INSECT BEHAVIOR 357 
chain, each link of which is a simple reflex act. In fact, no 
sharp line can be drawn between reflexive and instinctive 
actions. 
Basis of Instinct.—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 stinging is entirely 
reflex ; a decapitated wasp retains the power to sting, directing 
its weapon toward any part of the body that is irritated; and 
a freshly emerged wasp, without any practice, performs the 
stinging movements with greatest precision. 
As Whitman observes, the roots of instincts are to be sought 
in the constitutional activities of protoplasm. 
Apparent Rationality.—The ostensible rationality of be- 
havior 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 detec- 
tion by remaining immovable. We cannot, however, believe 
that these insects “ feign death’ with any consciousness of 
the benefit thus to be derived. This act, widespread among 
animals in general, is instinctive, or reflex, as Whitman main- 
tains, being, at the same time, one of the simplest, most advan- 
tageous and deeply seated of all instinctive performances. 
Take the many cases in which 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 larve, 
of whose existence she can have no foreknowledge. Oviposi- 
tion is here an instinctive act, not performed until it is evoked 
by some sort of stimulus—perhaps an olfactory one—from a 
particular kind of plant. 
Stimuli.Some determinate sensory stimulus, indeed, is the 
necessary incentive to any reflex act. The first movements of 
a larva within the egg-shell are doubtless due to a sensation, 
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