24 EBERHARTS OUTLINES OF 



during the year, in the latitude of Illinois. This number 

 increases as we go farther south, and vice versa. 



The female insect is distinguished from the male in that 

 it has two spots on its wings, while the male has only one. 



These eggs are usually laid on the upper side of a 

 cabbage leaf, and ai-e not collected in a mass in one place, 



Fig. 26. Larva of European Cabbage Butterfly. 



but are scattered over the surface of the leaf. When 

 about to pupate, the larvae seek shelter under boards lying 

 in the field, or under the copings of walls and fences. 



Remedies. By far the greater number of Cabbage 

 Butterflies are destroyed by a parasite {Pteromalus pitpa- 

 rum), which lays its eggs on the pupa, and the little maggots 

 hatching out eat their way into the body of the insect, an 

 operation attended with much pain. Tbey devour the fatty 

 portions, thus preventing the pupa from transforming into 

 the perfect state. 



By placing boards in the cabbage field, the pupae, which 

 will soon be found on the under side of these, may be col- 

 lected and placed in a box covered with a screen, to allow 

 the parasites to hatch out and escape, while at the same 

 time the cabbage insect cannot. 



Of late years another natural remedy is rivalling the 

 parasite mentioned above, for its efficacy in disposing of 

 the Cabbage Butterfly. 



This is a contagious disease which is prevalent among 

 the larva?, and destroys them in a short time. Instances 

 are known where a whole field has been entirely cleared of 

 larvae in twenty-four hours. 



