388 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



observed three generations. In central Texas the beetles hiber- 

 nate over winter, but in south Texas they continue to breed in 

 the bins during the winter. 



Control. Dr. F. H. Chittenden (I.e.) recommends the follow- 

 ing methods for control in addition to the quarantine measures 

 which have been established by various states to prevent the 

 spread of the beetle in shipments of infested potatoes. Rotation 

 of crops, especially valuable since the weevil does not breed in 

 crops other than the sweet potato and does not breed in any 

 other plants except a few closely related weeds, is the first recom- 



FIG. 323. The sweet-potato root-borer (Cylas formicarius) : extreme left 

 hand figure, adult beetle, with enlarged antennae at right; figure at left 

 center, pupa; at right center, larva; at extreme right, portion of sweet- 

 potato tuber channeled by borer all figures except the last considerably 

 enlarged; natural sizes indicated by hair lines. (After Farmers' Bulletin, 

 No. 26, U. S. Dept. Agr.) 



mendation. Clean culture, including the destruction of all refuse 

 from infested fields, and the burning or feeding to hogs of all 

 damaged potatoes. Removal of the seed beds as far as possible 

 from the field where the potatoes are to be grown has also proven 

 of great value in reducing the amount of damage. Dipping the 

 plants, before setting, in a solution of lead arsenate and later, 

 spraying with an arsenical, zinc arsenite being suggested as 

 having given success, to kill the early appearing beetles, are 

 also recommended. Prompt harvesting, as soon as the potatoes 

 are ready, and the separation of damaged potatoes is necessary. 

 Keep down volunteer plants upon which the weevils can breed. 



