(^lAPTER II 



INSECTS INJURIOUS TO CABBAGE AND RELATED 

 CROPS 



In this chapter are treated the more important insect enemies 

 of cabbage, cauHflower, brussels sprouts, kohlrabi, kale, col- 

 lards, radish, turnip, mustard and horse-radish. With the 

 exception of horse-radish, these form a natural group of food 

 plants that serves as the common host for a large number of 

 insects, which, although showing a preference for certain crops, 

 can also thrive on the others. Many cruciferous weeds are 

 also food plants of these pests and may serve as centers of in- 

 festation from which the insects spread to cultivated crops. 

 The most important enemies of cabbage and related crops in 

 this country have been imported from the Old World but some 

 of the native insects have found in these succulent vegetables 

 satisfactory food plants. Of European origin are the cabbage 

 root-maggot, the common cabbage worm, the diamond-back 

 moth, the cabbage aphis, the cabbage curculio and the cabbage 

 seed-stalk weevil. The cabbage webworm had its original 

 home in the Old World tropics and the harlequin cabbage bug 

 spread into the United States from Central America during the 

 last half century. 



Horse-radish has relatively few insect enemies, the most 

 important being the harlequin cabbage bug and the horse- 

 radish flea-beetle. 



Cabbage and related crops are often seriously injured by cut- 

 worms and flea-beetles. These insects are treated in Chapters 

 XV and XVII. 



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