Geographical position of Santo Domingo.
Physical geography.
The inhabitants.
Mixed races.
Negroes and Indians compared.
Women.
Establishment of the Chontales Gold-Mining Company.
My house and garden.
Fruits.
Plantains and bananas; probably not indigenous to America:
propagated from shoots: do not generally mature their seeds.
Fig-trees.
Granadillas and papaws.
Vegetables.
Dependence of flowers on insects for their fertilisation.
Insect plagues.
Leaf-cutting ants: their method of defoliating trees: their nests.
Some trees are not touched by the ants.
Foreign trees are very subject to their attack.
Method of destroying the ants.
Migration of the ants from a nest attacked.
Corrosive sublimate causes a sort of madness amongst them.
Indian plan of preventing them ascending young trees.
Leaf-cutting ants are fungus-growers and eaters.
Sagacity of the ants.
The gold-mining village of Santo Domingo is situated in the
province of Chontales, Nicaragua, in latitude 12 degrees 16
minutes north and longitude 84 degrees 59 minutes west, nearly
midway between the Atlantic and the Pacific, where Central America
begins to widen out northward of the narrow isthmus of Panama and
Costa Rica. It is in the midst of the great forest that covers most
of the Atlantic slope of Central America, and which continues
unbroken from where we had entered it, at Pital, eastward to the
Atlantic; westward it terminates in a sinuous margin about seven
miles from the village, and there commence the lightly timbered and
grassy plains and savannahs stretching to the Lake of Nicaragua.
The surface of the land in the forest region forms a succession of
ranges and steep valleys, covered with magnificent timber and much
undergrowth. Santo Domingo lies about 2000 feet above the level of
the sea, and the hills around it rise from 500 to 1000 feet higher.
It is built in the bend of a small stream, the head waters of a
branch of the Blewfields river, on a level, low piece of ground,
with the brook winding almost round it, and, beyond that, encircled
by an amphitheatre of low hills in the hollow of which it lies. The
road to the mines runs through it, and forms the main street,
having on each side thatched stores and irregularly built houses.
The inhabitants, about three hundred in number, are entirely
dependent on the mines around, there being no cultivation or any
other employment in the immediate neighbourhood. The people are of
a mixed descent, in which Indian blood predominates, then Spanish
with a slight admixture of the Negro element, whilst amongst the
rising generation many fair-haired children can claim paternity
amongst the numerous German and English workmen that have been
employed at the mines. The store-keepers form the aristocracy of
the village. They are indolent; lounging about, or lying smoking in
their hammocks the greater part of the day, but generally civil and
polite. They are particular in their dress, and may often be seen
in faultless European costume, silk umbrella in hand, in twos or
threes, taking a short quiet walk up the valley. The lower class of
miners are scantily and badly clothed, especially when they come
first to the mines. They are bare-footed, with poor ragged cotton
trousers and a thin jacket of the same material. Generally, after
being a year or two at the mines, they begin to wear better
clothing, and may often be seen with a new shirt, which to show off
is worn hanging down outside, like a surtout coat. Amongst these
are many pure Indians, short sturdy men, who make the steadiest
workmen, patient and industrious, but with little appreciation of
the value of money, and spending the whole of their wages at the
end of the month, before they resume work. At these times the
commandant comes in from the town of Libertad, about nine miles
distant, with half-a-dozen bare-footed soldiers carrying old
muskets on their shoulders, and levies blackmail upon the poor
patient "Mosas," as they are called, in the shape of a fine for
drunkenness. But the "aguardiente," a native-made rum, is
nevertheless always kept on hand, being a government monopoly, and
ever ready, so that the Mosas may have no excuse to be sober and
escape being fined.
Even in their drink the poor Indians are not very violent, and get
intoxicated with surprising stolidity and quietness. Amongst the
half-breeds, especially where the Negro element exists, there are
often quarrellings and rows, when they slash away at each other
with their long knives or "machetes," and get ugly cuts, which,
however, heal again quickly.
Both the Negroes and Indians are decidedly inferior to the whites
in intellect, but they do not differ so much from the Europeans as
they do from each other. The Negro will work hard for a short
while, on rare occasions, or when compelled by another, but is
innately lazy. The Indian is industrious by nature, and works
steadily and well for himself; but if compelled to work for
another, loses all heart, and pines away and dies. The Negro is
talkative, vivacious, vain, and sensual; the Indian taciturn,
stolid, dignified, and moderate. As freemen, regularly though
poorly paid and kindly treated, the Indians work well and
laboriously in the mines; but the Negro seldom engages either in
that or any other settled employment, unless compelled as a slave,
in which condition he is happy and thoughtless. I do not defend
slavery, but I believe it to be a greater curse to the masters than
to the slaves, more deteriorating to the former than to the latter.
The Spaniards at first enslaved the Indians, but they died away so
rapidly that in a very short time the indigenes of the whole of the
once-populous islands of the West Indies were exterminated, and
large numbers of Indians were carried off from the mainland to
supply their places, but died with equal rapidity; so that the
Spaniards found it more profitable to bring negroes from Africa,
who thrived and multiplied in captivity as readily as the enslaved
Indians pined away and died. In Central America there never were
many black slaves; since the States threw off the yoke of Spain
there have been none; and this comparative scarcity of the Negro
element makes these countries much more pleasant and safer to dwell
in than the West Indies, where it is much larger. The Indian seldom
or never molests the whites, excepting in retaliation for some
great injury; whilst amongst the free Negroes, robbery, violence,
and murder need no other incentives than their own evil passions
and lust.
The women at Santo Domingo are much the same as those found at all
the small provincial towns of Central America. Morality is at a low
ebb, and most of them live as mistresses, not as wives, for which
they do not seem to suffer in the estimation of their neighbours.
This is greatly due in Nicaragua, as it is throughout Central and
South America, to the profligate lives led by the priests, who,
with few rare exceptions, live in concubinage more or less open.
The women have children at an early age, and make kind and
indulgent mothers.
(PLATE 4. COMMISSIONER'S HOUSE AT SANTO DOMINGO.)
The village is bounded to the eastward by the mines and hacienda of
the Chontales Mining Company, whose houses, workshops, and
machinery are on rising ground on each side of the valley, with the
brook running down between. About fifty acres of the forest have
been cut down, and a great deal of this is fenced in and covered
with grass. Going up the valley from the village, on the right hand
side, about fifty yards from the road, on a grass-covered slope,
stand the houses of the commissioner and cashier, in the latter of
which the medical officer also lives. The former, a large,
white-washed, square, two-storied, wooden house, with verandahs
round three sides of it, and communicating by a covered passage
with a detached kitchen behind, had been built by one of my
predecessors, Captain Hill, R.N., who did not live to inhabit it.
It was a roomy, comfortable house, commanding a view of the
machinery, workshops, and part of the mines on the other side of
the valley, and formed my residence for upwards of four years.
The slope in front of the house, down to the river, was covered
with weedy bushes when I arrived; but I had these cleared away, and
a fine greensward of grass took their place. On this I planted
young orange, lime, and citron trees; and I had the pleasure,
before I left, to see them beginning to bear their fine fruit. To
the west of the house was a dell, covered with fallen logs and
rubbish thrown from the hill, in which was a perennial spring of
limpid water. I had the logs and rubbish gathered together and
burnt, put a light fence round it, and formed a small vegetable,
fruit, and flower garden. The mango and avocado trees had not come
into bearing before I left; but pineapples, figs, grenadillas,
bananas, pumpkins, plantains, papaws, and chioties fruited
abundantly. The last named is a native of Mexico; it is a climbing
plant with succulent stems and vine-like leaves, and grows with
great rapidity. The fruit, of which it bears a great abundance, is
about the size and shape of a pear, covered with soft prickles. It
is boiled and eaten as a vegetable, and resembles vegetable marrow.
At Santo Domingo it continues to bear a succession of fruits during
eight months of the year.
Next to maize, plantains and bananas form the principal sustenance
of the natives. The banana tree shoots up its succulent stem, and
unfolds its immense entire leaves with great rapidity; and a group
of them waving their silky leaves in the sun, or shining ghostly
white in the moonlight, forms one of those beautiful sights that
can only be seen to perfection in the tropics. There are a great
many varieties of them, and they are cooked in many ways--boiled,
baked, made into pastry, or eaten as a fruit. The varieties differ
not only in their fruits, but in the colour of their leaves and
stems; the natives can distinguish them without seeing the fruit,
and have names for each, by which they are known throughout all
Central America, Mexico, and Peru. These names are of Spanish
origin; and this fact, together with the absence of any native,
Mexican, or Peruvian name for the fruit, inclines me to adopt the
opinion of Clavigero, who contends, in opposition to other writers,
that the plantain and banana were not known in these countries
before the Spanish conquest, but were first brought from the
Canaries to Hayti in 1516, and from thence taken to the mainland.
Neither the sugar-cane* nor the plantain is given in the list of
the indigenous productions of Mexico by the careful and accurate
Hernandez. (* The sugar-cane is said never to bear seed in the West
Indies, Malaga, India, Cochin China, or the Malay Archipelago.
--Darwin's "Animals and Plants under Domestication" volume 2 page
169.) The natives made sugar from the green stems of the maize.
Humboldt thinks that some species of plantain were indigenous to
America; but it seems incredible that such an important fruit could
have been overlooked by the early historians. In the old world the
cultivation of the banana dates from the earliest times of which
tradition makes mention. One of the Sanscrit names was
bhanu--fruit, from which probably the name "banana" was derived.*
(* Humboldt's "Aspects of Nature" volume 2 page 141.)
Both the plantain and the banana are always propagated from shoots
or suckers that spring from the base of the plants; and it is to be
remarked that the pineapple and the bread-fruit, that are also
universally grown from cuttings or shoots, and have been cultivated
from remote antiquity, have in a great measure lost the faculty of
producing mature seed. Such varieties could not arise in a state of
nature, but are due to selection by early races of mankind, who
would naturally propagate the best varieties; and, to do this, seed
was not required. As the finest kinds of bananas, pineapples, and
bread-fruit are almost seedless, it is probable that the nutriment
that would have been required for the formation of the seeds has
been expended in producing larger and more succulent fruits. We
find some varieties of oranges, which also have been cultivated
from very early ages, producing fruits without seeds; but as these
trees are propagated from seeds, these varieties could not become
so sterile as those just mentioned. There can be no doubt that the
seedless varieties of banana, bread-fruits, and pineapples have
been propagated for hundreds of years; and this fact ought to
modify the opinions generally entertained by horticulturists that
the life of plants and trees propagated from shoots or cuttings
cannot be indefinitely prolonged in that way. Perhaps this may be
the case in trees, such as apples, that have come under their
notice; and the reason that the varieties die out after a certain
time, if not reproduced from seed, may be that the vigour of the
trees is at last used up by the production of mature seed, but that
in the seedless bananas, pineapples, and bread-fruits this does not
happen.
Figs grow well in Nicaragua, and by many their luscious fruit is
preferred to all others. My trees suffered greatly from the attacks
of a large and fine longicorn beetle (Taeniotes scalaris, Fab.)
which laid its eggs in the green bark, and produced white grubs
that mined into the stem. I had to dig down to them with a knife to
extricate them and prevent them destroying the young trees. We were
surrounded at a short distance by the forest, in which grow many
species of wild fig-trees; and this probably was the reason that my
trees suffered so much, for at Granada the fig-growers were not
troubled with this insect.
The grenadilla is the fruit of one of the passion-flowers
(Passiflora quadrangularis), and is shaped like a large oblong
apple, which it also resembles in perfume. It makes fine tarts and
puddings, being somewhat like the gooseberry in taste. I had much
difficulty in preserving it from being eaten by small forest rats
that came out of the woods, where they had already been accustomed
to eat the wild fruit of this climber.
The moist, warm climate seemed to suit the papaw tree, as it grew
with great vigour, and produced very large and fine melon-like
fruits. The green fruits are excellent for making pastry, if
flavoured with a little lime-juice.
In vegetables, I grew three species of sweet potatoes--yellow,
purple, and white skinned, and which differ also in their leaves
and flowers; cabbages, kidney-beans, pumpkins, yuccas (Jatropha
manihot), quequisque (a species of arum, Colocasia esculenta),
lettuces, tomatoes, capiscums, endives, parsley, and carrots.
The climate was too damp to grow onions; neither could I succeed
with peas, potatoes, or turnips. Scarlet runners (Phaseolus
multiflorus) grew well, and flowered abundantly, but never produced
a single pod. Darwin has shown that this flower is dependent, like
many others, for its fertilisation upon the operations of the busy
humble-bee, and that it is provided with a wonderful mechanism, by
means of which its pollen is rubbed into the head of the bee, and
received on the stigma of the next plant visited.* (* "Gardener's
Chronicle" October 24, 1857 and November 14, 1858; also T.H. Farrer
in "Annals of Natural History" October 1868.) There are many
humble-bees, of different species from ours, in tropical America;
but none of them frequented the flowers of the scarlet runner, and
to that circumstance we may safely ascribe its sterility. An
analogous case has been long known. The vanilla plant (Vanilla
planifolia) has been introduced from tropical America into India,
but though it grows well, and flowers, it never fruits without
artificial aid. It is the same in the hothouses of Europe. Dr.
Morren, of Liege, has shown that, if artificially fertilised, every
flower will produce fruit; and ascribes its sterility to the
absence, in Europe and India, of some insect that in America
carries the pollen from one flower to another.* (* Taylor's "Annals
of Natural History" volume 3 page 1.) When those interested in the
acclimature of the natural productions of one country on the soil
of some distant one, study the mutual relations of plants and
animals, they will find that in the case of many plants it is
important that the insects specially adapted for the fertilisation
of their flowers should be introduced with them. Thus, if the
insect or bird that assists in the fertilisation of the vanilla
could be introduced into and would live in India, the growers of
that plant would be relieved of much trouble, and it might be
thoroughly naturalised. Judging from my experience, it would be
useless to attempt the acclimature of the scarlet-runner bean in
Chontales unless the humble-bee were also introduced.
Caterpillars, plant-lice, bugs, and insect pests of all kinds were
numerous, and did much harm to my garden; but the greatest plague
of all were the leaf-cutting ants, and I had to wage a continual
warfare against them. During this contest I gained much information
regarding their habits, and was successful in checking their
ravages, and I shall occupy the remainder of this chapter with an
account of them.
LEAF-CUTTING ANTS.
Nearly all travellers in tropical America have described the
ravages of the leaf-cutting ants (Oecodoma); their crowded,
well-worn paths through the forests, their ceaseless pertinacity in
the spoliation of the trees--more particularly of introduced
species--which are stripped bare and ragged with the midribs and a
few jagged points of the leaves only left. Many a young plantation
of orange, mango, and lemon trees has been destroyed by them. Again
and again have I been told in Nicaragua, when inquiring why no
fruit-trees were grown at particular places, "It is no use planting
them; the ants eat them up." The first acquaintance a stranger
generally makes with them is on encountering their paths on the
outskirts of the forest crowded with the ants; one lot carrying off
the pieces of leaves, each piece about the size of a sixpence, and
held up vertically between the jaws of the ant; another lot
hurrying along in an opposite direction empty-handed, but eager to
get loaded with their leafy burdens. If he follows this last
division, it will lead him to some young trees or shrubs, up which
the ants mount; and then each one, stationing itself on the edge of
a leaf, commences to make a circular cut, with its scissor-like
jaws, from the edge, its hinder feet being the centre on which it
turns. When the piece is nearly cut off, it is still stationed upon
it, and it looks as though it would fall to the ground with it;
but, on being finally detached, the ant is generally found to have
hold of the leaf with one foot, and soon righting itself, and
arranging its burden to its satisfaction, it sets off at once on
its return. Following it again, it is seen to join a throng of
others, each laden like itself, and, without a moment's delay, it
hurries along the well-worn path. As it proceeds, other paths, each
thronged with busy workers, come in from the sides, until the main
road often gets to be seven or eight inches broad, and more
thronged than the streets of the city of London.
After travelling for some hundreds of yards, often for more than
half a mile, the formicarium is reached. It consists of low, wide
mounds of brown, clayey-looking earth, above and immediately around
which the bushes have been killed by their buds and leaves having
been persistently bitten off as they attempted to grow after their
first defoliation. Under high trees in the thick forest the ants do
not make their nests, because, I believe, the ventilation of their
underground galleries, about which they are very particular, would
be interfered with, and perhaps to avoid the drip from the trees.
It is on the outskirts of the forest, or around clearings, or near
wide roads that let in the sun, that these formicariums are
generally found. Numerous round tunnels, varying from half an inch
to seven or eight inches in diameter, lead down through the mounds
of earth; and many more from some distance around, also lead
underneath them. At some of the holes on the mounds ants will be
seen busily at work, bringing up little pellets of earth from
below, and casting them down on the ever-increasing mound, so that
its surface is nearly always fresh and new-looking.
Standing near the mounds, one sees from every point of the compass
ant-paths leading to them, all thronged with the busy workers
carrying their leafy burdens. As far as the eye can distinguish
their tiny forms, troops upon troops of leaves are moving up
towards the central point, and disappearing down the numerous
tunnelled passages. The out-going, empty-handed hosts are partly
concealed amongst the bulky burdens of the incomers, and can only
be distinguished by looking closely amongst them. The ceaseless,
toiling hosts impress one with their power, and one asks--What
forests can stand before such invaders? How is it that vegetation
is not eaten off the face of the earth? Surely nowhere but in the
tropics, where the recuperative powers of nature are immense and
ever active, could such devastation be withstood.
Further acquaintance with the subject will teach the inquirer that,
just as many insects are preserved by being distasteful to
insectivorous birds, so very many of the forest trees are protected
from the ravages of the ants by their leaves either being
distasteful to them, or unfitted for the purpose for which they are
required, whilst some have special means of defence against their
attacks. None of the indigenous trees appear so suitable for them
as the introduced ones. Through long ages the trees and the ants of
tropical America have been modified together. Varieties of plants
that arose unsuitable for the ants have had an immense advantage
over others that were more suitable; and thus through time every
indigenous tree that has survived in the great struggle has done so
because it has had originally, or has acquired, some protection
against the great destroyer. The leaf-cutting ants are confined to
tropical America; and we can easily understand that trees and
vegetables introduced from foreign lands where these ants are
unknown could not have acquired, excepting accidentally, and
without any reference to the ants, any protection against their
attacks, and now they are most eagerly sought by them. Amongst
introduced trees, some species of even the same genus are more
acceptable than others. Thus, in the orange tribe, the lime (Citrus
lemonum) is less liked than the other species; it is the only one
that I ever found growing really wild in Central America: and I
have sometimes thought that even in the short time since the lime
was first introduced, about three hundred years ago, a wild variety
may have arisen, less subject to the attacks of the ants than the
cultivated variety; for in many parts I saw them growing wild, and
apparently not touched. The orange (Citrus aurantium) and the
citron (Citrus medicus), on the other hand, are only found where
they have been planted and protected by man; and, were he to give
up their cultivation, the only species that would ultimately
withstand the attacks of the ants, and obtain a permanent footing
in Central America, would be the lime. The reason why the lime is
not so subject to the attacks of the ants is unknown; and the fact
that it is so is another instance of how little we know why one
species of a particular genus should prevail over another nearly
similar form. A little more or less acridity, or a slight chemical
difference in the composition of the tissues of a leaf, so small
that it is inappreciable to our senses, may be sufficient to ensure
the preservation or the destruction of a species throughout an
entire continent.
The ravages of this ant are so great that it may not be without
interest for me to enter upon some details respecting the means I
took to protect my own garden against their attacks, especially as
the continual warfare I waged against them for more than four years
made me acquainted with much of their wonderful economy.
In June 1869, very soon after the formation of my garden, the
leaf-cutting ants came down upon it, and at once commenced denuding
the young bananas, orange, and mango trees of their leaves. I
followed up the paths of the invading hosts to their nest, which
was about one hundred yards distant, close to the edge of the
forest. The nest was not a very large one, the low mound of earth
covering it being about four yards in diameter. At first I tried to
stop the holes up, but fresh ones were immediately opened out: I
then dug down below the mound, and laid bare the chambers beneath,
filled with ant-food and young ants in every stage of growth; but I
soon found that the underground ramifications extended so far, and
to so great a depth, while the ants were continually at work making
fresh excavations, that it would be an immense task to eradicate
them by such means; and notwithstanding all the digging I had done
the first day, I found them the next as busily at work as ever at
my garden, which they were rapidly defoliating. At this stage, our
medical officer, Dr. J.H. Simpson,* came to my assistance, and
suggested pouring carbolic acid, mixed with water, down their
burrows. (* This gentleman, beloved by all who knew him, of rare
talent, and with every prospect of a prosperous career before him,
died at Jamaica from hydrophobia, between two and three months
after being bitten by a small dog that had not itself shown any
symptoms of that disease.) The suggestion proved a most valuable
one. We had a quantity of common brown carbolic acid, about a pint
of which I mixed with four buckets of water, and, after stirring it
well about, poured it down the burrows; I could hear it rumbling
down to the lowest depths of the formicarium four or five feet from
the surface. The effect was all I could have wished: the marauding
parties were at once drawn off from my garden to meet the new
danger at home. The whole formicarium was disorganised. Big fellows
came stalking up from the cavernous regions below, only to descend
again in the utmost perplexity.
Next day I found them busily employed bringing up the ant-food from
the old burrows, and carrying it to a new one a few yards distant;
and here I first noticed a wonderful instance of their reasoning
powers. Between the old burrows and the new one was a steep slope.
Instead of descending this with their burdens, they cast them down
on the top of the slope, whence they rolled down to the bottom,
where another relay of labourers picked them up and carried them to
the new burrow. It was amusing to watch the ants hurrying out with
bundles of food, dropping them over the slope, and rushing back
immediately for more. They also brought out great numbers of dead
ants that the fumes of the carbolic acid had killed. A few days
afterwards, when I visited the locality again, I found both the old
burrows and the new one entirely deserted, and I thought they had
died off; but subsequent events convinced me that the survivors had
only moved away to a greater distance.
It was fully twelve months before my garden was again invaded. I
had then a number of rose-trees and also cabbages growing, which
the ants seemed to prefer to everything else. The rose-trees were
soon defoliated, and great havoc was made amongst the cabbages. I
followed them to their nest, and found it about two hundred yards
from the one of the year before. I poured down the burrows, as
before, several buckets of water with carbolic acid. The water is
required to carry the acid down to the lowest chambers. The ants,
as before, were at once withdrawn from my garden; and two days
afterwards, on visiting the place, I found all the survivors at
work on one track that led directly to the old nest of the year
before, where they were busily employed making fresh excavations.
Many were bringing along pieces of the ant-food from the old to the
new nests; others carried the undeveloped white pupae and larvae.
It was a wholesale and entire migration; and the next day the
formicarium down which I had last poured the carbolic acid was
entirely deserted. I afterwards found that when much disturbed, and
many of the ants destroyed, the survivors migrate to a new
locality. I do not doubt that some of the leading minds in this
formicarium recollected the nest of the year before, and directed
the migration to it.
Don Francisco Velasquez informed me, in 1870, that he had a powder
which made the ants mad, so that they bit and destroyed each other.
He gave me a little of it, and it proved to be corrosive sublimate.
I made several trials of it, and found it most efficacious in
turning a large column of the ants. A little of it sprinkled across
one of their paths in dry weather has a most surprising effect. As
soon as one of the ants touches the white powder, it commences to
run about wildly, and attack any other ant it comes across. In a
couple of hours, round balls of the ants will be found all biting
each other; and numerous individuals will be seen bitten completely
in two, whilst others have lost some of their legs or antennae.
News of the commotion is carried to the formicarium, and huge
fellows, measuring three-quarters of an inch in length, that only
come out of the nest during a migration or an attack on the nest or
one of the working columns, are seen stalking down with a
determined air, as if they would soon right matters. As soon,
however, as they have touched the sublimate, all their stateliness
leaves them: they rush about; their legs are seized hold of by some
of the smaller ants already affected by the poison; and they
themselves begin to bite, and in a short time become the centres of
fresh balls of rabid ants. The sublimate can only be used
effectively in dry weather. At Colon I found the Americans using
coal tar, which they spread across their paths when any of them led
to their gardens. I was also told that the Indians prevent them
from ascending young trees by tying thick wisps of grass, with the
sharp points downwards, round the stems. The ants cannot pass
through the wisp, and do not find out how to surmount it, getting
confused amongst the numberless blades, all leading downwards. I
mention these different plans of meeting and frustrating the
attacks of the ants at some length, as they are one of the greatest
scourges of tropical America, and it has been too readily supposed
that their attacks cannot be warded off. I myself was enabled, by
using some of the means mentioned above, to cultivate successfully
trees and vegetables of which the ants were extremely fond.
(PLATE 5. NEST OF LEAF-CUTTING ANT.)
Notwithstanding that these ants are so common throughout tropical
America, and have excited the attention of nearly every traveller,
there still remains much doubt as to the use to which the leaves
are put. Some naturalists have supposed that they use them directly
as food; others, that they roof their underground nests with them.
I believe the real use they make of them is as a manure, on which
grows a minute species of fungus, on which they feed;--that they
are, in reality, mushroom growers and eaters. This explanation is
so extraordinary and unexpected, that I may be permitted to enter
somewhat at length on the facts that led me to adopt it. When I
first began my warfare against the ants that attacked my garden, I
dug down deeply into some of their nests. In our mining operations
we also, on two occasions, carried our excavations from below up
through very large formicariums, so that all their underground
workings were exposed to observation. I found their nests below to
consist of numerous rounded chambers, about as large as a man's
head, connected together by tunnelled passages leading from one
chamber to another. Notwithstanding that many columns of the ants
were continually carrying in the cut leaves, I could never find any
quantity of these in the burrows, and it was evident that they were
used up in some way immediately they were brought in. The chambers
were always about three parts filled with a speckled, brown,
flocculent, spongy-looking mass of a light and loosely connected
substance. Throughout these masses were numerous ants belonging to
the smallest division of the workers, which do not engage in
leaf-carrying. Along with them were pupae and larvae, not gathered
together, but dispersed, apparently irregularly, throughout the
flocculent mass. This mass, which I have called the ant-food,
proved, on examination, to be composed of minutely subdivided
pieces of leaves, withered to a brown colour, and overgrown and
lightly connected together by a minute white fungus that ramified
in every direction throughout it. I not only found this fungus in
every chamber I opened, but also in the chambers of the nest of a
distinct species that generally comes out only in the night-time,
often entering houses and carrying off various farinaceous
substances, and which does not make mounds above its nests, but
long, winding passages, terminating in chambers similar to the
common species, and always, like them, three parts filled with
flocculent masses of fungus-covered vegetable matter, amongst which
are the ant-nurses and immature ants. When a nest is disturbed, and
the masses of ant-food spread about, the ants are in great concern
to carry every morsel of it under shelter again; and sometimes,
when I had dug into a nest, I found the next day all the earth
thrown out filled with little pits that the ants had dug into it to
get out the covered up food. When they migrate from one part to
another, they also carry with them all the ant-food from their old
habitations. That they do not eat the leaves themselves I convinced
myself; for I found near the tenanted chambers, deserted ones
filled with the refuse particles of leaves that had been exhausted
as manure for the fungus, and were now left, and served as food for
larvae of Staphylinidae and other beetles.* (*This theory that the
leaf-cutting ants feed on a fungus which they cultivate has been
confirmed by Mr. Fritz Muller, who had arrived at it independently
in Brazil. His observations on this and various other habits of
insects are contained in a letter to Mr. Charles Darwin, published
in "Nature" of June 11, 1874.)
These ants do not confine themselves to leaves, but also carry off
any vegetable substance that they find suitable for growing the
fungus on. They are very partial to the inside white rind of
oranges, and I have also seen them cutting up and carrying off the
flowers of certain shrubs, the leaves of which they neglected. They
are particular about the ventilation of their underground chambers,
and have numerous holes leading up to the surface from them. These
they open out or close up, apparently to keep up a regular degree
of temperature below. The great care they take that the pieces of
leaves they carry into the nest should be neither too dry nor too
damp, is also consistent with the idea that the object is the
growth of a fungus that requires particular conditions of
temperature and moisture to ensure its vigorous growth. If a sudden
shower should come on, the ants do not carry the wet pieces into
the burrows, but throw them down near the entrances. Should the
weather clear up again, these pieces are picked up when nearly
dried, and taken inside; should the rain, however, continue, they
get sodden down into the ground, and are left there. On the
contrary, in dry and hot weather, when the leaves would get dried
up before they could be conveyed to the nest, the ants, when in
exposed situations, do not go out at all during the hot hours, but
bring in their leafy burdens in the cool of the day and during the
night. As soon as the pieces of leaves are carried in they must be
cut up by the small class of workers into little pieces. I have
never seen the smallest class of ants carrying in leaves; their
duties appear to be inside, cutting them up into smaller fragments,
and nursing the immature ants. I have, however, seen them running
out along the paths with the others; but instead of helping to
carry in the burdens, they climb on the top of the pieces which are
being carried along by the middle-sized workers, and so get a ride
home again. It is very probable that they take a run out merely for
air and exercise. The largest class of what are called workers are,
I believe, the directors and protectors of the others. They are
never seen out of the nest, excepting on particular occasions, such
as the migrations of the ants, and when one of the working columns
or nests is attacked; they then come stalking up, and attack the
enemy with their strong jaws. Sometimes, when digging into the
burrows, one of these giants has unperceived climbed up my dress,
and the first intimation of his presence has been the burying of
his jaws in my neck, from which he would not fail to draw the
blood. The stately observant way in which they stalk about, and
their great size, compared with the others, always impressed me
with the idea that in their bulky heads lay the brains that
directed the community in its various duties. Many of their
actions, such as that I have mentioned of two relays of workmen
carrying out the ant-food, can scarcely be blind instinct. Some of
the ants make mistakes, and carry in unsuitable leaves. Thus grass
is nearly always rejected by them, yet I have seen some ants,
perhaps young ones, carrying in leaves of grass. After a while
these pieces were invariably brought out again and thrown away. I
can imagine a young ant getting a severe earwigging from one of the
major-domos for its stupidity.
I shall conclude this long account of the leaf-cutting ants with an
instance of their reasoning powers. A nest was made near one of our
tramways, and to get to the trees the ants had to cross the rails,
over which the waggons were continually passing and repassing.
Every time they came along a number of ants were crushed to death.
They persevered in crossing for several days, but at last set to
work and tunnelled underneath each rail. One day, when the waggons
were not running, I stopped up the tunnels with stones; but
although great numbers carrying leaves were thus cut off from the
nest, they would not cross the rails, but set to work making fresh
tunnels underneath them. Apparently an order had gone forth, or a
general understanding been come to, that the rails were not to be
crossed.
These ants do not appear to have many enemies, though I sometimes
found holes burrowed into their nests, probably by the small
armadillo. I once saw a minute parasitic fly hovering over a column
of ants, near a nest, and every now and then darting down and
attaching an egg to one entering. Large, horned beetles (Coelosis
biloba) and a species of Staphylinus are found in the nests, but
probably their larvae live on the rotten leaves, after the ants
have done with them.