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What I Saw in an Ant's Nest: Polyergus

Pierre Huber, son of the famous entomologist, was the first to describe the slave-making instincts in a species (Polyergus rufescens) noted for its predaceous instincts, and subsequent observations have shown that other species participate in these habits. Polyergus is thoroughly dependent on slaves. Without these bondsmen it is difficult to see how the ants could exist. Huber tells us that the workers of this species perform no work save that of capturing slaves. Use and wont, and the habit of depending entirely on their servitors, have produced such changes in the structure of the ants that they are unable to help themselves. The jaws of these ants are not adapted for work; they are carried by their slaves from an old nest to a new one; What I Saw in an Ant's Nest 219 and, more extraordinary still, they require to be fed by their slaves, even with plenty of food close at hand. Out of thirty of these ants placed by Huber in a box, with some of their larvæ and pupæ, and a store of honey, fifteen died in less than two days of hunger and of sheer inability to help themselves. When, however, one of their slaves was introduced, the willing servitor "established order, formed a chamber in the earth, gathered together the larvæ, extricated several young ants that were ready to quit the condition of pupæ, and preserved the life of the remaining Amazons." It must be noted that there are very varying degrees in the dependence of the ant-masters on their slaves. In the recognition of this graduated scale of relationship and dependence, indeed, will be found the clue to the acquirement of this instinct. The horse-ant (Formica rufa) will carry off the larvæ and pupæ of other ants for food, and it sometimes happens that some of these captives, spared by their cannibal neighbors, will grow up in the nest of their captor. A well-known ant, the Formica sanguinea, found in the South of England, is however, a true slave-making species, but exhibits no such utter dependence on its servitors as does Polyergus. The slave-making habit is not only typically developed in the Sanguineas, but the bearing of the captives to their masters indicate a degree of relationship and organization such as could hardly be conceived to exist outside human experience. The Sanguineas make periodical excursions, and, like a powerful predatory clan, carry off the pupæ or chrysalides of a neighboring species, F. fusca. Thus the children of the latter race are born within the nest of their captors in an enslaved condition. As slaves "born and bred," so to speak, they fall at once into the routine of their duties, assist their masters in the work of the nest, and tend and nurse the young of the family. The slaves, curiously enough in this instance, are black in color, whilst the masters are twice the size of the servitors, and are red in color, and that the slaves are true importations is proved by the fact that males and females of the slave species are never developed within the nest of the masters, but only within those of their own colonies. The slaves in this instance rarely leave the nest, the masters foraging for food, and employing their captives in household work, as it were; whilst, when the work of emigration occurs, the masters carry the slaves in their mouths like household goods and chattels, instead of being carried by them, as in the case of Polyergus.