43 



being in considerabh' greater numbers. Here undoubtedly was 

 a new F. exsecta colony, founded b\- a young queen of that ant, 

 which had entered a F. fusca nest, and been accepted by them. 

 Hamm tells us he found a mixed colony of F. exsecta and F . fusca 

 on August 26th, 1911, at Bove}' Tracey, Devon. 



In North America mixed colonies of F. exsecioides, correspond- 

 ing to our F. exsecta, but with larger females, and F. subsericea, 

 very similar to our F. fusca, have been found by Forel at Hart- 

 ford, Conn., and by Schmitz, who found five near Beatty, Pa. 

 All were small colonies, none containing more than fifty workers 

 of each species, and a female of F. exsectoides was always present. 

 Wheeler has also found similar colonies, and he states the 

 queen is very passive and conciliatory and is readily ado])ted b\' 

 the host workers. 



This list of natural mixed colonies leaves no doubt that 

 ants of both the F. rufa and F. exsecta groups are Temporary 

 Social Parasites on F. fusca and its races, but numerous experi- 

 ments have been carried out by Wheeler, Wasmann, Vieh- 

 MEYER and others with generally successful results. The females 

 usually employ conciliatory methods to secure adoption, but 

 where they meet with stubborn resistance, they resort to force 

 to secure their ends. Thus Viehmeyer had a truncicola female 

 which was only accepted by some F. fusca workers after some 

 da3-s of fighting. She had evidently suffered in the struggle, 

 for ten days after her acceptance she died. 



In one of Wasmann's experiments where a F. rufa female 

 was adopted into a F. fusca nest which contained a F. fusca 

 female, in May 1909, the F. rufa female, after a few days, killed 

 the F. fusca female, and bit oft' her head. 



The last writer states that during twenty years he always 

 found that F. rufa and F. pratensis females, kept alone, died 

 before laying eggs. We found in March 1912 that though old 

 F. rufa females lay eggs when isolated, they pay no attention 

 to them, but leave them scattered about where they have fallen. 



We now give some of our own experiments. 



In January 1910, Donisthorpe placed some forty workers of 

 F. fusca V. fusco-rufiharbis, from Whitsand Ba\', Cornwall, in 

 one chamber of a two-chambered Fielde-Janet nest, blocking 

 the passage between the two chambers with cotton-wool. In the 



