How ants communicate

Language is essential to effective government among social creatures. Without means of communication of some sort, it would be impossible for societies to hold together and to act together in those communal movements which are alike the evidence and the end of social organizations.

Thus we infer that some way of making known the common will and aim must exist among such insects as ants, bees, wasps, and termites that maintain permanent sodalities. And so we find it in ant communes. Thus is preserved unity and efficiency, by holding the citizens together; by disseminating purposes and influences important to civic success; and by securing at once mobility of action and the concentrated force of the republic, for peaceful service, for common defence, and for aggressive enterprise.

Men commonly think of language as a vocal medium for conveying thought and emotion from one individual to others. As thus defined, insects are dumb, for they have no true voice nor organs of speech such as belong to "articulate speaking men." They also lack the means of uttering such cries as characterize birds and brutes. But if we take language as simply an understandable medium for expressing emotions, insects are thus endowed. By certain movements of the body and of parts of the body, especially the wings, antennae, and jaws, and by sounds made by various organs in sundry ways, they convey to one another the primitive and simple emotions of their hind and of all animate beings. In taking up the subject as it bears upon ants, we shall best reach such conclusions as seem at present attainable by considering it in relation to insects in general.

The language of insects may be regarded as mimetic, when emotions are expressed by gestures or acts; pteratic, when by wing vibrations; spiracular, when made known by sounds issuing from the breathing tubes or spiracles; stridulatory, when conveyed by the friction of one organ against another; and antennal, when the antennae, or "feelers," are the media of communication.

Insects express emotion mimetically - that is, by bodily gestures. Mimetic language, though more limited in its ability to convey ideas, is not less intelligible than vocal speech. Indeed, a glance of the eye, a movement of the hand, a shrug of the shoulder, a stamp of the foot, a toss of the head, may betray in man the true thought or feeling within him, even when spoken language is used to conceal it. How apt a medium mimetic language may become for expressing clearly a wide range of ideas one may see among the inmates of institutions for the deaf and dumb. We may find, perhaps, that this medium serves insects no less effectively for communication within that limited range - of ideas, shall we say? - to which their faculties are confined.

Let us stand before this oak-tree and watch a double stream of mound-making ants thronging up and passing down the well-marked trail that leads to a herd of aphides upon some oak-tree branches. The motion of a finger near the trunk attracts the attention of a sentinel, one of a number that seem to be guarding the flanks of the column. It halts, thrusts out its antennae, and shows signs of excitement. As an experiment, the finger is moved slowly within an inch or more of the ant. Its antennae wave rapidly. Its head and body jerk with eager intentness. It stretches forth its head, and reaches out its fore legs, with jaws eagerly agape and antennae quivering. The whole attitude and every bodily detail clearly express to the observer the idea of vigilance, of suspicion, of a challenge, of a purpose to repel.

As plainly as if it had spoken, the sentinel has said: "I suspect you! I test you! I bid you begone!" We onlookers understand this. Is it supposable that the ants themselves do not understand? From the tree-path we turn to the conical mound
whence these ants are issuing. It stands silent in the shadow of the tall surrounding trees, its quietude broken only by the movements of a few worker-ants, who are lazily dumping pellets of soil from one of the few upper ports. At the base of the cone, where most of the gates are located, the column stretches across the grove to the aphis-covered oak. Give the mound a sharp blow with foot or hand. What a change! Instantly the whole community is aroused. From every gate pours forth a surging torrent of irate sentinels, followed by other inmates, until, in an incredibly brief time, the mound is covered with angry insects. They run to and fro, their bodies a-quiver as they go. They challenge one another with crossed antennae.

They peer at every unusual object in their way. They startle, and stand rampant at the vibration of every sharp sound. The surface fairly buzzes with the excited creaturelings, their whole mien and attitude saying, unmistakably: " Our home has been attacked! We are in danger! Rally to the defence! Death to our enemies!". We change the field of observation. The writer was once standing before the great round web of a female Orange Argiope (Argiope aurantium), a large and handsome orbweaving spider, testing with a tuning-fork its sense of hearing, when a bee flew by in exploitation of a flowering honeysuckle vine that covered an arbor on which the web was hung. The droning of its wingstrokes as it flitted from flower to flower fell upon the ear as a token of content. To all and sundry it said, or seemed to say, what no doubt it felt: "I am a well satisfied bee!"

But in a hapless moment it touched the spider's orb. Its feet were entangled in the sticky threads. Straight way its wings began to move violently, and their buzzing, together with the attitude of the body and of every member thereof, expressed the creature's fear. These varied as the bee became more thoroughly entangled, now waxing, now waning, until the audible notes produced by its enfeebled movements seemed to utter its growing sense of danger and dread.

Meanwhile, and the interval was rarely brief, Madam Argiope underwent a striking change. She had been enjoying peacefully a dejeune of cold Diptera, taken through the fibres of a silken saclet in which her prey was encased, and which hung upon the upper part of the oval rug that overlay her central seat. But instantly the bee struck the web her whole being was transformed. She dropped her lunch bag. Her reposeful attitude was changed into one of eager animation and intense ferocity. Every spine and bristle upon her legs, her body armature, seemed to be erect, and her fangs were open. With a rush, like the vault of a cat upon a sparrow, she charged over her web, and, seizing the bee with her fore paws, shot forth upon it from her expanded spinnerets a band of silk. All the while revolving the insect between her swiftly moving fore feet, she soon had it swathed as closely as a mummy.

This done, her outward seeming of tense energy relaxed, and having suspended her empouched captive to a twisted strand of her broken snare, she left it hanging there, like a cured ham to the rafters of an oldfashioned smoke-house, and quietly resumed her interrupted luncheon on the fly. In all this, Argiope was without speech; yet her varying emotions were plainly and, one may conclude, not incorrectly, read by the observer from her motions. As for the bee, its last audible utterance was a low and broken hum that sounded like the expiring wail of apian despair.

Now entered upon this tragic scene of animated nature, man the philanthropist, his pity crossed, let it be confessed, with a strain of curiosity to know the condition of the prisoner. "Poor bee," quoth the observer," this great and greedy spider has quite enough food without you!" With a pair of pocket-scissors an opening was made into the swathing-sac. Not without protest from Argiope, however, who, feeling these movements through the delicately strung meshes of her web, feared that her prey was escaping, and rushed upon it. She was turned back by a smart tap upon the head; whereat she seized the tip of her rug and began to oscillate her snare, as though to shake off an intruder.

When this diversion had quieted down, the scissors were plied again. As the rent lengthened, the bee seemed to awake and began to stir. One leg appeared, then a wing. Thereupon issued a low hum of satisfaction, which rose into a higher note, apparently of vexation, as the body gradually appeared. At length, with a burst of limbs and wings, the insect was free. There was no mistaking the character of her emotions now; they were not jubilant. She was mad! - and was waxing madder in remembrance of the indignity put upon her. Her wings vibrated with a velocity that raised their responding sound to a high note which plainly signified wrath and vengeance. The observer, at least, understood; for instead of turning its wrath upon its captor, the bee made straightway for its liberator with sting outthrust, and with that peculiar buzz which bee familiars know as a war note.

Discretion -- in that case "the better part of valor" - justified retreat. Moreover, the quest was not quite ended. It had been determined that an insect can be captured and swathed and trussed up by a spider without impairment of aught but her temper. But it remained to see what her beeship would do ; and that soon appeared. Its pursuit of its back-stepping deliverer ended, it turned again to the honeysuckle vine, and took up its search for pollen and nectar as though life had known no "hairbreadth escapes" from deadly peril, and timely rescue therefrom. Her war note died away into the old droning hum of peaceful industry and busy contentment.

Here we have a series of actions by which two invertebrates clearly communicated their emotions. The spider passed rapidly through stages reaching from quiet enjoyment of food to intense passion of the chase and ferocity in capture, and to the repose of success when the prey was secured. Thence the course swung to rearoused energies under apprehension of loss, and to fear of some unknown superior foe when rapped by the observer, and anxiety to defend herself therefrom, as shown by shaking her web.

The bee, too, had swift transitions: from her hum of contented industry to the subdued note of resignation to her fate when shut up in her silken sarcophagus; thence to vivid reawakening to life, with her sense of injury, her blind wrath and revenge, the wish to strike at something; and so back to where the cycle began: at the song of peaceful labor. In all these stages these children of the wild betrayed their current moods to man. "There was speech in their dumbness, language in their very gestures." No careful observer of their natural actions and of the field-life of their kind can doubt that, within limits indefinite and difficult to define, like actions among the more highly organized insects are understood by one another.

Still further, it does not seem probable that the ability thus to make known their emotions is limited to such modes of expression as. human intelligence can interpret. Beyond the sphere of ideas and sentiments whose symbols men can discern, there doubtless are others peculiar to themselves, and therewith due methods of intercommunication.

In the cases above cited the actions may be said to have been simply the unconscious physical expression of natural animal impulses, without any purpose to communicate the same to another, such as language implies. Even so, it should be considered, first, that these examples are given as types of other uses of mimetic language behind which lies the undoubted purpose to communicate. And, second, that the rude evolutionary germs of language in primitive man may have been the utterance of just such impulses; and little more need be claimed for insects. It marks the impassable difference between the psychic powers of man and those of insects that human language, spoken and written, has developed into its marvellous proportions, while the symbolism of insects, and of animals generally, retains the crudity of ancestral types, and apparently can never pass beyond this bar of nature.

There was something more in this typical living tableau of the spider and the bee than "gesture language"; for the wing movements of the bee, as we shall presently note, were special media of communication. But the language of natural bodily motions may claim some further attention here. If an unarmed man be threatened by his fellow, his almost unconscious mode of expressing his feelings will be to dodge or crouch or flee; if he be afraid; or if he be brave and his combativeness be aroused; to throw himself back upon one leg and put up his fists in self-defense. Under like conditions a bear will rise upon its hams and extend its fore paws, and a horse will rear upon his hind legs and strike out with the fore legs and hoofs.

It is a long step from the primate, the ungulate, and the ruminant to the invertebrate. But let us present similar conditions to certain spiders - say, the "tarantula" of the southwestern United States. It takes a rampant position, resting upon its two pairs of hind legs, while its two front pairs, palps, and fangs are thrown up in striking posture. The same attitude may be seen in the little jumping spiders (Attidae) around our house walls and vines.

From the tarantula turn to the stream of agricultural ants of Texas, pouring over the roads that lead into their harvest fields. Fix your eye upon this worker, returning home carrying a grain of ant rice. Every motion of her body, which fairly palpitates as she hastens on, shows her sense of importance and satisfaction in service. Now tap her with your pencil point. What a transition! She instantly stops, drops her burden, and rises rampant, the fore part of her erect person declaring unmistakably that she is startled, angry, and means to fight. She thus takes her place as a link in the chain of life leading down from man, among the creatures that communicate their belligerent mood and purpose by bodily attitude and gesture.

But something more than signals and gestures appealing to the eyes met the observer of that affair between the orbweaver and the bee among the honeysuckle blooms. The bee's wings made effective appeal to his ears, and by their varying vibrations gave a fair token of her tempers. This was "pteratic language." The droning among the flowers, the quivering amid the spider's meshes, the sharp buzzing of flight after release sounded in unmistakable notes the insect's amiability, anxiety, or anger. One can detect these varying notes as he walks his garden and field while the bees are foraging among the flowers or while one watches by his beehives. So, mayhap, Shakespeare did near by Anne Hathaway's door, or while treading the pathway across
the fields from Avon to her cottage gate, and saw the busy workers, like raiding soldiers,

"Make boot upon the summer's velvet buds; The singing masons building roofs of gold."

Gardner, an English writer on the Music of Nature (1832), makes the curious statement that he was once in the gallery of the Royal Exchange to view the money dealers in the court below. He was struck not only by the likeness of the scene to the interior of a beehive, but by the similarity of the sound, the buzz of the two thousand voices being perceptibly amalgamated into the "key of F." This is the key, the author concluded, to which the most prevalent sounds of nature may be referred - a fact by which musicians have unconsciously been influenced; for scarcely an ancient composition appears in any other key, except its relative minor, for the first hundred years of the art. In Queen Elizabeth's Virginal Book of four hundred folio pages nearly all the pieces are confined to this key. There is not an instance of a sharp being placed at the clef.

According to the same author, the house-fly and the honey-bee hum in F on the first space. The bumblebee, the contra-basso of the tribe, performs the same note, but an octave lower. The present writer is able to confirm this conclusion only in part. F seems to him to be a nearly true note for the common fly as tested by his ear, unaided by an instrument. But the wing - note of bees and the general tone of a large miscellaneous company of insects humming above a bed of flowers-hydrangeas, for example - seemed to him to be A, as tested by the flute as well as by the ear.

Recently the vibration of insects' wings - their pteratic language - has been studied from the character of the note caused thereby, the pitch determining the number of vibrations on the basis of two hundred and fifty-six per second for the note C.

Tuning-forks are perhaps the most convenient instruments for such experiments, which may be made by any one who has an ordinarily good ear for musical sounds. The writer has used his flute with some measure of success. The house-fly has a wing-tone of F, or three hundred and fiftytwo vibrations per second. The honey-bee strikes A, which means that it moves its wings at the rate of four hundred and forty times a second. When, burdened with its weight of pollen, the bee is on its homestretch, its wing-tone falls to E, indicating three hundred and thirty vibrations a second.

An interesting confirmation of these results has been made by fixing a fly within a carbonized cylinder revolved by clock-work. The tips of the fly's agitated wings left at every stroke a slight mark upon the smoked surface of the glass, which, being counted, gave substantially the same result as above - viz., three hundred and thirty wing-strokes a second.

To be sure, such tones as these may be held to be a mere mechanical product or reflex; yet that they have the power to express certain ideas will be clear to one who will observe the effect produced upon a community of bees or hornets by the buzzing of one of their number when angry. The excitement runs rapidly from one to another, until many members are visibly affected. The original irate had certainly communicated her mood to her fellows. Even insects of alien species seem to understand such wing-stroke language. Let an angry hornet or yellowjacket course the suburbs of a populous ant hill, and the knowledge of her temper will be conveyed to the ants, who apparently understand that a highly keyed note is a threat which they must needs resent. It is a question how such information is conveyed; but perhaps, like a coursing motorcar, the intruder may give forth not only a hostile note but a pernicious smell!

Before entering further upon this theme, it behooves both writer and reader to remember not only the vast gulf which separates us from insects as well as the common bonds of nature that unite us to them. Entomologists have already disclosed much of the real life of the lowly creatures that share with us the earth; but we have as yet scarcely passed beyond the threshold of the temple of knowledge that Nature has reared around us. Many problems that have barely been stated remain unsolved or partly solved, though our scant knowledge might be far more complete "would men observingly distil it out."
Innumerable other problems doubtless are beyond the screen, duly to rise as the horizon of discovery shall enlarge.
What know we, for example, beyond the narrowest bounds, of the senses of ants-of their number, their quality, their range? What know we of the endless degrees of sounds and shades of color that may form the world within which insects move, familiar to them, but a terra incognita to us? May there not be a Nature within our known Nature, worlds within our knowable world - like the successive enclosures within a Chinese "nest" of boxes - of which insects know, and wherein may be their largest moiety of life? To them a wild meadow, a flower-garden, a grove, or a brook-side may be a boundless scene of beauty and activity, friendly and hostile, such as we might depict as a fairyland. Therein may be landscapes hidden from our eyes, with many grades of color, fair or grewsome, and octaves of sounds, pleasant or fearsome, that lie beyond human senses or even human fancy. Of this world, or these world-spheres, much must remain unknown to us - at least, in this cumbered state of existence. But to penetrate it further and further, to unlock its secret doors, to explore and disenchant its chambers of mysteries, and to interpret to mankind its inarticulate symbols - this is the highest function of the true natural history.