BEHAVIOUR 107 



The facts, as shown by the careful observations of the 

 Peckhams, are that the part of the body where the cater- 

 pillars are stung varies with different females of the same 

 species of wasp ; only occasionally does the wasp inflict a 

 series of stings along the mid ventral line. Moreover, the 

 victims found in the wasps' nests are often dead, and the 

 wasp grubs can feed and grow if supplied with a dead or 

 even decomposing victim. '* We believe that the primary 

 purpose of stinging is to overcome resistance and to prevent 

 the escape of the victims, and that incidentally some of them 

 are killed and others paralysed." Such considerations 

 warn us that the student of insect behaviour who does not 

 allow for individual variations in the habits of the same 

 species may readily fall into the error of regarding all insects 

 as utterly unconscious automatic machines, or into the 

 opposite error of assigning to them intelligence and fore- 

 sight of a degree far beyond that warranted by the facts of 

 their behaviour. 



The habits of egg-laying and providing in advance for 

 the needs of offspring as yet unhatched, some of which have 

 been briefly considered, are clearly to a large extent in- 

 stinctive ; most details of an insect's complex behaviour 

 directed to these ends result from her inborn tendency to 

 respond in certain ways to suitable surroundings and stimu- 

 lation. It is instructive, in this connection, to turn to some 

 examples of behaviour in larval insects which appear to 

 suggest prevision of the needs involved in the future final 

 transformation into the adult form. Such prevision is of 

 course impossible ; a highly imaginative observer might 

 convince himself that a butterfly laying eggs knows what 

 will happen to her offspring after hatching because she was 

 once a caterpillar herself, but he could hardly be persuaded 

 that a larva foresees its transformation into a winged insect, 

 and knows the conditions, often seemingly difficult, that 

 will have to be overcome in connection therewith. Yet 

 numerous larv^ae of different orders follow specialised modes 

 of behaviour which are related to their future needs, and 

 thus afford striking example of the part played in the life 



