NOTES ON PSITHYRUS. 31 



On the first day (August 10) the laboriosus queen seized nearly 

 every worker with which she came in contact and rolled the latter 

 toward the ventral side of her abdomen, and made movements as 

 if to sting her victim. This mauling, as a rule, lasted for only a 

 few seconds, when the worker, which in every case was absolutely 

 passive, was again released. In seizing the workers, both the man- 

 dibles and the first pair of legs were usually employed simulta- 

 neously, but on one occasion a worker was first lifted up by the 

 pile of its thorax with the mandibles and then rolled below the body 

 of the Psithyrus. None of the workers seemed to be any the 

 worse for this mauling. 1 



On the second day (August n) the Psithyrus queen only occa- 

 sionally seized a worker and treated it in the manner described. 

 On the third day (August 12) this rough treatment of the Bremus 

 workers became still less frequent, and thereafter the behavior of 

 the Psithyrus queen and the vagans workers was quite peaceful. 2 



The attitude of the Psithyrus and the Brenms queen toward each 

 other was somewhat different. From the very start the Psithyrus 

 paid little or no attention to the latter, but during the first few days 

 the Bremus queen avoided her rival whenever they met, and usually 

 turned the tip of her abdomen toward the Psithyrus, as if to ward 

 off an attack. However, these signs of hostility on the part of the 

 B remits queen gradually decreased and ceased completely after the 

 fourth or fifth day, and thereafter both queens lived quite peace- 

 fully together. 



To the vagans males, of which several were present when the 

 Psithyrus first entered the nest, and to two young vagans queens 

 which hatched on September 15, the Psithyrus paid no attention 

 whatsoever, nor did any of these young queens and males exhibit 

 the slightest sign of fear toward the Psithyrus. 



1 Sladen ('12, p. 253) who observed a Ps. rupestris queen, which he had 

 placed in a B. lapidarius nest, treat the lapidarius workers in a manner sim- 

 ilar to that described above, concluded that the workers were too small to get 

 hurt, but, as will be seen later, this is not an adequate explanation. 



2 This agrees with similar observations by Smith ('55, p. 210) and 

 Wheeler ('04, p. 353). According to the former, the Psithyri "live on 

 the most friendly terms with the industrious part of the community," and 

 the latter, in the case of ants, found that " the relations between the [For- 

 mica] consocians queen and the incerta workers were perfectly cordial." 



