iv CAMPONOTIDES SLAVE-MAKING ANTS 149 



nilidulus lives only with F. rufa. Amongst the most peculiar 

 of its dependants we may mention large beetles of the genera 

 Cetonia and Clythra, which in their larval state live in the 

 hills of the wood-ant. It is probable that they subsist on some 

 of the vegetable matter of which the mounds are formed. Adlerz 

 has given some attention to the division of labour amongst the 

 different forms of the workers of ants, and says that in F. rufa it 

 is only the bigger workers that carry building and other materials, 

 the smaller individuals being specially occupied in the discovery 

 of honey-dew and other Aphid products. In Camponotus it 

 would appear, on the other hand, that the big individuals leave 

 the heavy work to be performed by their smaller fellows. 



The wood-ant and its near allies have been, and indeed still 

 are, a source of great difficulty to systematists on account of the 

 variation that occurs in the same species, and because this differs 

 according to locality. Our European F. rufa. has been supposed 

 to inhabit North America, and the interesting accounts pub- 

 lished by M'Cook of the mound-making ant of the Alleghanies 

 were considered to refer to it. This Insect, however, is not F. 

 rufa, as was supposed by M'Cook, but F. exsectoides, Forel. It 

 forms colonies of enormous extent, and including an almost in- 

 credible number of individuals. In one district of about fifty 

 acres there was an Ant City containing no less than 1700 of 

 these large ant-hills, each one teeming with life. It was found 

 by transferring ants from one hill to another that no hostility 

 whatever existed between the denizens of different hills ; the 

 specimens placed on a strange hill entered it without the least 

 hesitation. Its habits differ in some particulars from those of 

 its European congener ; the North American Insect does not close 

 the formicary at night, and the inquilines found in its nest are 

 very different from those that live with F. rufa in Europe. 

 Whether the typical wood -ant occurs in North America is 

 doubtful, but there are races there that doubtless belong to 

 the species. 



F. sanguined is very similar in appearance to its commoner 

 congener F. rufa, and is the only slave-making ant we possess in 

 Britain. This species constructs its galleries in banks, and is 

 of very courageous character, carrying out its military operations 

 with much tactical ability. It is perfectly able to live without 

 the assistance of slaves, and very frequently does so ; indeed it 



