The Trailhead Queen was dead. At first, there was no overt sign that her long life was ending: no fever, no spasms, no farewells. She simply sat on the floor of the royal chamber and died. As in life, her body was prone and immobile, her legs and antennae relaxed. Her stillness alone failed to give warning to her daughters that a catastrophe had occurred for all of them. She lay there, in fact, as though nothing had happened. She had become a perfect statue of herself. While humans and other vertebrates have an internal skeleton surrounded by soft tissue that quickly rots away, ants are encased in an external skeleton; their soft tissues shrivel into dry threads and lumps, but their exoskeletons remain, a knight’s armor fully intact long after the knight is gone. Hence the workers were at first unaware of their mother’s death. Her quietude said nothing, and the odors of her life, still rising from her, signalled, I remain among you. She smelled alive.
The deception was made easier by the fact that in life she had never given orders or led them in activities of any kind—even though she could have performed all their tasks if she chose. She had taken the only initiatives she ever took all in a burst, at the beginning of her adult life, when she had abandoned the colony of her birth and, along with it, her mother and her sisters. First, she had spread her four membranous wings and flown into the air. There, she’d joined a swarm of flying males and other virgin queens. One of the males had caught her. He’d clamped his legs around her body, and the couple had spiralled down to the ground. On landing, he had used the large claspers at the rear end of his body to hold their genitalia together as he completed the insemination. Within five minutes, the act was finished, and the queen shook the male loose. All the sperm she had received flowed up into a special bag-shaped organ in her abdomen, where it would stay until called on to fertilize her eggs. It might last for years into the future. Each sperm was endowed with a potential life span equal to her own.
In contrast, the father of all her children was programmed to die almost immediately after the mating. The only thing that he had ever done was accept meals regurgitated to him by his sisters, as if he were a nestling bird, and wait, and wait some more, and finally take the one short flight from his home, followed by five minutes of copulation. In other words, the male was no more than a guided missile loaded with sperm, his life’s work a single ejaculation. Afterward, he was left with only one instruction, to be enforced if necessary by his sisters: Don’t come back. He had been issued a one-way ticket. He had no chance at all of survival. A delicate creature, he could not find food, or feed himself if he stumbled across some. He would die by dehydration, or crushed in the beak of a bird, or chopped into pieces by the jaws of an enemy ant, or, less quickly, pierced by the bloodsucking proboscis of an assassin bug.
To escape the same fate, the newly mated future Queen of the Trailhead Colony, full-brained and powerfully muscled, hurried to find shelter. She had to get back underground as quickly as possible. First, however, she had to take a few minutes to shed her wings. To do that, she simply bent her middle legs forward, pressed them against the base of the wings, and snapped them off. This mutilation caused no injury to the rest of her body; it caused no pain. The Queen was a parachutist who slipped her harness upon landing. Now she could move more quickly to avoid the ants, spiders, and other predators hunting around her in the grassroots jungle.
Soon she came upon an open space between grass clumps, a small clearing at the Lake Nokobee trailhead. By luck she had found an ideal site to build a nest. She began at once to dig a vertical tunnel in the sandy clay soil. Her movements were swift and precise, and within minutes she had deepened the shaft to more than her body length. This provided her some degree of protection, but she needed to proceed as quickly as possible. Her life remained in constant danger.
At a predetermined depth, which she measured by the time it took her to climb up and down the shaft, the young Queen turned to the side and began to excavate a wider space. She continued until she had fashioned a round chamber about three times wider than the vertical shaft. Her safety was now enhanced but not insured. Predators and marauding ants could still climb down the shaft to attack her. But at least now the enemies would be confined to a narrow space by the walls of the shaft and forced to confront the young Queen’s thrusting stinger and snapping jaws head on before they could reach her vulnerable body.
Even with the excavation of the first chamber complete, the Trailhead Queen had heavy work ahead. First, she laid a small cluster of eggs on the earthen floor. These tiny objects she was compelled to lick continuously. It was an urgent task: to the peril from enemies above was now added the threat of bacteria and fungi teeming in the soil all around her. If the eggs were not regularly cleaned and coated with antibiotic saliva, they would soon be overgrown by an invading mold and consumed. From a single bacterium in the soil, millions could proliferate on any ant tissue left unprotected.
But the dice fell right for the Queen of the Trailhead Colony. As tiny larvae hatched from her eggs, she fed them food secreted from a large gland that partly filled her head and emptied through her mouth. This baby food was manufactured from her own fat stores and was created by the metabolism of her now useless wing muscles. From the reserves of her own body, the young Queen reared a dozen workers. All were female. They were tiny and weak, barely able to perform the work necessary for the little colony to survive. By necessity, they came into the world as midgets. If each had been larger, fewer of them could have been reared—too few to provide sufficient labor for the survival of the newborn colony.
Some of these pioneers, guided entirely by instinct, because no one existed to teach them, set out to forage for food. Others took care of the Queen and reared the next generation of workers to maturity. Still others devoted time to enlarging the nest. Failure to perform all these tasks with exactitude would have meant death for the colony. The young Queen could no longer help. She herself desperately needed help to continue living. Her expendable body tissues were depleted. They had almost all been fed to the larval daughters, and now she was starving.
The first foragers venturing timidly away from the nest were able to bring back a few scraps of food. Their prizes included a fallen mosquito, a bit of shed caterpillar skin, and a newly hatched spiderling, which was enough to keep the colony alive and allow the Queen to regain some of her weight and strength. The workers of the next generation, raised on food harvested from terrain outside the nest, were somewhat larger and stronger than the first generation. They began to dig out more tunnels to accommodate the growing population. As the colony expanded, its home became a labyrinth of chambers and connecting galleries—an enemy-proof fortress. A mound of excavated soil formed above it, reinforcing the roof and retaining the warmth of the sun.
As the months passed, the Queen, growing heavy with egg-filled ovaries, retreated ever deeper into the earth, distancing herself from the still dangerous nest exterior. She had become an extreme specialist: she laid eggs, while the workers performed all the labor necessary to raise her offspring, their sisters. They were the Queen’s hands and feet and jaws, and increasingly they replaced her brain. They functioned together as a well-organized whole, dividing up the tasks without regard to their own welfare. The Trailhead Colony began to resemble a large, diffuse organism. In a word, it became a superorganism.
By the time the colony had reached its full mature size, two years after the nuptial flight of the Queen, it contained more than ten thousand workers. It was able, in the following year, to rear virgin queens, and males, and through them to give birth to new colonies. By that time the Queen was producing eggs at the average rate of one every fifteen minutes. Heavy and torpid, she lay in the royal chamber at the bottom of the subterranean nest, five feet below the surface, a distance of four hundred ant lengths. By human scale, the ant city was the equivalent of two hundred underground stories. The mound of excavated soil capping the nest added another fifty stories aboveground.
The Queen may not have been the leader of this miniature civilization, but she was the fountainhead of all its energies and growth, the key to its success or failure. The metronomic pumping out of fertilized eggs from her twenty ovaries was the heartbeat of the colony. The ultimate purpose of all the workers’ labor—their careful construction of the nest, their readiness to risk their lives in daily searches for food, their suicidal defense of the nest entrance—was that she continue to create more altruistic workers like themselves. One worker, or a thousand workers, could die and the colony would go on, repairing itself as needed. But the failure of the Queen would be fatal.
Now, after twenty more years, the catastrophe had occurred. The death of the Queen was the greatest challenge the colony had faced since the days of its founding. Yet the workers could not take action until they were certain that the Queen was dead. Already, they knew that something was not right, that something unnamed had settled upon them, but they did not yet realize the extent of the problem. So the Trailhead Colony thrummed on for a while longer with bustle and precision. Like a large ship at sea, it could not be easily diverted from the shoals in front of it.
Because ants live most of their lives in underground darkness, they cannot communicate through sight or sound. Pheromonal, they think only in taste and smell. The members of the Trailhead Colony transmitted their messages using about a dozen chemical signals, which they picked up by smelling one another constantly with sweeps of their antennae. An ant who was well fed said to a less well-fed nest mate, Smell this, and if you are hungry eat. If the ant approached and was in fact hungry, she extended her tongue, and the donor ant rewarded her by regurgitating liquid directly into her mouth. When a wood thrush flew by the Trailhead mound carrying a grasshopper to her own nest and dropped part of the crushed insect to the ground, a patrolling worker found it in less than a minute and triggered a chain action. The worker examined the grasshopper, tasted it briefly, then ran back to the nest entrance. On the way, she touched the tip of her abdomen repeatedly to the ground, laying down a thin trail of chemicals. Entering the nest, she rushed up to each nest mate she passed, brushing her face close to theirs. With their antennae, her nest mates detected both the trail substance and the smell of grasshopper. The signals now proclaimed, Food. I have found food. Follow my trail! Soon a mob of ants ran out, followed the trail, and gathered around the delicious grasshopper haunch. Some of the first to arrive ran back to the nest, laying trails of their own, reinforcing the message, saying, Come on, come on, we need help. The ants still by the grasshopper piece began to drag it toward the nest entrance. A catbird perched on the branch of a nearby tree saw the activity and swept down to investigate. She pecked at the grasshopper, scattering the ants and injuring several. The ants expelled a pheromone from a gland that opened at the base of their jaws. A chemical vapor spread fast. It shouted, Danger! Emergency! Run!
And so the business of the Trailhead Colony was conducted. Messages were created, sometimes with a single chemical substance, sometimes with the same substance at different concentrations, and on occasion with two or more in combination. Meanings changed according to where the substances were delivered. Some signals, such as the alarm pheromones, spread and faded fast, drawing the attention of nest mates locally, but not persevering long enough to create panic throughout the colony. Some odors spread slowly and lasted a long time. Among these were the royal pheromones of the Trailhead Queen. Even as her body began to decay, the pheromones she had manufactured in life persisted in the minds and bodies of her colony.
Her visual appearance, her stillness, meant nothing. The Queen could have lain on her back with her legs held rigidly up in the air. She could have turned red, black, metallic gold, or any other hue or shade—it would not have mattered. The Queen had to smell dead in order to be classified as dead. And not from the blends of substances in corpses which are repellent to the human nose—not, for example, from the loathsome skatole and indole that distinguish human feces, nor the trimethylamine that rises dramatically from spoiled fish. Such chemicals, when encountered alone, would have caused alarm in the ants, but only oleic acid and its ester, which are the products of fat decomposition, were effective messengers of death. These substances, when encountered on the corpse of a nest mate, caused the ants to pick it up and carry it away for disposal.
Within a week, the constant licking of the royal corpse in the Trailhead Colony began to break it into pieces. The pheromones that had bonded the Queen to the workers now hastened her funeral. One by one, the fragments, reeking of oleic compounds, were carried out of the royal chamber. Unknowingly, the ants bade farewell to their mother. No ceremony was performed. Instead the workers bearing the body parts wandered alone through the nest galleries in search of the Trailhead cemetery. This place had no special shape, nor did it contain any token of remembrance, even for a queen. It was merely a chamber at the periphery of the underground nest. The ants dumped all kinds of debris into it, including discarded cocoons shed by newly emerged adults, inedible pieces of prey, and deceased colony members. When the corpse carriers came close to the refuse chamber, they turned their burdens over to cemetery workers. These specialists were ants who constantly rearranged and added to the refuse piles. They stayed close to their work and were for the most part avoided by their nest mates.
In cemetery work and all other activities, the guiding principle of the Trailhead Colony was self-sacrifice. The dominance of the colony over its individual members was total. A worker’s life story was programmed to be subordinate to the superorganism’s needs. If a worker died, the colony was weakened to some measurable but relatively inconsequential extent; the deficit could be quickly made up by rearing another worker in the nursery. If, on the other hand, a worker behaved selfishly, consuming for a good part of her life more resources than she contributed, this weakened the colony far more than if she had the decency to desert or die.
The colony’s members had given up the chance to reproduce, at least as long as the Queen was alive and healthy. They willingly accepted tasks—foraging, soldiering—that would almost certainly lead to early death. The sick and the injured did not seek help; they moved on their own to the outermost nest chambers. Dying workers often left the nest completely, thereby avoiding the spread of infectious diseases. Older workers who were healthy but approaching the end of their natural life span also emigrated to the nest perimeter. From there, they often became foragers, exposing themselves to a much higher risk from enemies. When defending the nest, the elders were among the most suicidally aggressive. They were obedient to a simple truth that separates our two species: humans send their young men to war; ants send their old ladies.
Within two weeks, the Queen’s chemical signals had dropped to a hardly detectable level in the outermost reaches of the nest, and the Trailhead myrmidons understood instinctively that they were in trouble. The workers began to change in subtle ways. Even when the Queen was still alive, the thinning of her pheromones had caused alterations in the bodies of the young soldiers headquartered in the nest. The largest members of the worker caste, the soldiers had massive heads with powerful muscles and sharp-toothed jaws like serrated wire cutters. They were the iron, the physical power, the viciousness of the colony. Usually, they served only to defend the nest from intruders or to guard large food sources against rival colonies. But they also had the ability to reproduce. Their capacious abdomens contained half a dozen ovaries that could produce eggs. Amazons all, they could adapt from warriors to mothers.
When they were no longer inhibited by the Queen’s pheromones, the soldiers began to release hormones that stimulated growth in their ovaries. Abandoning their regular duties, they moved deeper into the nest, closer to the dwindling piles of larvae and pupae. As the last shards of the old Queen’s body were carried into the cemetery, several of her rival successors began to lay eggs. They were now soldier-queens, and the only hope that the colony had of re-starting its own growth. Their fertility might renew the energy of the Trailheaders, but would it save the colony? The ants could not know. All they could do was react.
The ordinary workers accepted the new status of the soldier-queens. Their tolerance represented a profound shift in the behavior of the colony as a whole. If the Queen had remained alive and well, and continued to broadcast her special scent, the response to any usurper would have been swift and violent: to reproduce in the presence of a healthy queen is strictly forbidden. The odds against the success of such an affront to authority are long, the gamble is dangerous, and only a very few make the attempt. When a usurper starts to lay her own eggs and place them among those of a healthy queen, or when she merely becomes capable of doing so, she is harassed by her nest mates. Her sisters refuse to regurgitate food to her. They stand over her, pulling at her legs and antennae. They may use their stingers to cripple or kill her, or spray her with a poisonous secretion. And they eat any eggs that she manages to lay. Only when the queen dies is the taboo lifted—and then only for a few individuals.
But now a second crisis arose. The candidate royals began to quarrel among themselves for control. They converged on the brood chambers and jostled for position there. They struggled to climb on top of their rivals. The winners in these encounters seized their opponents’ legs and antennae and dragged them away. Unlike their thousands of ordinary nest mates, they recognized one another as individuals. In time a dominance hierarchy formed, similar to a pecking order among chickens and rank orders among wolves. The Trailhead female who emerged as the alpha contender—in other words, the one who was able to chase away all her rivals—won the reproductive role. Egg-laying and larval growth resumed in a reduced but orderly manner.
If the Trailhead Colony could not understand the history of its own species, how much did it understand of its current condition? How could it make the right decisions for survival? In fact, the Trailhead Colony knew a great deal. Worker ants are far more than automated specks running around on the ground. Even with a brain one-millionth the size of a human’s, an ant can learn a simple maze half as fast as a laboratory rat, and remember the directions to as many as five different destinations when she forages away from the nest. After exploring a new terrain, a worker can integrate all the seemingly haphazard twists and loops she made and, amazingly, return to the nest in a straight line. She can learn and recall the special odor of the colony to which she belongs. The Trailhead Colony, when all the learning and thought of its workers came together, was very smart, by insect standards—and, with the unifying power of its Queen lost and its population growth plummeting, it needed to call on that group intelligence to regain its balance.
When one of the soldier-queens dominated its rivals and became the new queen, the recovery of the colony seemed to be under way. A stream of eggs was laid. Larvae began to fill the empty brood chambers. Their odor and hunger signals joined with the pheromones of the new Soldier-Queen and spread through the nest. The power was returning. More foragers took the field.
The renewed activity was short-lived, however. The colony was doomed by a hereditary trait even more basic than the altruism of the workers and the pheromonal ties that bound them together. The Trailheaders, along with all ants of all kinds that have ever existed, back to the birth of ants, in the late Jurassic period, used a strange but elegant genetic method to fix the sex of an individual at birth. Fertilized eggs develop into females, which can become queens or workers, and unfertilized eggs develop into males, which can do nothing but inseminate females. The Soldier-Queen had never mated. Her children all arose from unfertilized eggs and were therefore male drones, contributing nothing to the welfare of the colony. They had weak mandibles and small brains but huge eyes and genitalia. They were wondrously adapted for mating after flying up in the air with virgin queens, but even if they managed to accomplish this it would do nothing for the Trailhead Colony. The males created by the Soldier-Queen would not mate with her or with other potential soldier-queens. They were programmed to mate only during nuptial flights away from the nest.
No way out existed for the Trailhead Colony. The linchpin of its existence was gone and could not be replaced. The colony could for a while contribute, through its production of males, to the gene pool of the population of colonies all around it, and in that way eke out one last bit of Darwinian profit. But it could do nothing more for its own physical existence. With each passing day it became more vulnerable. Its territory and even its flesh were coveted by others. Neighboring colonies were likely to learn of its decline, and when that happened there would be war.
For years, the Trailhead nest had been protected by a ten-thousand-member force. Fifteen per cent of its adult members were soldiers. A soldier’s exoskeleton, twice the size of that of an ordinary worker, is literally heavy armor: thick, tough, and pitted in places for resilience and strength. A pair of spines project backward from the midsection of the body to protect the waist. Spikes protect the neck, and the rear margin of the head is curved forward, forming a helmet. When attacked, the soldier can pull in her legs and antennae and tighten up the segments of her body, turning her entire surface into a shield. The ordinary Trailhead workers, while built for labor, were also available for combat. They served as the light infantry, using the swiftness and the agility of their supple bodies to dart in and out of enemy lines, seizing any leg or antenna available, and holding onto it until their nest mates could close in and grab another body part. When the adversary was finally pinned and spread-eagled, others piled on to bite, sting, or spray her with poison.
But now the number of able-bodied adults had begun to dwindle, and the survivors were growing old. The decline of the colony was being observed by its closest neighbor, the Streamside Colony, a younger and now more powerful superorganism. Early one morning, an élite Streamside worker, followed by a squad of her nest mates, left her home to assess the strength of the Trailhead Colony. (About ten per cent of the worker force in any colony earns élite status, by initiating more tasks and working harder and more persistently than the other ants.) As the élite scout left on her journey, she remembered the route more or less precisely. She had been to the Trailhead territory before, and she carried a compass in her head, using the sun as a lodestar. This reliance on the sun could have been the source of a huge error for an ant, because the sun travels across the sky, its angle constantly changing. However, each ant also has a biological clock, set to the twenty-four-hour cycle and run with a precision far beyond the capacity of an unaided human brain. Using her clock, the scout was able to adjust her trajectory and stay on track. She was also guided by the prominent features of the landscape that she had memorized during earlier trips. A pair of pine seedlings were one such signpost, a circular opening in the canopy a second, a dark shadow beneath a holly shrub a third. Then there was the odor terrain, parts of which the scout had memorized on earlier trips. As the ground rushed by two millimetres beneath her body, she turned her antennae downward, enough to almost touch the earth, and swung them from side to side. The odors she detected as she ran, specific in their mixture, intensity, and gradient, gave her detailed information about her location and direction of travel. They were her combined field guide and topographic map.
The Streamside scout was heading in the direction of the enemy nest but not to the nest itself. She consciously came to a halt at a flat, open area halfway there. On arriving, she mingled with her nest mates and—an extraordinary event for ants—she and the others also mingled freely with some scouts from the Trailhead Colony. After a short time, the representatives from the two colonies began to perform a kind of dance together, though they were not performing in any human sense of the word. The scouts were gathering information that would allow them to assess the strength of the opposing colony; they were also trying to advertise their own strength, without risk of injury or death. The dance, in short, was a highly formalized probe.
At the time of this tournament, the Streamside Colony was at its peak. The Streamside Queen was only six years old, the equivalent of thirty years in a human life span. She was in her prime, bursting with eggs, and she reeked of sweet-smelling royal pheromone. Her colony’s nest was on firm, productive ground at the edge of an undisturbed patch of deciduous scrub woodland. Close by in the woods a small stream gave the nest protection on one side. On the other side, a miniature ravine dropped away, too steep to harbor the nests of potential rivals. The Streamsiders had not chosen this site for their own protection. They were just lucky that their Queen had landed there.
As the Streamside scouts gathered in the arena, they found their Trailhead counterparts assembling in almost equal numbers. A few climbed up onto pebbles to serve as sentinels. The first scouts on both sides to encounter the enemy ran home to recruit reinforcements, laying odor trails to excite and guide their nest mates and carrying faint smears of the enemy’s odor on their own body surfaces to identify the opposition. Within an hour, hundreds of ants from both colonies were milling around, and the original scouts, all of whom were relatively small and thin, had been joined by contingents of the more massively built soldier ants.
The opposing forces were careful not to start a battle. Their displays were the equivalent of military parades, designed to impress the enemy, to persuade her of their numbers and their strength. As the tournament unfolded, the individual performers made themselves appear as large as possible. They inflated their abdomens by pumping them full of fluid. They straightened their legs to form stilts and strutted around every foreign worker they encountered—sometimes bumping against one. Other ants posed on pebbles, exaggerating their size even more. They never threatened to attack. A few small workers served as counters, trying to estimate the size of the enemy’s soldier force. The larger the force, the more intense the effort the counters made to attract others from their own colony to the tournament. A weakness in their recruiting effort was a signal of their colony’s weakness.
Even before the death of the Trailhead Queen, and increasingly now that she was gone, the military pomp of the Trailhead Colony was in decline. As the tournaments continued on a daily basis, the Trailheaders gradually and carefully pulled back from the first territorial boundary where the military parades had taken place and tried to start the tournaments closer to home, where their soldiers could be called more quickly to the field. But this tactic did not fool the Streamside scout and her front-line nest mates, who pushed even harder and mounted increasingly conspicuous displays. There was nothing that the Trailheaders could do but continue to pull back, day after day, thereby ceding swathes of their foraging territory.
The retreat was not in itself a defeat. There was still a chance that the Trailheaders might eke out a victory, or at least force a draw. Closer to their nest, they could recruit whatever reinforcements were available on a minute-to-minute basis. The Streamsiders were forced, on the other hand, to accept a disadvantage. They had to travel almost the entire distance between the two nests in order to continue the tournaments. With the lines of communication stretched so far, the adjustments made by the Streamsider force were slow and inaccurate. The weaker Trailheaders came close to striking a balance. If that occurred, they might hold their opponents in place indefinitely, perhaps all the way to the end of the foraging season. The loss of part of their territory would be an acceptable price for their own survival.
After three weeks, the Trailheaders had surrendered all the territory that lay between them and the Streamside Colony. There was a possibility that this conquest would be enough for the Streamsiders. They had achieved a great victory without the loss of a single life on either side. If they called off the tournaments now, a long standoff—a Pax Formicana, so to speak—might come to the two domains. Peace with honor was not, however, the way of the Nokobee anthills, and the Streamside dancers suddenly switched to an all-out attack on the Trailhead Colony. No more propaganda for them, no more bluffing.
The assault began as an unplanned chain reaction among the Streamside players. Increasingly excited by the competition, they came closer and closer to the threshold that separates hostile display from overt combat. They circled around the Trailheaders more tightly, bumping harder and more frequently. Finally, when the Trailheaders had been crowded into a space only several feet wide in front of their nest mound, a Streamside worker—the original élite scout—single-handedly began the war. She attacked the first Trailheader she encountered, spraying her with a combination of alarm pheromones and poisonous secretions. The odor of these materials galvanized the nest mates closest to her. They launched an attack of their own. Two workers in combat quickly led to four, four to eight, and onward, spreading violence exponentially through the assembled Streamsider ranks. Some of the Trailheaders quickly broke away from the battle and rushed back to their nest to recruit reinforcements. Others responded to the attack by fighting back.
Soon the battle was a furious and deadly melee. The Trailheaders were too weak to hold their ground. The Streamsiders drove through the dissolving mass of defenders, attacking each one they could catch. All the ants had now abandoned the tournament mode, deflating their abdomens and relaxing the stiltlike stiffness of their legs. Fighters on both sides climbed on top of their opponents, seizing legs and antennae with their sawtooth jaws, gnashing and stinging whatever vulnerable body parts they could reach.
Soon dead and dying workers from both sides littered the battlefield. Most of the casualties were Trailheaders. Many of the surviving Trailheaders gave up combat and retreated into the nest. Those who hesitated were run down and killed as though they were prey. They were, in fact, prey. Their bodies were treated like those of subdued grasshoppers and caterpillars. After battle, the dead and the injured were collected and eaten by their conquerors.
The defense of the Trailhead Colony collapsed completely within a half hour. A few of the survivors, dodging their pursuers, ran back and forth between their nest and the main battle site, trying to measure the magnitude of the disaster. The last among them finally pulled back into the nest entirely. As they neared the entrance, a few turned and continued the fight, keeping the area immediately around the entrance clear of the enemy. With the help of others, they then dragged in nearby pieces of soil, charcoal, and leaf litter, and piled them up to form a plug in and on top of the entrance until the Trailhead nest was a sealed and hidden bunker. The victorious Streamside army poured over its surface, and some pressed on to explore the newly conquered land beyond.
The siege of the Trailhead nest had begun. During the next day, and for days to follow, Trailhead foragers slipped out for brief periods to search for whatever scraps of food had been overlooked by the Streamside patrols combing the area. Some were caught; some were killed. Others retreated too quickly to be successful in their foraging. Within a week, the colony began to starve. The nurse ants killed and cannibalized the last of the larvae and pupae, their own baby nest mates, and regurgitated their liquid and tissue to other adults. Finally, no reserves were left except the dwindling fat in the bodies of the huddled survivors.
The end approached quickly for the Trailhead Colony. Streamside scouts converged on the shielded entrance of the Trailhead nest and attacked it. Trailhead soldiers poured out of the entrance in a last desperate effort to protect their home. In the tumult that followed, many fighters on both sides were killed or crippled. Finally, the weakened Trailheaders began to pull back. One by one, the workers gave up their resistance, turning away and running down the main gallery and into the lateral galleries and chambers deep in the nest. The Trailhead soldiers, however, did not retreat. They regrouped instead, forming a tight circle around the nest entrance with their heads facing outward, ready to fight to the last ant. Their snapping jaws held off the attackers into the late-afternoon hours. For a while, it appeared that they had succeeded in reversing the battle. As the light faded, the Streamsiders, true to the biological clock of their species, pulled away and returned home.
But the withdrawal was not a retreat by the Streamsiders; nor was it a victory for the Trailheaders. In the confusion that reigned through the night, the Trailhead Colony felt—it knew—that it was in extreme difficulty. It had no conception of defeat, but the nest interior was filled with the odor of alarm and recruitment pheromones released by both sides during the attempted Streamsider break-in. The fighters were contaminated by the alien odor of the invaders. They could see the battle flags of the enemy, so to speak; they could hear the continuous shriek of alarms.
Agitated ants ran back and forth through the rooms and galleries of the nest, to no special purpose. The colony was not yet aware of the ultimate meaning of its own mood and actions, but it was instinctively preparing for one last maneuver, a final, almost suicidal response that might yet save some of its members. The only option that remained to them was a burst of flight to the outside, every ant for herself. With luck a few survivors might then reassemble and re-start the colony elsewhere. That is, if they had a real queen. But, of course, they had only their inadequate Soldier-Queen.
Lamentation and hope were mingled among the Trailhead inhabitants. The ants were a doomed people in a besieged city. Their unity of purpose was gone, their social machinery halted. No foraging, no cleaning and feeding of larvae, no queen for them to rally around. The order of the colony was dissolving. Out there, indomitable and waiting, were the hated, filthy, unformicid Streamsiders. Finally, all that the Trailheaders knew was terror, and the existence of a choice—they could fight or run from the horror. There was nothing else left in their collective mind. ♦
