wheeler: ants of the genus formica. 427 



Host (Temporary). F. fusca. 



North and Middle Europe, south as far as the Pyrenees and south- 

 ern slopes of the Alps ; Caucasus, Siberia ; occurring only in the moun- 

 tains in Southern Europe. 



The typical F. rufa constructs large mound-nests of vegetable 

 debris, usually pine-needles, in open forests, preferably of coniferous 

 trees. A single colony may have several of these nests, which are con- 

 nected with one another by run-ways. New colonies (not new nests !) 

 are formed, as Wasmann and I have shown, by temporary social para- 

 sitism, the recently fecundated female finding a home in a F. fusca 

 colony and permitting these ants to bring up her young. The fusca 

 queen is either destroyed by the intrusive rufa queen or by her own 

 offspring, so that when the fusca workers eventually die off, a pure 

 colony of rvfa remains. New nests are formed by adoption of rufa 

 queens which leave the parental formicary with detachments of 

 workers. 



The forms F. polyctena Forster and F. pinipMla Schenck are based 

 on specimens which differ somewhat from the typical form in pilosity; 

 poh/ctcna having the head and thorax almost hairless, whereas pini- 

 pihila is more pilose. 



21. F. RUFA rufa var. meridionalis Nassonov. 



F. rufa var. meridionalis Nassonov, Arb. Lab. zool. Univ. Moskau, 1889, 4, 

 p. 17, ^ ; Ruzsky, Formicar. Imper. Ross., 1905, p. 330; Emery, Deutsch. 

 ent. zeitschr., 1909, p. 186. 



Worker. Differing from the typical form in color, the red parts 

 being brownish yellow, the legs brown. Hairs very sparse. 



Siberia. 



It is not impossible, as Emery seems to imply, that this variety may 

 be based on immature specimens of the typical pratensis. 



22. F. rufa rufa var. rufopratensis Forel. 



F. rufa var. rufopratensis Forel, Denks. Schweiz. gesell. naturw., 1874, 26, 

 p. 53, y 9 cf ; Emery, Deutsch. ent. zeitschr., 1909, p. 186. 



Worker and Male transitional in color and pilosity, and Female 

 in the smoothness of the gaster, between the typical rufa and the sub- 

 species pratensis. These various characters are combined in the most 

 manifold manner and degrees in different specimens. 



