CHAPTER XII 



SWEET POTATO INSECTS 



The sweet potato in the United States is not, as a rule, 

 subject to serious injury by insects, except in limited areas 

 where the weevil has become established. When the plants 

 are just set out, they are likely to be attacked by flea-beetles 

 (see page 332) and by tortoise beetles. In Florida the late 

 crop is often seriously injured by the sweet potato white-fly. 



The Tortoise Beetles 



Sweet potato vines are subject to injury soon after trans- 

 planting by several species of tortoise beetles that eat out 

 more or less circular holes in the leaves. These leaf-beetles 

 are flattened below and convex above and have the margins 

 of the prothorax and wing-covers broadly expanded and more 

 or less semi-transparent, giving the insect a regularly oval 

 outline. The head is concealed under the expanded margin 

 of the prothorax. The beetles have a striking resemblance 

 in form to miniature turtles — hence their common name. The 

 larvae are sometimes known as peddlers from their habit of 

 carrying their cast skins and excrement in a pack over the 

 back supported on two long spines arising at the posterior 

 end of the body. Along the edge of the body is a row of rather 

 large branched spines. 



In New Jersey, the beetles appear on the sweet potato plants 

 as soon as they are transplanted in late May or early June 

 and, after feeding for a time, lay eggs from which a new brood 



235 



