JOURNAL 



OF THE 



jOpfD igoFk Cinlomologirfll jSoriFtg. 



Vol. XXIV. JUNE, 1916. No. 2. 



NOTES ON SOME SLAVE-RAIDS OF THE WESTERN 



AMAZON ANT (POLYERGUS BREVICEPS 



EMERY).! 



By William Morton Wheeler, 

 Forest Hills, Mass. 



While camping during the summer of 1*915 at Fallen Leaf Lake 

 near Lake Tahoe, in the Sierras of California, I had an opportunity to 

 observe several slave-raids of the western amazon ant (Polyergus 

 rufescens Latr. subsp. breviceps Emery), a form not hitherto knov\rn 

 to occur in California. In my book on the ants- 1 described a few forays 

 of this ant in Colorado, but the Californian colonies exhibited some 

 peculiarities of behavior not heretofore observed in any of our North 

 American amazons. Only five colonies were seen during ten days de- 

 voted to the study of the ants of the Lake Tahoe region, so that in 

 this locality P. breviceps is evidently much rarer than in certain 

 localities {c. g., Florissant) at the same or greater elevations in the 

 Rocky jMountains of Colorado. The slave in all the colonies was an 

 ill-defined variety of Formica fusca, less pubescent than var. sub- 

 sericea Say or argcntea Wheeler and larger and less shining than the 

 typical form of the species. 



The notes taken on the following dates refer to as many different 

 colonies : 



1 Contributions from the Entomological Laboratory of the Bussey Insti- 

 tution, Harvard University, No. 113. 



- Ants, Their Structure, Development and Behavior. Columbia Univ. 

 Press, igio, p. 475-477. 



107 



