ROMANCE OF THE INSECT WORLD CHAP. 



In some cases the duration of larval life extends 

 over one, two, or even five years. In all species it is 

 much influenced by the weather and other circum- 

 stances, for cold as a rule retards growth and warmth 

 hastens it. Many larvae have an almost unlimited 

 power of endurance of cold, and may be frozen hard 

 without the slightest injury. That a severe winter is 

 highly beneficial for the crops in precluding proba- 

 bility of insect attack in the following spring is utter 

 fallacy. But though larvae will bear great cold, they 

 are extremely susceptible to over-supply of moisture, 

 whether from rain or from dampness of food, a 

 characteristic worthy of consideration when attempt- 

 ing to exterminate an insect pest. 



Suppose that an insect is near the completion of 

 its term of growth, when for the last time as a larva 

 it will cast its coat, and will emerge therefrom in the 

 next stage of its existence a pupa. Great changes 

 in its internal organs since its exclusion from the egg 

 are beginning to take place, and greater ones are yet 

 to come. As before its previous but less momentous 

 larval skin-sheddings, it seems to suffer inconvenience, 

 it becomes exceedingly restless and irritable, it 

 neglects food and diminishes in weight, and, as if 

 aware of its distressing delicacy and defencelessness 

 when the skin is abandoned, as a rule it makes haste 

 to seek or construct some shelter with care and con- 

 sideration, where, secure from harm, the otherwise 

 disastrous revolution may be effected, and the hapless 

 stage of pupal life may be lived through. Many 

 species, like the silk-worm caterpillar, secrete and 

 draw a gummy fluid from their mouths, and spin a 



