Ant partnerships—How some ants feed—Persuasive methods—An
_imperium in imperio_—Amusement by instinct—Begging
the question—Nest within nest—Ant errors v. human
perfection—Distorted arguments—How partnerships
begin—Housing an enemy—Ant ogres.
THE relation of slave and slave-master—to use the received
terminology—is not the only one of a social and friendly nature in
which ants of different species stand towards one another; for as will
have been gathered in the previous chapter, slavery amongst ants is a
quite friendly institution, conducted, in fact, upon the
“liberty-equality-fraternity” principle. Some species of ants,
however, inhabit the nests of other species, or build their own amidst
theirs in such a way as almost to make them one, and thus they live as
perpetual guests, not only without paying for such accommodation by
rendering their hosts any services, but often forcing these latter to
be of service to them in other ways also. Thus, a small species of
Texan ant whose first or Christian name is _Leptothorax_, but whose
surname has not yet been fixed upon, lives on these terms in the nests
of a larger one, the celebrated _Myrmica brevinodis_. Whether
Professor Wheeler was the discoverer of the little ant I am not quite
sure, but he was the first, I think, to observe its relations with the
big one and those of the big one with it, and his account of them is
excessively interesting. “A small dish,” he says, “containing a syrup
of sugar and water was placed near the nest (an artificial one under
close observation). This was soon found by two of the _Myrmica_
workers, which at once gorged themselves with the liquid and returned
into the nest.”[56] Soon afterwards a _Leptothorax_ worker entered it
also, and having run or tracked down one of the two honey-gorged
creatures, forthwith got up on to its back, and, seated there, began
to lick its head, an attention which it supplemented with a soft,
persuasive titillation with its antennæ, whilst at the same time
communicating a motion to its abdomen, which Professor Wheeler is so
convinced must have been accompanied with certain sounds—known to the
learned as stridulations—that he does not hesitate to affirm that it
was thrown “into stridulatory oscillation.” Nor was the _Myrmica_ deaf
to such an appeal. It slackened its pace, hesitated, then paused, and
as though unable longer to resist the influence, folded its antennæ
and appeared to give itself up to the full pleasure of the thing. The
tempter, now, still making soft play with the antennæ, lowered its own
head, and began to lick the _Myrmica_ first on one cheek and then the
other, including also the mandibles and parts adjoining. Thus
fostered, a dewy moisture, drawn evidently from the reservoir of
lately swallowed nectar, began to glisten on the lips of the large
ant, and, increasing rapidly to a droplet, was re-imbibed by the
expectant little one. “The latter,” says Professor Wheeler, “then
dismounted, ran to another _Myrmica_, climbed on its back, and
repeated the very same performance. Again it took toll, and passed on
to still another _Myrmica_.”[56] Up to the present the attention of
Professor Wheeler had been concentrated on the doings of this one
individual, but now, turning his attention to other parts of the nest,
he “observed that nearly all the _Leptothorax_ workers were similarly
employed. In one corner a number of _Myrmica_ workers had formed a
circle about a few of their small larvæ, which they were cleansing and
feeding. A _Leptothorax_ soon found its way to this cluster, and
stepped from the back of one ant to that of another, lavishing a
shampoo on each in turn, and apparently filling its crop with the
liquid contributions thus solicited.”
The above method of obtaining food appears to be peculiar to these ant
parasites. Beetles, for example, solicit it either by taps or touches
with the antennæ—which is a similar one indeed, but does not go so far
nor involve a ride—or else by stroking the face of their host with their
fore-feet. Other species of ants, when soliciting food from one another
or demanding it from their slaves, employ a more or less similar method,
whilst the _Lepismid_ that we have before spoken of is a thief pure and
simple. Licking seems to be the personal discovery of _Leptothorax_, and
being licked the peculiar privilege of _Myrmica brevinodis_. That it is
a valued one is clear, but the price asked for it is not always
forthcoming, possibly because there is not always anything to forthcome.
On such barren occasions _Leptothorax_ makes the best of a bad job, and
dismounting from its first love, runs about looking for another.
Sometimes, after having licked the head and face of its patron, the poor
petitioner turns round and proceeds to do the same by its abdomen. This,
perhaps, is a last effort of persuasion, but Professor Wheeler rather
supposes the surface of _Myrmica’s_ body to be “covered with some
agreeable secretion.” Queen _Myrmicas_, however, seem to be very rarely
treated to any sort of licking, and males apparently never. The reason
of this, probably, is that both queens and males are themselves
accustomed to receive their food from the workers by a similar process
of regurgitation, and are probably therefore not in the habit of
regurgitating it. They are therefore neglected by the little parasites,
who console themselves by being all the more insistent with those who
have something to give. These—that is to say, the workers—are waylaid
whenever they enter the nest, as having presumably found something to
eat outside it, and, in order to be on the spot, at once their
importunate lickers, who seem to live in a perpetual state of crying,
“Give! give!” keep in the more or less immediate proximity of the
entrance, or entrances, should there be more than one. Professor
Wheeler, indeed, doubts if the _Leptos_ ever feed themselves in the
ordinary way, but inasmuch as they were on one occasion seen by him to
do so, such doubt appears to me to be uncalled for.
These little ants make, in regard to the big ones within whose nest they
live, a sort of _imperium in imperio_. In a small chamber surrounded by
the large galleries of the _Myrmicas_, and communicating with these by a
passage too narrow for the latter to pass through, lives the queen with
a small number of workers; eight of them in the nest observed by
Professor Wheeler, together with a few larvæ, almost filling the cavity.
They appear to be on affectionate terms with one another, the workers
feeding their queen in the most assiduous manner, and she often playing
with them like a cat with her kittens, throwing them on to their backs,
and then “hugging and kissing them” (as Professor Wheeler describes it)
_con amore_. Not that the Professor himself takes this view of it, for
after hesitating whether to ascribe such behaviour to maternal
affection, “the play instinct,” or hunger, he decides for the latter—on
what grounds, since there was a continual passage of viands from one ant
to another, the queen especially being “assiduously fed,” I am unable to
see. What, too, is “the play instinct,” except a mere term made use of
in order to suggest the idea of automatism in regard to an act which
hardly seems to admit of such an interpretation? Instincts represent
imperious necessities which, if not attended to, the species must fail
or perish. Such, at any rate, are the grounds on which they must be
supposed to have been originally built up. But what creature has had to
play in order to survive? Not ants, surely, who work so hard that they
cannot stand in need of more exercise than their daily life affords
them. Nor, it would seem, is such an instinct developed amongst other
insects, which again seems to show that it cannot be of any great
importance. When, therefore, we find that ants, the most wonderful of
all insects, do play, this strongly suggests their possession of an
intelligence analogous to that of the higher animals. Instinct, however,
is largely independent of intelligence, such as we understand it, and
therefore, to allude to “the play instinct” in ants before the
instinctive character of the act has been made out, is to prejudge the
question whether ants are automatic or reasoning beings.
The smallness of the passages leading from the interior chamber of
_Leptothorax_ to the broad galleries of the _Myrmicas_ suggests that the
latter were not intended to pass through them; but we cannot really draw
this inference, since an ant in tunnelling would allow for the size of
its own body, but not for that of another species. Certain it is that
the big ants constantly force their way through the narrow passages,
thus partly breaking down the wall, and that they are then received by
the little ones in a quite friendly manner, and persuaded to part with
some of their interior stores. Still, when this has been effected, their
friends seem mildly desirous that they should go, and, as soon as they
have gone, set to work to repair the breaches made by their entrance. No
sooner has this been done, however, than they are broken down again, and
so it may continue, apparently, for an indefinite period, at any rate in
nests constructed for observational purposes, and where the conditions
are, therefore, more or less artificial. Whether it is so to anything
like the same extent under nature may well be doubted, for that any
creature should live in a state of never-ending useless labour does not
seem likely; and, moreover, unless the one ant could have made itself
comfortable within the nest of the other, why should it have become
established there at all? But whatever it may be outside the study, this
is Professor Wheeler’s account of what fell under his observation: “At
one p.m.,” he tells us, “the _Myrmica_ workers discovered the
hiding-place of their little companions, and two of them, in single
file, shouldered their way through the narrow passage, enlarging it as
they proceeded. As soon as the head of the first _Myrmica_ appeared in
the chamber, the _Leptothoraxes_ which had been attending to their
morning toilet and that of their larvæ, and to the careful arrangement
of their eggs, turned to meet the intruders.”
“Now dreadful deeds
Might have ensued,”
and for such an upshot, indeed, upon the first occasion, Professor
Wheeler was prepared. “For an instant,” he says, “I fully expected to
see a fierce battle, but I had misjudged the _Leptothorax_ character. To
my surprise the _Myrmicas_ on entering were received with a profusion of
shampooing, and, though sadly crowding the occupants of the little
chamber, they let themselves down comfortably, and appeared to
experience all the sensuous satisfaction of a couple of _roués_ who have
dropped into a Turkish bath for the night. Yet the little _Leptos_,
though behaving in this friendly manner” (their conduct indeed was not
more disinterested than upon other occasions), “seemed to have some dim
desire to remove the _Myrmicas_ from their nest, for from time to time
one was seen to pull with her mandibles at the fore leg or antenna of
one of the intruders, as if to remind her that there are limits to
polite hospitality.” Professor Wheeler adds that “this was the only act
even approaching hostility witnessed between the two species. The
_Myrmicas_ never showed the slightest irritation towards the _Leptos_,
never seized them in their mandibles or even menaced them. They seemed
rather to look upon the little creatures with gentle benevolence, much
as human adults regard little children. They never passed their little
guests without the antennal greeting, and the _Leptos_ shampooed their
hosts with comical zeal.”[56] The continued breaking down and repair of
the dividing wall is then described, with the conclusion that “in their
natural environment the _Leptothoraxes_ would not be cramped for space,
and would probably dig their cell where they would not so frequently be
disturbed by their inquisitive hosts.”
As regards the possible effects upon the _Myrmicas_ of having thus
frequently to render up food swallowed for their own nourishment, it
must be remembered that amongst most ants this is a thing of custom;
and, again, it seems probable that there would be an internal sense on
the part of the regurgitating individual as to concessions of this
nature having gone as far as it was healthy that they should go. As we
have seen, they are not infrequently refused. Professor Wheeler,
however, came to the conclusion that _Myrmica_ colonies suffer very
considerably from this cause, and on this he makes the following
comment: “If I have correctly estimated the influences which may tend to
diminish the fecundity and prosperity of the _Myrmicas_, we have in this
double nest another striking demonstration of the complete absence in
ants of any faculty of reason. For if the _Myrmicas_ possessed a glimmer
of this faculty they could easily annihilate the gluttonous little
nest-mates that are for ever roaming about their galleries like so many
animated stomach-pumps.”[56] Yes, truly a _most_ “striking
demonstration,” seeing that we human ants can annihilate, all in a
moment, any evil that has insensibly gained a footing amongst us, and
with which we have been familiarised from birth. Custom, growing
gradually from unnoticed beginnings, plays no part at all amongst
us—never affects our views in the very slightest degree. In Europe we
hang up all the brewers and distillers; whilst mobs of infuriated
Chinamen rend in pieces the vendors of opium and crushers of their
women’s feet. There is no such thing in _human_ nature as tolerating an
evil for the pleasure that lives in it; no _man_ ruins his health, and
sinks into an early grave, through being a slave to sensual pleasures.
Nor can what is manifestly wrong seem right to _us_; there is no
pernicious, obstinate, wilful shutting of _our_ eyes. What a contrast
does all this present with such a state of affairs as we are here
considering! And how plain it is that there can be no reasoning power in
the ant, since reason and right conduct are synonymous with man!
What is the origin of these strange co-partnerships—for there are
others—which we find existing between ants of two different species
living in the same or in one double nest? As we know, the different
species of ants are commonly very hostile to one another; and for any to
enter the nest of some other one is to court destruction, if they be not
the stronger party. Nay, they dare not even enter a strange nest of
their own species. It seems probable, therefore—this, at least, is my
own view of it—that such friendly cohabitation has come about through
the channel, not of peace, but of war—through successful encroachments
which, from being unavoidable, have come gradually to be less and less
resented, till the two parties, mingling freely, have learnt to live on
other terms. Now there are ants which live, like ogres, in the nests of
other species, preying upon their eggs and young. Such a one is
_Solenopsis fugax_—to whom we will come presently—but it is perhaps even
more interesting to find in species between whom relations of a similar
nature to those which we have been considering exist, occasional slight
traces of a mutual hostility. As between the _Leptos_ and _Myrmicas_
indeed this has only as yet been noticed, very faintly, on the part of
the former; but in regard to another pair who live together—our great
wood-ant, namely, _Formica rufa_ and tiny little _Formicoxenus
nitidulus_—Professor Wheeler remarks: “On one occasion in one of my
artificial nests, in which the ants had previously lived on good terms
with one another, I saw a _Formica_ touching a _Formicoxenus_ with her
antennæ and menacing her with her mandibles, but she departed without
even attempting to seize her. In the same nest I found a _Formicoxenus_
which had seized the leg of a _Formica_ in its mandibles and had died in
this position.”[57] Other observers, too, have from time to time—but
only very occasionally—noticed facts of the same sort. Through such
exceptional slight indications we may perhaps see, “as in a glass
darkly,” what things were at the beginning.
Let us now look at the beginning. _Solenopsis fugax_, Sir John Lubbock
tells us, “makes its chambers and galleries in the walls of the nests of
larger species, and is the bitter enemy of its hosts. The latter cannot
get at them because they are too large to enter the galleries. The
little _Solenopses_, therefore, are quite safe, and, as it appears, make
incursions into the nurseries of the larger ant and carry off the larvæ
as food. It is as if we had small dwarfs about eighteen inches to two
feet long harbouring in the walls of our houses and every now and then
carrying off some of our children into their horrid dens.”[58] This is
the general proposition. Monsieur Janet can add a few particulars. “The
_Solenopsis_,” he says, “may establish itself near almost any other ants
of our country, and is found especially with....” Here follows a list
all in Latin, but our common Wood-ant—the large one that makes those
great heaps of pine-needles—and the Amazon, or slave-making ant, are
contained in it.[59] “The _Solenopsis_ nest,” continues M. Janet, “may
partially surround that of its neighbour’s, or it may even be partly
excavated in the masses of earth which separate the galleries of the
latter. In each case—and probably, too, when, as is frequent, there is
not such close contiguity—fine connecting galleries enable the
_Solenopsis_ to make incursions into the nests of their neighbours,
where, as we shall see, they find an abundance of food. The actual nest
consists of a number of small circular chambers about 8-20 mm. in
diameter and only 6-8 mm. in height. Most of these chambers are
separated from one another by several centimetres, and are connected by
slender galleries, often less than two millimetres in diameter, entering
the chambers at their walls, ceilings, or floors, which latter are
remarkably clean, smooth, and hard.”[59]
The food of which these horrid little ants find such an abundance is, of
course, the cocoons and larvæ of their unfortunate neighbours, and M.
Janet gives the following account of the way in which they dispose of
them: “From ten to thirty of them,” he says, “climb up on to a cocoon
and cover it with little perforations which, finally, becoming
confluent, enable them to reach its contents. If it contains a pupa, the
legs and antennæ fall an easy prey to the mandibles of the _Solenopses_.
In this case the victim is cut into, sucked, and torn into very small
pieces, which the ants hasten to carry away into the interior of the
nest. The operation is much more difficult in the case of a larva which
has just spun its cocoon. Such a one I have seen the _Solenopses_ drag
into the interior of the nest and keep working at for twenty-four hours.
At the expiration of this period the larva began to look flaccid (as may
be believed), and was covered with little black dots which were,
sometimes, double, corresponding with the little wounds made by the
mandibles of its assassins. Numbers of the latter were busy lapping up
the liquid which exuded from the wounds, but it was not until thirty-six
hours had elapsed that the larva was entirely devoured.”[59] This is
certainly not a pleasant picture, yet, if our surmise is correct, the
remote descendants of these murderous _Solenopses_ may become as
harmless and as pretty in their ways as the little _Leptos_, a
reflection which goes far to discount any uncomfortable feelings we
might otherwise have been inclined to have in regard to the general plan
or scheme of things. Thus, in nature, though occasionally a slight
shadow may seem to rest upon the landscape, the next moment the very
memory of it is lost in a blaze of sunlight glory.
Forel believes that when a _Solenopsis_, and one of the larger species
of ants that it plagues, meet, the latter are unable to see it on
account of its small size, so that, practically, it is invisible. This
seems a strange doctrine, since the same ants can see smaller things;
and yet, from their behaviour under such circumstances, M. Janet is
inclined to think so too. It can hardly be that they shun combat, though
the _Solenopses_, in spite of their small size, are able, even here, by
virtue of their numbers, and being armed with stings, to meet their
victims, as one may almost call them, upon equal terms. M. Janet,
indeed, once saw so strong and warlike a species as the slave-making
_Formica sanguinea_ killed by some half-dozen _Solenopses_, but he adds
that on such occasions a considerable number of the latter were,
generally, killed also. This, however, is not sufficient to abate the
evil, so perhaps the molested species, finding that fighting is of no
use, accustomed to see _Solenopses_ from their birth, recognising, too,
as a part of their own atmosphere, the distinctive smell which they, no
doubt, possess, accept them like some disagreeable part of their lives,
and try to make the best of it.
-----
Footnote 56:
The American Naturalist, vol. 35, No. 419.
Footnote 57:
The American Naturalist, July, 1901.
Footnote 58:
Lubbock, Ants, Bees, and Wasps, pp. 78, 79.
Footnote 59:
Janet, Etudes sur les Fourmis.
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