150 The Sweet Potato 



more active. Frequently potatoes in storage that have 

 been little affected during the winter may be entirely 

 riddled in the two spring months. In the field or draw- 

 bed, the beetles first feed on leaves and the stems of 



FiGTJBE 20. — Sweet potato badly infested by sweet potato weevil, 

 decidedly dry, but showing break at middle where living larvse, 

 pupae, and adults were found. Somewhat reduced. 



the young plants, eating or gnawing irregular holes 

 and excavations in them. After the plants reach a 

 sufficient size to become woody, the eggs are deposited 

 on the stem near the surface of the ground. If the 

 ground is loose or cracked from the baking sun, the 

 female will follow the vine down as far as possible and 

 deposit her eggs there. If the tubers themselves are 

 exposed to the surface, eggs are usually deposited on 

 them. The young larva eats into the potato, leaving 

 an irregular tunnel or furrow filled with excrement. 

 They burrow and feed throughout the winter until 

 their full growth is reached, when they form an oval 

 cavity or pupal cell, usually near the surface of the 

 potato, in which they pupate. In cases in which the 

 eggs are deposited on the vines in the -field, the larvse 

 bore down the stem until they reach the potato and 



