10 CIRCULAR 4 2 2, U. S. DEPARTMENT OF AGRICULTURE 



majority of the larvae observed constructed loosely woven cocoons 

 (fig. 6) , -upon the completion of which they became sluggish and in- 

 active. From less than a day in warm weather to a week or more 

 during the cooler weather of spring and fall was consumed in the 

 prepupal stage. The last larval skin was cast off and remained in 

 the cocoon. In some instances larvae pupated naked, especially when 

 low temperatures and poor-quality foods made conditions unfavorable 

 for growth. 



Figure 6. — Cocoons of the tobacco moth spun beneath a floor board of a tobacco ware- 

 house for purposes of overwintering and pupation. 



THE PUPA 



The pupae are semiactive when disturbed, being able to wriggle 

 the abdomen and roll about in the cocoon. When removed from the 

 cocoon or disturbed by prodding, they wriggle energetically. The 

 tendency is for the disturbed pupae to squirm away from bright 

 lights. They are light brown in color when newly formed, turning 

 a darker brown with age (fig. 7). 



The average of the pupal periods ranged from 5 days in hot 

 summer weather to 25 days during the cool periods in spring and fall. 

 Many hundreds of pupae that transformed late in the fall died 

 during the winter. Several hundred infested hogsheads in unheated 

 storages were examined by the writers late in the winter and no living 

 pupae were found. The maximum length of the pupal period ob- 



