for evil, and the prodigious rapidity with which they increase under
favourable circumstances would soon cause them to overrun the whole
earth, to the extinction of almost every other creature, were these
circumstances not controlled by an all-wise Providence, who keeps a
constant check upon their progress by causing one insect to feed
upon another, and who has formed almost innumerable other creatures
(including birds, reptiles, and fishes) with instincts which lead them
to feed upon insects in every stage of their development (fish devour
the larvæ of many insects which inhabit the waters during the first
stage of their existence); but it occasionally happens, when some of
these salutary checks upon their increase are withdrawn, that they
multiply with such fearful rapidity as to produce a complete famine,
for they eat up everything before them. Who has not heard of the
plagues of Locusts and the depredations of the White Ants? The swarms
of Locusts in Africa will sometimes cover many hundred square miles of
surface, and in this space not a vestige of any vegetation would remain
after their visit. The description of the prophet Joel is sublime: "The
land is as the garden of Eden before them, and behind them a desolate
wilderness: yea, and nothing shall escape them.... The earth shall
quake before them, the heavens shall tremble: the sun and the moon
shall be dark, and the stars shall withdraw their shining."
[Illustration: FIG. 21.--LOCUST (Locusta Migratoria).]
But it is kindly ordained that these visitations shall only
occasionally take place, and even when they do, terrible as is the
infliction, a benefit in reality outweighing the injury often succeeds;
for the land in these countries is often made almost barren by the
quantities of tangled roots and stubble on the surface of the earth,
which by the destructive powers of these insects is completely removed,
and their manure left in its place, so that the fertility of the ground
is much increased (often tenfold) after their visits.
The thousands of species of insects which exist, render it impossible
in a work like this, even to name them, but under the separate orders
will be given a slight outline of the more important.
[Illustration: FIG. 22.--THE STAG BEETLE (Lucanus cervus).]
Insects are divided, according to the character of their wings, into
nine orders.
1. COLEOPTERA (Black-winged).
The Coleoptera are those insects generally denominated Beetles, they
have four wings, the two outer of which are not used to fly with, but
as cases to cover and protect the other two; they are called "elytra,"
are horny and firm in texture, and in some cases, as the Diamond Beetle
and Musk Beetle, beautifully ornamented; the under pair of wings fold
transversely so as to pack up under the outer ones, which are shorter.
All Beetles live but one season, both sexes die before winter, leaving
nothing but their eggs to continue the species, the larvæ which come
from these are very destructive, eating most voraciously; for the most
part, Beetles feed on decaying substances such as dung, &c., and are
therefore useful creatures; there are between 40,000 and 50,000 species
of them. Beetles have been called the scavengers of nature, and truly
they are so, for they (with other insects) clear off all dead matter,
whether animal or vegetable; the Geotrupes stercorarius, and others,
dig holes in the ground and bury the excrement which is deposited on
the surface, thus doing a great service to vegetation, taking it down
to nourish the roots of the grass and other plants instead of allowing
it to harden and decompose on the surface. All dead animals are at once
attacked and devoured by insects, and the Beetles play their full share
in this necessary operation.
There are certain Beetles, called Burying Beetles (Necrophorus
vespillo), which remove the earth from under the dead bodies of small
animals, such as birds or mice, till they are beneath the level of the
ground, when they cover them up and deposit their eggs in them; these
bodies form stores of food for the future larvæ.
The Stag Beetle (Lucanus cervus, fig. 22), the Dor Beetle (Geotrupes
stercorarius), the Cockchaffer (Melolontha vulgaris), the Musk Beetle
(Cerambyx moschatus, fig. 16), and the Lady-bird (Coccinella), are
well-known members of this order.
2. ORTHOPTERA (Straight-winged).
The Orthoptera are those insects whose wings fold longitudinally; they
have two pairs, but the anterior pair are horny and serve as wing-cases
to the posterior pair; their food is chiefly vegetable, but to many
of their species any kind is acceptable, as their mouths are suitable
for grinding-up hard substances. The Locusts (Locustidæ, fig. 21),
Grasshoppers (Gryllidæ), Crickets (Achetidæ, fig. 16), and Cockroaches
(Blattidæ), or Black-beetles, as they are sometimes incorrectly called,
belong to this tribe. Their metamorphoses are not so complete as in
many other insects, for they never entirely change their form; the
larva as it leaves the egg has no wings, but otherwise is much like the
parent; it changes its skin several times, which stage is analogous to
the pupa state, after casting it five times and obtaining wings, it
becomes the imago or perfect insect. The ravages of the Locusts are so
well known that little need be said; the following is from Kirby and
Spence's Entomology:--
"Although this animal be not very tremendous for its size, nor very
terrific in its appearance, it is the very same whose ravages have been
the theme of naturalists and historians in all ages, and upon a close
examination you will find it to be peculiarly fitted and furnished for
the execution of its office. It is armed with two pairs of very strong
jaws, the upper terminating in short, and the lower in long teeth,
by which it can both lacerate and grind its food; its stomach is of
extraordinary capacity and powers; its hind legs enable it to leap to a
considerable distance, and its ample vans are calculated to catch the
wind as sails, and so to carry it sometimes over the sea; and although
a single individual can effect but little evil, yet when the entire
surface of a country is covered by them, and every one makes bare the
spot on which it stands, the mischief produced may be as infinite as
their numbers. So well do the Arabians know their power, that they make
a Locust say to Mahomet, 'We are the army of the Great God; we produce
ninety-nine eggs; if the hundred were completed, we should consume the
whole earth and all that is in it.'"
3. NEUROPTERA (Nerve-winged).
The Neuroptera comprise the Dragon-fly (Libellulina, fig. 16), Ant-lion
(Myrmelion), Caddis-flies (Phryganidæ), and the May-flies (Ephemera);
these insects have wings of a beautiful network structure, as may be
seen in the Dragon-fly, they make their appearance about the middle of
June in the locality of ditches and ponds. The Caddis-fly is noted for
the peculiar case which the larva makes for itself; the larva inhabits
the water and the ease is made of little fragments of wood, shell, and
sand, agglutinated together so as to float; the perfect insect is not
aquatic, and flies away when formed. The May-flies are noted for the
shortness of their existence, the larvæ live in the water, and many
of them are eaten by fishes who are very fond of them, but sufficient
numbers come to the perfect state, to form complete clouds in the air
where the larvæ were, these creatures live but a day, and some of
their species but an hour or two, in the perfect state, they deposit
their eggs in the water, which come to life in the mud at the bottom.
The flight of these fragile beings and their short-lived holiday
festivities are well described by Kirby and Spence:--
"In the beginning of September, for two successive years, I was so
fortunate as to witness a spectacle of this kind, which afforded me
a more sublime gratification than any work or exhibition of art has
power to communicate. The first was in 1811. Taking an evening walk
near my house, when the sun, declining fast towards the horizon,
shone forth without a cloud, the whole atmosphere over and near the
stream swarmed with infinite myriads of Ephemeræ and little gnats of
the genus chironomus, which in the sun-beam appeared as numerous and
more lucid than the drops of rain, as if the heavens were showering
down brilliant gems. Afterwards, in the following year, one Sunday,
a little before sunset, I was enjoying a stroll with a friend at a
greater distance from the river, when in a field by the road-side
the same pleasing scene was renewed, but in a style of still greater
magnificence; for, from some cause in the atmosphere, the insects
at a distance looked much larger than they really were. The choral
dances consisted principally of Ephemeræ, but there were also some
chironomi, the former, however, being most conspicuous, attracted our
chief attention. Alternately rising and falling, in the full beam they
appeared so transparent and glorious, that they scarcely resembled
anything material; they reminded us of angels and glorified spirits
drinking life and joy in the effulgence of the Divine favour. The Bard
of Twickenham, from the terms in which his beautiful description of his
sylphs is conceived in the 'Rape of the Lock' seems to have witnessed
the pleasing scene here described:--
'Some to the sun their insect wings unfold,
Waft on the breeze, or sink in clouds of gold;
Transparent forms, too fine for mortal sight,
Their fluid bodies half dissolved in light;
Loose to the wind their airy garments flew,
Thin glittering textures of the filmy dew,
Dipt in the richest tincture of the skies,
Where light disports in ever mingling dyes,
While every beam new transient colours flings,
Colours that change whene'er they wave their wings.'"
4. HYMENOPTERA (Membrane-winged).
The Hymenoptera are those insects which have four membraneous wings.
The Bees (Apidæ, fig. 16), Wasps (Vespidæ), the Ants (Formicidæ), and
the Ichneumon Flies (Ichneumonidæ), are the chief tribes of this order.
The Bees, Wasps, and Ants are celebrated for forming societies, more
perfectly arranged and governed than in any other creatures but man.
It is curious that the most perfect instincts (such as approach so
nearly to reason that they almost defy us to make a distinction) should
have been given by the Creator to creatures so far removed from man
in the scale of existence, and so little resembling him in any other
particular. This is one of the stumbling-blocks in the way of those who
wish to have it believed that all animals are progressive from certain
types, which cannot be got over; if such were the case, man would be
most nearly imitated by the Apes, and these again by those most nearly
allied to them, and so on downwards, but here we find a government
almost as perfect as that of the human species--an arrangement of work,
a division of labour, buildings, storehouses, &c.--showing nearly all
the social habits and feelings of man, in creatures who in form and
size have no resemblance to him.
Kirby and Spence, in describing the societies of insects, say:--"But
when we consider the object of these societies, the preservation and
multiplication of the species, and the means by which that object is
attained (the united labours and co-operation of perhaps millions
of individuals), it seems as if they were impelled by passions very
similar to those main-springs of human associations which I have just
enumerated. Desire appears to stimulate them, love to allure them, fear
to alarm them. They want a habitation to reside in and food for their
subsistence. Does not this look as if desire were the operating cause
which induces them to unite their labours to construct the one and
provide the other? Their nest contains a numerous family of helpless
brood. Does not love here seem to urge them to exemplary and fond
attention, and those unremitted and indefatigable exertions manifested
by the whole community for the benefit of these dear objects? Is it
not also evident by their general and singular attachment to their
families, by their mutual caresses, by their feeding each other, by
their sympathy with suffering individuals and endeavours to relieve
them, by their readiness to help those that are in difficulty, and
finally by their sports and assemblies for relaxation? That fear
produces its influences upon them seems no less evident, when we see
them agitated by the approach of enemies, endeavour to repel their
attacks, and to construct works of defence. They appear to have besides
a common language, for they possess the faculty, by significative
gestures and sounds, of communicating their wants and ideas to each
other."
Numerous works have been entirely devoted to the habits and instincts
of Bees and Ants, and very interesting they are, but it would be
impossible to give an intelligible account of them in the small space
allotted in this volume.
The wax of which Bees build their beautiful six-sided cells, and
which is the whole source of all the wax used by men for a variety of
purposes, is secreted in little scales or flakes, between the joints
of the abdomen, from whence the wax-making Bees take it to build the
comb; the cells of the comb are filled with honey, which is obtained
by the Bees (by means of the apparatus shown at fig. 23), from the
nectaries of flowers in the form of nectar, and is converted into honey
in the honey-bag of the Bee, from whence it is discharged into the
cells. Bees also collect the pollen from the flowers they visit, this
adheres to the hairs on the Bee, and is scraped and brushed off, and
collected into two little lots, which the Bee carries on each hind leg,
this pollen is made into bee-bread. By scattering the pollen, flowers
are often fecundated, for there are many plants, the female flowers of
which are separate from the males, and it is only by insects and the
wind, that the females are fecundated, for the Bee, with the pollen
adhering to every part, first visits one flower and then another in
search of nectar.
[Illustration: FIG. 23.--HONEY-LAPPING APPARATUS OF WILD
SEA-BEE (Halictus), (_a_, magnified; _a b_, more highly
magnified).]
[Illustration: FIG. 24.--WHITE ANTS (1, Winged Female; 2,
Female, distended with eggs).]
[Illustration: FIG. 25--NESTS OF WHITE ANTS.]
With respect to the Ants, Kirby and Spence give the following account
of the building of their habitations,
"The nest of _Formica brunnea_ is composed wholly of earth, and
consists of a great number of stories, sometimes not fewer than
forty, twenty below the level of the soil, and as many above,
which last, following the slope of the ant-hill, are concentric.
Each story, separately examined, exhibits cavities in the shape of
saloons, narrower apartments, and long galleries which preserve the
communication between both. The arched roofs of the most spacious
rooms are supported by very thin walls, or occasionally by small
pillars and true buttresses; some having only one entrance from
above, others a second, communicating with the lower story; the
main galleries, of which, in some places, several meet in one large
saloon, communicate with other subterranean passages, which are often
carried to the distance of several feet from the hill. These insects
work chiefly after sunset. In building their nest they employ soft
clay only, scraped from its bottom when sufficiently moistened by a
shower, which, far from injuring, consolidates and strengthens their
architecture. Different labourers convey small masses of this ductile
material between their mandibles, and with the same instrument they
spread and mould it to their will, the antennæ accompanying every
movement. They render all firm by pressing the surface lightly with
their fore feet; and however numerous the distinct masses of clay
composing these walls, and though connected by no glutinous material,
they appear when finished, one single layer, well united, consolidated
and smoothed. Having traced the plan of their structure, by placing
here and there the foundations of the pillars and partition-walls,
they add successively new portions; and when the walls of a gallery or
apartment, which are half a line thick, are elevated about half an inch
in height, they join them by springing a flattish arch or roof from one
side to the other. Nothing can be a more interesting spectacle than
one of these cities while building. In one place vertical walls form
the outline, which communicate with different corridors by openings
made in the masonry; in another we see a true saloon, whose vaults
are supported by numerous pillars; and further on are the cross-ways
or squares where several streets meet, and whose roofs, though often
more than two inches across, the Ants are under no difficulty in
constructing, beginning the sides of the arch in the angle formed by
two walls, and extending them by successive layers of clay till they
meet; while crowds of masons arrive from all parts with their particles
of mortar, and work with a regularity, harmony, and activity, which can
never enough be admired. So assiduous are they in their operations,
that they will complete a story with all its saloons, vaulted roofs,
partitions and galleries, in seven or eight hours. If they begin a
story, and for want of moisture are unable to finish it, they pull down
again all the crumbling apartments that are not covered in."
Every one has heard of the destructive as well as constructive
qualities of the "White Ant;" another quotation from Kirby and Spence
will illustrate both.
"When they find their way into houses or warehouses nothing less hard
than metal or glass escapes their ravages; their favourite food,
however, is wood of all kinds, except the Teak, and Ironwood, which
are the only sorts known, that they will not touch; and so infinite
are the multitudes of the assailants, and such is the excellence of
their tools, that all the timber-work of a spacious apartment is often
destroyed by them in a few nights. Exteriorly, however, everything
appears as if untouched; for these wary depredators (and this is what
constitutes the greatest singularity of their history) carry on all
their operations by sap and mine, destroying utterly the inside of
solid substances, and scarcely ever attacking their outside until they
have first concealed it and their operations with a coating of clay.
A general similarity runs through the proceedings of the whole tribe,
but the large African species, called by Smeathman Termes bellicosus,
is the most formidable. These insects live in large clay nests, from
whence they excavate tunnels all round, often to the extent of several
hundred feet; from these they will descend a considerable depth below
the foundation of a house, and rise again through the floors; or,
boring through the posts and supports of the building, enter the roof
and construct their galleries in various directions.
"If a post be a convenient path to the roof, or has any weight to
support, (how they discover it is not easily conjectured), they will
fill it with their mortar, leaving only a track-way for themselves, and
thus, as it were, convert it from wood into stone as hard as many kinds
of freestone. In this manner they soon destroy houses, and sometimes
whole villages, when deserted by their inhabitants, so that in two or
three years not a vestige of them will remain. These insidious insects
are not less expeditious in destroying the wainscoating, shelves,
and other fixtures of a house, than the house itself; with the most
consummate art and skill they eat away the inside of what they attack,
except a few fibres here and there, which exactly suffice to keep the
two sides, or top and bottom, connected, so as to retain the appearance
of solidity after the reality is gone; and all the while they carefully
avoid perforating the surface, unless a book or any other thing that
tempts them should be standing upon it.
"Koempfer, speaking of the White Ants of Japan, gives a remarkable
instance of the rapidity with which these miners proceed. Upon rising
one morning he observed that one of their galleries of the thickness of
his little finger had been formed across his table; and upon a further
examination he found that they had bored a passage of that thickness
up one foot of the table, formed a gallery across it, and then pierced
down another foot into the floor; all this was done in the few hours
that intervened between his retiring to rest and his rising."
Most of this order are armed with some weapon of defence. The Bee
and Wasp have each a most formidable sting, with which they are able
to inflict a wound fatal to most insects. The Ants have a peculiar
secretion, consisting of formic acid, which they eject with great
force, and which has a very disagreeable smell. The eggs of Ants when
hatched produce a small grub, which spins itself a sort of cocoon,
and in this state it so much resembles a grain of corn, that it has
been mistaken for it; this error has given rise to the supposition
that Ants store up corn for winter, whereas they never eat corn, but
the care they take of these larvæ, removing them from place to place,
taking them up in their mandibles and running along with them, has been
mistaken for the act of storing away grains of corn.
5. STREPSIPTERA (Twisted-winged).
This order includes but a few species; Dr. Baird in his Cyclopædia,
gives the following account of them:--
"Certain insects were discovered by Kirby, living parasitic in the
abdomen of some Andrenæ, which at that time were nondescript, and could
not be referred to any existing order. They were afterwards placed
in an order by themselves, which he called Strepsiptera. The larvæ
live in the bodies of Bees, Wasps &c., and the males only undergo a
perfect metamorphosis; the females, even when adult, have neither legs,
wings, nor eyes, but resemble larvæ, and continue to live parasitic in
the bodies of the Hymenopterous insects within which they were born.
The characters are thus taken from the male and consist chiefly in
the structure of the wings. The anterior pair are quite rudimentary,
being transformed into a pair of short, slender, contorted appendages
resembling narrow balancers or halters. The posterior pair are large
and membraneous, their nervures are only longitudinal, so that they are
able to fold them like a fan. They have large globular eyes, with the
facets few, but of comparatively large size."
[Illustration: FIG. 26.--STYLOPS ANDRENÆ.]
About ten or twelve species are known, forming a small family,
"Stylopidæ." The genus Stylops may be taken as the type, and contain
such species as have the tarsi with four points and the antennæ with
six."
6. LEPIDOPTERA (Scaly-winged).
[Illustration: FIG. 27.--SCALES FROM MOTH'S WING (Magnified).]
This order includes the Butterflies and Moths, they have four wings,
which are large and covered with minute scales, which are for the
most part of a heart or battledore shape, as in fig. 27. The wings of
these insects are many of them beautifully marked and tinged. There
are about 12,000 species, by some divided into "diurnal" (or those
which fly by day), "crepuscular" (or those which fly in the evening),
and "nocturnal" (or those flying by night). The Moths are mostly
crepuscular and nocturnal, while the Butterflies are chiefly diurnal,
but the most usual distinction between the Moth and Butterfly consists
in the form of the antennæ, those of the Moth being feather-shaped,
while those of the Butterfly have a small knob at the end, or, as it
is called, "club-shaped." The Lepidoptera feed upon the nectar of
flowers, for which purpose they are furnished with a long proboscis or
"Haustellium," which is curled up under the head, it consists of two
semi-cylindrical pieces which when placed side by side form a tube, up
which the nectar is drawn by capillary attraction. The metamorphosis
of these insects is complete.
The Silkworm (Bombyx mori) belongs to this order. It is the most
important of all insects to man, as from it alone all the silk of
commerce is obtained. Its cocoon is of a beautiful yellow colour,
varying in shade from orange to pale straw-colour; the silk of one
cocoon weighs somewhere about three grains; it would therefore, at
this calculation, take 1920 worms to spin one pound. The annual import
of silk into this country alone is about 7,000,000 pounds, it must
therefore take 13,440,000,000 Silkworms to supply us with silk yearly!
The Silkworm feeds almost exclusively on the leaves of the mulberry.
[Illustration: FIG. 28.--THE SILKWORM (Bombyx mori). 1, the
Eggs; 2, the young Silkworms; 3, the full-grown Silkworm; 4, the
Cocoon; 5, the Chrysalis; 6, the Moth.]
7. HEMIPTERA (Half-winged).