232 BRITISH ANTS. 



In 1913 Crawley made some nine more experiments, but in all but 

 one the umbrata females were killed by the nigra workers. In the 

 successful experiment, with a small queenless colony of D. nigra, 

 the umbrata female though considerably attacked at first was 

 eventually accepted. 



It is conceivable therefore that in nature a female might enter 

 an outlying part of a nest and be gradually accepted by most of the 

 workers until she was able to enter the nest proper. 



No cases are known of the host queen and the parasite living 

 together in a nest, so, unless a female can only be adopted by a 

 queenless colony, it must sometimes happen that a female is 

 accepted by a colony already possessing a queen of its own species. 

 In such a case the intruder must either kill the rightful queen 

 herself, as the female of (non-British) Bothriomyrmex kills the queen 

 of her host Tapinoma, or the workers of the host species must 

 themselves assassinate their own queen, as do the workers of 

 Tetramorium caespitwn when they have accepted a female Aner gates 

 atratulus. 



Crawley confined several queens of umbrata with queens of nigra, 

 and the latter were always killed by the former, which, although a 

 little the smaller, is stronger and possesses more powerful mandibles 63 . 



On July 29th, 1913, I introduced a deflated fertile female 

 umbrata, captured after a marriage flight at Weybridge, into a 

 small queenless colony of D. aliena obtained at Weybridge on 

 July 10th, 1912 the queen of which, a D. mixta, had died on 

 November 5th, 1912. The umbrata female was promptly attacked 

 and nearly killed, so she was removed and died two days afterwards 

 from the injuries she had received. A second umbrata female taken 

 at the same time as the former was introduced into the aliena nest 

 and was only slightly attacked ; she killed three of the workers and 

 by the next day she was accepted and has lived in the nest as queen 

 ever since. On May 24th, 1914, she laid her first eggs, and by July 

 25th she laid a large number and her gaster was considerably 

 swollen. On August 3rd a few workers hatched, which however 

 proved to be aliena (from parthenogenetic e'ggs laid by the workers), 

 but on August 27th the first umbrata worker appeared. A fair 

 number hatched up to the end of September, all very small ; 

 every one, however, was killed after a few days by the aliena 

 workers. The umbrata female laid many more eggs, and by 

 November a large number of half -grown and small larvae (presum- 

 ably umbrata) were present. 



On September 15th, 1913, Pinkney introduced a dealated 

 D. umbrata female taken just after swarming into a colony of 

 D. aliena he had obtained at Woolacombe on August 27th, 1913. 

 Only one worker appears to have attacked her, and she was finally 

 accepted the same day, and was alive and well, living as the queen 

 of the colony, on February 15th, 19 14 67 . 



