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 that occurred it would do nothing for the Trailhead Colony. Those created by the Soldier-Queen would not mate with her or other potential Soldier-Queens. They were programmed to mate during nuptial flights away from the nest.
No way out existed for the Trailheaders; the colony was in a terrible fix. The linchpin of its social existence was gone and could not be replaced. Like a player in a Greek tragedy, it had been undone by the unfolding of events prescribed by its own unalterable nature. The source of its early success had become its fatal flaw. The colony could for a while contribute, through its production of males, to the gene pool of the population of colonies all around Dead Owl Cove, and in that way tweak out one more bit of Darwinian profit. But it could do nothing more for its own physical existence. With each passing day it became more vulnerable as a superorganism.
As the Trailhead Colony struggled in this pitiless world, its territory and even its very flesh were coveted by others. It would not merely fade away, holding on until a final worker sat alone in the nest. On the contrary, the neighboring colonies were likely to learn of its decline, and when that happened there would be war. And when war came, there was only the slimmest chance that the queenless Trailhead Colony could win.
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FOR A WHILE the Trailhead Colony, while stricken, still retained most of its military strength. Fifteen percent of its adult members were soldiers. They were contracted to be hoplites, or heavily armored infantry. Twice the size of an ordinary worker, a soldier's exoskeleton was literally heavy armor: thick, tough, and pitted in places like a shield for resilience and strength. A pair of spines projected backward from the midsection of the body to protect the waist. Spikes extended forward from the midsection to protect the neck, and the rear margin of the head was curved forward, turning that part of the surface into a helmet. When attacked, the hoplite soldier could pull in her legs and antennae and tighten up the segments of her body in order to turn her entire body surface into a shield.
The ordinary Trailheader workers, while built for labor, were also available for combat. Then they served as the equivalent of light infantry. Because their exoskeletons were much thinner than those of the hoplites, they were not inclined to stand fast in battle. Instead, they used the swiftness and agility of their supple bodies, running around their enemies, darting in and out, seizing any leg or antenna available, holding on to it, slowing the opponent enough for nestmates to close in and seize another body part. When the adversary was finally pinned and spread-eagled, others piled on to bite, sting, or spray it with poison. This swarm attack, in which a crowd of fighters rush a formidable opponent simultaneously, was the same as used by wolves circling a moose, or infantrymen attacking an enemy firebase.
Such was the force, originally ten thousand strong, that had protected the Trailheader nest against all enemies. Now the number of able-bodied adults had begun to decline, and the survivors were growing old.
The decline of Trailhead Colony was being closely watched by its closest neighbor, the Streamside Colony. This younger and now more powerful superorganism was prepared to take advantage of its neighbor's misfortune.
Early one morning, an elite Streamsider worker, followed by a squad of her nestmates, left her nest to assess the strength of the Trailhead Colony. Precise monitoring of the enemy strength was not easy. The two nests were separated by about two thousand ant lengths, or a distance of twenty yards. The scout, if allowed to travel in a straight line on a smooth surface, might have covered that distance in under six minutes. But a straight run was not possible, because the terrain was filled with obstacles that were scarcely