290 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



plants or when the stalks harden, the larvae leave the stalks and 

 enter the tubers, particularly where they may be exposed. Where 

 potatoes are exposed by being insufficiently covered the moths 

 will lay their eggs directly upon them, as they also do upon 

 potatoes exposed in the field after digging. 



Most of the observations upon the life history seem to have 

 been made upon the insect when breeding in stored potatoes. 

 The eggs are about one-fiftieth inch long, oval, white, and laid 

 singly or in pairs, about the eyes of the potatoes, or in similar 

 rough places, where they are seen with difficulty. They hatch 

 in a week or ten days, and the young larvae are about one- 

 twenty-fifth inch long of a transparent white color. The 

 larvae burrow beneath the skin and bore into the potatoes, 

 filling their burrows with frass and excrement, which soon give 

 rise to various rots which cause the destruction of the tuber, 

 already rendered unfit for food by the burrows. The larvae 

 become full grown in about six or seven weeks. They are then 

 about a half inch long. The head is dark brown; the first 

 segment is an old rose color, with dark brown shield on the 

 back; the second segment is a similar clouded pink; while the 

 third and succeeding segments are a clouded white, often becom- 

 ing yellowish or greenish, according to the food eaten. The full- 

 grown larva returns to the mouth of the burrow and there makes 

 its cocoon, or leaves it and forms the cocoon in some depression 

 of the potato or in some crack of the storage vessel or in a fold 

 of the bag. The cocoon is constructed quite differently from 

 that of most moths as described by Mr. Clarke. The larva first 

 makes a mat of silk and then forms an outer layer to the surface 

 of which particles of dirt and rubbish adhere so that the cocoon 

 is well concealed. When this pocket-like cocoon is finished the 

 larva enters it and closes the open end and in it transforms to 

 the pupa. The pupal stage lasts about two weeks, so that the 

 complete life cycle requires from nine to twelve weeks, there being 

 several generations during the year, according to the temperature. 



Control. As the insect breeds on various common weeds of 

 the Nightshade family (Solonacece) , it is important that they be 



