180 The Potato 



the best method to keep them in check is to rake the fields 

 over after digging the potatoes and bum all the refuse. 

 Destroy also all other solanaceous plants which may be 

 - growing in the neighborhood. 



The stalk-borer {Pa'pavpema nitella) 



The potato is probably not the normal food plant of this 

 insect, but when other food material, such as certain weeds, 

 tomatoes, corn, cotton and some grasses, are lacking, the 

 potato is sometimes infested. The adult is a gray moth, 

 and the larvae do damage by boring into the stems of the 

 plants on which they feed. 



The insect lives over winter by means of eggs which are 

 laid in the fall in masses of fifty or sixty on grasses and 

 weeds. The eggs hatch in the spring, and the larvae 

 puncture the leaves and then work down into the stalk. 

 Frequently they travel from one plant to another. The 

 larvae, when mature, eat holes in the sides of the stalks and 

 pupate. Late in August, the adults emerge and lay eggs 

 for next year's flock. There is one generation in a year. 



Control. — The stalk-borer should have the same treat- 

 ment as the stalk-weevil. 



White grvhs (Lachnosterna species) (Fig. 12) 



These are the larvae of the May-beetles or Jime-bugs. 

 They are large, white, soft-bodied grubs which are com- 

 monly found in sod ground. They feed on the roots of 

 many plants and sometimes eat into the tubers of pota- 

 toes, especially those planted on new ground. 



This insect lives in the ground over winter either as an 



