TREATMENT OF STBANGEES. 125 



Lasius fiavus (belonging to one of my nests of domesti- 

 cated ants) had been feeding some hours previously, 

 though none were there, or, indeed, out at all, at the 

 moment. The entrance to the nest was about eight 

 inches off ; but she walked straight to it and into the 

 nest. A second wandered about for four or five minutes, 

 and then went in ; a third, on the contrary, took a wrong 

 direction, and, at any rate for three-quarters of an hour, 

 did not find the entrance. 



At that time, however, I did not ascertain what 

 became of the specimens thus introduced into a strange 

 community. I thought it would be worth while to 

 determine this, so I subsequently (1881) took six ants 

 from one of my nests of L. flavus, marked them, and 

 introduced them into another nest of the same species. 

 As in the preceding cases they entered quite readily; 

 but though they were not at first attacked, they were 

 evidently recognised as strangers. The others ex- 

 amined them carefully, and at length they were all 

 driven out of the nest. Their greater readiness to enter 

 a strange nest may perhaps be accounted for by the fact 

 that, as a subterranean species their instinct always is 

 to conceal themselves underground, whereas, F. fiisca, 

 a hunting species, does not do so except to enter its 

 own nest. 



How do these ants and bees recognise their com- 

 panions ? The difficulty of believing that in such 

 populous communities every individual knows every 

 other by sight, has led some entomologists to suppose 



