BEES AND ANTS—A ROBBER MOTH—ANTS THAT KEEP COWS AND SLAVES—ANTS
THAT ARE HONEY-POTS—ANTS THAT SOW AND REAP.
The most wonderful of all insects—that, at least, would be the general
opinion—are bees and ants. As bees are so very well known, and kept by so
many people, I will not say much about them here, which will leave more
space for the ants. Of the two, bees perhaps are the finer architects,
for nothing quite so wonderful as their rows of hexagonal cells is to
be found in an ant’s-nest. “He must be a dull man,” says Darwin, “who
can examine the exquisite structure of a comb, so beautifully adapted
to its end, without enthusiastic admiration”; and he goes on to observe
that “bees have practically solved a recondite problem, and have made
their cells of the proper shape to hold the greatest possible amount
of honey, with the least possible consumption of precious wax in their
construction.” No doubt these wonderful cells are now made instinctively,
yet the bees can adapt their architecture to special circumstances, which
shows the possession of reasoning power. Thus, should a piece of the
comb fall down, they will not only fix it, by wax, in its new position,
but, what is much more extraordinary, will strengthen the attachments
of the other combs, lest they should fall too—for there can be no other
reason for such an act. Bees, again, are sometimes much annoyed by the
death’s-head moth which enters the hive at night, and devours the honey,
apparently without danger to itself, though why this should be the case
we do not know. After having suffered for some time, however, the bees
barricade the entrance by building behind it a wall of wax and propolis,
through which they make a hole large enough to admit themselves, but
which quite excludes the bulky body of the moth. Here, too, we have
reason and foresight in a high degree, as much, I think—perhaps more
so—as has ever been observed in any occasional act of an ant, devised
to meet special circumstances. For it is only in years in which the
death’s-head moth is specially abundant that the bees act in this way;
and, moreover, when it seems no longer required, they remove the barrier
they have made.
The puzzling thing is that acts like this seem to show higher
intelligence than, to judge by various experiments, one would think
either ants or bees possessed. The results, for instance, of the
experiments made by Lord Avebury in this direction, are rather
disappointing than otherwise, especially with ants, creatures so far
advanced in civilisation, as we may call it, and the ways of man, that
they keep both cows and slaves, milking the one and making the others
work for them. The cows are represented by little insects called aphides,
one species of which we are accustomed to see upon our rose trees, and
the milk is a drop of nectar which they exude from the abdomen, upon the
ants gently tapping them there with their antennæ. Various kinds of ants
milk various kinds of aphides, and some keep them in their nests, where,
indeed, they are born, their eggs being tended with the same care as
those of the ants themselves. Thus we see amongst ants a creature kept
and used regularly for a certain purpose, as domestic animals are amongst
ourselves, and this, as far as we know, is unique in the animal world.
The aphides, too, belong to a family of insects quite distinct from the
Hymenoptera, amongst which the ants are included.
Ant-slaves, on the other hand, are ants themselves, though belonging to
another species than their masters. The latter raid their nests and carry
off, without injury, the larvæ and pupæ, which they afterwards hatch out
in their own. These ants, therefore, are born into slavery, so that they
do not know their condition, if we could suppose that that would disquiet
them, and, moreover, they are not ill-used, but treated in every respect
as well as though they belonged to the community in which they have been
born. The only thing that makes them slaves is that they work for the
ants by whom they have been captured, but this they do _con amore_—ants
love working—so that there is no hardship in it. They work, however, in
varying degrees, some species of slave-making ants being accustomed to
do a certain amount for themselves, whilst others even require to be
fed, and are often carried by their slaves, who, of course, do all the
regular household business of building, feeding the young, bringing food
to the nest, etc., etc. When Huber—the great French observer of ants and
bees—placed thirty of this latter kind of slave-making ants in a box,
with some of their larvæ and pupæ and a supply of honey, but without
any slaves, “more than one half of them died of hunger in less than two
days.” The others were languid and without strength, and appeared able to
do nothing. Commiserating their condition, Huber at length gave them a
slave. “This individual, unassisted, established order, formed a chamber
in the earth, gathered together the larvæ, extricated several young ants
that were ready to quit the condition of pupæ, and preserved the life of
the remaining Amazons,” as Huber calls these slave-raiders, in allusion
to their sex. It is only the worker ants of any species who are taken
away by others, whilst still immature, to be afterwards hatched out as
slaves, for they alone would be of use. Both ants and bees, as is well
known, are divided into three different sets or castes, the males, the
perfect females, who become queens and are the founders of the community,
and the immature females or workers, who are the most interesting of the
three, and by whom the whole work of the hive or nest is carried on.
One of the most extraordinary of all ants—and therefore of all insects—is
the honey-ant of Mexico (with some adjoining regions) and Australia.
Amongst these, a certain section of the community take the place of
aphidæ amongst other ants. They live but to distribute honey to the rest,
and by reason of this, and the remarkable way in which their purpose is
accomplished, may be said to be living honey-pots. In the first place,
they are themselves fed with honey by the workers, who swallow it and
bring it up from their stomachs in the way in which a pigeon brings up
food for its young—a process which is called “regurgitation.” During
this process the abdomen of the honey-bearers begins to swell, and by
degrees becomes quite globular, and of such a disproportionate size to
the rest of the body that the latter projects from it like a piece of
stick, and is raised high above the ground. When thus fully distended it
is difficult for the insect to walk—a feat which it can only accomplish
sideways—but it has, as a rule, no necessity to do so, and only clings
motionless to the vaulted roof of the cell or chamber in which it is
enclosed. This is of a roughly circular shape, about three inches across,
and an inch or three-quarters of an inch in height. It is called the
honey-chamber, and in it a number of these honey-bearers reside—if
they may not rather be said to be stored—hanging closely together, and
looking like a bunch of currants or small amber-coloured grapes—for
their abdomens are transparent, so that the honey shows through them. It
used to be thought that these ants had no stomachs, so that the abdomen
itself made the jar for the honey. This, however, is a mistake. The honey
on being swallowed, is received into the stomach, and this by swelling
inordinately, causes the abdomen to swell too. It is interesting that
whilst the floors of these honey-chambers are quite smooth, the roof is
rough, so that the ants, fixing their feet upon the granulated surface,
can cling there more securely. We need not suppose, however, that the
ants produce this result purposely, for it is by their constantly walking
over the floors of the chambers that they become smooth and polished.
Here, then, we have the honey-jars. The workers when they are hungry
come to them, and lifting their mouths up to the mouth of the jars, the
honey from the latter is poured—or regurgitated—into them. In doing this
the honey-bearing ant—or, as she is often called, from the shape of her
abdomen, the rotund—throws her head up, and a drop of clear, amber fluid
is then seen to exude from her mouth, which is eagerly licked up by the
workers.
It is to be presumed that the latter crawl up the walls of the
honey-chambers in order to be fed by the rotunds; but I am not quite sure
whether Mr. MacCook, who kept these ants, and is the authority upon them,
ever actually saw them do this. On the other hand, he often saw them fed
upon the ground; but then, I think, he had put the honey-bearing ants
there. In his book he gives some interesting illustrations of the feeding
taking place. It used to be thought that these poor honey-pot ants were
unable to walk, and lived all their lives in one place. This, however,
is not the case. Mr. MacCook tells us that he has “frequently seen them
coming out of their chambers, ascending the galleries, and moving freely
about them.” They went sideways, and half slid and half crawled along.
Again, when he placed them on a table, they were able to move “with no
little agility.” If, however, they happened to fall from the roof where
they were clinging, which sometimes they did through people shaking them,
they were not able to get up again, but lay there helpless. It is not
always, however, that these honey-jars are full, and when they are half
or three-quarters empty they can walk very much better.
Some ants, it is now well known, are accustomed to store up grain in
their nests during the summer or autumn, so as to have a supply of food
during the winter. Long ago this habit had been recorded by Solomon, who
says, “The ants are a people not strong, yet they prepare their meat
in the summer”; and again, “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.” Classic
writers have also dwelt upon this interesting point in ant economy, so
that for a long time it was taken for granted not only that some ants
stored grain, but that all of them did. However, when the European
species began to be observed very carefully, this opinion was found to be
erroneous, and Huber and other investigators, having convinced themselves
that grain in these instances was not so stored, opinion began to go to
the other extreme, and the fact was denied altogether. It was supposed
that Solomon, and the ancient writers generally, had seen the ants
carrying their little white larvæ or pupæ—as anyone may do who disturbs a
nest—and that these had been mistaken for seeds.
For my part, I think that this is very likely to have been the case in
some instances, for until lately it has not been the custom to watch
insects, or indeed any animals, minutely, and it is not the business—and
often not the interest—of poets to verify matters of this kind. In the
Mishna, however, which is a collection of old Jewish writings, we find a
law relating to this grain stored up by the ants, and the ownership of
it; and anyone who had read this might have known that the thing was a
reality, since minute regulations about the possession of something can
hardly exist, unless that something exists, too. This is the law, which,
as will be seen, dealt fairly by everyone except by the ants—“The little
caves of ants, when in the midst of a standing crop, are adjudged to the
owner of the field; of those behind the reapers, the upper part is the
property of the poor, the lower of the proprietor.” Rabbi Meir, however,
decided that “all belong to the poor, since whatever is in doubt, in
gleaning, goes to the gleaner.”
Yet in spite of the strong presumption in favour of ant providence and
foresight, which this piece of ancient legislation raises, opinion was
against it, and it was not till 1829 that the question was set at rest
by Lieutenant-Colonel Sykes, who, whilst at Poonah, in India, saw and
examined these “little caves of the ants” and also the ants carrying the
seeds, not into but out of them. “Each ant,” he tells us, “was charged
with a single seed; but, as it was too weighty for many of them, and as
the strongest had some difficulty in scaling the perpendicular sides of
the cylindrical hole leading to the nest below, many were the falls of
the weaker ants with their burdens, from near the summit to the bottom.”
The ants, however, that thus fell never relaxed their hold of the grain
they were carrying, and, with a perseverance affording a useful lesson
to humanity, “steadily recommenced the ascent, after each successive
tumble, nor halted in their labour until they had crowned the summit and
lodged their burden on the common heap.” This observation was made just
after the heavy rains of the Indian monsoon. The seeds had probably got
wet, and the ants were bringing them up to dry in the sun.
Here then, at last, the truth of the ancient opinion as to ants storing
grain was vindicated; but now came another and still more wonderful
discovery. A harvesting ant—one, that is to say, that stored grain—was
found to inhabit Texas, and Dr. Lincecum, who lived for twelve years in
that country, came to the conclusion that this species not only stored
the grain, but planted it, too, so as to have a crop of seeds next
year, just as a farmer plants wheat. In an account of this ant which
Dr. Lincecum sent to Darwin, who read it before the Linnean Society, he
says: “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. 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 to 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 smooths 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,” continues Dr. Lincecum,
thus supporting the observations of Lieutenant-Colonel Sykes, “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 1877 Mr. MacCook visited Texas on purpose to find out whether the
harvesting ants really sowed the seed, as Dr. Lincecum had reported,
for of course anyone may be mistaken. He saw a good deal of what Dr.
Lincecum had seen, but not all, which is no wonder, since he only stayed
a few weeks, whereas Dr. Lincecum had lived in the country for twelve
years. Mr. MacCook could not make up his mind upon the subject, but he
saw no reason why the ants should not sow their seed, nor has he given
any better explanation of their clearing a space and not letting anything
but their ant-rice grow upon it. There can, I think, be very little doubt
that Dr. Lincecum was right in his opinion. We need have no difficulty
in believing that some ants have fields and raise crops upon it, because
there are other kinds, which, though they do not do this, do other things
which are quite as wonderful, and demand quite as much intelligence. Mr.
Belt, too, as we shall see, in a little, believes that some ants in South
America grow mushrooms and make beds to grow them on.
This is the description which Mr. MacCook gives of the way in which a
harvesting-ant carries its grain of rice—as big almost and heavy as
itself—to the nest. “At last a satisfactory seed is found. It is simply
lifted from the ground, or, as often happens, has to be pulled out of the
soil, into which it has been slightly pressed by the rain or by passing
feet. Now follows a movement which at first I thought to be a testing
of the seed, and which, indeed, may be partially that; but finally I
concluded that it was the adjusting of the burden for safe and convenient
carriage. The ant pulls at the seed-husk with its mandibles, turning
and pinching or feeling it on all sides. If this does not satisfy, and
commonly it does not, the body is raised by stiffening out the legs,
the abdomen is curved underneath, and the apex applied to the seed. I
suppose this to be simply a mechanical action for the better adjusting
of the load. Now the worker starts homeward. It has not lost itself in
the mazes of the grass-forest. It turns directly towards the road (one of
the little roads made by the ants, as they come and go to and from their
nest) with an unerring judgment. There are many obstacles to overcome.
Pebbles, pellets of earth, bits of wood, obtruding rootlets, or bent-down
spears of grass block up or hinder the way. These were scarcely noticed
when the ant was empty-handed. But they are troublesome barriers now
that she is burdened with a seed quite as thick, twice as wide, and half
as long as herself. It is most interesting to see the skill, strength,
and rapidity with which the little harvester swings her treasure over or
around, or pushes it beneath these obstacles. Now the seed has caught
against the herbage as the porter dodges under a too narrow opening. She
backs out and tries another passage. Now the sharp points of the husk are
entangled in the grass. She jerks or pulls the burden loose, and hurries
on. The road is reached, and progress is comparatively easy. Holding the
grain in her mandibles well above the surface, she breaks into what I may
describe with sufficient accuracy as a ‘trot,’ and with little further
interruption reaches the disk (the cleared space round the nest, that is
to say) and disappears within the gate.”
The seeds, when thus brought into the nest, are stored by the ants in
long galleries, or in vaulted chambers, the floors of which have been
specially prepared for its reception. It is a very curious thing that the
stored seeds, though they often become quite moist, do not germinate, as
would be the case under ordinary circumstances, if we, for instance, were
to lay them in some cave or cellar. Were they to do so they would become
bitter, and, of course, unfit for food, so that it seems as if the ants
must have some way of stopping the process of nature. What this way is
we do not know, but if, out of a great many thousands, some of the seeds
do begin to sprout, the ants bite off the little rootlet or radicle that
then makes its appearance, by which act the germination is prevented from
going farther. It is quite as wonderful that the ants should have found
out how to prevent the seeds from growing in their nests—and do it in two
ways—as it is that they should plant it in fields specially prepared for
it to grow upon.