Insects Affecting Sweet Potatoes 145 



arsenate spray is advised, using 4 or 5 pounds arsenate 

 of lead to 50 gallons of water. To make the spray stick 

 better 1 pound of fisK-oil soap may be used. This 

 should be applied as soon as the young larvae are noticed. 

 Eiley succeeded in bringing but a number of para- 

 sites from the larvse; this is probably one reason why 

 the insect does no more damage. It is thought that 

 the parasites, especially in the southern states where the 

 winters are mild, will partially if not completely con- 

 trol this pest. 



SWEET POTATO WEEVIL (FigS. 16—23) 



Cylas formicarius 



Within the last decade, by far the most serious in- 

 sect pest of sweet potatoes has proven to be the sweet 

 potato weevil. While this insect has been present in 

 the United States since about 18Y9 and its ravages have 

 been noticed locally in Texas, Louisiana and Florida, yet 

 it was not until the beginning of the War when the whole 

 world was looking to the United States for its food sup- 

 ply that the seriousness of this pest was recognized. 



In 191Y the Bureau of Entomology started investiga- 

 tions with the idea of control and in some instances 

 eradication. This insert was found in Texas, Louisi- 

 ana, Mississippi, Alabama, Florida and Georgia, and 

 also our insular possessions. It is estimated that Texas 

 in 191Y raised $9,000,000 worth of sweet potatoes and 

 suffered a loss of 20 per cent, or $1,800,000. Louisi- 

 ana, with a crop valued at $5,000,000 lost 12 per cent, 

 or $600,000, and Florida with a $4,000,000 crop lost 

 $400,000 worth. Thus it will he seen that the loss 

 in the southern states is about $3,000,000 or $4,000,- 



