92 INSECTS OF ECONOMIC IMPORTANCE 



they hatch and the larvie tunnel through the tubers 

 ruining them ; the Hfe cycle is about 5 weeks in hot 

 weather and there are several generations each sea- 

 son. 



Control — Do not use slips or potatoes from 

 weevil-infested localities; rotate crops and do not 

 plant potatoes more than one year on same soil; 

 burn or feed all infested tubers when crop is har- 

 vested; clean up all vines, culls, and rubbish in the 

 fields; destroy volunteer sweet potato plants and 

 morning-glory plants; spray potato plants with ar- 

 senate of lead, 5 pounds to 100 gallons of water as 

 soon as weevils appear. 



OTHER INSECTS INJURIOUS TO SWEET 

 POTATOES 



Golden tortoise beetle (Copfocycia bicolor). 

 Black-legged tortoise beetle (Cassida nigripes). 

 Sweet potato plume-moth (PferopJionts mono- 

 dactyl its). 

 Cutworms (Several species). 



CABBAGE PESTS 



The cabbage root-maggot ^ {Phorbia brassiccc) 

 Order — Diptera 



This pest is a small fly imported from Europe; 

 it attacks cabbage, radishes, cauliflower, and other 

 cruciferous plants; it also attacks cabbage plants 

 in seed beds and causes much injury. 



The flies appear early in the spring, first two 

 wrecks of May, and deposit their eggs in crevices 

 in the soil close to the stem of the plant ; they hatch 

 in a w^eek or ten days and the young maggots im- 

 mediately burrow along the surfaces of the young 



8 Slingerland— Cornell Univ. Expt. Stat., Bull. 78. 

 Schoene — N, Y. State Expt. Stat., Bulls. 301, 334, 419. 



