446 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



THE POTATO TUBER MOTH 310 



Phthorimcea operculella (Zeller) (Family Gelechiida*) 



(Gclecliia operculella Zeller) 



(Bryotropha solanella Boisduval) 



(Figs. 454-458) 



Description. — The larva varies from white to slightly pink, the 

 head being black. When full grown it is about f inch long. The cocoon 



is spun of fine white web, the chrysalis 

 being light brown in color and about 

 i inch in length. The wings of the 

 adults are decidedly gray in color 

 with the bodies silvery. They are 

 about i inch long. The eggs are small, 

 globular and pearly white. 



Life History. — The eggs are laid on 

 the leaves and 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 caterpillars, which 

 feed upon the leaves, and work 

 within the stems and tubers in the 

 fields and only upon the tubers when 

 they are stored in bins. It requires 

 from three to five weeks for the larva 1 

 to mature, when they seek sheltered 

 places and spin cocoons in which to 

 pupate. During the winter the pupal period may occupy several 

 months, but in the summer and 

 fall from fourteen to twenty 

 days are required. The adults 

 are night flyers and are espe- 

 cially abundant in the fall, 

 particularly when early pota- 

 toes 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 infestation. The adults 

 live but a few days. 



Nature of Work. — The most 

 characteristic work in this 

 State is that of the larva 3 upon 

 the potato tubers, which con- 

 sists in making b u r r o w s 

 through till parts, as shown in 

 Figs. 454. 456. The larvae also attack the stems and mine 



Fig. 4f>4. — Potato showing the bur- 

 rows of the potato tuber moth, Phthori- 

 ■maa operculella (Zfill. ). Natural size. 

 (Original) 



Fig. 

 tuber 

 Enlari 



455. — Larvae and pupa? of the potato 

 moth, Phthorimwa operculella (Zell. ). 

 rd one and one fourth times. (Original) 



the leaves. 



ai,1 In the Eastern States and other countries this insect is known as the splitworm 

 of the tobacco and the tobacco miner, because of its habits in mining the leaves of 

 tobacco plants. 



