IMPORTED CABBAGE WORM 



231 



on the leaves of any food plant available. It requires about a 

 week for the eggs to hatch, and the larvae grow rapidly. It requires 

 about two weeks for them to attain their full growth. They then 

 transform into chrysalids, which are suspended by threads of silk 

 from the leaves of food plants. The chrysalid changes from being 

 greenish at first to a light brown. In one or two weeks the butter- 

 flies emerge. In the South there are from one to four or five broods 

 each season. The last generation passes the winter in the chrysalid 

 form among the old stalks and rubbish in the field. 



Injury. This insect eats large, irregular holes in the leaves 

 of cabbage, cauliflower, and related plants, and disfigures the heads 

 of cabbage and cauliflower by deposits of excrement. 



FIG. 240. Cabbage 



maggot: a, larva; 6, pupa; c, adult female; d, head of male; e, antennae. 

 Hair lines show actual sizes. (After Riley.) 



Control. Cabbages and cauliflower are not susceptible to 

 injury by Paris green; hence, Paris green may be used upon cab- 

 bages for this insect as strong as four or five pounds to fifty gallons 

 of water without any injury whatever to the plant. A little soap, 

 however, should be added to the water to enable it to spread over 

 the leaf; otherwise the spray runs off the leaf like water off of a 

 duck's back. There is absolutely no danger to human beings on 

 account of spraying cabbages. In the first place, little or none of 

 the poison gets inside the head, and it has been demonstrated 

 satisfactorily that a person would have to eat several bushels of 

 sprayed cabbages at one sitting in order to obtain enough poison 



