FORMICA. 259 



sistent ones away, she finally entered one of the doors of the nest 

 and was lost to view 82 . 



On August 21st, 1910, Taylor and I again visited Parkhurst 

 Forest, and during the day we found in an enclosure of young fir 

 trees a very small rufa nest, which consisted of a small mound only 

 eight or nine inches in diameter and about three inches high, but 

 built of rufa materials in the usual way. The nest, which was most 

 carefully dug up, only reached a depth of about six inches into the 

 earth, and contained about one hundred and fifty, mostly very 

 small rufa workers, a rufa queen, some fifty fusca workers, and a 

 number of cocoons, which hatched later and proved to be rufa 

 workers, but no fusca female was present 82 . 



On June 10th, 1911, in the Black Wood at Rannoch, I found 

 a dead dealated rufa female in a, fusca nest under a stone, which had 

 evidently entered the fusca nest and had been killed by the workers, 

 and on June 14th in the same locality, high up on a mountain 

 where no rufa nests occur, I observed a dealated rufa female 

 walking round a stone over a fusca nest. She eventually got under 

 the stone and entered the nest, which contained a small fusca 

 colony, but owing to lack of time I was unable to investigate 

 further 84 . 



In June, 1911, Ruschkamp found in a weak colony of F. fusca at 

 Alt-Valkenburg, a dealated rufa queen ; some fusca larvae and 

 pupae were present, but no fusca queen occurred 87 . 



On June 5th, 1912, R. Brun, having discovered a fairly strong 

 colony of F. fusca under a stone near Glarus, proceeded to dig it 

 up, but having unfortunately crushed the one fusca queen present, 

 he replaced the workers and went away. Eight days later he 

 revisited the spot, and found that the fusca workers had accepted 

 a rufa female in place of their own dead queen 91 . 



This list of natural mixed colonies and observations in nature 

 leaves no doubt that Formica rufa is a temporary social parasite 

 in F. fusca colonies, but numerous experiments have been carried 

 out by Brun, Crawley, Donisthorpe, Kutter, Ruschkamp, Wasmann, 

 Wheeler, and Viehmeyer, etc., 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. 



It is a remarkable fact that in no single instance, when a mixed 

 rufa-fusca colony has been found in nature, has a fusca queen been 

 present. It is evident that a rufa female either selects a queenless 

 fusca nest, or, if a fusca queen is present, the latter is probably 

 killed by the rufa queen. 



F. rufa and pratensis females, if kept alone, either die without 

 laying eggs, or pay no attention to them if laid, but leave them 

 scattered about where they have fallen. I have made a number 

 of experiments to test if it was possible for a rufa and fusca queen to 



