INSTINCT. s ' ! 



CHAPTEE VI 



INSTINCT 



THE remarkable actions of the wasps related in the 

 foregoing chapter naturally give rise to the question, 

 What prompts and directs snch actions ? Activities of 

 this class are common ti> all, or nearly all, of each spe- 

 cies possessing snch traits. Each works after its own 

 manner and in a way that is uniform for each specie^. 

 Some of these acts occur before the insect is old enough 

 to be taught. Such acts are said to be instinctive. In- 

 stinctive acts are for the most part, if not altogether, 

 performed without reflection. Insects do certain things 

 in a certain way. Their actions seem to accord with 

 their natural surroundings, but should their environ- 

 ments be changed their actions are not changed accord- 

 ingly. For instance, a certain wasp provisions its nest 

 with a large grasshopper. The wasp drags the grass- 

 hopper along by one of the antenna 1 . When the antenna' 

 are cut off, the wasp looks around the head, and finding 

 no antenna 1 , gives up the task and flies away. It never 

 occurs to the wasp to take hold of a leg and proceed. 

 An excellent example is the case <if the trap-door spider, 

 not itself an insect, but one of the insect allies. This 

 trap-door spider makes its home in tubular burrows 

 beneath the surface of the ground. It covers its tube 

 with a hinged trap-door. When the spider is pur- 

 sued it seeks refuge within its home, closing the trap- 

 door after it. Where these spiders dwell the ground 



