POTATO INSECTS 163 



The insect ranges from Virginia to Colorado and southward 

 and on the Pacific Coast is present in CaUfornia and Washing- 

 ton. It is also known as a serious enemy of the potato in 

 Australia, New Zealand, the Mediterranean region and South 

 Africa. Besides potato and tobacco, the insect sometimes 

 attacks eggplant and tomato, mining the leaves and stalks 

 and burrowing in the fruit. Its wild food plants include com- 

 mon nightshade, horse-nettle, Jamestown weed and several 

 other solanaceous plants. 



The potato tuber moth has been studied most carefully in 

 California and in France. The caterpillars not only infest 

 the tubers both in the field and in storage but also mine the 

 leaves and petioles and bore into the stalks. The parent moth 

 has an expanse of a little more than ^ inch. The front wings 

 are yellowish brown, more or less spotted and mottled with 

 dark brown. The hind wings are light yellowish brown and 

 provided with a long fringe. The moths appear in the field 

 early in the spring and deposit their eggs singly, usually on the 

 underside of the potato leaves. The egg is oval, about -^V inch 

 in length, pearly white with a faint iridescence, becoming 

 leaden gray just before hatching. The eggs hatch in three to 

 five days. On hatching, the young larva bores into the leaf 

 where it produces a blotch mine. As it increases in size, it 

 may migrate to another leaf or bore down through the petiole 

 and into the stalk, causing the branch to wilt and die. When 

 full-grown the caterpillar is about ^ inch in length, white, 

 tinged with pink or greenish above, with the head and cervical 

 shield dark brown and with the small anal plate light brown. 

 It reaches maturity in two weeks to seventeen days in warm 

 weather. When ready to pupate, the larva constructs a small 

 grayish silken cocoon about ^ inch in length, which is covered 

 with dirt and pieces of excrement. The cocoons are sometimes 

 found in the opening of the burrow, in trash at the base of the 

 plant or more commonly in the dried leaves still clinging to the 



