Cole-crop Insects 111 



rows into the stem and crown ; restricted as a pest to the mari- 

 time provinces of Canada. Control: Spray with arsenate of 

 lead (paste) , 2 lbs. in 50 gals, of water. 



Zebra catekplllae {Mamestra picta). — A brightly colored 

 caterpillar, 2 in. long when full-grown, black, with two bright 

 yellow stripes on each side of the body. It often attracts 

 attention, but rarely causes serious damage. Control: Spray- 

 ing with an arsenical as for the green cabbage worm. 



Cabbage aphis {ApMs hrassicce). — A mealy grayish-green 

 plant-louse that often occurs in dense masses on the underside 

 of the leaves and on the tender leaves on the heart of the 

 plant ; most abundant and destructive in seasons of drought. 

 Control: Thorough spraying with so-called whale-oil or fish-oil 

 soap, 10 lbs. in 100 gals, water, or with " Black Leaf 40 " tobacco 

 extract, % pint in 100 gals, water with 4 or 5 lbs. soap added. 

 L'se long leads of hose equipped with short extension rods and 

 direct the spray by hand. For effective work, a pressure of 

 150 to 175 lbs. should be maintained and enough of the spray 

 applied to wet the lice thoroughly. 



Turnip aphis (Aphis pseudohrassicw) . — A plant-louse closely 

 related to the cabbage aphis and often confused with it. Con- 

 trol: Same as for the cabbage aphis. 



Spinach aphis (Myzus persicw). — See under Spinach. 



Cabbage root-maggot (PliorMa Itrassicce). — Small whitish 

 maggots about % in. long which taper toward the head. They 

 first attack the tender rootlets and then burrow In the main 

 root, causing the plants to wilt and die. In the North they 

 are most destructive to early cabbage in the field and late 

 cabbage in the seed-bed. Control: Seed-beds are best pro- 

 tected from maggot attack by screening them with cheese- 

 cloth covers. The bed is surrounded by 6 or 8 in. boards 

 placed on edge and the cheesecloth is stretched over the top, 

 being supported by galvanized wires running over short posts. 

 Early cabbage in the field may be protected by placing tarred 

 paper discs around the plants when they are set out. Recent 

 experiments in Canada indicate that corrosive sublimate, 1 part 



