ants is that for domestic work and the care of larvae. “Not until later do ants learn to distinguish between friend and foe; not until later do they realise that they are members of a single ant community on behalf of which they have to fight.”[1]
Forel next presents the fact, even more surprising, that the intensity of the warrior instinct is directly proportional to the size of the collectivity. Two ants of enemy species meeting at a distance from their respective nests or from their own folk, will avoid one another and run away in opposite directions. Even if you come across the armies in full combat, and you remove from the ranks an ant belonging to either side and shut the two by themselves in a small box, they will do one another no harm. If, instead of taking merely two, you shut up a moderate number from either side within a narrow space, they will fight half-heartedly for a while, but soon cease to struggle, and often end by making friends. In such circumstances, says Forel, they will never resume the struggle. But put these same ants back among the fighting forces of their respective sides, and separate them by a reasonable distance, so that they might live at peace, and you will see them return to the attack; the individuals which a moment before were avoiding one another with repugnance or fear, will now furiously engage in mutual slaughter.[2] It thus appears that the combative instinct is a collective contagion.
Sometimes this epidemic assumes unmistakably morbid attributes.[3] In proportion as it extends and in proportion as the struggle is prolonged, the fighting rage becomes a positive frenzy. The very same ant, which at the outset was timid, will now be affected with a paroxysm of furious madness. She no longer knows what she is about. She throws herself upon her own companions, kills the slaves that are endeavouring to calm her, bites everything she touches, bites fragments of wood, can no longer find her way. Other members of the community, slaves as a rule,
