorated,
but rendered, both to the eye and senses, warm and comfortable, she
then stores up in it a quantity of pollen and honey, until she has
filled it to the height of half an inch, when she deposits the egg,
for whose wants and, as we might say, even luxuries, she has thus
elegantly provided, folding some of the hangings carefully over it. The
remainder of the cavity is filled with loose earth. We have taken it
for granted, in this account, that the insect really takes a pleasure
in the brilliant colours with which she ornaments her cell; but it is
only right to say, in addition, that we have, of course, no positive
proof that such is really the case. For aught we know, her motives may
be very different; it is, however, an amusing way to consider these
actions, be the explanation of them what it may.
[Illustration: _Finished Cell._]
We fear, however, we dare not promise our readers the same success
as that which attended M. Réaumur and his companions. It has been
thought, that this interesting insect is not a native of our island,
and it is certain it has not been commonly observed amongst us; but Mr.
Rennie, in his work on Insect Architecture, says, that at a beautiful
sea-bathing village in Ayrshire, he once found in a footpath a great
number of the perforations of the tapestry-bee. At all events, they
deserve looking for.
[Illustration: _Leaf tubes._]
Although we have, perhaps, lingered long enough over the insect cradle,
we must spare room for one or two more remarks on this subject, and
it were almost a shame, while speaking thereon, to omit a notice of
one of the most elegant cradles of all--one made with rose-leaves! As
Réaumur's account of the manner in which he first became acquainted
with these egg depositories is very pleasantly written, we shall
extract the substance of it from his work. It was one day in July,
1736, that a gentleman of rank, accompanied by his suite and his
gardener, who was in a state of great alarm, waited upon an eminent
naturalist in Paris. The gardener had left his master's country-seat,
near Rouen, to proceed with all haste to the metropolis, in order to
communicate to his master the terrible tidings, that his ground was
bewitched! He had the courage, however, to pick up the spells, or
charms, which the sorcerer had placed in the earth, and to carry them
to his master, in full belief that they were sufficient to convince
all the world of the reality of the enchantment. He had, indeed,
in the first instance, taken them to the parish priest, begging his
counsel, and both came to the same conclusion--that, without doubt,
the garden was now enchanted ground! When the gentleman saw the little
things his gardener called charms,--which are here represented,--he
was much perplexed, although his good sense led him to ridicule the
idea of the bewitchment of his property by such means. He applied to
his medical adviser for a solution of this problem; but, alas! he was
no entomologist, and could not enlighten him; but he directed him
to the naturalist of whom mention has been made, and whose name was
M. Nollet. On being admitted to the presence of this gentleman, the
terror-stricken gardener hastily put on the table the little rolls
of leaves he considered to be spells, and which had been made, with
some evil design, as he doubted not, by the malevolent hands of some
sorcerer. Fortunately, M. Nollet had in his museum some rolls of leaves
formed with equal art by beetles; he produced them, and showed them
to the affrighted man, assuring him, that, without doubt, they had
been formed by insects, and that it was therefore highly probable that
the rolls in question were the productions of some other insects of a
different species. The gardener looked incredulous, being apparently
unwilling to give up his alarm, until M. Nollet, greatly to his horror,
took up one of those little leaf-rolls which had caused him so much
uneasiness, and carefully unfolding it, drew from thence a fat little
larva. The moment the gardener saw the little creature, his fears and
troubled aspect vanished, and an air of cheerfulness spread over his
face, such as one might imagine as the result of deliverance from some
fearful peril. The only reward M. Nollet would receive from the poor
man for thus dissipating his cares and fears was, that he should leave
the leaf-rolls with him, and, collecting more of them, should send
them to M. Réaumur's address, for him to examine. This little anecdote
affords us a good illustration of the connexion of superstitious fears
with ignorance on points of natural history, and sets before us, in
well-relieved contrast, the foolish terrors of the unlearned gardener
with the collected bearing of the learned naturalist. Would that this
anecdote stood alone in the records of natural history! We have already
seen that it does not; and that the most groundless apprehensions have
taken their rise in the most innocent and trifling of natural causes.
[Illustration: _The Bee with a leaf cut._]
By and by, after a little careful investigation, the true artificer of
these spells was discovered, and proved to be a lowly insect, which
has been since called the rose-leaf-cutter bee. On closer examination,
these rolls of leaves,--which are almost as long and as large as a
tooth-pick case,--were found to be made up of six or seven cells,
each separate from the rest, placed end to end, and covered with a
common coating of leaves. The manner in which the roll is formed is as
follows:--The insect sometimes makes a perforation in decayed wood,
sometimes in the well-trodden earth of a footpath; this she drives to
the depth of, perhaps, nine inches, and she then proceeds to hang this
apartment with its green tapestry,--for it must be understood, it is
not the leaves of the flower, but of the stem of the rose-tree,--or,
in other words, the green leaves, that she selects for this purpose.
The insect alights upon what she considers to be a suitable leaf, and
begins with her sharp jaws to cut out a piece of a crescent form from
its edge. When she has cut, perhaps, half-way round, or rather more,
she sets her wings in motion, so as to keep her balanced in the air,
lest she should drag away the half-cut piece before it was properly
divided from the leaf. When cut, she places it in a perpendicular
position between her legs, and flies away with it to her cell. She
then simply folds it into a proper form, and overlays the cell walls
with this leafy covering, not using any cement to make it retain its
form, but relying upon the natural elasticity of the leaf to keep it
close pressed against the wall in the manner in which she places it.
Repeating this process several times, she finally completes each cell
with exquisite art and care, and taking the precaution of arranging
all her joints and seams so that they shall not present themselves
in the same place, but covering them over with pieces of leaf, so
as to strengthen them, and in many other respects exhibiting an
amount of mechanical and mathematical skill never sufficiently to be
admired, she now deposits the minute egg in it which is to become the
toilsome, busy, patient, and clever being,--the full-grown insect of
her own species. Mindful of its future wants, she then compounds a
delicate mass of pink conserve, which she collects from thistles, and
subsequently stops up each cell with thin pieces of leaf, as exactly
round as if they had been cut out with a punch, or by means of some
mathematical instrument.
Réaumur says he often, in the month of May, on looking at his
rose-trees, detected these insects at their work; all he had to do
was, to stand and patiently watch by the side of a tree, the leaves
of which exhibited the singular marks made by this insect. Many times
have the same appearances arrested our attention, and without doubt
that of the reader. The spectacle of insect ingenuity which it affords
well promises to repay a little exertion in endeavouring to find out
the nest to which the pieces are conveyed, and some neighbouring post
or footpath will probably discover it to us after a sharp scrutiny.
Sometimes the insect makes a bad choice of a leaf; it may be, perhaps,
too tough for her; but she soon discovers her mistake, and leaves it,
half cut, to seek a better on the same branch.
[Illustration: _A Rose-branch cut by the Bee._]
The nest formed by a species of moth for depositing her eggs in, is one
equally interesting to describe. From the resemblance of her actions
to the well-known account of those of the eider-duck, whose maternal
love strips her breast of down for the purpose of protecting her eggs,
we might almost venture to call this moth the eider-moth, were it not
that it is known under another and far less appropriate name--the
gipsy-moth. Indeed, in the care of the insect the mother's love is,
as we might say, even more powerful than in the bird; for, while the
latter has the pride and pleasure of seeing her little ones grow up
around her, the poor insect, after stripping herself of her own soft,
warm down, thus testifying her love to her offspring even to death,
presently expires. The insect in forming her nest first plucks off, by
means of a singular instrument, like a pair of tweezers, with which
she is provided, a little portion of down from her body; seated upon a
tree, she attaches this to its trunk, and then deposits an egg in it,
which immediately adheres to the down, and becomes coated with it. The
remainder of her operations, until she has deposited the entire number
of eggs, are but repetitions of the same actions. When the process is
at an end, she begins to form a regular tile or covering to her nest,
and this she effects with a degree of skill not unworthy of the most
consummate thatcher. She arranges the hairs of the down just as the
thatcher does his stems of straw for the cottage roof, so that they
all slope downwards, resembling much the smooth pile of a hat. By this
arrangement of the down, it is next to impossible that in the most
drenching shower the eggs, warmly wrapped up within, should be wetted
or otherwise injured, and the down itself, being a material which, as
we all know, is a non-conductor, preserves the eggs from the influence
of the most severe frosts. In shape, this nest of eggs resembles a
skittle, or a truncated cone, the broad end downwards. The engraving
represents this form, and also shows the insect at work constructing
the nest.
[Illustration: _The Nest of the Gipsy-moth._]
[Illustration: _Eggs of Lackey-moth._ (_Natural size, and magnified._)]
Let us now pass on, to mention, that many eggs are deposited without
any special protection of the kind we have described, and without what
would be with propriety termed a nest. A moth, called the lackey-moth,
frequently ornaments the young twigs of trees in our gardens with
exquisite bracelets of glistening white eggs, looking like beads. From
two to three hundred of these eggs are glued on by the insect around
the twig, by means of a tenacious waterproof cement, and are arranged
with an accuracy of the most marvellous character, in a close spiral
line upon the twig. The cement employed by the insect in uniting her
eggs, and in varnishing them over, is so hard as to serve the purpose
of a covering, which admirably casts off the rain, and preserves the
eggs free from injury by the elements all the winter long. Many eggs
are simply glued on irregularly upon the stems and leaves of plants,
their shells or outer coating, together with the protecting varnish,
being sufficient to preserve them from the inclemencies of the weather;
but some are piled together with the most striking regularity, in
regular columns of eggs.
In addition to these, it is proper to state, that some insects lay
their eggs in the body of the young of others. Of these, those which
are most dreaded by the insect tribe are the little but terrible flies,
called Ichneumons. They are so called because in their actions they
agree with the popular account of those of the ichneumons of Egypt,
which were venerated as the destroyers of the eggs of serpents and
crocodiles. "Such," say Messrs. Kirby and Spence, "is the activity
and address of the ichneumons, that scarcely any concealment, except
perhaps the waters, can secure their prey from them; and neither bulk,
courage, nor ferocity, avail to terrify them from effecting their
purpose. They attack the ruthless spider in his toils; they discover
the retreat of the little bee, that for safety bores deep into timber;
and though its enemy, the ichneumon, cannot enter its cell, by means
of her long ovipositor (organ for depositing the egg), she reaches the
helpless grub, which its parent vainly thought secured from every foe,
and deposits in it an egg, which produces a larva that destroys it. In
vain does the destructive _cecidomia_ of the wheat conceal its larvæ
within the glumes that so closely cover the grain; three species of
these minute benefactors of our race, sent in mercy by Heaven, know
how to introduce their eggs into them, thus preventing the mischief
they would otherwise occasion, and saving mankind from the horrors of
famine. In vain, also, the _cynips_, by its magic touch, produces the
curious excrescences on various trees and plants, called gulls, for the
nutriment and defence of its progeny. This parasite insect discovers
its secret chamber, pierces its wall, however thick, and commits the
destroying egg to its offspring." In vain, also, might we add, does
the sand-wasp excavate her deep cell for her young ones; for when once
the ichneumon has discovered the retreat, the destruction of the young
larvæ is inevitable. She pierces through the defences piled over the
mouth of the cavity, with all the precision and patience of a higher
creature, and rests not until she has thrust down her long ovipositor,
and placed the egg in the body of the helpless prisoner below, when she
flies away, confident that the days of her victim are numbered, and
having thus doomed him to be eaten up alive! The common caterpillar,
which, by its ravages in our cabbage rows, makes itself a little too
familiar to us, has a fierce enemy in these flies; they dart upon it,
pierce its body in many places, laying an egg in each wound; these
in due time become hatched, and eat their way out of the body of the
poor caterpillar, who soon dies, while the larvæ, after undergoing
their proper transformations, become perfect insects themselves, fully
equipped to proceed to the same work in some other individual of the
caterpillar kind.
To man, this ordinance of the Creator, that some insects should lay
their eggs in the bodies of others, and so destroy them, is of
inestimable benefit. It is quite impossible to imagine what would be
the result, were weevils, caterpillars, and such like insects, to be
permitted to multiply without a check. Produce of all kinds would soon
be consumed, and the desolations of an universal famine would overwhelm
man and beast. But God has been pleased to ordain it otherwise. In
proportion to the increase of the destroyers is the increase of those
that prey upon and destroy them. Thus, what has been well called the
balance of creation is preserved, and by means of the insects in
question, conjoined to other causes, is the command to the destroying
powers enforced--"Hitherto shall ye come, but no farther."
CHAPTER II.
STRUCTURE AND CONTENTS OF THE EGG.
In the past pages we have now considered shortly the various methods of
depositing the eggs of insects, and have seen that the nursing place
where the young being is produced, differs widely both in point of its
position, and of the external circumstances which variously affect
it. For some are the deep-bored galleries in timber; for some, the
hard-wrought tunnel, scooped by an insect out of a rock; for some, the
ingeniously-formed boat or raft, which is to carry its cargo of life
buoyant on the dancing waters "all the days of its appointed time,
waiting until its change come;" for some, the cell of earth lined with
painted hangings, exquisite in make and colour; for some, the little
leaf-case, curiously folded together; but for others, none of those
works of insect art are provided; they, hid in a rain-proof covering of
varnish, lie open to every eye, or scattered here and there on all and
every kind of flower and herbage, lie at the mercy of every wandering
foot. While, lastly, others are buried with a cruel yet merciful
art, in the bodies of myriads of unsuspecting members of the insect
community, lying, like the seeds of evil in the heart of the infant,
dormant awhile, but destined to grow with its growth and to strengthen
with its strength.
The time has, therefore, now come that we should speak a little more
particularly upon the nature and character of the eggs of insects. The
shape of an insect's egg, although frequently something of an oval in
its outline, is very various; in fact, were the egg of some peculiar
species placed in the field of a microscope, probably not one general
observer out of a hundred could in the least imagine what the object at
which he was looking really was. Sometimes they are oval and exactly
resemble the form of the egg of the bird; but in other instances they
are of the most irregular and fantastic appearance. Some look like
pill-boxes tied over and down their sides with string; others look like
tiny flasks, with many raised ribs upon their surface; others have lids
and springs. The gnat's egg resembles a chemist's phial, or one of the
new bottles for holding aërated waters; and those of the dung-fly have
two little pieces sticking out at the top on each side to prevent them
sinking too deep into the matter upon which they are deposited.
[Illustration: _Various forms of Eggs._]
[Illustration: _Eggs of Lace-winged Fly._]
The eggs of some insects strikingly resemble the little shells like
turbans with which we are most of us familiar. A very singular variety
of egg which has often caused much perplexity to naturalists is the
egg of the lace-winged fly. Réaumer says, "I had observed them several
years without actually knowing what they were. Others as well as myself
had noticed that on the leaves and twigs of many trees were a number
of minute stalks placed together, scarcely as thick as a hair, their
colour was nearly white, and they were about an inch in length; there
were sometimes ten or twelve placed in a bunch; the end of each stalk
bore a small head of an egg-like or oblong figure. They appeared to me
to be fungi, the little head precisely resembling the appearance of
moulds as seen under the microscope; but they were larger in size."
They were, in fact, the eggs of the fly in question. When the larva
escapes from them they have much the appearance of little vases; and
the same author assures us that they were once described and engraved
by a naturalist as some curious minute flower growing on the leaves of
the elder, for which he was unable to account. The representation of
them in the cut will enable the reader to form his own opinion as to
the difficulty of ascertaining whether they were flowers or the nests
of an insect.
[Illustration: _Manner of depositing the Egg._]
The manner in which these eggs are thus regularly placed by the
insect is interesting. Placing herself upon the leaf in the attitude
represented, she fastens a thread to the leaf, draws it out in the same
way as a spider does her lines, and when it has got sufficiently firm
the wise insect then puts forth the egg, glueing it to the extremity
of the stalk; this done, she quits it and begins to form another,
repeating the same actions until the proper number is laid. Poised on
the summit of these slender pillars the eggs are secure from every
invader but man himself, and in time there comes from them the larva
which is to become the beautiful insect, the "lace-winged fly," in all
the elegance of its form.
From what has been already stated, the surface of the eggs of insects,
it will be perceived, is by no means in all cases smooth and polished
as in the case of birds. Far otherwise. To look at some of them by the
help of a magnifying glass we should imagine that they were covered
with very fine lace net, others appear as if some clever engraver had
been chasing some intricate design upon their surface. The eggs of a
species of butterfly are studded over with an infinite number of little
knots or tubercles; and those of another are capped at the top with
sculptured work disposed in the form of a circular tiling or roof to
the egg. Some also closely resemble embossed buttons.
He who has thus adorned these minute objects with beauty of form
and carving, has likewise bestowed upon them the most beautiful and
variegated colours--colours such as no human art can imitate. But from
the small size of the eggs it is difficult to appreciate this beauty
in them except when they occur in a mass. The most common tints are
white, yellow, and green, but the richer and rarer hues are also to
be found among them. Thus, the eggs of a moth are of a beautiful blue
colour, banded in the most delicate manner by three zones or rings of
brown, the contrast being very pleasing. Another moth, which loves
to deposit its eggs in the bark of the willow, produces them tinged
with a purple more delicate than ever Tyrian lady wore as the finest
produce of the dyer's art. In the deep crevices of the bark of the elm,
and only, therefore, to be found by sharp scrutiny, another moth lays
eggs of a lovely pink. Messrs. Kirby and Spence write, "We remember
once being much surprised at seeing the water at one end of a canal
in our garden as red as blood; upon examining it further we found it
discoloured by an infinite number of minute red eggs." Sometimes eggs
are spotted, and thus resemble the eggs of many birds; and, strange to
say, sometimes they change colour in a very remarkable manner; so that,
as far as colour is concerned, an observer could scarcely believe that
the egg was the same he beheld, perhaps, a few days previously. The
eggs of the chameleon fly, as we are told by the gentlemen last quoted,
are at first pure white; then change to green, and finally turn to a
deep olive-green. Others are at first mouse-coloured, then reddish,
and, lastly, black. The eggs of a kind of moth we have seen first of
the colour of sulphur, then becoming _green_, after that _rose-colour_,
and lastly, _black_. In the instances of the common gnat and silk-worm,
similar changes of colour take place. The eggs of the gnat are first
white, then green, and finally gray; and those of the silk-worm are in
the first instance of a pale yellow, and ultimately take on a violet
tint.
Having thus noticed these points in connexion with the Life of an
Insect, we are led to that most important of all periods, the dawn
of life in the egg, or, in common terms, the period of hatching. But
before proceeding to the subject, may we not pause and wonder as we
behold the varied manifestations of the Creator's wisdom in the actions
of the minute, and, as we often call them, insignificant creatures of
whom we have spoken? Should David say, when he beheld the sun, moon,
and stars, as the work of a Divine hand, "Lord, what is man, that thou
considerest him, or the son of man, that thou regardest him!" And
shall not we, as we contemplate the few particulars here set down of
the wonders of insect-life, exclaim, with even greater astonishment,
"What are these, that thou considerest _them_?" Let no one then say,
that entomology, or any other natural science whose field of study lies
chiefly among the minute portions of creation, are profitless sciences,
when they can reveal to us such a display of the power, wisdom, and
love of God, as is exhibited even in this small portion of the Life of
an Insect.
Let us then take up one of these eggs, so minute, but containing within
it the rudiments of a being which is in time to assume a form of
considerable magnitude, by comparison, and to be adorned with colours
richer than art can boast of, and let us examine it on the field of a
tolerably powerful microscope. We need not look far for a specimen. In
the dark corner of the ceiling in a neglected room, after removing the
mass of dust-filled webs that have accumulated there for months, we may
find without difficulty a spider's nest of eggs. A more pleasant place
to search for insects' eggs is, perhaps, the garden; and if in the
crevices of the bark of the trees, or attached to twigs or branches,
none can be found, we can almost certainly promise success if the
reader will carefully and patiently search the angles of the garden
walls, particularly if he has noticed in the preceding autumn many
of the beautiful webs of the garden-spider. There, in some sheltered
recess, where the pattering rain-drops may be heard, but never venture
in, and where few eyes would detect them, may be found little round
yellow balls, of the size of a small cherry, made of the most beautiful
golden-coloured silk, and attached by a slender stalk to the wall, or
perhaps, to a twig. Sometimes they exhibit the more elegant and curious
appearance shown in the figure on the next page, resembling an inverted
wine-glass or pear.
[Illustration: _Nests of Garden-Spider._]
On taking our prize in-doors, by the aid of a very sharp penknife
we may succeed in cutting it smoothly open, and in turning out some
of the delicate eggs which lie warmly covered up at the bottom.
Taking one of them up on the point of the knife, and laying it on the
microscope-field, we shall be able to see something of the anatomy of
an insect's egg.
First, we may notice what seems to be the shell; that is, the outer
covering of the egg. This is very different to the hard, calcareous
eggshell of birds. It is stated not to contain any lime in its
composition as the shells of birds do; for when the eggs of insects are
put into very weak sulphuric acid and water, which would act on the
lime if it were present in their composition, they are not affected by
it. Although, therefore some eggs of insects are very hard: so hard
indeed as to resist severe pressure with the nail, they do not owe
their hardness, as do the eggs of birds, to any lime in their chemical
composition. The outer coat or shell is apparently simply membraneous,
frequently varying greatly in thickness, being sometimes as dense and
horny as we have mentioned, and at others, so delicate as to burst with
the gentlest touch.
[Illustration: _Nests of Spiders._]
Could we now do, what it is so easy to do with the egg of a
fowl,--carefully take off a little portion of this outer shell, we
should be able to inspect its contents more accurately. But in the case
of most who read this book, this extremely delicate task will prove
after many trials probably a hopeless failure. Let us state, therefore,
what some expert and talented observers have found within the insect's
egg. It appears, then, that although there is both a "yolk" and a
"white" in the tiny egg before us, that they are not quite so distinct
as in the bird. Yet, they are sufficiently separate from one another
to make their differences complete. Probably the reader has noticed in
the hen's egg a little round spot in the middle of the "yolk" or yellow
portion; from this the future bird is produced. Although from their
extreme minuteness it is difficult to detect anything of this kind in
the eggs of insects, some observers state they have seen a similar
little spot in them also. Thus, M. Herold says, that in the eggs of the
very insect whose nest we have robbed, the garden spider, "this little
spot can be seen as a minute white point immediately under the shell,
and in the middle of its circumference." This was seen by holding it
up to the light, and the spot was more carefully examined by gently
pressing the contents of a spider's egg upon a watch-glass. Mr. Rennie
says, that "the point where the caterpillar originates, answering to
the scar in the eggs of birds, we can readily distinguish even by the
naked eye in the larger species of eggs, as it lies always immediately
under the shell." But it may be doubted whether, without the assistance
of some one versed in entomology, many who make the same attempt,
will succeed. So much depends in looking at any object upon whether
we know what to look for or not, so that things which are as clearly
seen as possible by the eyes of the initiated, are not seen at all by
any others. To perceive some things in natural history, and many in
science, the senses of sight, hearing, and touch, require to be well
educated, and they then become apparent enough.
And is this all that we can mention about the structure of an egg?
This indeed is all. Can it be possible? Is there no striking and
broad difference to mark the nature of the future insect? Is the egg
of a spider the same in the number and nature of its parts as that
of a butterfly, or the egg of a gnat as that of a beetle? Surely, as
we should imagine, there must be some important differences between
these, otherwise why such immense differences in the perfect insect?
Could any one imagine that a grasshopper and a house-fly, so strangely
unlike each other in their perfect forms, originated in eggs to either
of which the same description of an insect's egg would accurately
answer, and leave nothing out? However great our amazement, the fact
is unquestionable. The egg of every insect at first consists of an
outer covering, a white, a yolk, and the little spot we have alluded
to. We might have thought that in creating so many different species of
insects, which differ so surprisingly in form as the insect tribes do,
the great Creator would have formed their eggs essentially different
too. But, except in the matter of shape, all are originally alike;
and the wisest philosopher is unable to inform us of any essential
difference in the eggs of insects at first. The eye of God, who knows
the end from the beginning, sees some difference inappreciable to the
eye of man. He said to this kind, "Be thou thus," and to that, "Be thou
different;" but until the time comes when the young insect is much more
advanced, it is not possible for us to recognise those marks of variety
which His hand has laid upon them from the beginning.
CHAPTER III.
LIFE BEGINS IN THE EGG.
The eggs of birds are, in most instances, hatched by the warmth of the
mother, who sits for a certain time covering them with her wings and
downy breast. But the exception to the rule in insects is that the
mother has anything to do with rearing her young brood; the cases in
which this takes place will be noticed in our next chapter. Generally
speaking, the eggs of insects are hatched by the increasing temperature
of the air in spring. The following sketch, extracted from Mr. Darwin's
interesting Journal of the Voyage of the Beagle, sets before us, in
a very pleasing manner, the awakening influence of this season to
all nature:--"When we first arrived at Bahia Blanca, September 7th,
1832, we thought nature had granted scarcely a living creature to this
dry and sandy country. By digging, however, in the ground, several
insects, large spiders, and lizards, were found, in a half-torpid
state. On the 15th a few animals began to appear, and, by the 18th,
(three days from the equinox,) everything announced the commencement
of spring; the plains were ornamented by the flowers of a pink
wood-sorrel, wild peas, _oenotheræ_, and geraniums; and the birds
began to lay their eggs. Numerous beetles were crawling about, while
the saurian tribe, the constant inhabitants of a sandy soil, darted in
every direction."
As to the torpid animal and buried seed, so to the carefully laid up
egg, the returning warmth of the air is the signal for the commencement
of life. The winter-clouds roll reluctantly back, as the genial days of
spring advance, and the changes which are to have their accomplishment
in the production of a living being out of the minute object before
us, are set in movement as the days grow bright and pleasant. That the
hatching of the egg, in most cases, is due chiefly to the stimulating
influence of heat, is now well ascertained. The school-boy who has ever
amused himself with silk-worms can well assure us of this fact, for he
is in the habit of hatching the insect's eggs by carefully wrapping
them in paper, and keeping them in his waistcoat-pocket, where they
have all the comfort and warmth of his body to bring them forward. In
countries where the silk-worm is reared, women carry them in their
bosom, and by this means cause the young larva to come forth from the
egg in much less time than it would naturally occupy. By removing a
twig of a plant upon which in the preceding autumn an insect may have
been found to have deposited its eggs, into a warm room, an opportunity
will be had of putting this operation practically to the test. In a
short time it will be found that the eggs are all hatched, and that
a number of minute larvæ are crawling actively about, while their
brethren in the snow-covered fields are yet safely asleep in the shell.
On the other hand, eggs which would otherwise be hatched the same
year are arrested by the advancing cold of the winter season, and are
now compelled to wait until the ensuing spring, before their time of
hatching arrives. Evidently, therefore, to the commencement of the
life of an insect the condition of the external temperature is an
all-important consideration. Before proceeding immediately to consider
the nature of the changes, it may be mentioned as an interesting fact,
that although the eggs of insects are very quickly sensible of a slight
increase of heat, and in consequence of its application to them very
soon begin to live, yet they will endure the most severe degrees of
cold almost without injury. As an illustration of this point we may
transcribe a few sentences from a paper by the great Spallanzani upon
this subject:--
"The year 1709, when the thermometer fell to 1° Fahrenheit," or
thirty-one degrees below freezing point, "is celebrated for its rigour
and its fatal effects on plants and animals. 'Who can believe,'
exclaims Boerhaave, 'that the severity of this winter did not destroy
the eggs of insects, especially those exposed to its influence in the
open fields, on the naked earth, or on the branches of trees? Yet, when
the spring had tempered the air, these eggs produced as they usually
did after the mildest winters.'" He adds further on, "I have exposed
eggs to a more rigorous trial than the winter of 1709--those of several
insects, and among others the silk-worm, moth, and elm-butterfly, were
enclosed in a glass vessel, and buried five hours in a mixture of ice
and rock-salt, the thermometer falling 6° below zero. In the middle of
the following spring, however, caterpillars came from all the eggs,
and at the same time as from those which had suffered no cold. In the
following year, I submitted them to an experiment still more hazardous.
A mixture of ice and rock-salt, with the burning spirit of nitre,
reduced the thermometer 22° below zero, that is, 23° lower than the
cold of 1709, or 52° lower than the point at which water freezes. They
were not injured, as I had evident proof--by their being hatched."
When it is known that many seeds will not endure these degrees of cold
without injury, and those even of some tolerably hardy plants, it
is the more surprising to find such apparently delicate and readily
damaged objects as the eggs of these members of the insect tribe thus
resisting an intensity of cold to which, in a state of nature, they
are scarcely ever exposed. It is impossible to assign any rational
explanation of these singular facts. It is undoubtedly owing to this
power of resisting the generally deadly influence of extreme cold
that we find insects reappear in spring, even in countries where the
winter is much prolonged, and is of extreme severity. Thus, in Lapland
we should have probably thought that the rigour of the climate would
have been fatal to all insects in winter, in any condition, whether
in the egg, or in other forms; but, as the poor inhabitants know to
their cost, it is far different. The mosquitoes swarm in that country
in numbers so prodigious that they have been compared to a fall of
snow, or to the dust of the earth. The wretched natives cannot take a
mouthful of food, or lie down to sleep in their cabins, unless they
are fumigated to a degree almost dangerous to life. They fill the
mouth and nostrils, and, minute though they are, render existence
almost a burden by their blood-thirsty propensities. Not even thick
plasters of the most offensive compounds,--tar, oil, and grease, are
sufficient to shield the Laplander's skin from their attacks. The
great John Hunter considered that this power of resisting cold was,
in some unexplained manner, connected with the existence of a living
principle in the egg, which had the effect of withstanding a degree
of cold that would otherwise have been fatal to it; but, after all,
this is only an apology for an explanation. When we are unable to
clear up the difficulties of a natural history question like this,
although we cannot explain, we are not prohibited from admiring, and
can clearly perceive, that in thus endowing the eggs of insects with a
self-preservative power, God has manifested his wisdom and forethought;
for had it been otherwise, the lapse of a few seasons would have
depopulated the insect world, leaving us, it is true, without a gnat
or a mosquito to annoy us, but also without a silk-worm, or a bee, to
supply us with the precious products of insect industry.
The frosts have disappeared, the air brightens, the sun loses its pale
aspect, and glows with a more golden face. The days lengthen, the
breeze has lost its penetrating chilliness, gentle showers descend
and water the earth, and there is a general voice heard all over
creation,--"Spring has come!" The eggs of a thousand insect species
have already perceived its presence, and the newly-awakened beings
within hasten to welcome it by bursting from the shell, their long
occupied, but now for ever forsaken dwelling-place. Sometimes the young
larva bursts through the thin walls of the shell by main force, or eats
its way through by means of its jaws, which is occasionally a task of
many hours' duration. "In many instances, however," write Messrs. Kirby
and Spence, "the larva is spared this trouble, one end of the egg being
furnished with a little lid, or trap-door, which it has but to force
up, and it can then emerge at pleasure. Such lids are to be found in
the eggs of several butterflies and moths. The eggs of a species of
bug, besides a convex lid, are furnished with a very curious machine,
as it would seem, for throwing it off. This machine is dark brown, of
a horny substance, and of the shape of a crossbow; the bow-part being
attached to the lid, or pushing against it, and the handle, by means of
a membrane, to the upper end of the side of the egg."
But if, in our account of the various attendants on the opening of
spring, we had mentioned every circumstance that takes place at that
time, alas! for any poor insects, or, at least, for a large number
of them, who should be hatched at that time. The warm air and gentle
shower, and brighter sky, would ill satisfy them in the absence of all
_food_, and they would be born, by a cruel destiny, only to starve and
die. We well know this is not the case; but there are, probably, few
persons who have ever thought much upon the admirable arrangement by
which the occurrence of such a calamity to many of the insect tribes
is avoided. We need scarcely remind the reader that in the opening
sentence of the last paragraph there is one most important omission in
the sketch of the phenomena of returning spring; that is, that there
is no mention of what takes place in _plants_,--of the putting forth
of their young and tender leaves. Now, as a majority of insects in the
larva state are vegetable-feeders, we can easily understand that the
unfortunate little beings if hatched before the appearance of leaves
would, without doubt, quickly perish for lack of proper food. Yet the
returning warmth of the air is all that is requisite to call the insect
into existence, and if by the time it is ready to burst from the shell
there is not food all prepared for it, it must die. The difficulty has
been beautifully provided for; and perhaps, few other instances of
the wisdom of the Creator in forming the insect world are so full of
instructive thought as this. It has been ordained, then, that soon as
winter is over, the plant is _first_ to obey the voice of spring, and
to awake; and the bursting buds on its lower boughs are already full
charged with sap long before the young insect being that is to be fed
therewith has left the shelter of the egg.
One of the talented authors of the Introduction to Entomology relates
a pleasing anecdote in reference to this simple, yet admirable
arrangement, and mutual adjustment of these two events,--the awakening
of life in the plant and in the insect. "On the 20th of February, 1816,
observing the twigs of the birches in the Hull Botanic Garden to be
thickly set, especially about the buds, with minute oval black eggs
of some insect with which I was unacquainted, I brought home a small
branch, and set it in my study, in which is a fire daily, to watch
their exclusion. On the 28th of March I observed that a numerous brood
of _aphides_ had been hatched from them, and that two or three of the
lower buds had expanded into leaves, upon the sap of which they were
greedily feasting. This was full a month before either a leaf of the
birch appeared, or the egg of an _aphis_ was disclosed in the open
air." Thus showing that the coming to life of the branch and of the
insects resting on it, was beautifully arranged to take place each at
the proper time.
It is very singular to add, that as some trees acquire their leaves
earlier or later than others, the eggs of insects which are deposited
on them, never are hatched before the leaves appear, even while some
of their companion eggs of a different species, and placed, therefore,
on different trees, may have long since sent their young into the
world. Thus, we learn that not only has God been pleased to arrange
_generally_ the hatching of the eggs of insects, and the putting
forth of the leaves of trees, so that the latter shall precede the
former, but it has also been ordered that the eggs deposited on each
_particular_ plant shall be hatched just when the time of that plant's
putting forth its leaves shall arrive, at whatever period that may be.
This may be more readily comprehended by an example: thus, there is no
difference, so far as we can perceive, between the eggs of the little
insects just mentioned as feasting on the leaves of the birch, and
those whose food is the leaf of the ash; yet the birch will be in leaf
nearly a month before the ash-tree, and the eggs deposited on it will
therefore be hatched a month before those placed upon the ash, although
both trees are in the same position with regard to warmth, and may
even, perhaps, be within a yard or two of one another. What a beautiful
and mysterious link is this, between events so disproportionately
important as the clothing of a great tree with its leafy garments and
the coming to life of a little throng of beings, whose dwelling-place
is a small twig, and whose world a green leaf! Yet it was not too
insignificant a matter for Him to arrange whose dwelling-place is
eternity, and who takes up the islands as a very little thing. Does God
take thought for these, and will He not much more care for and arrange
well every event in the lives of his faithful children? Surely, yes.
Speaking generally, the time taken up in hatching the eggs of insects
is very variable. It is a general rule that the eggs which are laid in
the autumn must abide the return of spring before they will be hatched.
But when eggs are deposited in the summer, they are often hatched in a
very short time. The eggs of the painted-lady butterfly are hatched in
about eight days, those of the lady-bird in a little less, from five
to six days; the eggs of another species of butterfly occupy a month,
those of spiders three weeks, those of bees only three days, and those
of the meat-fly shorter than any--only a few hours; it has even been
stated that in very warm weather the eggs of the meat-fly will be
hatched in about two hours! In most of these cases much depends upon
the weather; but even this does not operate beyond certain limits, for
it has been said that in the month of June, even if silk-worm's eggs
were placed in an ice-house, they would be hatched in spite of the
cold, but this observation deserves to be repeated.
It would be impossible to make the exact nature of the changes which
take place in the egg from first to last easily understood in a work of
this kind. They have occupied the laborious investigation of talented
observers with the highest powers of the microscope, and although
much is now known on the subject, it is of a nature too abstruse to
be dwelt upon in our unpretending volume. As we may well imagine,
the changes are wonderful indeed which from a little drop of fluid
matter, contained perhaps in a shell not larger than a pin's head,
end in the development of the living and active larva, who makes his
speedy escape out of his shell-cradle. But they must be studied in the
scientific treatises which are written upon this subject, and they are
so interesting as amply to repay the task of investigation. It may be
added, however, as a curious fact, that contrary to the general rule
in the egg of birds, some of the eggs of insects actually grow larger
before they are hatched, and frequently the shape alters also.
In our account of the nests made by insects for their eggs, the
examples quoted, although they furnished us with many proofs of a
mother's care and forethought on the part of the insect, yet there was
no instance given of anything like the solicitude displayed by the
hen over her eggs. Are there then no anxious mothers concerned in the
well-being of their eggs among insects also? In the next chapter some
instances of a mother's care over the young larvæ will be given; and
before we conclude the present, mention may be made of some interesting
observations upon this subject made by the eminent naturalist M.
Bonnet. The insect upon which his observations were made was the
spider, so commonly found on turning up a log of wood in the fields,
or a clod of earth. She carries her eggs about with her in a little
round white pouch of silk attached to her body. Well has it been said,
"Never miser clung to his treasure with more tenacious solicitude than
this spider to her bag. Though apparently a considerable incumbrance,
she carries it with her everywhere." M. Bonnet found that he could not
beat away the affectionate creature from her treasure, and on forcibly
removing it from her she instantly lost her ferocious aspect and became
tame. In this emergency she stops to look around her, and begins to
walk at a slow pace, and searches diligently on every side for her lost
eggs, nor will she fly if threatened by the bystander. If, however, out
of compassion, the bag is restored to her, she darts forward, catches
it up with all the intensity of a mother's love, and runs away with it
as fast as possible to some secret place where she may again have the
opportunity of attaching it to her body. In order to put this insect's
affection for her eggs to a test, M. Bonnet threw a spider with her
bag into the den of a ferocious insect, called an ant-lion, who lurks
at the bottom, like the Giant in the "Pilgrim's Progress," waiting for
poor insect-travellers to drop into the pit which it forms, and then,
rushing out, devours them. "The spider endeavoured to escape, and was
eagerly remounting the side of the pit, when I again tumbled her to
the bottom, and the ant-lion, more nimble than the first time, seized
the bag of eggs with his jaws, and attempted to drag it under the sand.
The spider, on the other hand, made the most strenuous efforts to
keep her hold, and struggled hard to defeat the aim of the concealed
depredator; but the gum which fastened her bag not being calculated
to withstand such violence, at length gave way, and the ant-lion was
about to carry off the prize in triumph. The spider, however, instantly
regained it with her jaws, and redoubled her efforts to snatch the bag
from the enemy; but her efforts were vain, for the ant-lion being the
stronger, succeeded in dragging it under the sand. The unfortunate
mother, now robbed of her eggs, might at least have saved her own life,
as she could easily have escaped out of the pitfall; but wonderful
to tell, she chose rather to be buried alive along with her eggs. As
the sand concealed from my view what was passing below, I laid hold
of the spider, leaving the bag in the power of the ant-lion. But the
affectionate mother, deprived of her bag, would not quit the spot where
she had lost it, though I repeatedly pushed her with a twig. Life
itself seemed to have become a burden to her since all her hopes and
pleasures were gone for ever."
As this spider may be easily found in the localities we have mentioned,
it may interest some of our readers to make trial of the mother's care
for her eggs; but, let us hope, only in a gentle spirit. Never let us
be guilty of the cruelty above narrated, and leave the disconsolate
mother, after her hard struggle for her treasure, without restoring
it back to her. Even in an insect, a mother's love, so faithful,
self-devoted, and constant, is a sacred thing; and while, as an
illustration of the care it has pleased the Creator to implant in it
for its offspring, it may be lawful to put it to the trial, it is wrong
and cruel to do more. Never let us, for our own amusement, give even to
an insect that depth of anguish and despair so beautifully expressed in
the words of Jacob, as translated in the margin of our Bibles: "And I,
as I am bereaved of my children,--I am bereaved."
"In order to prove," says the author of Insect Architecture, "whether a
spider of this species could distinguish her own egg-bag from that of
a stranger, we interchanged the bags of two individuals which we had
put under inverted wine-glasses; but both manifested great uneasiness,
and would not touch the strange bags. We then introduced one of the
mothers into the glass containing her own eggs and the other spider;
but even then she did not take to them, which we attributed to the
presence of the other, as all spiders nourish mutual enmity. Upon
removing the stranger, however, she showed the same indifference to her
eggs as before, and we concluded that, after having lost sight of them
for a short time, she was no longer able to recognise them."
The common earwig, a name at which some, who little know the beautiful
traits in her character, are apt to shudder, still more closely
resembles the affection of a higher animal than does the spider just
mentioned. The following most interesting notice of her proceedings
was published by a writer[B] in the _Penny Magazine_ some time since.
He says: "About the end of March I found an earwig brooding over her
eggs in a small cell scooped out in a garden border; and in order to
observe her proceedings, I removed the eggs into my study, placing
them upon fresh earth under a bell glass. The careful mother soon
scooped out a fresh cell, and collected the scattered eggs with great
care to the little nest, placing herself over them--not so much, as it
afterwards appeared, to keep them warm, as to prevent the too rapid
evaporation of their moisture. When the earth began to dry up, she
dug the cell gradually deeper, till at length she got almost out of
view; and whenever the interior became too dry, she withdrew the eggs
from the cell altogether, and placed them round the rim of the glass,
where some of the evaporated moisture had condensed. Upon observing
this, I dropped some water into the abandoned cell, and the mother
soon afterwards replaced her eggs there. When the water which had been
dropped had nearly evaporated, I moistened the outside of the earth
opposite the bottom of the cell, and the mother, perceiving this,
actually dug a gallery right through to the spot where she found the
best supply of moisture. Having neglected to moisten the earth for
some days, it again became dry, and there was none even round the rim
of the glass as before. Under these circumstances, the mother earwig
found a little remaining moisture quite under the clod of earth, upon
the board of the mantel-piece, and thither she forthwith carried her
eggs. The subsequent proceedings were not less interesting; for though
I carefully moistened the earth every day, she regularly changed the
situation of the eggs morning and evening, placing them in the original
cell at night, and on the board under the clod during the day, as if
she understood the evaporation to be so great when the sun was up, that
her eggs might be left dry before night. I regret to add, that during
my absence the glass had been removed and the mother escaped, having
carried away all her eggs but one or two, which soon shrivelled up."
Our diligent little exemplars, the ants, are equally careful about
their eggs. So soon as they are produced, the ants catch them up and
convey them to a separate chamber, moistening them with their tongues,
and incessantly turning them backwards and forwards. They are the
objects of constant solicitude until they are hatched; they are carried
hither and thither according as the temperature of the nest varies.
On a sunny morning they are brought out and laid to bask in the warm
air; but if the sky becomes overcast, and heavy clouds threaten rain,
the careful nurses whip up the eggs and hasten with them down to the
deepest recesses of the nest. They even appear to imitate the brooding
of the hen, and sit upon the eggs to impart to them some of the warmth
of their own bodies.
Before concluding this chapter, and entering upon the more striking
manifestation of life in the form of the insect which will next
come under our observation, it will be useful just to allude to the
comparative number of eggs which some insects produce, which we shall
place in the form of a table:--
The Noon-day Fly 2
The Flea 12
May Flies 100
Silk-worm Moth 500
Other Moths 1000 to 1600
Wasps 40,000
Bees 50,000
The most enormous number of all is produced by the queen of the white
warrior ants. She deposits sixty eggs every minute, which is at the
rate of 31,557,600 eggs in the course of a year, if we allow that she
goes on laying at the same rate constantly, which is, perhaps, scarcely
correct.
Were all the eggs produced by insects to be hatched and to bring
forth living progeny, we may well ask what would become of mankind?
Unquestionably in a short time their numbers would multiply so
excessively as to sweep every green thing off the face of the earth,
and man and beast would experience all the horrors of famine. But they
are the sport of a thousand accidents, which destroy them and keep down
the threatened excess of population in this world of busy creatures.
And when the young larva has been put forth, this check upon their
tendency to over multiplication is still more prominently displayed, as
we may presently have occasion to remark.
[Illustration: FEROCIOUS LARVÆ OF DRAGON-FLY.
Page 120.]
PART II.--THE LARVA.
CHAPTER I.
THE YOUNG LARVA.
The generality of insects, as has been before mentioned, are destined
never to behold the birth of their progeny, nor to experience either
the pleasures or the cares of parents surrounded by their families.
Their anxieties cease when they have carefully stored up their eggs,
and their existence is generally soon afterwards at an end. The insect
world, therefore, presents us with but few opportunities of witnessing
the display of a parental affection on the part of its members; but,
as was mentioned in the conclusion of the last chapter, a few examples
of the kind do exist, and, perhaps, the very fact of their being few
in number contributes to make them the more interesting to us. We have
seen a noble instance of self-devotion on the part of a poor spider
in defence of her eggs. Let us now turn to some examples of the love
of an insect mother for her young larva. If the reader will carefully
search the twigs and leaves of the birch-tree in the month of July he
may possibly succeed in finding the little insect, the field-bug, of
which mention is about being made, and witness for himself the strange
spectacle described in the following account from the great work on
insects by De Geer. In order that it may be recognised, we have here
adjoined a representation of the insect. Its colour is a greenish gray
on the back, dotted all over with very minute black spots; the under
portion of the insect is greenish yellow, with black spots. It lives
upon the sap of the birch-tree.
[Illustration: _The Field-bug._]
"The mother," says De Geer, "was accompanied by a troop of little ones,
sometimes as many as forty in number. She remained constantly with
them, generally on a twig or leaf. I noticed that the little ones and
their mother did not always remain in the same place, and that as soon
as the mother began to move to another position, all the little ones
began to run after her, and stopped whenever the mother halted. She
used to take them, as it were, for a walk from twig to twig, or from
one leaf to another, parading up and down the branches of the tree,
and she conducted them wherever she pleased, just as a hen does her
chickens. It frequently afforded me great pleasure to observe their
movements. One day I cut a young branch of the birch-tree inhabited by
such an insect family, and I immediately saw the mother, apparently
in great anxiety, begin to flap her wings violently, but without
attempting to fly away, as though she would frighten away her enemy. At
another time she would have immediately made her escape, thus plainly
showing that she remained only in order to defend her young brood."
As if to furnish an instance of precisely the opposite import, the
cruel and murderous father of this interesting little family is one
of the greatest enemies the poor mother has to contend against.
This hard-hearted parent does not hesitate whenever he falls in
with one of his children to seize him and eat him up! If the mother
spies him at this horrible feast she immediately attacks him in the
manner described; and does her utmost to deter him from his cannibal
propensities, by placing herself in an attitude of determined
resistance before him. Was ever mother's love more plainly manifested
than this love? No other instance of an affection so strange and strong
is to be found in the tribe to which she belongs.
The care of the earwig not only extends to her eggs, but also to her
young larvæ. "In the beginning of June," writes the author last quoted,
"I found under a stone a female earwig, surrounded by a number of
little creatures which I discovered to be her tiny family. She did not
attempt to leave them, and they frequently ran and crouched under her,
just as chickens under the wing of a hen. I took them up and placed
them under a sand-glass, under which I had put a little fresh earth.
They did not bore into the earth; and it was most curious to see them
running for shelter under the mother, and pushing about between her
feet, while she remained perfectly quiet. I fed them with pieces
of ripe apple, which the mother seized and ate with great avidity,
detaching morsels of it by means of her teeth, and swallowing them. The
young ones also ate a little of it, but with less avidity."
When the eggs of the spider mentioned in the last chapter as so
devotedly attached to its treasure as to prefer death to parting with
them, are hatched, they make their way out of the bag by an opening in
it, being assisted by the mother in this difficult task. De Geer indeed
states that this is the reason why the mother clings so tenaciously to
the bag of eggs, as if she knew that her assistance in extricating her
young from it was necessary. But this is not altogether correct, as
they are able to make their way out by themselves in due time. When the
young larvæ have come forth from the shell they run towards the mother,
and climb upon her body; some get on her head, some on her back, and
some on her limbs. In this manner she carries them about, and is said
to feed them until they become strong enough to shift for themselves.
"I have more than once been gratified," (writes one of the authors
of the Introduction to Entomology,) "by a sight of this interesting
spectacle; and when I nearly touched the mother, thus covered by
hundreds of progeny, it was most amusing to see them all leap from her
back, and run away in all directions."
For another instance of affection almost maternal for the young and
helpless larvæ, let us take a peep into an ant's nest. So soon as ever
the young larvæ emerge from the eggs they require the unremitting
attention of the best and most careful nurses in order to rear them.
They must be kept clean, fed, and taken for an airing as regularly
as the day returns. By means of their tongues, which are incessantly
used in licking them, their coats are kept of the most snowy white.
They are fed three or four times a day by their nurses, who take care
to masticate the food for them, and thus prepare it for their tender
mouths. But the most strange part is their regularly being taken out
for the benefit of the air and warmth. Some of the ants at the top of
the nest watch for the first beams of the welcome sun, and, as soon
as they pour upon the nest, they hasten down below in a great bustle
to wake up the nurses, and bid them take the young ones out of their
chambers and bring them up to the light, which these indefatigable
ants quickly set about to do. After basking there all day long the
nurses take care not to expose the delicate constitutions of the larvæ
to the chill evening air; and soon as the sun begins to sink towards
the horizon they carefully take them up and carry them to the warm deep
cell below. For fear, perhaps, of their taking cold, they never allow
them to be taken out in raw, damp, or frosty weather. It must not be
forgotten, however, that these ants are not the parents of the larvæ;
they are only the nurses.
But it becomes us now to pursue the more immediate subject of these
remarks, and ask the reader's attention to a few particulars about the
_larva_. It is a great pity, for the sake of a clear perception of the
facts of insect history, that there is a sad confusion of names in use
among the majority of persons in speaking of the different forms and
changes of insects. Who would imagine that caterpillar, grub, maggot,
and larva, signified one and the same stage of the life of an insect?
This abuse of terms cannot but render the knowledge of any science
less easily retained than it would otherwise be, for the question is
continually arising in the mind--If these all mean the same, why is
not one term enough to express them? Let us then renounce those of
uncertain meaning, and when we wish to give a name to the insect just
emerged from its eggshell, let us call it by its proper name, the
_Larva_.[C]
The larva, then, is the first form assumed by the insect on quitting
its shell. No more a little inactive object lies before us, as in the
egg and its slumbering tenant, but a sharp fellow, full of life, and
soon walking off the field of the microscope, should we happen to be
looking at it in that way, or from our book or table, should it be
there placed by us for observation. By what hidden and mysterious power
this has been effected who can tell? It was not heat alone that could
animate the contents of the shell, nor could all a mother's care do
more than preserve it from injury. It is very possible that chemistry
had _some_ share in it, and when the tiny being first awoke in the
shell the oxygen of the air undoubtedly was necessary to its health,
and the fulfilment of its early functions, but no more. Not chemistry,
nor electricity, nor heat, nor any other known force could effect this
wonderful change of apparently inanimate fluid into a lively, active,
and well-organized being; much less could either of these give it
its definite form, causing one larva to differ from another in its
characters. No, we cannot tell how it has taken place, nor what has
wrought the change; but we know the author of it--even Him who from the
beginning created all things, and established those principles which,
though hidden from our eyes, work out the marvels of the created world.
It is enough for us to know and to remember this. Should we attempt
more, we should probably fall under the Scripture reproof, "Professing
themselves to be wise, they became fools."
Speaking generally, insects in the larva form appear as fleshy worms,
having long and round bodies, marked with rings, and provided with a
head and a certain number of legs, mostly six. How different in this
condition, from the ballroom gaiety of the butterfly, or the elegant
robes of the lace-wing flies. To look at a number of larvæ, all
crawling over one another, and bearing perhaps not the most loving
behaviour to each other as they scramble about, who would dream that,
in a little while, those slowly moving bodies will be whirled through
the air faster than our feet can pursue, or even than the eye can
follow? Who also, but one well versed in the knowledge of insects,
could venture to say what insect could be formed by this or that larva,
now so little resembling winged insects at all?
[Illustration: _Larvæ unlike the future Insects._]
[Illustration: _Larvæ like the future Insects._]
In studying the forms and appearances of various larvæ, we shall find
that some of them bear a tolerably close resemblance to the future
insect; while others, on the contrary, do not resemble their future
condition at all; and had we to decide to what tribe of insects they
belonged, merely judging by their shape and character, we should be
sorely perplexed to do so, and if we did, we should often in all
probability be very far wrong. We need not go far for an illustration,
first, of a larva like the perfect insect, and next, for one totally
unlike it. Taking a candle and exploring into some snug hole near the
kitchen fire-place, we shall not be long, probably, before we extricate
a number of the larvæ of the cricket. Those of the bug also are very
like the perfect insect; so also are young spiders, cockroaches and
grasshoppers. These all resemble more or less perfectly the insect in
its complete form.
Even amongst the larvæ not resembling the perfect insect, a little
attention will enable us to perceive a sort of general resemblance
between those of different genera and species, which we may call the
Larva family likeness. This consists in the form of the body, in a
number of instances; but in all in the ring-like marks or segments
of the body, as they are called, which are _thirteen_ in number. If
the reader will take the trouble to count the rings in the larvæ of
different insects, he will generally find that they are thirteen in
number. The general resemblance of larvæ to one another may also be
noticed. The larva is, in every instance, destitute of wings. In many
cases, larvæ are provided with feet, in many others they have none. And
in some instances, they have no distinct head, as in the larva of the
blow fly.
[Illustration: _Larvæ of Butterflies._]
By far the larger number of larvæ belong to this class; that is, they
do not resemble the perfect insect. Do not resemble! could any one
believe that these strange, and some of them awful looking larvæ ever
became _butterflies_? yet they all belong to that tribe of insects.
[Illustration]
In order to give a clear conception of the structure of a larva, we may
briefly mention the names of its various parts. First then, there is a
_head_ of various shapes, sometimes of the shape of a heart, sometimes
round or triangular. Attached to the head are the two _antennæ_; or,
as they are commonly called, _feelers_, most probably an incorrect
expression, as it appears that insects may possibly _hear_ as well as
feel by their means. At the side of the head are the _eyes_, which are
formed much more simply than those of the perfect insect. Next is the
_mouth_, provided with its upper and lower pair of jaws. Then there is
the _body_ and its _legs_; and lastly, there is in many larvæ, living
in the water, a _tail_, which, strange to say, is provided with a
delicate tube, through which the larva breathes. A beautiful instance
of such an appendage to the body of the larva, is represented in the
adjoining cut; the various parts of the larva are also represented in
the accompanying figure.
[Illustration: _Diagram of a Larva._]
* * * * *
We may now enter upon a few particulars connected with the general
history of insects in the larva form.