VARIETIES OF WASP SOCIETY 



"queen-eggs " can be laid. Later he kept a number of nests 

 warm by day, but exposed either the grubs, or the adult wasps, 

 or both, to hot (25 ° C) or cold (5 C) conditions at night. 

 Thus there were four experimental conditions : grubs hot, 

 wasps hot ; grubs hot, wasps cold ; grubs cold, wasps hot ; 

 grubs cold, wasps cold. He found that when the wasps were 

 kept cold at night, the grubs turned into workers, but when 

 they were kept warm, into queens. The temperature at which 

 the grubs themselves were kept was immaterial. This suggests 

 that temperature in some way alters the behaviour or physio- 

 logy of the workers so that they give the grubs different food. 

 Nobody has yet detected any special queen-food in wasps, 

 but a change in the type of secretions produced by the 

 workers and mixed with the ordinary food might be very 

 difficult to demonstrate. It is not yet possible to relate these 

 experiments in any simple way to what happens under 

 completely natural conditions. 



THE POLYBIA WASPS 



Most wasp biology was studied first in Europe and much 

 more is known about the behaviour of the species of cooler 

 climates than of those in the tropics. This has led, almost by 

 accident, to the view, held at least implicitly, that the normal 

 thing is to have an annual colony, started by a single queen. 

 The truth is, however, that the majority of wasps, as of most 

 other kinds of insects, live in the tropics, and it is much more 

 likely that social life arose there. When it is realised that 

 social life, at any rate as soon as it makes any real forward 

 step, involves the sterilisation of a considerable proportion 

 of potential egg-layers, it seems almost certain that these 

 organisations first arose in warmer climates. Except in 

 conditions which make continuous breeding possible, many 

 of the advantages of a social organisation are lost. The kernel 



e 65 



