INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 457 



cabbage, cauliflower, horseradish, kale, mignonette, mustard, nastur- 

 tium, radish, rape, sweet alyssum and turnip. 



Control. — The larva, working as they do into the heads of the 

 cabbages, make control measures practically impossible after they have 

 once begun. Young plants may well be protected by arsenical sprays, 

 which are applied with safety until the heads are half-grown. Clean 



Fig. 467. — Female butterfly of the imported cabbage worm. 

 Pontia rupa (Linn.). Enlarged one and one half limes. 

 (Original) 



culture should be practiced and no cabbage or host plants allowed to 

 grow during the interval between crops unless they are freely sprayed 

 with strong solutions of arsenicals. Spraying with white hellebore kills 

 the caterpillars without danger to the plants or the consumer. Fortu- 

 nately most of the cabbage grown in California is raised near tin- 

 ocean, during the winter, and is usually quite free from this pest. 



Fig 46S. — The southern cabbage butterfly, Pontia protodice (Boisd.). 

 Male and female. Natural size. (After Riley) 



