SLAVE-MAKING HABITS OF ANTS 



BY LOUIS I. DUBLIN, Ph D. 

 College of the City of New York 



Stranger, perhaps, than anything else in the life of the ants is 

 the story of their slave-making habits. The A T ery idea of de- 

 pendence is opposed to all the activities of these forms among 

 which such strong instincts for productive work exist. It is 

 remarkable, too, that these habits should have arisen in species 

 in which the integrity of the colony is so universally preserved 

 and in which any intrusion from without is so actively resented. 

 Yet there can be no doubt of the existence of this institution 

 among them; for every stage of slavery from the simplest to the 

 most complex conditions is now a matter of easy observation. 

 It is the aim of this account to describe some of the more typical 

 cases of slavery in the order of their increasing complexity, and 

 then briefly to attempt an explanation of their origin and 

 development. 



The reader will recall, perhaps, the very common and active 

 red ants known as Formica sanguinea or more familiarly as the 

 sanguinary ants, (Fig. i). These show the first pronounced 

 condition of this peculiar habit. In the spring the sanguinary 

 queen, just returned from her wedding flight and full of eggs, is 

 most often found in an old nest of a closely related species Formica 

 fusca, surrounded by a small number of queenless workers of the 

 latter species. This is the beginning of the large slave-colonies 

 very common later in the summer. Strange as it may seem, 

 these workers do not resent the presence of the intruder as ants 

 generally do; but feed and protect her with that same loyalty 

 which characterises their treatment of their own queen. Among 

 these she lays her eggs which, carefully tended by the fusca 

 workers, soon hatch into the first lot of sanguinaries. These 

 constantlv increase in numbers and make the colony more and 

 more mixed in character. A new composite colony is thus pro- 

 duced in which, through a new division of labor, the good of all 

 is assured. The fuscas or slaves live freely, working without 

 any apparent restraint; but as they are queenless, it is clear 

 that with time thev would decrease in numbers while their 



