386 WILLIAM MORTON WHEELER 



that in this case Myrmicine ants are selected. A. frigidus, as 

 I have shown, confines its depredations to Camponotine ants 

 of the genus Formica and selects only the queens, which are, of 

 course, the largest and most nutritious caste. This specializa- 

 tion in diet, while highly advantageous to the wasps, is very 

 destructive to the ants, since each fecundated queen is really 

 a potential colony. Still the prey preferred by frigidus, namely 

 F. fusca and its var. subsericea, notwithstanding the depreda- 

 tions of the wasps and of our numerous slave-making and tem- 

 porarily parasitic species of Formica, maintain their status as 

 far and away the most abundant ants of their genus in the 

 northeastern states and Canada. They are able to support this 

 greedy host of praedators and parasites because they are ex- 

 tremely prolific, hardy, or eurythermic, and of a very indus- 

 trious and peaceable disposition. 



