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Chap. VII Instinct.

Slave-making instinct.—

We will now turn to the extraordinary slave-making instinct of certain Ants. The Formica (Polyerges) rufescens, as was first discovered by Pierre Huber, a better observer even than his celebrated father, is absolutely dependent on its slaves. Without their aid the species in a single year would certainly become extinct. The males and females do no work: and the workers or sterile females, though most energetic and courageous in capturing slaves, do no other work when the community is once established. They are incapable of making their own nests or feeding their own larvæ: when their old nest is found inconvenient, and they have to migrate: it is the slaves which determine the migration, and actually carry their masters in their jaws. So utterly helpless are the masters, that when Huber shut up thirty of them without a slave, but with the food which they like best, and with their own larvæ and pupæ to stimulate them to work, they did nothing: they could not even feed themselves, and many perished of hunger with food close at hand. Huber then introduced a single slave (F. nigra fusca) and she instantly set to work fed and saved the survivors: made s

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[child's watercolour of birds and a butterfly by Francis or Horace Darwin]