INSECTS 



provender, enjoying for a while a new life free from the 

 domestic routine that has bound them since the days of 

 their infancy. But even their liberty has an ulterior pur- 

 pose: the time is now approaching when their lives as 

 caterpillars must end and the creatures must go through 

 the mysteries of transformation, which, if successfully 

 accomplished, will convert them into winged moths. It 

 would clearly be most unwise for the caterpillars of a 

 colony to undergo the period of their metamorphosis 

 huddled in the remains of the tent, where some untoward 

 event might bring destruction to them all. Nature has, 

 therefore, implanted in the tent caterpillar a migratory 

 urge, which now becomes active and leads the members of 



a family to scatter far and 



^^^^^pif£.tJ8?si^^g^^p allowed for the dispersal, 



; , J ^aPJi anc l ^en, as each wan- 



derer feels within the 

 first warnings of ap- 

 proaching dissolution, it 

 selects a suitable place 



Fie. m. The cocoon of a tent cater- r i ■ ir • 



pillar. (Natural size) *Or inclosing Itself 111 a 



cocoon. 



It is difficult to find many cocoons in the neighborhood 

 where large numbers of caterpillars have dispersed, but 

 such as may be recovered will be found among blades of 

 grass, under ledges of fences, or in sheds and barns where 

 they are not disturbed. The cocoon is a slender oval or 

 almost spindle-shaped object, the larger ones being about 

 an inch long and half an inch in width at the middle 

 (Plate 14 E, Fig. 151). The structure is spun of white silk 

 thread, but its walls are stiffened and colored by a yellow- 

 ish substance infiltrated like starch through the meshes 

 of the fabric. 



In building the cocoon the caterpillar first spins a loose 

 network of threads at the place selected, and then, using 

 this for a support, weaves about itself the walls of the final 



[282] 



