6 



BtTLLETIN 421, V. S. DEPARTMEI^T OF AGRICULTIJRE. 



In large fields near the one mentioned above larvae could be found 

 in most of the plants, but apparently the vigor of the plants was not 

 noticeably affected and the amount of damage done, if any, was 

 certainly small. Taking all things into consideration, the damage 

 done by the tuber moth to the growing plant in southern California 

 is shght in comparison to that caused to tubers. 



The tuber-feeding larva injures the potatoes themselves by tunneling 

 through them, so filling these tunnels with excrement and fungus that 

 the potatoes, even if not severely injured, are very unsightly and of 

 small market value. The character of the injury (figs. 3-5) does not 

 seem to be influenced by the condition of the tuber or chmatic condi- 



FiG. 3.— Potato sliced to show advanced injury by potato tuber-moth larvae. (Original.) 



tion, some larvse digging subepidermal channels while others tunnel 

 directly through the substance of the tuber. The loss consists not 

 only of the actual substance of the tuber which is channeled and 

 ruined, but is also due to the fact that badly injured tubers are 

 unsightly and undesirable for food, - 



ECONOMIC IMPORTANCE. 



Since the first report of the tuber moth, large losses have been 

 reported from various sections of the world. Analysis of these reports 

 shows beyond a doubt that in mild, . dry chmates the tuber moth 

 works very serious injury to stored potatoes. In similar chmates, 



