1 903] FOLSOM : — INSECT PS YCHOLOG V 1 5 



INSECT PSYCHOLOGY. 



BY JUSTUS WATSON FOLSOM, CHAMPAIGN, ILL. 



This article is intended to summarize, without much argument, some of the 

 best approved views of the present upon this difficult subject. 



Insects are eminently instinctive ; though their automatic behavior is often so 

 remarkably successful as to appear rational, instead of purely instinctive. 



Instinct, as distinguished from reason, attains' adaptive ends without prevision 

 and without experience. For example, a butterfly selects a particular species of 

 plant upon which to lay her eggs. Caterpillars of the same species construct the 

 same kind of nest, though so isolated from one another as to exclude the possi- 

 bility of imitation. Every caterpillar that pupates accomplishes the intricate pro- 

 cess after the manner of its kind, without the aid of experience. 



Instinctive actions all belong to the reflex type, — they consist of coordinated 

 reflex acts. A complex instinctive action is a chain, each link of which is a simple 

 reflex act. In fact, no sharp line can be drawn between reflexive and instinctive 

 actions. 



Reflex acts, the elements from which instinctive actions are compounded, are 

 the inevitable responses of particular organs to appropriate stimuli, and involve no 

 volition. The presence of an organ normally implies the ability to use it. The 

 newly born butterfly needs no practice preliminary to flight. The process of sting- 

 ing is entirely reflex; a decapitated bee retains the power to sting, directing its 

 weapon toward any part of the body that is irritated, and a freshly emerged bee, 

 without any practice, performs the stinging movements with the greatest precision. 



As Whitman observes, the roots of instincts are to be sought in the constitu- 

 tional activities of protoplasm. 



The ostensible rationality of behavior among insects, as was said, often leads 

 one to attribute intelligence to them, even when there is no evidence of its existence. 

 As an illustration, many plant-eating beetles, when disturbed, habitually drop to 

 the ground and may escape detection by remaining immovable. We cannot, how- 

 ever, believe that these insects "feign death" with any consciousness of the bene- 

 fit thus to be derived. This act, widespread among animals in general, is instinctive, 

 or reflex, as Whitman maintains, being, at the same time, one of the simplest, most 

 advantageous and deeply seated of all instinctive performances. 



Take the many cases where an insect lays her eggs upon only one species of 

 plant. The philenor butterfly hunts out Aristolochia, which she cannot taste, in 

 order to serve larvae, of whose existence she can have no fore knowledge. Ovipo- 



