LEADING VEGETABLE CROPS I33 



larvae from an inch to ij^ inches in length, covered 

 with fine black dots. There are two and three 

 broods of this insect each season in the North. A 

 number of natural enemies have developed, which 

 largely keep this pest under control, but it is 

 often necessary to use insecticides of some kind for 

 its direct destruction. The most satisfactory in- 

 secticide is pyrethrum or hellebore. The active 

 principle of these powders is volatile, and the 

 poisonous properties are lost in a few days' ex- 

 posure to the air, making them perfectly safe to use. 

 Before the plants have begun to head arsenate of 

 lead will prove an effective and safe poison. 



The cabbage louse is an insect widely dissemi- 

 nated over the United States, usually becoming more 

 numerous and troublesome during extremely dry 

 seasons. In the North the insects appear in late 

 May or early June. They attack both the upper 

 and lower sides of the leaves, causing them to curl 

 and finally wither and die. The eggs are deposited 

 on the stems and refuse leaves, where they pass the 

 winter. One effective method of control suggests 

 itself, viz., to gather and burn all stalks and leaves 

 as soon as cutting is over. Kerosene emulsion 

 seems to be the most effective direct treatment. 

 The stock solution described elsewhere is diluted 

 one gallon to 15 before application. 



The cabbage root maggot is found attacking the 

 roots of all cruciferous plants, but is especially 

 troublesome upon cabbage, cauliflower and radish. 

 The adult insect is a small fly resembling the com- 

 mon house fly. It makes its appearance during late 

 April and early May, and deposits its eggs at the 

 surface of the ground near the plant. In from eight 

 to ten days the eggs hatch and the larva or maggot 



