432 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



planted sweet potatoes are much less seriously injured, as the 

 beetles will seek out their wild food-plants and become established 

 upon them, so that late planting may be resorted to when neces- 

 sary or more convenient. Well grown, stocky plants will better 

 withstand injury, and liberal fertilization will enable them to make 

 a quick growth even if slightly checked. 



Tortoise-beetles or Gold-bugs * 



Of all the insects affecting the sweet potato, the brilliant, little 

 golden beetles which form one tribe (CV/.s.s<'</<r) of the large family 

 of leaf-beetles, are the most common and are quite peculiar to it. 

 They are beautiful insects, some of the species appearing like drops 

 of molten gold, which has given them the name of " gold-bugs," 

 while the broad expansion of the thorax and wing-covers gives 

 them a fancied resemblance to a tortoise; hence the name " tortoise- 

 beetles." The species affecting the sweet potato are classed in 

 three different genera, but are sufficiently alike in their general 

 habits and life history to be treated together. 



Life History. The beetles hibernate over winter and'%. the 

 spring before the sweet-potato plants are set they feed on their 

 native food-plant, the morning glory. As soon as the plants are 

 set out, the beetles commence to eat large round holes in the leaves, 

 and so riddle them that many must often be replanted. The worst 

 damage, however, is done to the set on which the eggs are laid. 

 Rarely are the new shoots seriously eaten or are eggs laid upon 

 them. The larvae hatch during the first half of June in Maryland, 

 and require slightly over two weeks to become full grown. Though 

 the larvae do considerable damage by eating the foliage, it is not 

 nearly as serious as that done by the beetles. The larvae are almost 

 as disagreeable as the adult beetles are attractive, but are never- 

 theless very interesting creatures. Each of them is provided with 

 a tail-like fork at the end of the body which is almost as long as 

 the body, and in those species in which it is depressed, entirely 



* Family Chrysomelidae. 



