Even the hunting spiders and tarantulas fell before the black host. They killed many in their desperate self-defense, but the army ants could overwhelm anything--anything at all--by sheer numbers and ferocity. Killed or wounded ants served as food for their sound comrades. Only the web spiders sat unmoved and immovable in their collossal snares, secure in the knowledge that their gummy webs could not be invaded along the slender supporting cables. _3. THE PURPLE HILLS_ The army ants flowed over the ground like a surging, monstrous, inky tide. Their vanguard reached the river and recoiled. Burl was perhaps five miles away when they changed their course. The change was made without confusion, the leaders somehow communicating the altered line of march to those behind them. Back on Earth, scientists had gravely debated the question of how ants conveyed ideas to each other. Honeybees, it was said, performed elaborate ritual dances to exchange information. Ants, it had been observed, had something less eccentric. A single ant, finding a bit of booty too big for it to manage alone, would return to its city to secure the help of others. From that fact men had deduced that a language of gestures made with crossed antennae must exist. Burl had no theories. He merely knew facts, but he did know that ants could and did pass information to one another. Now, however, he moved cautiously along toward the sleeping-place of his tribe in complete ignorance of the black blanket of living creatures spreading over the ground behind him. A million tragedies marked the progress of the insect army. There was a tiny colony of mining bees, their habits unchanged despite their greater size, here on the forgotten planet. A single mother, four feet long, had dug a huge gallery with some ten offshooting cells, in which she had laid her eggs and fed her grubs with hard-gathered pollen. The grubs had waxed fat and large, become bees, and laid eggs in their turn within the same gallery their mother had dug out for them. Ten bulky insects now foraged busily to feed their grubs within the ancestral home, while the founder of the colony had grown draggled and wingless with the passing of time. Unable to bring in food, herself, the old bee became the guardian of the hive. She closed the opening with her head, making a living barrier within the entrance. She withdrew only to grant admission or exit to the duly authorized members,--her daughters. The ancient concierge of the underground dwelling was at her post when the wave of army ants swept over. Tiny, evil-smelling feet trampled upon her and she emerged to fight with mandible and sting for the sanctity of her brood. Within moments she was a shaggy mass of biting ants. They rent and tore at her chitinous armor. But she fought on madly, sounding a buzzing alarm to the colonists yet within.