When all the columns were established and the provision trains in full movement, I leaped out and scouted round for the rest of the army. I found that the pit was only an incident. In all directions lines of ants poured past, carrying booty of all sizes and descriptions. Here and there the huge soldiers walked slowly along the outskirts, directing stragglers, looking for danger, snapping at any roach or strange ant which rushed frantically by, and holding it until it was carried off by nearby workers.
I followed a column over logs and leaves to where it ascended a cecropia tree. A harvest of small arboreal insects was being gleaned high overhead. As I watched, there came a heavy downpour of rain, a typical shower of the tropics, with a scattering of heavy drops out of the full sunshine and then a sudden clouding and a straight deluge for a few minutes. The reaction of the ants was interesting. They did not like the water, and it was comical to see them tumble over one another to get under shelter. Like the doorways of city shops in a shower, every curled-up leaf was packed, and from every crevice of bark projected sundry abdomens and hind legs for which there was no room inside. When the bearer of a large bag of booty found a convenient corner, he backed into it and left his meat sticking out in the rain.
After the shower all came forth at full speed, but for some minutes there was considerable confusion. The sluice of water had evidently washed away much of the scent which stood for guide-posts, directing signs, and pointing hands along the trail. Only after many false starts were the old pathways discovered and again traversed. In one place the ants climbed a huge log and marched along the top for six or seven yards. I timed them carefully and found that on this straightaway track their average speed was two and a half feet in ten seconds. So they covered a mile in three hours and a half, and in all the army ants I have ever watched this rate of speed never slackens; in fact, it frequently greatly increases. When hot on the scent of prey they double their usual gait.
There are as many ludicrous sights to be seen in the ranks of army ants as there are among the banner-decked processions of the leaf-cutters. Along the tree-trunk track came three big white-heads straddling an inch-worm—in this case an inch-and-a-half-worm. They leaned forward and downward, the heads of those behind overlapping the abdomens in front, and they looked for all the world like the riders of an old-fashioned three-seated bicycle, spurting along the trail. Another simile, even more vivid, evoked the vision of some weirdly constructed, elongated myriopod with eighteen legs. After a hard fight, in the course of which I was stung twice, I unseated the trio and took the measuring worm away from them. As I lifted it from where it had fallen, at least fifty ants hurled themselves at the spot, jaws snapping, trembling with violent rage. I walked ten feet away and dropped the worm in the midst of another column, and within an equal number of seconds three new white-heads had mounted it and were hustling it along—the replicas in appearance and method of the first team.
Many species of stranger ants were killed and carried off as food, but now and then I noted a most significant exception. In three different parts of the glade I saw good-sized, pale, flesh-colored ants which walked unharmed in the very ranks of the terrible host. Unharmed they were, but not wholly above suspicion, and their progress was not an easy one. For every unburdened ant which passed leaped at the pale one, antennaed it fiercely for a moment and reluctantly released it. One could read their indecision as they slowly loosened their hold, turning again and again and waving their antennæ as if to make sure that it was not better to act on their suspicion and slay at once. Finally, they always passed on. The pale ones had some strange inaudible password, some sensory parole which protected them. And their total lack of fear showed their knowledge of their immunity. Even with the added sense of sight which they possessed, they chose voluntarily to accept this dubious, reluctantly accorded friendship. But it was probable that, even if they lived in the very community or nest of the army ants, theirs was the hard-earned dependence of neutrals who were liable to be knocked down at a moment's notice, and searched for any strange, inimical scent which would spell instant death.
In one place the army column made a slight détour round a hillock of sandgrains upon which a host of tiny brown ants was laboring. I thought it remarkable that such immunity should be accorded these dwarfs, and I sought the reason. It was forthcoming at once when I gingerly lifted a big soldier with the forceps and dropped him on the ant-hill. What occurred was a replica of the usual army ant scene, but enacted as if viewed through the large end of an opera-glass. Scores of the minute brown chaps rushed forth and for a moment fairly overbore the white-headed giant. Indeed, before he could recover he was dragged partly down a sandy hole. His jaws brandished and champed, but his assailants were so small that they slipped through them unharmed. Many actually seized the jaws themselves and were hurled through the air as they snapped together. Regaining his feet, the great army ant staggered off and, fortunately for him, rolled down a slope into another column of his own kind. Here he freed himself little by little, scraping off the minute fighting browns with the help of two very small workers, whose jaws, being much less in size, were better able to grip the diminutive furies. Their assistance was half-hearted, and the odor of the dead and dying pygmies was distinctly disliked by them. They were apparently well aware of the capabilities of these small cousins, and held them in high respect. This outburst of successful defense on the part of the small ants was unexpected. I glanced back at their hill and saw them unconcernedly piling up grains as if nothing had occurred to disturb them. I wondered if, with senses perfectly attuned, with an enlarging-glass ability of observation, one might not find still lesser communities which would in their turn consider the little brown ants as giants, and on the space of a pin's head attack them and fly at their throats.
A species of silvery-gray ant which was abundant in the glade was an object of special enmity, and even after one of these was killed and being carried along, passing army ants would rush up and give it a vicious, unnecessary nip. One such ant made its escape from the hold of a small worker; but before it had taken ten steps it was actually buried under a rolling mass of army ants. The flying leap with which these athletes make their tackle would delight the heart of any football coach, although their succeeding activities belong rather to savage warfare. Termites, or so-called white ants, are, curiously enough, immune from attack. Yet these slow-moving, fat-bodied creatures would seem first-rate food, and the fight which they could put up would not stand an instant before a concerted rush of battling army ants. The saving character is doubtless odor or taste. I dropped a tunnelful of these insects in the path of the army ants and they were quite ignored, although the black-and-white-headed fellows were terribly angry and excited.
I coveted a small beetle of peculiar pattern which the ants were hurrying along, and in taking it from them I accidentally cut an army ant in two. His abdomen rolled down a small slope and caused considerable panic among his fellows. They formed a ring round it and waved their antennæ in mid-air, the scent of the blood of their own kind causing them to forget hurry and burdens and their normal activities. The front part of the ant seemed but little inconvenienced and endeavored to seize and carry the load it had dropped. Little by little it began to realize that all was not right, and after one or two attempts to turn and investigate, it ran rapidly down the trail. I made a dab at it to put it out of what seems better called inconvenience than misery, but succeeded only in bisecting the thorax, so that there remained the head and front pair of legs. These lost nothing in activity, and by means of the single pair of legs the head rowed itself rapidly along, its antennæ twiddling vigorously those of every ant it met. This was uncanny, a little too much, and I ground the fraction of ant to powder. No wonder the army ant is such a virile creature, endowed with the most extreme emotions, when, with such a small section of its anatomy remaining it can continue to show such astounding activity.
One could study for hours the interactions among the army ants themselves. More than once I saw a good-sized ant transporting one of its fellows, exactly as it would carry a bit of booty. I tried to examine this ant, and to my surprise, both attacked me ferociously. The one which was carried was neither dead, ill, nor disabled, but very much alive. I cannot even suggest an explanation of this phenomenon, as it did not seem an attempt to aid a comrade in distress.
As dusk began to settle down, I found a column of ants which must have discovered and sacked the city of some stranger ants. They were laden with ant-booty: eggs, larvæ, and dead ants by the hundred. It was comprehensible, but what I did not at first understand was a dense line of ants moving solidly in one direction, all laden with large eggs and immature ants, which they were carrying with great care. A large number of the huge soldiers patrolled the outer flanks of the column, more than I had seen with all the other traffic lines together. I realized at last that I was looking at an actual moving of a portion of the army ant household itself. It was guarded and transported with all the care of which these insects were capable. The infant ants rested safely in the great jaws, the same jaws which all day had been busy slashing and biting and tearing, and carrying food for these same infants.