234 THE SOLITARY WASPS. 



the descendants of these individuals make the characteristic cov- 

 ering. Such cases are probably due to individual variation or 

 perhaps to atavism, this throwing back being not uncommon 

 among forms that are well known. 



Not all of the instinctive facts here enumerated are displayed 

 by each species studied, although as a general proposition they 

 are common to most of them. We have doubtless overlooked 

 some activities that should come under this head as we have 

 not made a thorough study of any sufficient number of species 

 to make a final settlement of the matter. For convenience we 

 give the eight primary instincts that we have enumerated in 

 tabular form. 



Instincts. 



1. Stinging. 



2. Taking a particular kind of food. 



3. Method of attacking and capturing prey. 



4. Method of carrying prey. 



5. Preparing nest and then capturing prey, or the reverse. 



6. The mode of taking prey into the nest. 



7. The general style or locality of nest. 



8. The spinning or not spinning of a cocoon, and its spe- 

 cific form when one is made. 



Intelligence. 



It is obviously more difficult to distinguish actions of this 

 class than of the other. One must be familiar with the normal 

 conditions of the insects in question before he is able to note 

 those slight changes in the environment that offer some oppor- 

 tunity for an adaptation of means to ends, or before he is com- 

 petent to devise experiments which will test their powers in this 

 direction. 



We find two classes of intelligent actions amcng the hymen- 

 optera which are sufficiently distinct to be considered separately, 

 although, like all natural groups, they grade into each other. 

 The first of these includes those actions that are performed by 



