FORMICA. 297 



in his possession, but he is now making further more careful experi- 

 ments. 



In quite young colonies workers only are reared, the males 

 and females only appearing when the colony has reached a 

 certain age ; afterwards worker cocoons occur, chiefly from July 

 to September, but they may occasionally be present, earlier or 

 later, in June and October. Male and female cocoons which I 

 collected in a nest of this species at Rannoch on July 16th, 1913, 

 hatched during the same month. The pupae are usually enclosed 

 in cocoons, but Schenck records finding naked pupae at Nassau 9 , 

 and I found a number of the latter in a nest at Weybridge on 

 July 22nd, 1911. 



We have seen that females of the rufa and exsecta groups are 

 unable to found their colonies alone the females of the sanguinea 

 group are equally incapable of founding such colonies. In 1909 I 

 took a number of fertile females, from Wo king, Aviemore, and 

 Bewdley, and isolated them in bowls, with damp sponges and sand, 

 where they remained for months without laying or excavating in the 

 sand, and eventually died 71 ; and again in 1910, under similar con- 

 ditions, fertile females from Woking laid eggs which were left 

 scattered about ; these were never attended to, and did not hatch, 

 the females dying 73 . Viehmeyer made similar experiments in 1909, 

 with the same results 66 . 



As we have seen, colonies of F. sanguinea often spread over a 

 large area, branch and twin nests being formed, and young females 

 are received back into the nests. 



One of my observation nests of sanguinea was obtained from 

 Woking in 1910, and when the queen died the next year I col- 

 lected some more females at Woking and introduced one of them 

 on May 5th, 1911. She was at once accepted by the sanguinea and 

 their slaves, and having lost one antenna and two legs by injury 

 when digging up the nest, was always recognizable. On May 27th, 

 1911, I introduced a second female, also from Woking but taken 

 from another nest, this also was accepted, as was also another 

 female taken at Woking in June, 1913, and introduced into the 

 nest on December 30th, 1913. All these three females laid eggs 

 every year and lived as queens in this nest until April, 1914, when 

 the whole colony perished. 



In 1905 Wheeler pointed out that although isolated sanguinea 

 queens are often seen running about on the ground and seeking 

 suitable nesting sites, no one had been able to show that these 

 insects can found colonies without the assistance of alien workers, 

 and he stated that a sanguinea queen very probably establishes her 

 colony in a depauperate nest of an auxiliary species 52 . Subsequently 

 in 1906, Wheeler proved the possibility of his suggestion by experi- 

 ments, with the American subspecies rubicunda [Bull. Amer. Mus. 

 NH. 22 33-105 (1906)], and in 1913 he says that in Europe 



