SOME INSECT PESTS IN THE WEST INDIES. 



59 



Sweet Potato Weevil* (Cyhis formicarius, Fab.). 

 This very characteristic insect (fig. 40) is a x^est of greater or less 

 importance in nearly all countries where the sweet potato is under 

 cultivation. It has been recorded from Africa, India, China, Mada- 

 gascar, Louisiana and Florida in the United States, and is said to be 

 a common pest in Cuba. Now, unfortunately, one has to record its 

 occurrence in Jamaica, though, so far as can be gathered, it is not 

 generally distributed in the West Indian Islands. Its introduction into 

 the United States was doubtless from Cuba, and the probability is that 

 before very long we shall find that it has been introduced from the same 

 country into the other adjacent islands. 



Fig. 40. — Sweet Potato Weevil, male and female. (Natural size and 



enlarged.) 



The larva or grub is a small, white, legless creature, which passes 

 the whole of its existence in eating or cutting tunnels in the tubers, 

 filling them with rejectamenta, which ultimately leads to the decay 

 of the potato. Pupation takes place in the tuber, the whole life-cycle 

 occupying about four weeks; and as one generation follows another in 

 rapid succession, the increase is often so great as to render the cultiva- 

 tion of the sweet potato almost impossible. The only practical measures 

 so far devised for dealing with this pest are : — 



1. To dig up the tubers as soon as they are found to be infested, 

 and feed those containing insects to stock. 



2. The complete removal of all tubers, as any that may be left in 



the ground will serve as breeding-places for the insects. 



* See Annual Report, Dept. Agriculture, Washington, 1879, p. 249, for article 

 on this pest. I am greatly indebted to Mr. E. J. Wortley for examples of this 

 curious weevil. 



