Insect Pests and Plant Diseases. 



185 



CABBAGE AND CAULIFLOWER. 



The green caterpillars (Fig. 159) hatch from eggs laid by the 



Cabbage-worm. common white butterfl}-. There are several broods every sea- 

 son. If plants are not heading, spray with kerosene emulsion 



or with Paris green to which the sticker has been added. If heading, apply 



hellebore. 



These small mealy plant-lice are especially troublesome during 

 cool, dry seasons when their natural enemies are less active. 



Cabbage aphis. Before the plants begin to head, spray with kerosene emulsion 

 diluted with 6 parts of water, or whale-oil soap, i lb. in 6 gals, 

 of water. 



The white maggots that feed on the roots (Fig. 160) hatch 

 from eggs laid by a small fly somewhat resembling the com- 

 mon house fly, near the plant at the surface of the ground. 

 Hollow out the earth slightly around every plant and freely 



apply carbolic acid emulsion diluted with 30 parts of water. Begin the treatment 



early, a day or two after the plants are up or the next day after they are set out. 



Repeat the application every 7 to 10 days until the latter part of Alay. It has also 



Cabbage 

 root-maggot. 



Fig. 160. Cabbage rooi-maggots. 



been found practicable to protect the plants by the use of tightly fitting cards 

 cut from tarred paper. Cornell Bulletin 78. 



ONION. 



Onion tops frequently turn white and die as the result of the 

 Onion thrips. feeding punctures caused by these minute yellowish insects. 



The injury is known as "white blast." Spray thoroughly with 

 kerosene emulsion diluted with 6 parts water, or whale-oil soap, i lb. in 4 gals, 

 of water. 

 Onion maggot. For treatment see cabbage root-maggot. 



