4^4 ANTS. 



ridiculous foray of a large rubicunda colony on a woodland variety of 

 M \rtnica scaln-inodis near Rockforcl, 111. The foray was carried out 

 exactly as if it had been directed against one of the normal auxiliary 

 species. After killing or putting to flight the scabrinodis, the rubicunda 

 returned to their nest with the small larvae and pupae of an ant belong- 

 ing to an entirely different subfamily. In another rubicunda nest in 

 the same \v>od, I found two of the Mat chambers full of uninjured 

 pupa? of scabrinodis. These had evidently been set apart from the 

 rubicunda young and from those of the normal auxiliaries (in this case 

 F. snh(cncsccns). Forel (1874) made a similar observation on a san- 

 auinca nest in which Lasius nigcr and L. flams cocoons had been 

 stacked up in a chamber by themselves. Near Rockford, 111., a large 

 number of subintegra workers were seen one morning to make a normal 

 assault on a Lasius a/nericanits colony and to return with a number of 

 cocoons in their jaws and many Lasius workers hanging to their legs 

 and antenna?. These forays, which are probably not at all infrequent 

 and are, moreover, undoubtedly undertaken by colonies of considerable 

 size and of some experience in capturing the normal auxiliaries, point 

 to hunger as one of the impulses which compels them to undertake 

 their expeditions. We can hardly suppose that sanguined workers, 

 even after some practice in making slaves, have any definite ideal asso- 

 ciation between the kidnapped pupae and the slaves that hatch from 

 them or they would not make forays on such unsuitable species. 



3. The Founding of the Sanguinea Colony. How do the mixed 

 colonies of the facultative slave-makers arise? As no one had been 

 able to observe the behavior of the sanguinea queen just after descend- 

 ing from her nuptial flight and while establishing her colony, Forel and 

 \Yasmann supposed that she must either be adopted by some colony 

 of the slave species or bring up unaided a brood of her own which 

 could then by dulosis make the mixed colony. During the summer of 

 1905 I performed a number of experiments on young, artificially 

 clealated queens, introducing them into nests containing several snb- 

 scricea workers with their brood. I here transcribe the account of one 

 of these experiments from my paper " On the Founding of Colonies 

 by Queen Ants" (1906^): 



July 8, 9 A. M. A rubicunda female was placed in a nest contain- 

 ing 33 subsericea workers, small and large, 150 cocoons, and a few 

 larvae. The workers at once seized their cocoons and fled into the 

 light chamber. One or two of them attacked the female, but she shook 

 them off and killed one of them. In the meantime some of the workers 

 kept stealing into the dark chamber for the purpose of securing cocoons 

 and carried them to the remotest corner of the light chamber. As the 



