SWEET POTATO INSECTS 239 



Control. 



Tortoise beetles are readily killed by spraying the vines 

 with arsenate of lead (paste), 2 pounds in 50 gallons of water, 

 taking care to spray the mixture on the underside of the leaves. 

 The young plants may also be protected from injury by dipping 

 them in a mixture of arsenate of lead and water as recommended 

 for the control of the sweet potato flea-beetle on page 333. 



Reference 

 Walsh and Riley, Am. Ent., 1, pp. 234-238. 1869. 



The Sweet Potato Weevil 



Cylas formicarius Fabricius 



This highly destructive pest of the sweet potato is a native 

 of the tropics. It was first seen in the southern United States 

 in 1875 and now occurs from Georgia and 

 Florida westward along the Gulf of Mexico 

 into Texas. The insect is also found in India, 

 Australia, Cochin China, Java, Madagascar 

 and the West Indies. The adult is a slender 

 snout-beetle about ^ inch in length (Fig. 147). 

 The head is dusky black ; the prothorax and 

 legs are reddish and the wing-covers a metallic 

 bluish black. The prothorax is strongly con- 

 stricted near the hind margin ; the snout is y^^ ' ^47 _ ^he 

 stout and is carried projecting forward. The sweet potato 

 beetles are decidedly ant-like both in form and ^^^^^ ' ' 



coloration. While they possess functional wings, they rarely 

 use them, but are sometimes attracted to lights. 



The beetle deposits her creamy w^hite, elongate oval eggs, 

 about ^ inch in length, singly in a small hollow eaten out 

 in the stem or in a tuber that has become exposed. The eggs 

 hatch in four to six days. The larvae hatching in the stems 



