PTERODACTYL PUPS led me to the wonderful Attas — the most astounding of the jungle labor-unions. We were all sitting on the Mazaruni bank, the night before the full moon, immediately in front of my British Guiana laboratory. All the jungle was silent in the white light, and only a big fish broke now and then. On the end of the bench was the monosyllabic Scot, who ceased the exquisite painting of mora buttresses and jungle shadows only for the equal fascination of searching bats for parasites. Then the great physician, who had come six thousand miles to peer into the eyes of birds and lizards in my dark-room, working with a gentle hypnotic manner that made the little beings seem to enjoy the experience. On my right sat an army captain, who had given more thought to the possible secrets of French chaffinches than to the approaching barrage. There was also the artist, who could draw a lizard’s head like a Japanese print, but preferred to depict impressionistic Laocoön roots.
These and others sat with me on the long bench and watched the moonpath. The conversation had begun with possible former life on the moon, then shifted to Conan Doyle’s Lost World, based on the great Roraima plateau, a hundred and fifty miles west of where we were sitting. Then we spoke of the amusing world-wide rumor, which had started no one knows how, that I had recently discovered a pterodactyl. One delightful result of this had been a letter from a little English girl, which would have made a worthy chapter-subject for Dream Days. For years she and her little sister had peopled a wood near her home with pterodactyls, but had somehow never quite seen one; and would I tell her a little about them — whether they had scales, or made nests; so that those in the wood might be a little easier to recognize.
When strange things are discussed for a long time, in the light of a tropical moon, at the edge of a dark, whispering jungle, the mind becomes singularly imaginative and receptive; and, as I looked through powerful binoculars at the great suspended globe, the dead craters and precipices became very vivid and near. Suddenly, without warning, there flapped into my field, a huge shapeless creature. It was no bird, and there was nothing of the bat in its flight —the wings moved with steady rhythmical beats, and drove it straight onward. The wings were skinny, the body large and of a pale ashy hue. For a moment I was shaken. One of the others had seen it, and he, too, did not speak, but concentrated every sense into the end of the little tubes. By the time I had begun to find words, I realized that a giant fruit bat had flown from utter darkness across my line of sight; and by close watching we soon saw others. But for a very few seconds these Pterodactyl Pups, as I nicknamed them, gave me all the thrill of a sudden glimpse into the life of past ages. The last time I had seen fruit bats was in the gardens of Perideniya, Ceylon. I had forgotten that they occurred in Guiana, and was wholly unprepared for the sight of bats a yard across, with a heron’s flight, passing high over the Mazaruni in the moonlight.
The talk ended on the misfortune of the configuration of human anatomy, which makes sky-searching so uncomfortable a habit. This outlook was probably developed to a greater extent during the war than ever before; and I can remember many evenings in Paris and London when a sinister half-moon kept the faces of millions turned searchingly upward. But whether in city or jungle, sky-scanning is a neck-aching affair.
The following day my experience with the Pterodactyl Pups was not forgotten, and as a direct result of looking out for soaring vultures and eagles, with hopes of again seeing a whiteplumaged King and the regal Harpy, I caught sight of a tiny mote high up in mid-sky. I thought at first it was a martin or swift; but it descended, slowly spiraling, and became too small for any bird. With a final, long, descending curve, it alighted in the compound of our bungalow laboratory and rested quietly — a great queen of the leafcutting Attas returning from her marriage flight. After a few minutes she stirred, walked a few steps, cleaned her antennæ, and searched nervously about on the sand. A foot away was a tiny sprig of indigo, the offspring of some seed planted two or three centuries ago by a thrifty Dutchman. In the shade of its three leaves the insect paused, and at once began scraping at the sand with her jaws. She loosened grain after grain, and as they came free they were moistened, agglutinated, and pressed back against her fore-legs. When at last a good-sized ball was formed, she picked it up, turned around and, after some fussy indecision, deposited it on the sand behind her. Then she returned to the very shallow, round depression, and began to gather a second ball.
I thought of the first handful of sand thrown out for the base of Cheops, of the first brick placed in position for the Great Wall, of a fresh-cut trunk, roughhewn and squared for a log-cabin on Manhattan; of the first shovelful of earth flung out of the line of the Panama Canal. Yet none seemed worthy of comparison with even what little I knew of the significance of this ant’s labor, for this was earnest of what would make trivial the engineering skill of Egyptians, of Chinese patience, of municipal pride and continental schism.
Imagine sawing off a barn-door at the top of a giant sequoia, growing at the bottom of the Grand Cañon, and then, with five or six children clinging to it, descending the tree, and carrying it up the cañon walls against a subway rush of rude people, who elbowed and pushed blindly against you. This is what hundreds of leaf-cutting ants accomplish daily, when cutting leaves from a tall bush, at the foot of the bank near the laboratory.
There are three dominant laborunions in the jungle, all social insects, two of them ants, never interfering with each other’s field of action, and all supremely illustrative of conditions resulting from absolute equality, freeand-equalness, communalism, socialism carried to the (forgive me!) anth power. The Army Ants are carnivorous, predatory, militant nomads; the Termites are vegetarian scavengers, sedentary, negative and provincial; the Attas, or leafcutting ants, are vegetarians, active and dominant, and in many ways the most interesting of all.
The casual observer becomes aware of them through their raids upon gardens; and indeed the Attas are a very serious menace to agriculture in many parts of the tropics, where their nests, although underground, may be as large as a house and contain millions of individuals. While their choice among wild plants is exceedingly varied, it seems that there are certain things they will not touch; but when any humanreared flower, vegetable, shrub, vine, or tree is planted, the Attas rejoice, and straightway desert the native vegetation to fall upon the newcomers. Their whims and irregular feeding habits make it difficult to guard against them. They will work all round a garden for weeks, perhaps pass through it en route to some tree that they are defoliating, and then suddenly, one night, every Atta in the world seems possessed with a desire to work havoc, and at daylight the next morning, the garden looks like winter stubble — a vast expanse of stems and twigs, without a single remaining leaf. Volumes have been written, and a whole chemist’s shop of deadly concoctions devised, for combating these ants, and still they go steadily on, gathering leaves which, as we shall see, they do not even use for food.
Although essentially a tropical family, Attas have pushed as far north as New Jersey, where they make a tiny nest, a few inches across, and bring to it bits of pine needles.
In a jungle Baedeker, we should double-star these insects, and paragraph them as ‘Atta, named by Fabricius in 1804; two Kartabo species, sexdens and cephalotes; Leaf-cutting or Cushie or Parasol Ants; very abundant. Atta, a subgenus of Atta, which is a genus of Attii, which is a tribe of Myrmicinœ, which is a subfamily of Formicidœ,’ etc.
With a feeling of slightly greater intimacy, of mental possession, we set out, armed with a name of one hundred and seventeen years’ standing, and find a big Atta worker carving away at a bit of leaf, exactly as his ancestors had done for probably one hundred and seventeen thousand years.
We gently lift him from his labor, and a drop of chloroform banishes from his ganglia all memory of the hundred thousand years of pruning. Under the lens his strange personality becomes manifest, and we wonder whether the old Danish zoölogist had in mind the slender toe-tips which support him, or in a chuckling mood made him a namesake of C. Quintius Atta. A close-up shows a very comic little being, encased in a prickly, chestnut-colored armor, which should make him fearless in a den of a hundred anteaters. The front view of his head is a bit mephistophelian, for it is drawn upward into two horny spines; but the side view recalls a little girl with her hair brushed very tightly up and back from her face.
The connection between Atta and the world about him is furnished by this same head: two huge, flail-shaped antennæ arching up like aerial, detached eyebrows — vehicles, through their golden pile, of senses which foil our most delicate tests. Outside of these are two little shoe-button eyes; and we are not certain whether they reflect to the head ganglion two or three hundred bits of leaf, or one large mosaic leaf. Below all is swung the pair of great scythes, so edged and hung that they can function as jaws, rip-saws, scissors, forceps, and clamps. The thorax, like the head of a titanothere, bears three pairs of horns — a great irregular expanse of tumbled, rock-like skin and thorn, a foundation for three pairs of long legs, and sheltering somewhere in its heart a thread of ant-life; finally, two little pedicels lead to a rounded abdomen, smaller than the head. This Third-of-an-inch is a worker Atta to the physical eye; and if we catch another, or ten, or ten million, we find that some are small, others much larger, but that all are cast in the same mould, all indistinguishable except, perhaps, to the shoebutton eyes.
When a worker has traveled along the Atta trails, and has followed the temporary mob-instinct and climbed bush or tree, the same irresistible force drives him out upon a leaf. Here, apparently, instinct slightly loosens its hold, and he seems to become individual for a moment, to look about, and to decide upon a suitable edge or corner of green leaf. But even in this he probably has no choice. At any rate, he secures a good hold and sinks his jaws into the tissue. Standing firmly on the leaf, he measures his distance by cutting across a segment of a circle, with one of his hind feet as a centre. This gives a very true curve, and provides a leaf-load of suitable size. He does not scissor his way across, but bit by bit sinks the tip of one jaw, hook-like, into the surface, and brings the other up to it, slicing through the tissue with surprising ease. He stands upon the leaf, and I always expect to see him cut himself and his load free, Irishman-wise. But one or two of his feet have invariably secured a grip on the plant, sufficient to hold him safely. Even if one or two of his fellows are at work farther down the leaf, he has power enough in his slight grip to suspend all until they have finished and clambered up over him with their loads.
Holding his bit of leaf edge-wise, he bends his head down as far as possible, and secures a strong purchase along the very rim. Then, as he raises his head, the leaf rises with it, suspended high over his back, out of the way. Down the stem or tree-trunk he trudges, head first, fighting with gravitation, until he reaches the ground. After a few feet, or, measured by his stature, several hundred yards, his infallible instinct guides him around pebble boulders, mossy orchards, and grass jungles to a specially prepared path.
Thus in words, in sentences, we may describe the cutting of a single leaf; but only in the imagination can we visualize the cell-like or crystal-like duplication of this throughout all the greal forests of Guiana and of South America. As I write, a million jaws snip through their stint; as you read, ten million Attas begin on new bits of leaf. And all in silence and in dim light, legions passing along the little jungle roads, unending lines of trembling banners, a political parade of ultra socialism, a procession of chlorophyll floats illustrating unreasoning unmorality, a fairy replica of ‘Birnam forest come to Dunsinane.’
In their leaf-cutting, Attas have mastered mass, but not form. I have never seen one cut off a piece too heavy to carry, but many a hard-sliced bit has had to be deserted because of the configuration of the upper edge. On almost any trail, an ant can be found with a two-inch stem of grass, attempting to pass under a twig an inch overhead. After five or ten minutes of pushing, backing, and pushing, he may accidentally march off to one side, or reach up and climb over; but usually he drops his burden. His little works have been wound up, and set at the mark ‘home’; and though he has now dropped the prize for which he walked a dozen antmiles, yet any idea of cutting another stem, or of picking up a slice of leaf from those lying along the trail, never occurs to him. He sets off homeward, and if any emotion of sorrow, regret, disappointment, or secret relief troubles his ganglia, no trace of it appears in antennæ, carriage, or speed. I can very readily conceive of his trudging sturdily all the way back to the nest, entering it, and going to the place where he would have dumped his load, having fulfilled his duty in the spirit at least. Then, if there comes a click in his internal time-clock, he may set out upon another quest — more cabined, cribbed, and confined than any member of a Cook’s tourist party.
I once watched an ant with a piece of leaf which had a regular shepherd’s crook at the top, and if his adventures of fifty feet could have been caught on a moving-picture film, Charlie Chaplin would have had an arthropod rival. It hooked on stems and pulled its bearer off his feet, it careened and ensnared the leaves of other ants, at one place mixing up with half a dozen. A big thistledown became tangled in it, and well-nigh blew away with leaf and all; hardly a foot of his path was smooth-going. But he persisted, and I watched him reach the nest, after two hours of tugging and falling and interference with traffic.
Occasionally an ant will slip in crossing a twiggy crevasse, and his leaf become tightly wedged. After sprawling on his back and vainly clawing at the air for a while, he gets up, brushes off his antennæ, and sets to work. For fifteen minutes I have watched an Atta in this predicament, stodgily endeavoring to lift his leaf while standing on it at the same time. The equation of push equaling pull is fourth dimensional to the Attas.
With all this terrible expenditure of energy, the activities of these ants are functional within very narrow limits. The blazing sun causes them to drop their burdens and flee for home; a heavy wind frustrates them, for they cannot reef. When a gale arises and sweeps an exposed portion of the trail, their only resource is to cut away all sail and heave it overboard. A sudden downpour reduces a thousand banners and waving, bright-colored petals to débris, to be trodden under foot. Sometimes, after a ten-minute storm, the trails will be carpeted with thousands of bits of green mosaic, which the outgoing hordes will trample in their search for more leaves. On a dark night little seems to be done; but at dawn and dusk, and in the moonlight or clear starlight, the greatest activity is manifest.
Attas are such unpalatable creatures that they are singularly free from dangers. There is a tacit armistice between them and the other labor-unions. The Army Ants occasionally make use of their trails when they are deserted; but when the two great races of ants meet, each antennæs the aura of the other, and turns respectfully aside. When Termites wish to traverse an Atta trail, they burrow beneath it, or build a covered causeway across, through which they pass and repass at will, and over which the Attas trudge, uncaring and unconscious of its significance.
Only creatures with the toughest of digestions would dare to include these prickly, strong-jawed, meatless insects in a bill of fare. Now and then I have found an ani, or black cuckoo, with a few in its stomach: but an ani can swallow a stinging-haired caterpillar and enjoy it. The most consistent feeder upon Attas is the giant marine toad. Two hundred Attas in a night is not an uncommon meal, the exact number being verifiable by a count of the undigested remains of heads and abdomens. Bufo marinus is the gardener’s best friend in this tropic land, and besides, he is a gentleman and a philosopher, if ever an amphibian was one.
While the cutting of living foliage is the chief aim in life of these ants, yet they take advantage of the flotsam and jetsam along the shore, and each low tide finds a column from some nearby nest salvaging flowerets, leaves, and even tiny berries. A sudden wash of tide lifts a hundred ants with their burdens and then sets them down again, when they start off as if nothing had happened.
The paths or trails of the Attas represent very remarkable feats of engineering, and wind about through jungle and glade for surprising distances. I once traced a very old and wide trail for well over two hundred yards. Taking little Third-of-an-inch for a type (although he would rank as a rather large Atta), and comparing him with a six-foot man, we reckon this trail, ant-ratio, as a full twenty-five miles. Belt records a leaf-cutter’s trail half a mile long, which would mean that every ant that went out, cut his tiny bit of leaf, and returned, would traverse a distance of a hundred and sixteen miles. This was an extreme; but our Atta may take it for granted, speaking antly, that once on the home trail, he has, at the least, four or five miles ahead of him.
The Atta roads are clean swept, as straight as possible, and very conspicuous in the jungle. The chief high-roads leading from very large nests are a good foot across, and the white sand of their beds is visible a long distance away. I once knew a family of opossums living in a stump in the centre of a dense thicket. When they left at evening, they always climbed along as far as an Atta trail, dropped down to it, and followed it for twenty or thirty yards. During the rains I have occasionally found tracks of agoutis and deer in these roads. So it would be very possible for the Attas to lay the foundation for an animal trail, and this, à la calfpath, for the street of a future city.
The part that scent plays in the trails is evidenced if we scatter an inch or two of fresh sand across the road. A mass of ants banks against the strange obstruction on both sides, on the one hand a solid phalanx of waving green banners, and on the other a mob of empty-jawed workers with wildly waving antennæ. Scouts from both sides slowly wander forward, and finally reach one another and pass across. But not for ten minutes does anything like regular traffic begin again.
When carrying a large piece of leaf, and traveling at a fair rate of speed, the ants average about a foot in ten seconds, although many go the same distance in five. I tested the speed of an Atta, and then I saw that its leaf seemed to have a peculiar-shaped bug upon it, and picked it up with its bearer. Finding the blemish to be only a bit of fungus, I replaced it. Half an hour later I was seated by a trail far away, when suddenly my ant with the blemished spot appeared. It was unmistakable, for I had noticed that the spot was exactly that of the Egyptian symbol of life. I paced the trail, and found that seventy yards away it joined the spot where I had first seen my friend. So, with occasional spurts, he had done two hundred and ten feet in thirty minutes, and this in spite of the fact that he had picked up a supercargo.
Two parts of hydrogen and one of oxygen, under the proper stimulus, invariably result in water; two and two, considered calmly and without passion, combine into four; the workings of instinct, especially in social insects, is so mechanical that its results can almost be demonstrated in formula; and yet here was my Atta leaf-carrier burdened with a minim. The worker Attas vary greatly in size, as a glance at a populous trail will show. They have been christened macrergates, desmergates and micrergates; or we may call the largest maxims, the average middle class mediums, and the tiny chaps minims, and all have more or less separate functions in the ecology of the colony. The minims are replicas in miniature of the big chaps, except that their armor is pale cinnamon rather than chestnut. Although they can bite ferociously, they are too small to cut through leaves, and they have very definite duties in the nest; yet they are found with every leaf-cutting gang, hastening along with their larger brethren, but never doing anything, that I could detect, at their journey’s end. I have a suspicion that the little minims, who are very numerous, function as light cavalry; for in case of danger they are as eager at attack as the great soldiers, and the leaf-cutters, absorbed in their arduous labor, would benefit greatly from the immunity ensured by a flying corps of their little bulldog comrades.
I can readily imagine that these nestling minims become weary and foot-sore (like bank-clerks guarding a reservoir), and if instinct allows such abominable individuality, they must often wish themselves back at the nest, for every mile of a medium is three miles to them.
Here is where our mechanical formula breaks down; for, often, as many as one in every five leaves that pass bears aloft a minim or two, clinging desperately to the waving leaf and getting a free ride at the expense of the already overburdened medium. Ten is the extreme number seen, but six to eight minims collected on a single leaf is not uncommon. Several times I have seen one of these little banner-riders shift deftly from leaf to leaf, when a swifter carrier passed by, as a circus bareback rider changes steeds at full gallop.
Once I saw enacted above ground, and in the light of day, something which may have had its roots in an Anlage of divine discontent. If I were describing the episode half a century ago, I should entitle it, ‘The Battle of the Giants, or Emotion Enthroned.’ A quadruple line of leaf-carriers was disappearing down a hole in front of the laboratory, bumped and pushed by an out-pouring, empty-jawed mass of workers. As I watched them, I became aware of an area of great excitement beyond the hole. Getting down as nearly as possible to ant height, I witnessed a terrible struggle. Two giants — of the largest soldier maxim caste — were locked in each other’s jaws, and to my horror, I saw that each had lost his abdomen. The antennæ and the abdomen petiole are the only vulnerable portions of an Atta, and long after he has lost these apparently dispensable portions of his anatomy, he is able to walk, fight, and continue an active but erratic life. These mighty-jawed fellows seem never to come to the surface unless danger threatens; and my mind went down into the black, musty deqths, where it is the duty of these soldiers to walk about and wait for trouble. What could have raised the ire of such stolid neuters against one another? Was it sheer lack of something to do? or was there a cell or two of the winged caste lying fallow within their bodies, which, stirring at last, inspired a will to battle, a passing echo of romance, of the activities of the male Atta?
Their unnatural combat had stirred scores of smaller workers to the highest pitch of excitement. Now and then, out of the mêlée, a medium would emerge, with a tiny minim in his jaws. One of these carried his still living burden many feet away, along an unused trail, and dropped it. I examined the small ant, and found that it had lost an antenna, and its body was crushed. When the ball of fighters cleared, twelve small ants were seen clinging to the legs and heads of the mutilated giants, and now and then these would loosen their hold on each other, turn, and crush one of their small tormenters. Several times I saw a medium rush up and tear a small ant away, apparently quite insane with excitement.
Occasionally the least exhausted giant would stagger to his four and a half remaining legs, hoist his assailant, together with a mass of the midgets, high in air, and stagger for a few steps, before falling beneath the onrush of new attackers. It made me wish to help the great insect, who, for aught I knew, was doomed because he was different — because he had dared to be an individual.
I left them struggling there, and half an hour later, when I returned, the episode was just coming to a climax. My Atta hero was exerting his last strength, flinging off the pile that assaulted him, fighting all the easier because of the loss of his heavy body. He lurched forward, dragging the second giant, now dead, not toward the deserted trail or the world of jungle around him, but headlong into the lines of stupid leaf-carriers, scattering green leaves and flower-petals in all directions. Only when dozens of ants threw themselves upon him, many of them biting each other in their wild confusion, did he rear up for the last time, and, with the whole mob, rolled down into the yawning mouth of the Atta nesting-hole, disappearing from view, and carrying with him all those hurrying up the steep sides. It was a great battle. I was breathing fast with sympathy, and whatever his cause, I was on his side.
The next day both giants were lying on the old, disused trail; the revolt against absolute democracy was over; ten thousand ants passed to and fro without a dissenting thought, or any thought, and the Spirit of the Attas was content.