THE SOCIAL INSECTS 



Polybias. This danger can be met in several ways; perhaps 

 the best is to have friendly relations with the ants. A few 

 species have achieved this, in what way we do not yet under- 

 stand, but they build their nests almost exclusively on trees 

 harbouring enormous ants' nests. These ants do not molest 

 them and the wasp colonies are in many cases long-lived. 

 Several kinds of birds have learnt to build their nests on the 

 same trees and seem to have the same immunity. Probably 

 the small, short-lived type of colony is an illustration of 

 another way of meeting the same difficulty. A small nest 

 does not represent a large stock of capital and when the ants 

 make an attack the wasps can desert the nest without irre- 

 parable loss. The queens, because there are several of them 

 and none of them has been laying at a very high rate for 

 long, have lost none of their mobility. They are not nest- 

 bound like the old queen of the common wasp. With the 

 aid of the swarm of workers, a new nest can be reconstructed 

 in twenty-four hours. We witnessed an actual example of 

 such an escape near the Kaieteur Falls. A few days after we 

 had found a nest, we noticed one morning that it was 

 deserted except for a few workers which were biting away 

 the envelope. Tracking these wasps down, we found a new 

 nest about ten yards away (Plates 25, 26, facing p. 80). The 

 cells of the old nest were perfectly clean inside and we assumed 

 that it had been raided by driver ants during the night. 



The advantage of the Polybia method of colony founda- 

 tion could be seen very clearly. The swarm consisted of 

 twenty-two queens and 118 workers and in two days they 

 were able to build a new nest of seven combs with 167 cells, 

 each one of which contained an egg. At this point, the nest 

 was raided again by driver ants, the tail of whose retreating 

 column we witnessed, and the cells were cleaned out once 

 more. This time we caught all the wasps for dissection. 



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