THE MONTHLY BULLETIN. 



167 



long. The cocoon is spun of fine white web, the chrysalis being light 

 brown in color and about three eighths of an inch in length. The wings 

 of the adults are decidedly gray in color with the bodies silvery. They 

 are about one inch long. 



Life History. — The small pearly-white eggs are laid on the stems of 

 growing potato plants or upon exposed tubers in early summer, or upon 

 the tubers at digging time. Within fifteen days they hatch into cater- 

 pillars, which feed upon the leaves, stems or tubers, or only upon the 

 latter when they are stored in bins. It requires from three to five weeks 

 to mature, when it seeks a sheltered place and spins a cocoon, in which 

 to pupate. During the w^inter the pupal period may occupy several 

 months, but in the summer and fall from fourteen to twenty days are 



Fig. 151. — Adults of the potato tuber moth {Phthorimwa operculella 

 Zeller) enlarged several times. (Essig, M. B. Cal. Hort. Com.) 



required. The adults are night flyers and are especially abundant in 

 the fall, particularly when early potatoes are dug. If the tubers are 

 exposed over night the females lose no opportunity to deposit their 

 many eggs, generally over all of them, so as to make a serious infesta- 

 tion. The adults live but a few days. 



Distribution. — Throughout the central and southern parts of the 

 State. 



Food Plants. — Potatoes, tobacco, nightshade, and cat-tails are 

 attacked. 



