SOLITARY AND SOCIAL WASPS 



Among the social insects the wasps seem to have changed 

 least from their solitary ancestors. Their colonies, even when 

 large and elaborate, never seem to attain to the high organi- 

 sation of the beehive or the ants' nest. Moreover, there are 

 good grounds for thinking that both bees and ants were 

 evolved in the remote past from ancestral wasp-like creatures. 

 The potentialities of the wasp-stock were probably all present- 

 in the ancestor of the two other groups. 



A HUNTING WASP 



Even a solitary wasp may be capable of elaborate behaviour, 

 and there is no better example of this than the species Ammo- 

 phila pubescens, which has become famous in the last few 

 years and is found in southern England. Many observers 

 had built up an incomplete picture of its behaviour over the 

 last fifty years, but during the war a very long and detailed 

 study of its habits was made by Baerends in Holland. He 

 marked many females with coloured paints so that each one 

 could be recognised again. In this way a detailed picture of 

 the nesting-cycle could be constructed. Soon after fertili- 

 sation, the female digs a nest in the form of a burrow in sandy 

 soil. The gallery descends for about an inch and then bends 

 at right angles and ends in a small oval chamber. Baerends 

 removed such nests bodily from the soil and replaced them 

 with a split block of plaster of Paris in which an artificial 



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