FORMICA. 257 



The females of this species have lost the power of founding their 

 colonies unaided ; as we have seen their communities spread over 

 a large area, and the success of the species is greatly helped by the 

 habit of colony splitting and forming branch nests. 



After the marriage flight large numbers of females are received 

 back into the parent or other nests in the vicinity ; some find 

 nests of another race, or of their own species elsewhere, whilst a 

 considerably smaller number, having flown to rufa-hee ground, 

 endeavour to enter a nest of Formica fusca. 



Probably the fact that rufa queens are received back into nests 

 of their own species over a large area, has caused them to lose the 

 instinct of colony-founding alone. 



The large size of rufa females in proportion to their workers 

 may also be due to the same reason, and the occasions on which 

 they actually need to found colonies with the aid of fusca are not 

 sufficiently frequent to have caused them to become dwarfed in 

 size, or to develop mimetic or myrmecophilous characters, as is the 

 case with some of the American forms. Large numbers of queens 

 often occur in rufa nests, and though an occasional nest may be 

 found in which it is difficult to detect a queen, the general rule is 

 for colonies of this species to possess a good many. Wasmann 

 records that in March, 1884, he found sixty old queens in a rufo- 

 pratensis nest at Exaeten 66 , and he subsequently mentions that he 

 has several times found more than sixty queens in rufa nests in 

 Dutch Limburg 72 . In April, 1911, Crawley and I dug up a rufa 

 nest at Porlock in which were considerably over one hundred 

 queens, and as we only investigated part of the nest the number 

 must have been much greater 90 . At Weybridge also, and elsewhere, 

 I have frequently observed a very large number of queens in a 

 single rufa nest, and this condition is evidently brought about by 

 the acceptance, and readmission, of females after the marriage 

 flight. 



It is also certain that females of the allied races will be accepted 

 into each other's nests in the same way ; Wasmann often found in 

 rufa or pratensis nests, and especially in that of the mixed form 

 rufo-pratensis, both rufa and pratensis queens side by side. In 

 April, 1904, at Luxemburg he observed seven queens in a pratensis 

 nest, of which five were true pratensis, one a rufa, and one a trun- 

 cicolo-pratensis 72 , and King has sent me to name from Nethy 

 Bridge females of pratensis and rufo-pratensis from the same nest, 

 the workers of this colony being rufo-pratensis, but much nearer to 

 pratensis than rufa. 



We now come to the founding of colonies by rufa queens in fusca 

 nests. In 1904 Wheeler suggested that when more attention had 

 been devoted to the incipient colonies of the European F. rufa (and 

 F. exsecta), these ants would be found to be temporary social 

 parasites in the colonies of F. fusca* 5 . This he was led to predict, 



