VARIETIES OF WASP SOCIETY 



laying ; they can then easily be identified. In other species, 

 especially in the ones where queens are numerous, most of 

 the wasps have ovaries more or less developed and it may 

 be possible to decide which are queens only by seeing which 

 ones have been fertilised. 



Most of these wasps build nests hanging from or attached 

 to trees, and they are often nests of very beautiful construc- 

 tion. Sometimes the outer envelope is covered with lichen or 

 bits of moss so as to make it almost invisible. There is also 

 wide variation in the plan of the nest. In the commonest 

 type each new comb is built on the outside of the lowest part 

 of the envelope and is enclosed by building out from the enve- 

 lope all round its edge. The exit hole, which is at the bottom 

 of the envelope, pierces each successive comb. All round their 

 periphery the combs are fused with the envelope, and the only 

 way the wasps can get from one to another is through the hole 

 which was the exit hole at an earlier stage in construction. 



According to the species, there are probably two sorts of 

 colony, short-lived and long-lived. The former break up 

 into new swarms after a few months' growth, whereas the 

 others last for several years. It has been claimed that in one 

 Brazilian species colonies may persist for twenty-five years, 

 and records of three or four years are certainly authentic. 

 The difference between these two types of colony depends 

 on the physiology and in particular on the length of life of 

 the queens, but it may also be related to different ways of 

 attaining efficiency in reproduction. 



We were very impressed by the dangerous life which these 

 wasps lead, especially by their constant exposure to attacks 

 from ants. Not only are they surrounded by a very much 

 greater variety and number of ants than one ever sees in 

 Europe, but the hordes of driver ants, which live exclusively 

 by hunting, are peculiar to the same parts of the world as the 



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