INJURIOUS TO CABBAGE AND CRUCIFEROUS CROPS 371 



old stalks and leaves it is obvious that they should be cleaned up 

 and the field plowed as soon as the crop is harvested. By leaving 

 a few piles of stalks, leaves and rubbish, the bugs might be concen- 

 trated and then destroyed. 



The most successful method of control yet devised is the use 

 of a trap-crop, to which the bugs are lured as they emerge from 

 hibernation and on which they may be destroyed before they 

 attack the cabbage. Kale planted in the fall or mustard planted 

 early in the spring serves well for a catch crop, and should be 

 planted in rows through the intended cabbage-field. The bugs 

 seem to prefer the kale to the young cabbage, and while concen- 

 trated upon it they should be killed by spraying them with pure 

 kerosene. The trap-crop may well be planted at different dates, 

 so that after one row has been destroyed by spraying, another will 

 invite the remaining bugs. The nymphs may be destroyed by 

 spraying them with 15 per cent kerosene emulsion or whale-oil soap, 

 one-half pound per gallon. Whale-oil soap used at the rate of 1 to 2 

 pounds to the gallon will kill most of the adult bugs hit by it 

 without injury to the cabbage, but dependence should not be 

 placed upon control by spraying, as its practicability on a large 

 scale is yet to be demonstrated. 



The Cabbage-aphis * 



Wherever cabbage is grown the common " cabbage-louse " 

 occasionally becomes abundant enough to do serious damage, 

 often destroying young plants, which become covered with the 

 disgusting masses of grayish aphides. They are found commonly 

 in almost every cabbage-patch, but usually their natural enemies 

 are so effective as to prevent their increase; otherwise they would 

 be one of the most serious pests of cruciferous crops. They may 

 be found on all of the cultivated and wild cruciferae, but cabbages 



* Aphis brassicce Linn. Family Aphididoe. See C. V. Riley, Report of 

 U. S. Commissioner of Agriculture, 1884, p. 317. C. M. Weed, " Insect 

 Life," Vol. Ill, p. 289. G. W. Herrick, Journal of Economic Ent., Vol. IV. 

 p. 219? F. H. Chittenden and C. H. Popenoe, Bulletin 2, Va. Truck Exp. 

 Sta., p. 22. 



