a new mine, if ejected by an experimenter from the old, as we have
frequently proved; but this is not the case with the social miners of
the henbane-leaf. Bonnet ejected one of these, and watched it with his
glass till it commenced a new tunnel, which it also enlarged with great
expedition; and in order to verify the assertion of Réaumur, that they
neither endeavour nor fear to meet one another, he introduced a second.
Neither of them manifested any knowledge of the other's contiguity,
but both worked hard at the gallery, as did a third and a fourth which
he afterwards introduced; for though they seemed uneasy, they never
attacked one another, as the solitary ones often do when they meet.[CB]
Bark-mining Caterpillars.
A very different order of mining caterpillars are the progeny of
various beetles, which excavate their galleries in the soft inner bark
of trees, or between it and the young wood (_alburnum_). Some of these,
though small, commit extensive ravages, as may readily be conceived
when we are told that as many as eighty thousand are occasionally found
on one tree. In 1783 the trees thus destroyed by the printer-beetle
(_Tomicus typographus_, Latr.), so called from its tracks resembling
letters, amounted to above a million and a half in the Hartz forest. It
appears there periodically, and confines its ravages to the fir. This
insect is said to have been found in the neighbourhood of London.
On taking off the bark of decaying poplars and willows, we have
frequently met with the tracks of a miner of this order, extending
in tortuous pathways, about a quarter of an inch broad, for several
feet and even yards in length. The excavation is not circular, but a
compressed oval, and crammed throughout with a dark-coloured substance
like sawdust--the excrement no doubt of the little miner, who is
thereby protected from the attacks of _Staphylinidæ_, and other
predaceous insects from behind. But though we have found a great
number of these subcortical tracks, we have never discovered one of
the miners, though they are very probably the grubs of the pretty
musk-beetle (_Cerambyx moschatus_), which are so abundant in the
neighbourhood of the trees in question, that the very air in summer is
perfumed with their odour. (J. R.)
[Mr. Rennie is undoubtedly right in his suggestion. I have found
similar holes in old willow trees, and have traced them throughout
their varied ramifications. They contain the larvæ and pupæ of the
musk-beetle, some of which may be seen in the Museum at Oxford. On
these trees, which mostly grow along the banks of the Cherwell, the
perfect beetle was so abundant that it might be taken in any number,
and, as described by Mr. Rennie, the air was perfumed with its powerful
and agreeable odour. So strong is the scent of this beetle, that I have
known it adhere to gloves after the lapse of many weeks, and I have
often caught the scent when passing along the road, and merely by the
aid of the nostrils discovered the insect.
On account of the vast number of carpenter-beetles, it is impossible to
notice more than a few of them, and we will therefore select some of
the most conspicuous. One of them, belonging to the genus _Ptilinus_,
is very familiar to us as boring into wooden furniture, and producing
the effect which is popularly called "worm-eaten." Fortunately, the
little creatures can be easily ejected, and the wood rendered free of
them ever afterwards. All that is needed is to take a syringe with a
very fine aperture--an injecting syringe is the best--and by its aid
to force into the holes a solution of corrosive sublimate in spirits
of wine--say a large teaspoonful of the powdered salt to a pint of
spirits. The rapidity with which the poisoned spirit permeates the wood
is wonderful, and in a short time it may be seen oozing out of twenty
or thirty holes at once. This solution is peculiarly effective, as it
kills all the insects, destroys every egg that it touches, and renders
the wood poisonous to the grubs that happen to escape. I used to be
greatly plagued with the Ptilinus among my ethnological collection,
until I tried the corrosive sublimate, and ever since my spears, bows
and arrows, and clubs have remained intact.
Another troublesome insect is the _Scolytus destructor_, which makes
its radiating tunnels between the bark and the tree. Whole forests have
been destroyed by this voracious little beetle, the bark having been
completely detached, and the tree necessarily killed. The habits of
this beetle are well described in the following passage.]
[Illustration: Bark mined in rays by beetle-grubs.]
We have frequently observed a very remarkable instinct in the grubs
of a species of beetle (_Scolytus destructor_, Geoffroy), which lives
under the dead bark of trees. The mother insect, as is usual with
beetles, deposits her eggs in a patch or cluster in a chink or hole in
the bark; and when the brood is hatched, they begin feeding on the bark
which had formed their cradle. There is, of course, nothing wonderful
in their eating the food selected by their mother; but it appears that,
like the caterpillars of the clothes-moth, and the tent insects, they
cannot feed except under cover. They dig, therefore, long tubular
galleries between the bark and the wood; and, in order not to interfere
with the _runs_ of their brethren, they branch off from the place of
hatching like rays from the centre of a circle: though these are not
always in a right line, yet, however near they may approach to the
contiguous ones, none of them ever break into each other's premises.
We cannot but admire the remarkable instinct implanted in these grubs
by their Creator; which guides them thus in lines diverging farther
and farther as they increase in size, so that they are prevented from
interfering with the comforts of one another.
[We now come to one or two of the beetles which bore deeply into the
very wood of the trees. As a rule, the musk-beetle keeps rather towards
the exterior of the tree, but there are many that are not so cautious,
and which besides damage the tree additionally by nibbling a quantity
of chips, wherewith they strengthen their cocoons. We will first take
the two insects which are shown in the accompanying illustration.
That on the right hand is a species of weevil, or Curculio, and is
an undescribed species belonging to the genus Rhyncophorus. It is a
native of Australia. The insect and its cocoon are drawn one third less
than their real size. The colour of the beetle is warm chestnut brown,
and the bold marks on the thorax are jet black. In its larval state
it burrows into the palm-trees, and when about to assume the pupal
condition it makes the remarkable cocoon which is figured. Generally,
these wooden cocoons are made of little chips which are bitten from the
wood, and woven together with silk. This cocoon, however, is made of
long fibres, which are torn rather than bitten, and are so long that
one of them will sometimes encircle the cell three times, making an
average length of nine inches. It is tolerably compact in structure,
and the colour is pale brown.
On the left hand is an opened cocoon of an English beetle belonging to
the genus Rhagium. Like the last-mentioned insect, the Rhagium prefers
long fibres to short chips, though it does not use them of such a
length as the Rhyncophorus. The cocoon is generally made between the
bark and the wood, from the latter of which the fibres are torn. In
consequence of the mode of structure, the cocoon is pale straw colour,
while the hollow in which it rests is quite dark.
[Illustration: Cocoon of Rhagium.
Rhyncophorus and cocoon.]
All entomologists are familiar with the pretty little wasp-beetle
(_Clytus arietis_), which derives its popular name from the
wasp-like colours of its body. In the larval state it is one of the
carpenter-grubs, and may be found in posts, fir-trees, and similar
localities. In this country, although plentiful, it is not numerous
enough to do much harm; but in Ceylon, a closely-allied species is
one of the pests of the island. It is popularly known by the title
of coffee-borer, from its habit of boring into the stems of the
coffee-plant. The landowner looks with absolute horror on this pretty
but destructive insect, and would pay a heavy sum annually to any one
who would undertake to extirpate the tiny foe. Whole plantations have
been swept off by it, and up to the present time no remedy has had
more than a temporary and partial success.]
Another capricorn beetle of this family is no less destructive to bark
in its perfect state than the above are when grubs, as from its habit
of eating round a tree, it cuts the course of the returning sap, and
destroys it.
[The late Mr. Waterton once showed me a stout branch which had fallen
on his head while he was standing under a tree, the branch having been
cut completely through by the jaws of some large longicorn beetle. The
mode in which the insect had severed the branch was exactly like that
which is practised by the beaver when it cuts down a tree.
[Illustration: Capricorn Beetle (_Cerambyx Lamia amputator_) rounding
off the bark of a tree.]
The burrows and cocoons of two other species of Cerambyx are shown
in the accompanying illustration, and in both cases may be seen the
provision which is made for the exit of the beetle after it has
attained the perfect condition. The double burrow of the left is that
of _Cerambyx carcharias_, and those on the right-hand figure are the
habitations of _Cerambyx populneus_. The reader will see how these
insects cut up the wood of the branch, and can well understand the
infinite mischief which can be done to a coffee plantation by the
Clytus.
The last wood-boring beetle which will be mentioned is the stag-beetle
of our own country. In the larval state this insect resides in tree
trunks, mostly towards the roots, and therefore escapes observation
more successfully than would be the case if it inhabited a higher
portion of the tree. When full-grown, the larva is of enormous
size, and the hole which it bores is necessarily of corresponding
dimensions. In some parts of England, the larvæ are popularly called
"Joe Bassetts," and are said to turn into "Pincher Bobs." The latter
title is a very appropriate one, as any one can testify who has allowed
a fine male stag-beetle to grip his finger between its jaws. As to the
Joe Bassett, it is simply a local name.]
[Illustration: _Cerambyx carcharias._]
[Illustration: _Cerambyx populneus._]
_CHAPTER XIII._
STRUCTURES OF GRASSHOPPERS, CRICKETS, AND BEETLES.
Grasshoppers, locusts, crickets, and beetles are, in many respects, no
less interesting than the insects whose architectural proceedings we
have already detailed. They do not, indeed, build any edifice for the
accommodation of themselves or their progeny; but most, if not all of
them, excavate retreats in walls or in the ground.
The house-cricket (_Acheta domestica_) is well known for its habit
of picking out the mortar of ovens and kitchen fire-places, where
it not only enjoys warmth, but can procure abundance of food. It is
usually supposed that it feeds on bread. M. Latreille says it only
eats insects, and it certainly thrives well in houses infested by
the cockroach; but we have also known it eat and destroy lamb's-wool
stockings, and other woolen stuffs, hung near a fire to dry. It is
evidently not fond of hard labour, but prefers those places where
the mortar is already loosened, or at least is new, soft, and easily
scooped out; and in this way it will dig covert ways from room to
room. In summer, crickets often make excursions from the house to the
neighbouring fields, and dwell in the crevices of rubbish, or the
cracks made in the ground by dry weather, where they chirp as merrily
as in the snuggest chimney-corner. Whether they ever dig retreats in
such circumstances we have not ascertained: though it is not improbable
they may do so for the purpose of making nests. M. Bory St. Vincent
tells us that the Spaniards are so fond of crickets that they keep them
in cages like singing birds.[CC]
The Mole-Cricket.
[Illustration: The Mole-Cricket, with a separate outline of one of its
hands.]
The insect, called, from its similarity of habits to the mole, the
mole-cricket (_Gryllotalpa vulgaris_, Latr.), is but too well known
in gardens, corn-fields, and the moist banks of rivers and ponds, in
some parts of England, such as Wiltshire and Hampshire, though it is
comparatively rare or unknown in others. It burrows in the ground,
and forms extensive galleries similar to those of the mole, though
smaller; and these may always be recognized by a slightly elevated
ridge of mould: for the insect does not throw up the earth in hillocks
like the mole, but gradually, as it digs along, in the manner of the
field-mouse. In this way it commits great ravages, in hotbeds and in
gardens, upon peas, young cabbages, and other vegetables, the roots
of which it is said to devour. It is not improbable, we think, that,
like its congener, the house-cricket, it may also prey upon underground
insects, and undermine the plants to get at them, as the mole has been
proved to do. Mr Gould, indeed, fed a mole-cricket for several months
upon ants.
The structure of the mole-cricket's arms and hands (if we may call
them so) is admirably adapted for these operations, being both very
strong, and moved by a peculiar apparatus of muscles. The breast is
formed of a thick, hard, horny substance, which is further strengthened
within by a double framework of strong gristle, in front of the
extremities of which the shoulder-blades of the arms are firmly
jointed: a structure evidently intended to prevent the breast from
being injured by the powerful action of the muscles of the arms in
digging. The arms themselves are strong and broad, and the hand is
furnished with four large sharp claws, pointed somewhat obliquely
outwards, this being the direction in which it digs, throwing the earth
on each side of its course. So strongly indeed does it throw out its
arms, that we find it can thus easily support its own weight when held
between the finger and thumb, as we have tried upon half-a-dozen of the
living insects now in our possession.
[Illustration: Nest of the Mole-Cricket.]
The nest which the female constructs for her eggs, in the beginning
of May, is well worthy of attention. The Rev. Mr. White, of Selborne,
tells us that a gardener, at a house where he was on a visit, while
mowing grass by the side of a canal, chanced to strike his scythe too
deep, and pared off a large piece of turf, laying open to view an
interesting scene of domestic economy. There was a pretty chamber dug
in the clay, of the form and about the dimensions it would have had if
moulded by an egg, the walls being neatly smoothed and polished. In
this little cell were deposited about a hundred eggs, of the size and
form of caraway comfits, and of a dull tarnished white colour. The eggs
were not very deep, but just under a little heap of fresh mould, and
within the influence of the sun's heat.[CD] The dull tarnished white
colour, however, scarcely agrees with a parcel of these eggs now before
us, which are translucent, gelatinous, and greenish.
Like the eggs and young of other insects, however, those of the
mole-cricket are exposed to depredation, and particularly to the
ravages of a black beetle which burrows in similar localities. The
mother insect, accordingly, does not think her nest secure till she has
defended it, like a fortified town, with labyrinths, intrenchments,
ramparts, and covert ways. In some part of these out-works she stations
herself as an advanced guard, and when the beetle ventures within her
circumvallations, she pounces upon him and kills him.
The Field-Cricket.
Another insect of this family, the field-cricket (_Acheta campestris_),
also forms burrows in the ground, in which it lodges all day, and comes
out chiefly about sunset to pipe its evening song. It is so very shy
and cautious, however, that it is by no means easy to discover either
the insect or its burrow. "The children in France amuse themselves with
hunting after the field-cricket; they put into its hole an ant fastened
by a long hair, and as they draw it out the cricket does not fail to
pursue it, and issue from its retreat. Pliny informs us it might be
captured in a much more expeditious and easy manner. If, for instance,
a small and slender piece of stick were to be thrust into the burrow,
the insect, he says, would immediately get upon it for the purpose of
demanding the occasion of the intrusion: whence arose the proverb,
_stultior grillo_ (more foolish than a cricket), applied to one who,
upon light grounds, provokes his enemy, and falls into the snares which
might have been laid to entrap him."[CE]
The Rev. Mr. White, who attentively studied their habits and manners,
at first made an attempt to dig them out with a spade, but without any
great success; for either the bottom of the hole was inaccessible, from
its terminating under a large stone, or else in breaking up the ground
the poor creature was inadvertently squeezed to death. Out of one thus
bruised a great number of eggs were taken, which were long and narrow,
of a yellow colour, and covered with a very tough skin. More gentle
means were then used, and these proved successful. A pliant stalk of
grass, gently insinuated into the caverns, will probe their windings to
the bottom, and bring out the inhabitant; and thus the humane inquirer
may gratify his curiosity without injuring the object of it.
When the males meet, they sometimes fight very fiercely, as Mr. White
found by some that he put into the crevices of a dry stone wall, where
he wished to have them settle. For though they seemed distressed by
being taken out of their knowledge, yet the first that got possession
of the chinks seized on all the others that were obtruded upon him with
his large row of serrated fangs. With their strong jaws, toothed like
the shears of a lobster's claws, they perforate and round their curious
regular cells, having no fore-claws to dig with, like the mole-cricket.
When taken into the hand, they never attempt to defend themselves,
though armed with such formidable weapons. Of such herbs as grow about
the mouths of their burrows they eat indiscriminately, and never in the
day-time seem to stir more than two or three inches from home. Sitting
in the entrance of their caverns, they chirp all night as well as day,
from the middle of the month of May to the middle of July. In hot
weather, when they are most vigorous, they make the hills echo; and, in
the more still hours of darkness, may be heard to a very considerable
distance. "Not many summers ago," says Mr. White, "I endeavoured to
transplant a colony of these insects to the terrace in my garden, by
boring deep holes in the sloping turf. The new inhabitants stayed some
time, and fed and sang; but they wandered away by degrees, and were
heard at a greater distance every morning; so it appears that on this
emergency they made use of their wings in attempting to return to the
spot from which they were taken."[CF] The manner in which these insects
lay their eggs is represented in the following figure, which is that of
an insect nearly allied to the crickets, though of a different genus.
[Illustration: _Acrida verrucivora_ depositing her eggs.
The usual position of the ovipositor is represented by dots.]
A more laborious task is performed by an insect by no means uncommon
in Britain, the burying beetle (_Necrophorus vespillo_), which may be
easily recognized by its longish body, of a black colour, with two
broad and irregularly indented bands of yellowish brown. A foreign
naturalist, M. Gleditsch, gives a very interesting account of its
industry. He had "often remarked that dead moles, when laid upon the
ground, especially if upon loose earth, were almost sure to disappear
in the course of two or three days, often of twelve hours. To ascertain
the cause, he placed a mole upon one of the beds in his garden. It
had vanished by the third morning; and on digging where it had been
laid, he found it buried to the depth of three inches, and under it
four beetles, which seemed to have been the agents in this singular
inhumation. Not perceiving anything particular in the mole, he buried
it again; and on examining it at the end of six days, he found it
swarming with maggots, apparently the issue of the beetles, which M.
Gleditsch now naturally concluded had buried the carcase for the food
of their future young. To determine these points more clearly, he put
four of these insects into a glass vessel, half filled with earth and
properly secured, and upon the surface of the earth two frogs. In less
than twelve hours one of the frogs was interred by two of the beetles;
the other two ran about the whole day, as if busied in measuring the
dimensions of the remaining corpse, which on the third day was also
found buried. He then introduced a dead linnet. A pair of the beetles
were soon engaged upon the bird. They began their operations by pushing
out the earth from under the body, so as to form a cavity for its
reception; and it was curious to see the efforts which the beetles
made, by dragging at the feathers of the bird from below, to pull it
into its grave. The male, having driven the female away, continued the
work alone for five hours. He lifted up the bird, changed its place,
turned it, and arranged it in the grave, and from time to time came
out of the hole, mounted upon it, and trod it under foot, and then
retired below, and pulled it down. At length, apparently wearied with
this uninterrupted labour, it came forth, and leaned its head upon
the earth beside the bird, without the smallest motion, as if to rest
itself, for a full hour, when it again crept under the earth. The next
day, in the morning, the bird was an inch and a half under ground, and
the trench remained open the whole day, the corpse seeming as if laid
out upon a bier, surrounded with a rampart of mould. In the evening it
had sunk half an inch lower, and in another day the work was completed,
and the bird covered. M. Gleditsch continued to add other small dead
animals, which were all sooner or later buried; and the result of his
experiment was, that in fifty days four beetles had interred, in the
very small space of earth allotted to them, twelve carcases, viz., four
frogs, three small birds, two fishes, one mole, and two grasshoppers,
besides the entrails of a fish, and two morsels of the lungs of an ox.
In another experiment, a single beetle buried a mole, forty times its
own bulk and weight, in two days."[CG]
In the summer of 1826, we found on Putney Heath, in Surrey, four of
these beetles, hard at work in burying a dead crow, precisely in the
manner described by M. Gleditsch. (J. R.)
Dung-Beetle.
A still more common British insect, the dorr, clock, or dung-beetle
(_Geotrupes stercorarius_), uses different materials for burying along
with its eggs. "It digs," to use the words of Kirby and Spence, "a
deep cylindrical hole, and carrying down a mass of the dung to the
bottom, in it deposits its eggs. And many of the species of the genus
_Ateuchus_ roll together wet dung into round pellets, deposit an egg
in the midst of each, and when dry push them backwards, by their hind
feet, to holes of the surprising depth of three feet, which they have
previously dug for their reception, and which are often several yards
distant. The attention of these insects to their eggs is so remarkable,
that it was observed in the earliest ages, and is mentioned by ancient
writers, but with the addition of many fables; as that they were all of
the male sex; that they became young again every year; and that they
rolled the pellets containing their eggs from sunrise to sunset every
day, for twenty-eight days, without intermission."[CH]
"We frequently notice in our evening walks," says Mr. Knapp, "the
murmuring passage, and are often stricken by the heedless flight of the
great dorr-beetle (_Geotrupes stercorarius_), clocks, as the boys call
them. But this evening my attention was called to them in particular,
by the constant passing of such a number as to constitute something
like a little stream; and I was led to search into the object of their
direct flight, as in general it is irregular and seemingly inquisitive.
I soon found that they dropped on some recent nuisance: but what powers
of perception must these creatures possess, drawn from all distances
and directions by the very little fetor which, in such a calm evening,
could be diffused around, and by what inconceivable means could odours
reach, this beetle in such a manner as to rouse so inert an insect
into action! But it is appointed one of the great scavengers of the
earth, and marvellously endowed with powers of sensation, and means of
effecting this purpose of its being. Exquisitely fabricated as it is
to receive impressions, yet probably it is not more highly gifted than
any of the other innumerable creatures that wing their way around us,
or creep about our paths, though by this one perceptible faculty, thus
'dimly seen,' it excites our wonder and surprise. How wondrous then the
whole!
"The perfect cleanliness of these creatures is a very notable
circumstance, when we consider that nearly their whole lives are
passed in burrowing in the earth, and removing nuisances; yet such is
the admirable polish of their coating and limbs, that we very seldom
find any soil adhering to them. The meloe, and some of the scarabæi,
upon first emerging from their winter's retreat, are commonly found
with earth clinging to them; but the removal of this is one of the
first operations of the creature; and all the beetle race, the chief
occupation of which is crawling about the soil, and such dirty employs,
are, notwithstanding, remarkable for the glossiness of their covering,
and freedom from defilements of any kind. But purity of vesture
seems to be a principal precept of Nature, and observable throughout
creation. Fishes, from the nature of the element in which they reside,
can contract but little impurity. Birds are unceasingly attentive to
neatness and lustration of their plumage. All the slug race, though
covered with slimy matter calculated to collect extraneous things, and
reptiles, are perfectly free from soil. The fur and hair of beasts, in
a state of liberty and health, is never filthy or sullied with dirt.
Some birds roll themselves in dust, and, occasionally, particular
beasts cover themselves with mire; but this is not from any liking or
inclination for such things, but to free themselves from annoyances, or
to prevent the bites of insects. Whether birds in preening, and beasts
in dressing themselves, be directed by any instinctive faculty, we know
not; but they evidently derive pleasure from the operation, and thus
this feeling of enjoyment, even if the sole motive, becomes to them an
essential source of comfort and of health."[CI]
The rose or green chafer (_Cetonia aurata_), which is one of our
prettiest native insects, is one of the burrowers, and, for the purpose
of depositing her eggs, digs, about the middle of June, into soft light
ground. When she is seen at this operation, with her broad and delicate
wings folded up in their shining green cases, speckled with white, it
could hardly be imagined that she had but just descended from the air,
or dropped down from some neighbouring rose.
* * * * *
The proceedings of the Tumble-Dung Beetle of America (_Scarabæus
pilularius_, Linn.) are described in a very interesting manner by
Catesby, in his 'Carolina.' "I have," says he, "attentively admired
their industry, and mutual assisting of each other in rolling their
globular balls from the place where they made them to that of their
interment, which is usually the distance of some yards, more or less.
This they perform breech foremost, by raising their hind parts, and
forcing along the ball with their hind feet. Two or three of them are
sometimes engaged in trundling one ball, which, from meeting with
impediments on account of the unevenness of the ground, is sometimes
deserted by them. It is, however, attempted by others with success,
unless it happens to roll into some deep hollow or chink, where they
are constrained to leave it; but they continue their work by rolling
off the next ball that comes in their way. None of them seem to know
their own balls, but an equal care for the whole appears to affect all
the community. They form these pellets while the dung remains moist,
and leave them to harden in the sun before they attempt to roll them.
In their moving of them from place to place, both they and the balls
may frequently be seen tumbling about the little eminences that are in
their way. They are not, however, easily discouraged; and, by repeating
their attempts, usually surmount the difficulties."
He further informs us that they "find out their subsistence by the
excellency of their noses, which direct them in their flight to
newly-fallen dung, on which they immediately go to work, tempering it
with a proper mixture of earth. So intent are they always upon their
employment, that, though handled or otherwise interrupted, they are not
to be deterred, but immediately, on being freed, persist in their work
without any apprehension of danger. They are said to be so exceedingly
strong and active as to move about, with the greatest ease, things that
are many times their own weight. Dr. Brichell was supping one evening
in a planter's house of North Carolina, when two of them were conveyed,
without his knowledge, under the candlesticks. A few blows were struck
on the table, and, to his great surprise, the candlesticks began to
move about, apparently without any agency; and his surprise was not
much lessened when, on taking one of them up, he discovered that it was
only a chafer that moved it."
We have often found the necklace-beetle (_Carabus monilis_) inhabiting
a chamber dug out in the earth of a garden, just sufficient to contain
its body, and carefully smoothed and polished. From the form of this
little nest, it would seem as if it were constructed, not by digging
out the earth and removing it, but chiefly by the insect pushing its
body forcibly against the walls. The beetles which we have found
nestling in this manner have been all males; and therefore it cannot be
intended for a breeding-cell; for male insects are never, we believe,
sufficiently generous to their mates to assist them in such labours.
The beetle in question appears to be partial to celery trenches (J.
R.); probably from the loose earth of which they are composed yielding,
without much difficulty, to the pressure of its body.
[Many of the subterranean larvæ which are turned up by the spade or the
plough are the imperfect conditions of earth-burrowing beetles, and
many of them are among the most insidious pests of the farmer, their
ravages being all the more dangerous because they are unseen.]
The most destructive, perhaps, of the creatures usually called grubs
are the larvæ of the may-bug or cockchafer (_Melolontha vulgaris_), but
too well known, particularly in the southern and midland districts of
England, as well as in Ireland, where the grub is called the Connaught
worm;[CJ] but fortunately not abundant in the north. We only once met
with the cockchafer in Scotland, at Sorn, in Ayrshire. (J. R.) Even
in the perfect state, this insect is not a little destructive to the
leaves of both forest and fruit trees. In 1823, we remember to have
observed almost all the trees about Dulwich and Camberwell defoliated
by them; and Salisbury says, the leaves of the oaks in Richmond Park
were so eaten by them, that scarcely an entire leaf was left. But it
is in their previous larva state that they are most destructive, as we
shall see by tracing their history.
The mother cockchafer, when about to lay her eggs, digs into the
earth of a meadow or corn-field to the depth of a span, and deposits
them in a cluster at the bottom of the excavation. Rösel, in order to
watch the proceedings, put some females into glasses half-filled with
earth, covered with a tuft of grass and a piece of thin muslin. In a
fortnight, he found some hundreds of eggs deposited, of an oval shape
and a pale-yellow colour. Placing the glass in a cellar, the eggs were
hatched towards autumn, and the grubs increased remarkably in size. In
the following May they fed so voraciously that they required a fresh
turf every second day; and even this proving too scanty provender, he
sowed in several garden pots a crop of peas, lentils, and salad, and
when the plants came up he put a pair of grubs in each pot; and in
this manner he fed them through the second and third years. During
this period, they cast their skins three or four times, going for this
purpose deeper into the earth, and burrowing out a hole where they
might effect their change undisturbed; and they do the same in winter,
during which they become torpid and do not eat.
[Illustration: Transformations of the Cockchafer (_Melolontha
vulgaris_). _a_, Newly-hatched larvæ. _b_, larva, one year old. _c_,
the same larva at the second year of its growth. _d_, the same three
years old. _e_, section of a bank of earth, containing the chrysalis of
the fourth year. _f_, the chafer first emerging from the earth. _g_,
the perfect chafer in a sitting posture. _h_, the same flying]
When the grub changes into a pupa, in the third autumn after it is
hatched, it digs a similar burrow about a yard deep; and when kept in
a pot, and prevented from going deep enough, it shows great uneasiness
and often dies. The perfect beetle comes forth from the pupa in January
or February; but it is then as soft as it was whilst still a grub, and
does not acquire its hardness and colour for ten or twelve days, nor
does it venture above ground before May, in the fourth year from the
time of its hatching. At this time, the beetles may be observed issuing
from their holes in the evening, and dashing themselves about in the
air as if blind.
During the three summers then of their existence in the grub state,
these insects do immense injury, burrowing between the turf and the
soil, and devouring the roots of grass and other plants; so that the
turf may easily be rolled off, as if cut by a turfing spade, while the
soil underneath for an inch or more is turned into soft mould like the
bed of a garden. Mr. Anderson, of Norwich, mentions having seen a whole
field of fine flourishing grass so undermined by these grubs, that in a
few weeks it became as dry, brittle, and withered as hay.[CK] Bingley
also tells us that "about sixty years ago, a farm near Norwich was so
infested with cockchafers, that the farmer and his servants affirmed
they gathered eighty bushels of them; and the grubs had done so much
injury, that the court of the city, in compassion to the poor fellow's
misfortune, allowed him twenty-five pounds."[CL] In the year 1785, a
farmer, near Blois, in France, employed a number of children and poor
persons to destroy the cockchafers at the rate of two liards a hundred,
and in a few days they collected fourteen thousand.[CM]
"I remember," says Salisbury, "seeing in a nursery near Bagshot,
several acres of young forest trees, particularly larch, the roots of
which were completely destroyed by it, so much so that not a single
tree was left alive."[CN] We are doubtful, however, whether this was
the grub of the cockchafer, and think it more likely to have been that
of the green rose-beetle (_Cetonia aurata_), which feeds on the roots
of trees.
_CHAPTER XIV._
ARCHITECTURE OF ANTS.--MASON-ANTS.
All the species of ants are social. There are none solitary, as is
the case with bees and wasps. They are all more or less skilful in
architecture, some employing masonry, and others being carpenters,
wood-carvers, and miners. They consequently afford much that is
interesting to naturalists who observe their operations. The genuine
history of ants has only been recently investigated, first by Gould
in 1747, and subsequently by Linnæus, De Geer, Huber, and Latreille.
Previous to that time their real industry and their imagined
foresight were held up as moral lessons, without any great accuracy
of observation; and it is probable that, even now, the mixture of
truth and error in Addison's delightful papers in the Guardian (Nos.
156, 157) may be more generally attractive than the minute relation
of careful naturalists. Gould disproved, most satisfactorily, the
ancient fable of ants storing up corn for winter provision, no species
of ants ever eating grain, or feeding in the winter upon anything. It
is to Huber the younger, however, that we are chiefly indebted for
our knowledge of the habits and economy of ants; and to Latreille for
a closer distinction of the species. Some of the more interesting
species, whose singular economy is described by the younger Huber, have
not been hitherto found in this country. We shall, however, discover
matter of very considerable interest in those which are indigenous;
and as our principal object is to excite inquiry and observation with
regard to those insects which may be easily watched in our own gardens
and fields, we shall chiefly confine ourselves to the ants of these
islands. We shall begin with the labours of those native ants which may
be called earth-masons, from their digging in the ground, and forming
structures with pellets of moistened loam, clay, or sand.
Mason-Ants.
We have used in the preceding pages the terms _mason-bees_ and
_mason-wasps_, for insects which build their nests of earthy materials.
On the same principle, we have followed the ingenious M. Huber the
younger, in employing the term mason-ants for those whose nests on the
exterior appear to be hillocks of earth, without the admixture of other
materials, whilst in the interior they present a series of labyrinths,
lodges, vaults, and galleries constructed with considerable skill. Of
these mason-ants, as of the mason-wasps and bees already described,
there are several species, differing from one another in their skill in
the art of architecture.
One of the most common of the ant-masons is the turf-ant (_Formica
cæspitum_, Latr.), which is very small and of a blackish-brown colour.
Its architecture is not upon quite so extensive a scale as some of the
others; but, though slight, it is very ingenious. Sometimes they make
choice of the shelter of a flat stone or other covering, beneath which
they hollow out chambers and communicating galleries; at other times
they are contented with the open ground; but most commonly they select
a tuft of grass or other herbage, the stems of which serve for columns
to their earthen walls.
We had a small colony of these ants accidentally established in
a flower-pot, in which we were rearing some young plants of the
tiger-lily (_Lilium tigrinum_), the stems of which being stronger than
the grass where they usually build, enabled them to rear their edifice
higher, and also to make it more secure, than they otherwise might.
It was wholly formed of small grains of moist earth, piled up between
the stems of the lily without any apparent cement; indeed it has been
ascertained by Huber, as we shall afterwards see, that they use no
cement beside water. This is not always to be procured, as they depend
altogether on rains and dew; but they possess the art of joining grains
of dry sand so as to support one another, on some similar principle, no
doubt, to that of the arch.
The nest which our turf-ants constructed in the flower-pot was
externally of an imperfect square form, in consequence of its
situation; for they usually prefer a circular plan. The principal
chambers were placed under the arches, and, when inspected, contained
a pile of cocoons, and pupæ. Beneath those upper chambers there were
others dug out deeper down, in which were also a numerous collection of
eggs and cocoons in various stages of advancement. (J. R.)
Mr. Knapp describes a still more curious structure of another species
of ant common in this country:--"One year," says he, "on the third of
March, my labourer being employed in cutting up ant-hills, or tumps
as we call them, exposed to view multitudes of the yellow species
(_Formica flava_) in their winter's retirement. They were collected in
numbers in little cells and compartments, communicating with others by
means of narrow passages. In many of the cells they had deposited their
larvæ, which they were surrounding and attending, but not brooding over
or covering. Being disturbed by our rude operations, they removed them
from our sight to more hidden compartments. The larvæ were small. Some
of these ant-hills contained multitudes of the young of the wood-louse
(_Oniscus armadillo_), inhabiting with perfect familiarity the same
compartments as the ants, crawling about with great activity with them,
and perfectly domesticated with each other. They were small and white;
but the constant vibration of their antennæ, and the alacrity of their
motions, manifested a healthy vigour. The ants were in a torpid state;
but on being removed into a temperate room, they assumed much of their
summer's animation. How these creatures are supported during the winter
season it is difficult to comprehend; as in no one instance could we
perceive any store or provision made for the supply of their wants.
The minute size of the larvæ manifested that they had been recently
deposited; and consequently that their parents had not remained during
winter in a dormant state, and thus free from the calls of hunger. The
preceding month of February, and part of January, had been remarkably
severe; the frost had penetrated deep into the earth, and long held it
frozen; the ants were in many cases not more than four inches beneath
the surface, and must have been enclosed in a mass of frozen soil for
a long period; yet they, their young, and the onisci, were perfectly
uninjured by it: affording another proof of the fallacy of the commonly
received opinion, that cold is _universally_ destructive to insect
life."[CO]
The earth employed by mason-ants is usually moist clay, either dug from
the interior parts of their city or moistened by rain. The mining-ants
and the ash-coloured (_Formica fusca_) employ earth which is probably
not selected with so much care, for it forms a much coarser mortar than
what we see used in the structure of the yellow ants (_F. flava_) and
the brown ants (_F. brunnea_). We have never observed them bringing
their building materials of this kind from a distance, like the
mason-bees and like the wood or hill ant (_F. rufa_); but they take
care, before they fix upon a locality, that it shall produce them all
that they require. We are indebted to Huber the younger for the most
complete account which has hitherto been given of these operations, of
which details we shall make free use.
"To form," says this shrewd observer, "a correct judgment of the
interior arrangement or distribution of an ant-hill, it is necessary to
select such as have not been accidentally spoiled, or whose form has
not been too much altered by local circumstances; a slight attention
will then suffice to show that the habitations of the different species
are not all constructed after the same system. Thus, the hillock raised
by the ash-coloured ants will always present thick walls, fabricated
with coarse earth, well-marked stories, and large chambers, with
vaulted ceilings, resting upon a solid base. We never observe roads, or
galleries, properly so called, but large passages, of an oval form, and
all around considerable cavities and extensive embankments of earth. We
further notice, that the little architects observe a certain proportion
between the large arched ceilings and the pillars that are to support
them.
"The brown ant (_Formica brunnea_), one of the smallest of the ants, is
particularly remarkable for the extreme finish of its work. Its body is
of a reddish shining brown, its head a little deeper, and the antennæ
and feet a little lighter in colour. The abdomen is of an obscure
brown, the scale narrow, of a square form, and slightly scolloped. The
body is one line and two-fifths in length.[CP]
"This ant, one of the most industrious of its tribe, forms its nest
of stories four or five lines in height. The partitions are not more
than half a line in thickness; and the substance of which they are
composed is so finely grained, that the inner walls present one smooth
unbroken surface. These stories are not horizontal; they follow the
slope of the ant-hill, and lie one upon another to the ground-floor,
which communicates with the subterranean lodges. They are not always,
however, arranged with the same regularity, for these ants do not
follow an invariable plan; it appears, on the contrary, that nature
has allowed them a certain latitude in this respect, and that they
can, according to circumstances, modify them to their wish; but
however fantastical their habitations may appear, we always observe
they have been formed by concentrical stories. On examining each
story separately, we observe a number of cavities or halls, lodges
of narrower dimensions, and long galleries, which serve for general
communication. The arched ceilings covering the most spacious places
are supported either by little columns, slender walls, or by regular
buttresses. We also notice chambers, that have but one entrance,
communicating with the lower story, and large open spaces, serving as a
kind of cross-road (_carrefour_), in which all the streets terminate.
"Such is the manner in which the habitations of these ants are
constructed. Upon opening them, we commonly find the apartments, as
well as the large open spaces, filled with adult ants; and always
observed their pupæ collected in the apartments more or less near the
surface. This, however, seems regulated by the hour of the day, and
the temperature: for in this respect these ants are endowed with
great sensibility, and know the degree of heat best adapted for their
young. The ant-hill contains, sometimes, more than twenty stories
in its upper portion, and at least as many under the surface of the
ground. By this arrangement the ants are enabled, with the greatest
facility, to regulate the heat. When a too-burning sun overheats their
upper apartments, they withdraw their little ones to the bottom of
the ant-hill. The ground-floor becoming, in its turn, uninhabitable
during the rainy season, the ants of this species transport what most
interests them to the higher stories; and it is there we find them more
usually assembled, with their eggs and pupæ, when the subterranean
apartments are submerged."[CQ]
Ants have a great dislike to water, when it exceeds that of a light
shower to moisten their building materials. One species, mentioned
by Azara as indigenous to South America, instinctively builds a nest
from three to six feet high,[CR] to provide against the inundations
during the rainy season. Even this, however, does not always save them
from submersion; and, when that occurs, they are compelled, in order
to prevent themselves from being swept away, to form a group somewhat
similar to the curtain of the wax-workers of hive-bees (see p. 133).
The ants constituting the basis of this group lay hold of some shrub
for security, while their companions hold on by them; and thus the
whole colony, forming an animated raft, floats on the surface of the
water till the inundation (which seldom continues longer than a day
or two) subsides. We confess, however, that we are somewhat sceptical
respecting this story, notwithstanding the very high character of the
Spanish naturalist.
It is usual with architectural insects to employ some animal secretion,
by way of mortar or size, to temper the materials with which they
work; but the whole economy of ants is so different, that it would be
wrong to infer from analogy a similarity in this respect, though the
exquisite polish and extreme delicacy of finish in their structures
lead, naturally, to such a conclusion. M. P. Huber, in order to resolve
this question, at first thought of subjecting the materials of the
walls to chemical analysis, but wisely (as we think) abandoned it for
the surer method of observation. The details which he has given, as the
result of his researches, are exceedingly curious and instructive. He
began by observing an ant-hill till he could perceive some change in
its form.
"The inhabitants," says he, "of that which I selected, kept within
during the day, or only went out by subterranean galleries which opened
at some feet distance in the meadow. There were, however, two or three
small openings on the surface of the nest; but I saw none of the
labourers pass out this way, on account of their being too much exposed
to the sun, which these insects greatly dread. This ant-hill, which
had a round form, rose in the grass, at the border of a path, and had
sustained no injury. I soon perceived that the freshness of the air and
the dew invited the ants to walk over the surface of their nest; they
began making new apertures; several ants might be seen arriving at the
same time, thrusting their heads from the entrances, moving about their
antennæ, and at length adventuring forth to visit the environs.
"This brought to my recollection a singular opinion of the ancients.
They believed that ants were occupied in their architectural labours
during the night, when the moon was at its full."[CS]
M. Latreille discovered a species of ants which were, so far as he
could ascertain, completely blind,[CT] and of course it would be
immaterial to them whether they worked by night or during the day.
All observers indeed agree that ants labour in the night, and a
French naturalist is therefore of opinion that they never sleep--a
circumstance which is well ascertained with respect to other animals,
such as the shark, which will track a ship in full sail for weeks
together.[CU] The ingenious historian of English ants, Gould, says
they never intermit their labours by night or by day, except when
compelled by excessive rains. It is probable the ancients were mistaken
in asserting that they only work when the moon shines;[CV] for, like
bees, they seem to find no difficulty in building in the dark, their
subterranean apartments being as well finished as the upper stories of
their buildings. But to proceed with the narrative of M. P. Huber.
"Having thus noticed the movements of these insects during the night,
I found they were almost always abroad and engaged about the dome of
their habitation after sunset. This was directly the reverse of what I
had observed in the conduct of the wood-ants (_F. rufa_), who only go
out during the day, and close their doors in the evening. The contrast
was still more remarkable than I had previously supposed; for, upon
visiting the brown ants some days after, during a gentle rain, I saw
all their architectural talents in full play.
"As soon as the rain commenced, they left in great numbers their
subterranean residence, re-entered it almost immediately, and then
returned, bearing between their teeth pellets of earth, which they
deposited on the roof of their nest. I could not at first conceive what
this was meant for, but at length I saw little walls start up on all
sides with spaces left between them. In several places, columns, ranged
at regular distances, announced halls, lodges, and passages which the
ants proposed establishing; in a word, it was the rough beginning of a
new story.
"I watched with a considerable degree of interest the most trifling
movements of my masons, and found they did not work after the manner
of wasps and humble-bees, when occupied in constructing a covering
to their nest. The latter sit, as it were, astride on the border or
margin of the covering, and take it between their teeth to model and
attenuate it according to their wish. The wax of which it is composed,
and the paper which the wasp employs, moistened by some kind of glue,
are admirably adapted for this purpose, but the earth of which the ants
make use, from its often possessing little tenacity, must be worked up
after some other manner.
"Each ant, then, carried between its teeth the pellet of earth it had
formed by scraping with the end of its mandibles the bottom of its
abode, a circumstance which I have frequently witnessed in open day.
This little mass of earth, being composed of particles but just united,
could be readily kneaded and moulded as the ants wished; thus when
they had applied it to the spot where they had to rest, they divided
and pressed against it with their teeth, so as to fill up the little
inequalities of their wall. The antennæ followed all their movements,
passing over each particle of earth as soon as it was placed in its
proper position. The whole was then rendered more compact by pressing
it lightly with the fore-feet. This work went on remarkably fast.
After having traced out the plan of their masonry, in laying here and
there foundations for the pillars and partitions they were about to
erect, they raised them gradually higher, by adding fresh materials.
It often happened that two little walls, which were to form a gallery,
were raised opposite, and at a slight distance from each other. When
they had attained the height of four or five lines, the ants busied
themselves in covering in the space left between them by a vaulted
ceiling.
"As if they judged all their partitions of sufficient elevation, they
then quitted their labours in the upper part of the building; they
affixed to the interior and upper part of each wall fragments of
moistened earth, in an almost horizontal direction, and in such a way
as to form a ledge, which, by extension, would be made to join that
coming from the opposite wall. These ledges were about half a line in
thickness; and the breadth of the galleries was, for the most part,
about a quarter of an inch. On one side several vertical partitions
were seen to form the scaffolding of a lodge, which communicated with
several corridors by apertures formed in the masonry; on another, a
regularly-formed hall was constructed, the vaulted ceiling of which
was sustained by numerous pillars; further off, again, might be
recognised the rudiments of one of those cross roads of which I have
before spoken, and in which several avenues terminate. These parts of
the ant-hill were the most spacious; the ants, however, did not appear
embarrassed in constructing the ceiling to cover them in, although they
were often more than two inches in breadth.
"In the upper part of the angles formed by the different walls, they
laid the first foundations of this ceiling, and from the top of each
pillar, as from so many centres, a layer of earth, horizontal and
slightly convex, was carried forward to meet the several portions
coming from different points of the large public thoroughfare.
"I sometimes, however, laboured under an apprehension that the building
could not possibly resist its own weight, and that such extensive
ceilings, sustained only by a few pillars, would fall into ruin from
the rain which continually dropped upon them; but I was quickly
convinced of their stability, from observing that the earth brought by
these insects adhered at all points, on the slightest contact; and that
the rain, so far from lessening the cohesion of its particles, appeared
even to increase it. Thus, instead of injuring the building, it even
contributed to render it still more secure.
"These particles of moistened earth, which are only held together by
juxtaposition, require a fall of rain to cement them more closely,
and thus varnish over, as it were, those places where the walls and
galleries remain uncovered. All inequalities in the masonry then
disappear. The upper part of these stories, formed of several pieces
brought together, presents but one single layer of compact earth. They
require for their complete consolidation nothing but the heat of the
sun. It sometimes, however, happens that a violent rain will destroy
the apartments, especially should they be but slightly arched; but
under these circumstances the ants reconstruct them with wonderful
patience.
"These different labours were carried on at the same time, and were
so closely followed up in the different quarters, that the ant-hill
received an additional story in the course of seven or eight hours. All
the vaulted ceilings being formed upon a regular plan, and at equal
distances from one wall to the other, constituted, when finished, but
one single roof. Scarcely had the ants finished one story than they
began to construct another; but they had not time to finish it--the
rain ceasing before the ceiling was fully completed. They still,
however, continued their work for a few hours, taking advantage of
the humidity of the earth; but a keen north wind soon sprung up, and
hastily dried the collected fragments, which, no longer possessing
the same adherence, readily fell into powder. The ants, finding their
efforts ineffectual, were at length discouraged, and abandoned their
employment; but what was my astonishment when I saw them destroy all
the apartments that were yet uncovered, scattering here and there over
the last story the materials of which they had been composed! These
facts incontestably prove that they employ neither gum, nor any kind of
cement, to bind together the several substances of their nest; but in
place of this avail themselves of the rain, to work or knead the earth,
leaving the sun and wind to dry and consolidate it."[CW]
Dr. Johnson of Bristol observed very similar proceedings in the case
of a colony of red ants (_Myrmica rubra?_), the roof of whose nest was
formed by a flat stone. During dry weather, a portion of the side walls
fell in; but the rubbish was quickly removed, though no repairs were
attempted till a shower of rain enabled them to work. As soon as this
occurred, they worked with extraordinary rapidity, and in a short time
the whole of the fallen parts were rebuilt, and rendered as smooth as
if polished with a trowel.
When a gardener wishes to water a plot of ground where he has sown
seeds that require nice management, he dips a strong brush into
water, and passes his hand backwards and forwards over the hairs for
the purpose of producing a fine artificial shower. Huber successfully
adopted the same method to excite his ants to recommence their labours,
which had been interrupted for want of moisture. But sometimes, when
they deem it unadvisable to wait for rain, they dig down (as we
remarked to be the practice of the mason-bees) till they arrive at
earth sufficiently moist for their purpose. They do not, however, like
these bees, merely dig for materials; for they use the excavations for
apartments, as well as what they construct with the materials thence
derived. They appear, in short, to be no less skilful in mining than in
building.
Such is the general outline of the operations of this singular species;
but we are still more interested with the history which M. P. Huber
has given of the labours of an individual ant. "One rainy day," he
says, "I observed a labourer of the dark ash-coloured species (_Formica
fusca_) digging the ground near the aperture which gave entrance to
the ant-hill. It placed in a heap the several fragments it had scraped
up, and formed them into small pellets, which it deposited here and
there upon the nest. It returned constantly to the same place, and
appeared to have a particular design, for it laboured with ardour and
perseverance. I remarked a slight furrow, excavated in the ground in a
straight line, representing the plan of a path or gallery. The labourer
(the whole of whose movements fell under my immediate observation) gave
it greater depth and breadth, and cleared out its borders; and I saw,
at length--in which I could not be deceived--that it had the intention
of establishing an avenue which was to lead from one of the stories
to the underground chambers. This path, which was about two or three
inches in length, and formed by a single ant, was opened above, and
bordered on each side by a buttress of earth. Its concavity, in the
form of a pipe (_gouttière_), was of the most perfect regularity: for
the architect had not left an atom too much. The work of this ant was
so well followed and understood, that I could almost to a certainty
guess its next proceeding, and the very fragment it was about to
remove. At the side of the opening where this path terminated was a
second opening, to which it was necessary to arrive by some road. The
same ant began and finished this undertaking without assistance. It
furrowed out and opened another path, parallel to the first, leaving
between each a little wall of three or four lines in height."
Like the hive-bees, ants do not seem to work in concert, but each
individual separately. There is, consequently, an occasional want of
coincidence in the walls and arches; but this does not much embarrass
them, for a worker, on discovering an error of this kind, seems to know
how to rectify it, as appears from the following observations:--
"A wall," says M. Huber, "had been erected, with the view of sustaining
a vaulted ceiling, still incomplete, that had been projected towards
the wall of the opposite chamber. The workman who began constructing
it had given it too little elevation to meet the opposite partition,
upon which it was to rest. Had it been continued on the original plan,
it must infallibly have met the wall at about one-half of its height;
and this it was necessary to avoid. This state of things very forcibly
claimed my attention; when one of the ants arriving at the place, and
visiting the works, appeared to be struck by the difficulty which
presented itself; but this it as soon obviated, by taking down the
ceiling, and raising the wall upon which it reposed. It then, in my
presence, constructed a new ceiling with the fragments of the former
one.
"When the ants commence any undertaking, one would suppose that they
worked after some preconceived idea, which, indeed, would seem verified
by the execution. Thus, should any ant discover upon the nest two
stalks of plants which lie crossways, a disposition favourable to
the construction of a lodge, or some little beams that may be useful
in forming its angles and sides, it examines the several parts with
attention; then distributes, with much sagacity and address, parcels
of earth in the spaces, and along the stems, taking from every quarter
materials adapted to its object, sometimes not caring to destroy the
work that others had commenced; so much are its motions regulated
by the idea it has conceived, and upon which it acts, with little
attention to all else around it. It goes and returns, until the plan is
sufficiently understood by its companions.
"In another part of the same ant-hill," continues M. Huber, "several
fragments of straw seemed expressly placed to form the roof of a large
house: a workman took advantage of this disposition. These fragments
lying horizontally, at half-an-inch distance from the ground, formed,
in crossing each other, an oblong parallelogram. The industrious insect
commenced by placing earth in the several angles of this framework,
and all along the little beams of which it was composed. The same
workman afterwards placed several rows of the same materials against
each other, when the roof became very distinct. On perceiving the
possibility of profiting by another plant to support a vertical wall,
it began laying the foundations of it; other ants having by this time
arrived, finished in common what this had commenced."[CX]
[Illustration]
M. Huber made most of his observations upon the processes followed by
ants in glazed artificial hives or formicaries. The preceding figure
represents a view of one of his formicaries of mason-ants.
We have ourselves followed up his observations, both on natural
ant-hills and in artificial formicaries. On digging cautiously into a
natural ant-hill, established upon the edge of a garden-walk, we were
enabled to obtain a pretty complete view of the interior structure.
There were two stories, composed of large chambers, irregularly oval,
communicating with each other by arched galleries, the walls of all
which were as smooth and well-polished as if they had been passed over
by a plasterer's trowel. The floors of the chambers, we remarked, were
by no means either horizontal or level, but all more or less sloped,
and exhibiting in each chamber at least two slight depressions of an
irregular shape. We left the under story of this nest untouched, with
the notion that the ants might repair the upper galleries, of which
we had made a vertical section; but instead of doing so they migrated
during the day to a large crack formed by the dryness of the weather,
about a yard from their old nest. (J. R.)
[Illustration]
We put a number of yellow ants (_Formica flava_), with their eggs
and cocoons, into a small glass frame, more than half full of moist
sand taken from their native hill, and placed in a sloping position,
in order to see whether they would bring the nearly vertical, and
therefore insecure, portion to a level by masonry. We were delighted to
perceive that they immediately resolved upon performing the task which
had been assigned them, though they did not proceed very methodically
in their manner of building; for instead of beginning at the bottom
and building upwards, many of them went on to add to the top of the
outer surface, which increased rather than diminished the insecurity
of the whole. Withal, however, they seemed to know how far to go, for
no portion of the newly-built wall fell; and in two days they had not
only reared a pyramidal mound to prop the rest, but had constructed
several galleries and chambers for lodging the cocoons, which we had
scattered at random amongst the sand. The new portion of this building
is represented in the figure as supporting the upper and insecure parts
of the nest.
[Illustration]
We are sorry to record that our ingenious little masons were found
upon the third day strewed about the outside of the building dead or
dying, either from over-fatigue or perhaps from surfeit, as we had
supplied them with as much honey as they could devour. A small colony
of turf-ants have at this moment (July 28th, 1829) taken possession of
the premises of their own accord. (J. R.)
_CHAPTER XV._
STRUCTURES OF THE WOOD-ANT OR PISMIRE, AND OF CARPENTER-ANTS.
The largest of our British ants is that called the Hill-ant by Gould,
the Fallow-ant by the English translator of Huber, and popularly
the Pismire; but which we think may be more appropriately named the
Wood-ant (_Formica rufa_, Latr.), from its invariable habit of living
in or near woods and forests. This insect may be readily distinguished
from other ants by the dusky black colour of its head and hinder
parts, and the rusty brown of its middle. The structures reared by
this species are often of considerable magnitude, and bear no small
resemblance to a rook's nest thrown upon the ground bottom upwards.
They occur in abundance in the woods near London, and in many other
parts of the country: in Oak of Honour Wood alone, we are acquainted
with the localities of at least two dozen,--some in the interior, and
others on the hedge-banks on the outskirts of the wood. (J. R.)
The exterior of the nest is composed of almost every transportable
material which the colonists can find in their vicinity; but the
greater portion consists of the stems of withered grass and short
twigs of trees, piled up in apparent confusion, but with sufficient
regularity to render the whole smooth, conical, and sloping towards
the base, for the purpose, we may infer, of carrying off rain-water.
When within reach of a corn-field, they often also pick up grains
of wheat, barley, or oats, and carry them to the nest as building
materials, and not for food, as was believed by the ancients. There
are wonders enough observable in the economy of ants, without having
recourse to fancy--wonders which made Aristotle extol the sagacity of
bloodless animals, and Cicero ascribe to them not only sensation, but
mind, reason, and memory.[CY] Ælian, however, describes, as if he had
actually witnessed it, the ants ascending a stalk of growing corn, and
throwing down "the ears which they bit off to their companions below."
Aldrovand assures us that he had seen their granaries; and others
pretend that they shrewdly bite off the ends of the grain to prevent it
from germinating.[CZ] These are fables which accurate observation has
satisfactorily contradicted.
[Illustration: Nest of Wood-Ant.]
But these errors, as it frequently happens, have contributed to a
more perfect knowledge of the insects than we might otherwise have
obtained; for it was the wish to prove or disprove the circumstance of
their storing up and feeding upon grain which led Gould to make his
observations on English ants; as the notion of insects being produced
_from_ putrid carcases had before led Redi to his ingenious experiments
on their generation. Yet, although it is more than eighty years since
Gould's book was published, we find the error still repeated in very
respectable publications.[DA]
The coping which we above described as forming the exterior of the
wood-ant's nest, is only a small portion of the structure, which
consists of a great number of interior chambers and galleries, with
funnel-shaped avenues leading to them. The coping, indeed, is one of
the most essential parts, and we cannot follow a more delightful guide
than the younger Huber in detailing its formation.
"The labourers," he says, "of which the colony is composed, not only
work continually on the outside of their nest, but, differing very
essentially from other species, who willingly remain in the interior,
sheltered from the sun, they prefer living in the open air, and do not
hesitate to carry on, even in our presence, the greater part of their
operations.
"To have an idea how the straw or stubble-roof is formed, let us take
a view of the ant-hill at its origin, when it is simply a cavity in
the earth. Some of its future inhabitants are seen wandering about
in search of materials fit for the exterior work, with which, though
rather irregularly, they cover up the entrance; whilst others are
employed in mixing the earth, thrown up in hollowing the interior,
with fragments of wood and leaves, which are every moment brought in
by their fellow-assistants; and this gives a certain consistence to
the edifice, which increases in size daily. Our little architects
leave here and there cavities, where they intend constructing the
galleries which are to lead to the exterior, and as they remove in
the morning the barriers placed at the entrance of their nest the
preceding evening, the passages are kept open during the whole time
of its construction. We soon observed the roof to become convex; but
we should be greatly deceived did we consider it solid. This roof is
destined to include many apartments or stories. Having observed the
motions of these little builders through a pane of glass, adjusted
against one of their habitations, I am thence enabled to speak with
some degree of certainty upon the manner in which they are constructed.
I ascertained that it is by excavating or mining the under portion of
their edifice that they form their spacious halls--low, indeed, and of
heavy construction, yet sufficiently convenient for the use to which
they are appropriated, that of receiving, at certain hours of the day,
the larvæ and pupæ.
"These halls have a free communication by galleries, made in the same
manner. If the materials of which the ant-hill is composed were only
interlaced, they would fall into a confused heap every time the ants
attempted to bring them into regular order. This, however, is obviated
by their tempering the earth with rain-water, which, afterwards
hardened in the sun, so completely and effectually binds together the
several substances, as to permit the removal of certain fragments
from the ant-hill without any injury to the rest; it, moreover,
strongly opposes the introduction of the rain. I never found, even
after long and violent rains, the interior of the nest wetted to more
than a quarter of an inch from the surface, provided it had not been
previously out of repair, or deserted by its inhabitants.
"The ants are extremely well sheltered in their chambers, the largest
of which is placed nearly in the centre of the building; it is much
loftier than the rest, and traversed only by the beams that support the
ceiling; it is in this spot that all the galleries terminate, and this
forms, for the most part, their usual residence.
"As to the underground portion, it can only be seen when the ant-hill
is placed against a declivity; all the interior may be then readily
brought in view, by simply raising up the straw roof. The subterranean
residence consists of a range of apartments, excavated in the earth,
taking an horizontal direction."[DB]
[It seems rather surprising that the wood-ants should be able, with
such materials as they employ, to make a dome-shaped structure, which
shall be furnished with cells and galleries, and yet shall endure rain
and wind, without being penetrated by the one or blown away by the
other. If the hill be closely examined, the little sticks of which it
is composed will be seen to have a definite, though not very regular
arrangement; and it is a noteworthy circumstance that the longest
are preserved for the galleries, being laid across each other in a
very ingenious manner, so as to prevent the material from falling and
filling up the galleries. This structure was shown very clearly in a
huge ant-hill in Bagshot Park. We introduced a sheet of plate glass
into the nest, so as to divide it perpendicularly into two halves, and
having given the insects six weeks to repair damages, we removed one
half of the hill, so that the whole interior of the other half could
be seen through the glass. The whole economy of the nest was thus made
clear, and the artificial arrangement of the materials showed itself
very plainly on the roofs of the cells and galleries.]
[Illustration]
M. P. Huber, in order to observe the operations of the wood-ant
with more attention, transferred colonies of them to his artificial
formicaries, plunging the feet of the stand into water to prevent their
escape till they were reconciled to their abode, and had made some
progress in repairing it.
[Under the glass shade on the top of the formicary may be seen the
mound which the wood-ants have raised, according to their custom, and
below, through the glass front, the reader may see the various passages
and cells which communicate with the hill above. As the ants require
that the lower part of their dwelling should be in darkness, a stout
wooden door can be shut over the glass to exclude the light.]
There is this remarkable difference in the nest of the wood-ants, that
they do not construct a long covert way as if for concealment, as
the yellow and the brown ants do. The wood-ants are not, like them,
afraid of being surprised by enemies, at least during the day, when
the whole colony is either foraging in the vicinity or employed on the
exterior. But the proceedings of the wood-ants at night are well worthy
of notice; and when M. Huber began to study their economy, he directed
his entire attention to their night proceedings. "I remarked," says
he, "that their habitations changed in appearance hourly, and that the
diameter of those spacious avenues, where so many ants could freely
pass each other during the day, was, as night approached, gradually
lessened. The aperture, at length, totally disappeared, the dome was
closed on all sides, and the ants retired to the bottom of their nest.
"In further noticing the apertures of these ant-hills, I fully
ascertained the nature of the labour of its inhabitants, of which I
could not before even guess the purport; for the surface of the nest
presented such a constant scene of agitation, and so many insects were
occupied in carrying materials in every direction, that the movement
offered no other image than that of confusion.
"I saw then clearly that they were engaged in stopping up passages; and
for this purpose they at first brought forward little pieces of wood,
which they deposited near the entrance of those avenues they wished to
close; they placed them in the stubble; they then went to seek other
twigs and fragments of wood, which they disposed above the first, but
in a different direction, and appeared to choose pieces of less size in
proportion as the work advanced. They, at length, brought in a number
of dried leaves, and other materials of an enlarged form, with which
they covered the roof: an exact miniature of the art of our builders,
when they form the covering of any building. Nature, indeed, seems
everywhere to have anticipated the inventions of which we boast, and
this is doubtless one of the most simple.
"Our little insects, now in safety in their nest, retire gradually
to the interior before the last passages are closed; one or two only
remain without, or concealed behind the doors on guard, while the
rest either take their repose, or engage in different occupations in
the most perfect security. I was impatient to know what took place in
the morning upon these ant-hills, and therefore visited them at an
early hour. I found them in the same state in which I had left them
the preceding evening. A few ants were wandering about on the surface
of the nest, some others issued from time to time from under the
margin of their little roofs formed at the entrance of the galleries;
others afterwards came forth, who began removing the wooden bars that
blockaded the entrance, in which they readily succeeded. This labour
occupied them several hours. The passages were at length free, and the
materials with which they had been closed scattered here and there over
the ant-hill. Every day, morning and evening, during the fine weather,
I was a witness to similar proceedings. On days of rain the doors of
all the ant-hills remained closed. When the sky was cloudy in the
morning, or rain was indicated, the ants, who seemed to be aware of it,
opened but in part their several avenues, and immediately closed them
when the rain commenced."[DC]
The galleries and chambers which are roofed in as thus described are
very similar to those of the mason-ants, being partly excavated in the
earth, and partly built with the clay thence procured. It is in these
they pass the night, and also the colder months of the winter, when
they become torpid, or nearly so, and of course require not the winter
granaries of corn with which the ancients fabulously furnished them.
Carpenter-Ants.
The ants that work in wood perform much more extensive operations
than any of the other carpenter insects which we have mentioned.
Their only tools, like those of bees and wasps, are their jaws or
mandibles; but though these may not appear so curiously constructed as
the ovipositor file of the tree-hopper (_Cicada_), or the rasp and saw
of the saw-flies (_Tenthredinidæ_), they are no less efficient in the
performance of what is required. Among the carpenter-ants, the emmet or
jet-ant (_F. fuliginosa_) holds the first rank, and is easily known by
being rather less in size than the wood-ant, and by its fine shining
black colour. It is less common in Britain than some of the preceding,
though its colonies may occasionally be met with in the trunks of
decaying oak or willow trees in hedges.
"The labourers," says Huber, "of this species work always in the
interior of trees, and are desirous of being screened from observation:
thus every hope on our part is precluded of following them in their
several occupations. I tried every expedient I could devise to surmount
this difficulty; I endeavoured to accustom these ants to live and work
under my inspection, but all my efforts were unsuccessful; they even
abandoned the most considerable portion of their nest to seek some
new asylum, and spurned the honey and sugar which I offered them for
nourishment. I was now, by necessity, limited to the inspection only of
their edifices: but, by decomposing some of the fragments with care, I
hoped to acquire some knowledge of their organization.
"On one side I found horizontal galleries, hidden in great part by
their walls, which follow the circular direction of the layers of the
wood; and on another, parallel galleries, separated by extremely thin
partitions, having no communication except by a few oval apertures.
Such is the nature of these works, remarkable for their delicacy and
lightness.
"In other fragments I found avenues which opened laterally, including
portions of walls and transverse partitions, erected here and there
within the galleries, so as to form separate chambers. When the work
is further advanced, round holes are always observed, encased, as
it were, between two pillars cut out in the same wall. These holes
in course of time become square, and the pillars, originally arched
at both ends, are worked into regular columns by the chisel of our
sculptors. This, then, is the second specimen of their art. This
portion of the edifice will probably remain in this state.
"But in another quarter are fragments differently wrought, in which
these same partitions, pierced now in every part, and hewn skilfully,
are transformed into colonnades, which sustain the upper stories, and
leave a free communication throughout the whole extent. It can readily
be perceived how parallel galleries, hollowed out upon the same plan,
and the sides taken down, leaving only from space to space what is
necessary to sustain their ceilings, may form an entire story; but as
each has been pierced separately, the flooring cannot be very level:
this, however, the ants turn to their advantage, since these furrows
are better adapted to retain the larvæ that may be placed there.
[Illustration: Portion of a Tree, with Chambers and Galleries chiseled
out by Jet-Ants.]
"The stories constructed in the great roots offer greater irregularity
than those in the very body of the tree, arising either from the
hardness and interlacing of the fibres, which renders the labour more
difficult, and obliges the labourers to depart from their accustomed
manner, or from their not observing in the extremities of their edifice
the same arrangement as in the centre: whatever it be, horizontal
stories and numerous partitions are still found. If the work be less
regular, it becomes more delicate; for the ants, profiting by the
hardness and solidity of the materials, give to their building an
extreme degree of lightness. I have seen fragments of from eight to
ten inches in length, and of equal height, formed of wood as thin
as paper, containing a number of apartments, and presenting a most
singular appearance. At the entrance of these apartments, worked out
with so much care, are very considerable openings; but in place of
chambers and extensive galleries, the layers of the wood are hewn in
arcades, allowing the ants a free passage in every direction. These
may be regarded as the gates or vestibules conducting to the several
lodges."[DD]
It is a singular circumstance in the structures of these ants, that all
the wood which they carve is tinged of a black colour, as if it were
smoked; and M. Huber was not a little solicitous to discover whence
this arose. It certainly does not add to the beauty of their streets,
which look as sombre as the most smoke-dyed walls in the older lanes
of the metropolis. M. Huber could not satisfy himself whether it was
caused by the exposure of the wood to the atmosphere, by some emanation
from the ants, or by the thin layers of wood being acted upon or
decomposed by the formic acid.[DE] But if any or all of these causes
operated in blackening the wood, we should be ready to anticipate a
similar effect in the case of other species of ants which inhabit
trees; yet the black tint is only found in the excavations of the
jet-ant.
We are acquainted with several colonies of the jet-ants (_Formica
fuliginosa_)--one of which, in the roots and trunk of an oak on the
road from Lewisham to Sydenham, near Brockley, in Kent, is so extremely
populous, that the numbers of its inhabitants appeared to us beyond any
reasonable estimate. None of the other colonies of this species which
we have seen appear to contain many hundreds. On cutting into the root
of the before-mentioned tree, we found the vertical excavations of much
larger dimensions, both in width and depth, than those represented by
Huber in the preceding cut (page 302). What surprised us the most was
to see the tree growing vigorously and fresh, though its roots were
chiseled in all directions by legions of workers, while every leaf, and
every inch of the bark, was also crowded by parties of foragers. On
one of the low branches we found a deserted nest of the white-throat
(_Sylvia cinerea_, Temminck), in the cavity of which they were piled
upon one another as close as the unhappy negroes in the hold of a
slave-ship; but we could not discover what had attracted them hither.
Another dense group, collected on one of the branches, led us to the
discovery of a very singular oak gall, formed on the bark in the shape
of a pointed cone, and crowded together. It is probable that the juice
which they extracted from these galls was much to their taste. (J. R.)
[Illustration: F. fuliginosa.]
Beside the jet-ant, several other species exercise the art of
carpentry,--nay, what is more wonderful still, they have the ingenuity
to knead up, with spider's-web for a cement, the chips which they
chisel out into a material with which they construct entire chambers.
The species which exercise this singular art are the Ethiopian
(_Formica nigra_) and the yellow ant (_F. flava_).[DF]
We once observed the dusky ants (_F. fusca_) at Blackheath, in Kent,
busily employed in carrying out chips from the interior of a decaying
black poplar, at the root of which a colony was established; but,
though it thence appears that this species can chisel wood if they
choose, yet they usually burrow in the earth, and by preference, as we
have remarked, at the root of a tree, the leaves of which supply them
with food.
* * * * *
Among the foreign ants we may mention a small yellow ant of South
America, described by Dampier, which seems, from his account, to
construct a nest of green leaves. "Their sting," he says, "is like
a spark of fire; and they are so thick among the boughs in some
places, that one shall be covered with them before he is aware. These
creatures have nests on great trees, placed on the body between the
limbs: some of their nests are as big as a hogshead. This is their
winter habitation; for in the wet season they all repair to these their
cities, where they preserve their eggs. In the dry season, when they
leave their nests, they swarm all over the woodlands, for they never
trouble the savannahs. Great paths, three or four inches broad, made by
them, may be seen in the woods. They go out light, but bring home heavy
loads on their backs, all of the same substance, and equal in size. I
never observed anything besides pieces of green leaves, so big that I
could scarcely see the insect for his burthen; yet they would march
stoutly, and so many were pressing forward that it was a very pretty
sight, for the path looked perfectly green with them."
Ants observed in New South Wales, by the gentlemen in the expedition
under Captain Cook, are still more interesting. "Some," we are told,
"are as green as a leaf, and live upon trees, where they build their
nests of various sizes, between that of a man's head and his fist.
These nests are of a very curious structure: they are formed by bending
down several of the leaves, each of which is as broad as a man's hand,
and gluing the points of them together, so as to form a purse. The
viscous matter used for this purpose is an animal juice which nature
has enabled them to elaborate. Their method of first bending down the
leaves we had no opportunity to observe; but we saw thousands uniting
all their strength to hold them in this position, while other busy
multitudes were employed within in applying this gluten that was to
prevent their returning back. To satisfy ourselves that the leaves
were bent and held down by the efforts of these diminutive artificers,
we disturbed them in their work; and as soon as they were driven from
their stations, the leaves on which they were employed sprang up with
a force much greater than we could have thought them able to conquer
by any combination of their strength. But, though we gratified our
curiosity at their expense, the injury did not go unrevenged; for
thousands immediately threw themselves upon us, and gave us intolerable
pain with their stings, especially those which took possession of our
necks and hair, from whence they were not easily driven. Their sting
was scarcely less painful than that of a bee; but, except it was
repeated, the pain did not last more than a minute.
"Another sort are quite black, and their operation and manner of life
are not less extraordinary. Their habitations are the inside of the
branches of a tree, which they contrive to excavate by working out
the pith almost to the extremity of the slenderest twig, the tree at
the same time flourishing as if it had no such inmate. When we first
found the tree we gathered some of the branches, and were scarcely
less astonished than we should have been to find that we had profaned
a consecrated grove, where every tree, upon being wounded, gave signs
of life; for we were instantly covered with legions of these animals,
swarming from every broken bough, and inflicting their stings with
incessant violence.
"A third kind we found nested in the root of a plant, which grows
on the bark of trees in the manner of mistletoe, and which they
had perforated for that use. This root is commonly as big as a
large turnip, and sometimes much bigger. When we cut it we found it
intersected by innumerable winding passages, all filled with these
animals, by which, however, the vegetation of the plant did not appear
to have suffered any injury. We never cut one of these roots that
was not inhabited, though some were not bigger than a hazel-nut. The
animals themselves are very small, not more than half as big as the
common red ant in England. They had stings, but scarcely force enough
to make them felt: they had, however, a power of tormenting us in an
equal, if not in a greater degree; for the moment we handled the root,
they swarmed from innumerable holes, and running about those parts of
the body that were uncovered, produced a titillation more intolerable
than pain, except it is increased to great violence."[DG]
The species called sugar-ants in the West Indies are particularly
destructive to the sugar-cane, as well as to lime, lemon, and
orange-trees, by excavating their nests at the roots, and so loosening
the earth that they are frequently uprooted and blown down by the
winds. If this does not happen, the roots are deprived of due
nourishment, and the plants become sickly and die.[DH]
[One or two examples of foreign ants are well worthy of notice. The
first of them is an insect whose habits bear strongly upon the familiar
passage in Proverbs, ch. vi. v. 6:--
"Go to the ant, thou sluggard; consider her ways, and be wise:
Which having no guide, overseer, or ruler,
Provideth her meat in the summer, and gathereth her food in the harvest."
This passage is one that has been often mentioned as a proof that the
Bible is not to be implicitly trusted. Judging from all the species of
ants known to entomologists, some writers argue that the author of the
proverb in question was ignorant of the real history of the ant, and
was taking up a popular fallacy.
[Still, although the ants of the old world are chiefly carnivorous, or
feed on soft substances, and in consequence have not the least idea
of hoarding food for the winter, there is one species of Brazilian
ant which absolutely builds houses, prepares ground, sows seed, reaps
the grain, and stores it away for future consumption. It is the
Agricultural Ant, _Atta malefaciens_, first described by Dr. Lincecum,
who watched the insect for twelve years before publishing an account
that he knew would at first be received with incredulity. The following
abstract of his paper appeared in the Journal of the Linnæan Society.
"The species which I have named 'Agricultural' is a large brownish
ant. It dwells in what may be termed paved cities, and like a thrifty,
diligent, provident farmer, makes suitable and timely arrangements for
the changing seasons. It is, in short, endowed with skill, ingenuity,
and untiring patience, sufficient to enable it successfully to contend
with the varying exigencies which it may have to encounter in the life
conflict.
"When it has selected a situation for its habitation, if on ordinary
dry ground, it bores a hole, around which it raises the surface three
and sometimes six inches, forming a low circular mound, having a very
gentle inclination from the centre to the outer border, which on an
average is three or four feet from the entrance. But if the location is
chosen on low, flat, wet land, liable to inundation, though the ground
may be perfectly dry at the time the ant sets to work, it nevertheless
elevates the mound, in the form of a pretty sharp cone, to the height
of fifteen or twenty inches or more, and makes the entrance near the
summit. Around the mound, in either case, the ant clears the ground
of all obstructions, and levels and marks the surface to the distance
of three or four feet from the gate of the city, giving the space the
appearance of a handsome pavement, as it really is.
"Within this paved area not a blade of any green thing is allowed to
grow, except a single species of grain-bearing grass. Having planted
this crop in a circle around, and two or three feet from the centre
of the mound, the insect tends and cultivates it with constant care,
cutting away all other grasses and weeds that may spring up amongst it,
and all around outside the farm circle to the extent of one or two feet
more. The cultivated grass grows luxuriantly, and produces a heavy crop
of small, white, flinty seeds, which under the microscope very closely
resemble ordinary rice. When ripe, it is carefully harvested and
carried by the workers, chaff and all, into the granary cells, where it
is divested of the chaff and packed away. The chaff is taken out and
thrown beyond the limits of the paved area.
"During protracted wet weather it sometimes happens that the
provision-stores become damp, and are liable to sprout and spoil. In
this case, on the first fine day, the ants bring out the damp and
damaged grain, and expose it to the sun till it is dry, when they carry
it back and pack away all the sound seeds, leaving those that had
sprouted to waste.
"In a peach orchard not far from my house is a considerable elevation,
on which is an extensive bed of rock. In the sand-beds overlying
portions of this rock are five cities of the agricultural ants,
evidently very ancient. My observations on their manners and customs
have been limited to the last twelve years, during which time the
inclosure surrounding the orchard has prevented the approach of cattle
to the ant-farms. The cities which are outside the inclosure, as well
as those protected in it, are at the proper season invariably planted
with the ant-rice. The crop may accordingly always be seen springing up
within the circle about the 1st of November every year. Of late years,
however, since the number of farms and cattle has greatly increased,
and the latter are eating off the grass much closer than formerly, thus
preventing the ripening of the seeds, I notice that the agricultural
ant is placing its cities along the turn-rows in the fields, walks in
gardens, inside about the gates, &c., where they can cultivate their
farms without molestation from the cattle.
"There can be no doubt that the particular species of grain-bearing
grass mentioned above is intentionally planted. In farmer-like manner
the ground upon which it stands is carefully divested of all other
grasses and weeds during the time it is growing. When it is ripe, the
grain is taken care of, the dry stubble cut away and carried off, the
paved area being left unencumbered until the ensuing autumn, when the
same ant-rice reappears within the same circle, and receives the same
agricultural attention as was bestowed upon the previous crop--and so
on, year after year, as I _know_ to be the case, in all situations
where the ants' settlements are protected from granivorous animals."
This interesting account is simply the result of twelve years' patient
investigation on the part of Dr. Lincecum, who took special care not to
invent a theory and to twist facts in accordance with it, but watched
the entire proceedings of the insects for a series of years.
[Illustration: Crematogaster.]
The preceding illustration represents the rather remarkable nest of
an Australian ant, belonging to the genus Crematogaster. This word
signifies "hanging-belly," and the name has been applied to the ant in
consequence of the manner in which its abdomen is held up in the air,
so that it overhangs the back.
As may be seen, the nest is of considerable size, and might from its
external appearance be mistaken for that of a wasp. The interior of it,
however, is even more elaborate, being full of little covered passages
interlacing with each other in a most intricate manner, but all leading
to the internal galleries.
The two nests which are shown in the next illustration are, if
possible, still more remarkable.
[Illustration]
The upper one is found in Cayenne, and is made by an insect called the
fungus ant (_Polyrachis bispinosa_), because the nest looks as if it
were made of fungus. It is not, however, composed of that material,
but of the fibre of the cotton-tree (_Bombax ceiba_).
The fibre is in itself very short, barely exceeding an inch in length,
but it is cut very much shorter by the ant, who contrives to felt it
together in a most curious manner, so that it is hardly possible to
trace the course of any one fibre. The size of the nest is, on an
average, about eight or nine inches in diameter. The insect itself is
given in the preceding illustration, but very much enlarged. If the
reader will look at the centre of the body, he will see the projections
which have given it the name of _bispinosa_, or two-spined.
The lower figure represents the nest of another species of ant
belonging to the same genus, and called scientifically, _Polyrachis
textor_. The nest is most ingeniously made of little pieces of wood and
tendrils, put together so as to form a kind of open net-work, through
which the interior of the nest is plainly visible. This insect inhabits
Malacca.]
_CHAPTER XVI_.
STRUCTURES OF WHITE ANTS, OR TERMITES.
When we look back upon the details which we have given of the industry
and ingenuity of numerous tribes of insects, both solitary and social,
we are induced to think it almost impossible that they could be
surpassed. The structures of wasps and bees, and still more those of
the wood-ant (_Formica rufa_), when placed in comparison with the size
of the insects, equal our largest cities compared with the stature
of man. But when we look at the buildings erected by the white ants
of tropical climates, all that we have been surveying dwindles into
insignificance. Their industry appears greatly to surpass that of our
ants and bees, and they are certainly more skilful in architectural
contrivances. The elevation, also, of their edifices is more than
five hundred times the height of the builders. Were our houses built
according to the same proportions, they would be twelve or fifteen
times higher than the London Monument, and four or five times higher
than the pyramids of Egypt, with corresponding dimensions in the
basements of the edifices. These statements are, perhaps, necessary to
impress the extraordinary labours of ants upon the mind; for we are
all more or less sensible to the force of comparisons. The analogies
between the works of insects and of men are not perfect; for insects
are all provided with instruments peculiarly adapted to the end which
they instinctively seek, while man has to form a plan by progressive
thought, and upon the experience of others, and to complete it with
tools which he also invents.
The termites do not stand above a quarter of an inch high, while their
nests are frequently twelve feet, and Jobson mentions some which he had
seen as high as twenty feet; "of compass," he adds, "to contain a dozen
men, with the heat of the sun baked into that hardness, that we used
to hide ourselves in the ragged tops of them when we took up stands to
shoot at deer or wild beasts."[DI] Bishop Heber saw a number of these
high ant-hills in India, near the principal entrance of the Sooty or
Moorshedabad river. "Many of them," he says, "were five or six feet
high, and probably seven or eight feet in circumference at the base,
partially overgrown with grass and ivy, and looking at a distance like
the stumps of decayed trees. I think it is Ctesias, among the Greek
writers, who gives an account alluded to by Lucian in his 'Cock,' of
monstrous ants in India, as large as foxes. The falsehood probably
originated in the stupendous fabrics which they rear here, and which
certainly might be supposed to be the work of a much larger animal
than their real architect."[DJ] Herodotus has a similar fable of the
enormous size and brilliant appearance of the ants of India.
Nor is it only in constructing dwellings for themselves that the
termites of Africa and of other hot climates employ their masonic
skill. Though, like our ants and wasps, they are almost omnivorous, yet
wood, particularly when felled and dry, seems their favourite article
of food; but they have an utter aversion to feeding in the light, and
always eat their way with all expedition to the interior. It thence
would seem necessary for them either to leave the bark of a tree, or
the outer portion of the beam or door of a house, undevoured, or to eat
in open day. They do neither; but are at the trouble of constructing
galleries of clay, in which they can conceal themselves, and feed in
security. In all their foraging excursions, indeed, they build covert
ways, by which they can go out and return to their encampment.[DK]
Others of the species (for there are several), instead of building
galleries, exercise the art of miners, and make their approaches under
ground, penetrating beneath the foundation of houses or areas, and
rising again either through the floors, or by entering the bottom of
the posts that support the building, when they follow the course of
the fibres, and make their way to the top, boring holes and cavities
in different places as they proceed. Multitudes enter the roof, and
intersect it with pipes or galleries, formed of wet clay, which serve
for passages in all directions, and enable them more readily to fix
their habitations in it. They prefer the softer woods, such as pine
and fir, which they hollow out with such nicety, that they leave the
surface whole, after having eaten away the inside. A shelf or plank
attacked in this manner looks solid to the eye, when, if weighed, it
will not out-balance two sheets of pasteboard of the same dimensions.
It sometimes happens that they carry this operation so far on stakes
in the open air, as to render the bark too flexible for their purpose;
when they remedy the defect by plastering the whole stick with a sort
of mortar which they make with clay, so that, on being struck, the form
vanishes, and the artificial covering falls in fragments on the ground.
In the woods, when a large tree falls from age or accident, they enter
it on the side next the ground, and devour it at leisure, till little
more than the bark is left. But in this case they take no precaution of
strengthening the outward defence, but leave it in such a state as to
deceive an eye unaccustomed to see trees thus gutted of their insides:
and "you may as well," says Mr. Smeathman, "step upon a cloud." It is
an extraordinary fact, that when these creatures have formed pipes in
the roof of a house, instinct directs them to prevent its fall, which
would ensue from their having sapped the posts on which it rests; but
as they gnaw away the wood, they fill up the interstices with clay,
tempered to a surprising degree of hardness, so that, when the house
is pulled down, these posts are transformed from wood to stone. They
make the walls of their galleries of the same composition as their
nests, varying the materials according to their kind; one species using
the red clay, another black clay, and the third a woody substance,
cemented with gums, as a security from the attacks of their enemies,
particularly the common ant, which, being defended by a strong, horny
shell, is more than a match for them, and when it can get at them,
rapaciously seizes them, and drags them to its nest for food for its
young brood. If any accident breaks down part of their walls, they
repair the breach with all speed. Instinct guides them to perform their
office in the creation, by mostly confining their attacks to trees that
are beginning to decay, or such timber as has been severed from its
roots for use, and would decay in time. Vigorous, healthy trees do not
require to be destroyed, and accordingly, these consumers have no taste
for them.[DL]
M. Adanson describes the termites of Senegal as constructing covert
ways along the surface of wood which they intend to attack; but though
we have no reason to distrust so excellent a naturalist, in describing
what he saw, it is certain that they more commonly eat their way into
the interior of the wood, and afterwards form the galleries, when they
find that they have destroyed the wood till it will no longer afford
them protection.
But it is time that we should come to their principal building, which
may, with some propriety, be called a city; and, according to the
method we have followed in other instances, we shall trace their
labours from the commencement. We shall begin with the operations of
the species which may be appropriately termed the Warrior (_Termes
fatalis_, Linn.; _T. bellicosus_, Smeath.).
We must premise, that though they have been termed white _ants_, they
do not belong to the same order of insects with our ants; yet they
have a slight resemblance to ants in their form, but more in their
economy. Smeathman, to whom we owe our chief knowledge of the genus,
describes them as consisting of kings, queens, soldiers, and workers,
and is of opinion that the workers are larvæ, the soldiers nymphæ, and
the kings and queens the perfect insects. In this opinion he coincides
with Sparrmann[DM] and others; but Latreille is inclined to think,
from what he observed in a European species (_Termes lucifugus_) found
near Bordeaux, that the soldiers form a distinct race, like the neuter
workers among bees and ants, while the working termites are larvæ,[DN]
which are furnished with strong mandibles for gnawing; when they become
nymphs, the rudiments of four wings appear, which are fully developed
in the perfect insects.
[Illustration: Termes bellicosus in the winged state.]
[It is now known that the differences of form among the termites are
accounted for as follows. The winged specimens are the fully developed
males and females, popularly called kings and queens. These crawl to
the aperture of their house and take flight, retiring to earth after
a short time. When a male and female meet each other, they cast off
their wings exactly as do the ants of our own country, and become the
founders of a new colony. Their soldiers are undeveloped males, and the
workers are undeveloped females.]
In the winged state, they migrate to form new colonies, but the greater
number of them perish in a few hours, or become the prey of birds, and
even of the natives, who fry them as delicacies. "I have discoursed
with several gentlemen," says Smeathman, "upon the taste of the white
ants, and on comparing notes, we have always agreed that they are most
delicious and delicate eating. One gentleman compared them to sugared
marrow, another to sugared cream and a paste of sweet almonds."[DO]
Mr. Smeathman's very interesting paper affords us the most authentic
materials for the further description of these wonderful insects; and
we therefore continue partly to extract from, and partly to abridge,
his account.
The few pairs that are so fortunate as to survive the various
casualties that assail them, are usually found by workers (larvæ),
which, at this season, are running continually on the surface of the
ground, on the watch for them. As soon as they discover the objects
of their search, they begin to protect them from their surrounding
enemies, by inclosing them in a small chamber of clay, where they
become the parents of a new community, and are distinguished from the
other inhabitants of the nest by the title of king and queen. Instinct
directs the attention of these labouring insects to the preservation
of their race, in the protection of this pair and their offspring.
The chamber that forms the rudiment of a new nest is contrived for
their safety, but the entrances to it are too small to admit of their
ever leaving it; consequently, the charge of the eggs devolves upon
the labourers, who construct nurseries for their reception. These are
small, irregularly-shaped chambers, placed at first round the apartment
of the king and queen, and not exceeding the size of a hazel-nut; but
in nests of long standing they are of great comparative magnitude, and
distributed at a greater distance. The receptacles for hatching the
young are all composed of wooden materials, apparently joined together
with gum, and, by way of defence, cased with clay. The chamber that
contains the king and queen is nearly on a level with the surface of
the ground; and as the other apartments are formed about it, it is
generally situated at an equal distance from the sides of the nest,
and directly beneath its conical point. Those apartments which consist
of nurseries and magazines of provisions, form an intricate labyrinth,
being separated by small, empty chambers and galleries, which surround
them, or afford a communication from one to another. This labyrinth
extends on all sides to the outward shells, and reaches up within it
to two-thirds or more of its height, leaving an open area above, in
the middle, under the dome, which reminds the spectator of the nave of
an old cathedral. Around this are raised three or four large arches,
which are sometimes two or three feet high, next the front of the area,
but diminish as they recede further back, and are lost amidst the
innumerable chambers and nurseries behind them.
Every one of these buildings consists of two distinct parts, the
exterior and the interior. The exterior is one large shell, in the
manner of a dome, large and strong enough to inclose and shelter the
interior from the vicissitudes of the weather, and the inhabitants from
the attacks of natural or accidental enemies. It is always, therefore,
much stronger than the interior building, which is the habitable part,
divided, with a wonderful kind of regularity and contrivance, into an
amazing number of apartments for the residence of the king and queen,
and the nursing of the numerous progeny; or for magazines, which are
always found well filled with stores and provisions. The hills make
their first appearance above ground by a little turret or two, in the
shape of sugar-loaves, which are run a foot high or more. Soon after,
at some little distance, while the former are increasing in height and
size, they raise others, and so go on increasing their number, and
widening them at the base, till their works below are covered with
these turrets, of which they always raise the highest and largest
in the middle, and by filling up the intervals between each turret,
collect them into one dome. They are not very curious or exact in the
workmanship, except in making them very solid and strong; and when,
by their joining them, the dome is completed, for which purpose the
turrets answer as scaffolds, they take away the middle ones entirely,
except the tops, which, joined together, make the crown of the cupola,
and apply the clay to the building of the works within, or to erecting
fresh turrets for the purpose of raising the hillock still higher; so
that some part of the clay is probably used several times, like the
boards and posts of a mason's scaffold.
When these hills are little more than half their height, it is a common
practice of the wild bulls to stand as sentinels on them, while the
rest of the herd are ruminating below. They are sufficiently strong
for that purpose, and at their full height answer excellently well as
places of look-out; and Mr. Smeathman has been, with four more, on
the top of one of these hillocks, to watch for a vessel in sight. The
outward shell, or dome, is not only of use to protect and support the
interior buildings from external violence and the heavy rains, but
to collect and preserve a regular degree of the warmth and moisture
necessary for hatching the eggs and cherishing the young. The royal
chamber occupied by the king and queen appears to be, in the opinion
of this little people, of the most consequence, being always situated
as near the centre of the interior building as possible. It is always
nearly in the shape of half an egg, or an obtuse oval, within, and may
be supposed to represent a long oven. In the infant state of the colony
it is but about an inch in length; but in time will be increased to
six or eight inches, or more, in the clear, being always in proportion
to the size of the queen, who, increasing in bulk as in age, at length
requires a chamber of such dimensions.
[Illustration: Queen distended with Eggs.]
Its floor is perfectly horizontal, and in large hillocks, sometimes
more than an inch thick of solid clay. The roof, also, which is one
solid and well-turned oval arch, is generally of about the same
solidity; but in some places it is not a quarter of an inch thick on
the sides where it joins the floor, and where the doors or entrances
are made level with it, at nearly equal distances from each other.
These entrances will not admit any animal larger than the soldiers or
labourers; so that the king and the queen (who is, at full size, a
thousand times the weight of a king) can never possibly go out, but
remain close prisoners.