74 INSECT BEHAVIOR 



if we alter the quantity of one ingredient the desired result is not 

 obtained. 



The experiment has in no way disproved that the creature's life 

 progresses by hard and fast rules. On the other hand, it confirms the 

 statement, and further, points out that each rule depends upon the 

 invariability of another for the ultimate success of the wasp. It 

 also tells us that feeding is governed by the amount of provisions in 

 the cell. Each mouthful stimulates a certain number of strokes from 

 the mandibles. Thus, when the normal provender is consumed by 

 the larva, it still continues to chew until the stimulus is gone. In the 

 cell containing two spiders, the poor wasplet found no end of good 

 things. It ate one spider. Its mandibles continued toward the limit 

 of their working hours and came bump into the second spider. The 

 stimulus was renewed, and its jaws commenced to work again, event- 

 ually dragging the unfortunate larva into death at the hands of in- 

 digestion. 



Thus we see the reason for hard and fast rules among insects. They 

 are entirely dependent upon them for their existence. Even so slight 

 a variation as my experiment provided, proves this to my satisfaction. 

 I varied the rule in one small particular with the result that the larva 

 was led unconsciously to its own destruction. 



To go back; the larva upon finishing its spider rests for a short 

 period before commencing its cocoon. This rest may be necessary 

 because there is nothing else to be done until the spinning fluid of 

 which the cocoon is to be made, commences to flow. Once started, a 

 network of strands is thrown across the cell. They pass for the most 

 part under the spinner so that the grub rests upon a net, stretched 

 midway between the top and bottom of the chamber. Later, upon 

 this preliminary support, a neat tubular cocoon is spun. It is rounded 

 at both ends, grayish yellow in color, glossy and rather transparent. 

 It measures eight by seventeen millimeters, and only partly fills the 



