31 





f" 



m 



i 



Fig. 25. 



The hind wings are leaden brown, and the under side of all the 

 wings is leaden brown, glossy, and without any dots. 



The antennae are whitish with dark rings, and the abdomen white. 

 There are two broods of this insect in this region, the moths of the 

 first appearing in May, and those of the second in August. They 

 hibernate in the pupa stage. 



The caterpillars, Fig. 25, a, (6, the top and c, the side of a seg- 

 ment,) appear in June or July and September; they are small and 

 cylindrical, tapering at both ends, pale green, and about one-fourth 

 of an inch long. The head has a yellowish tinge, and there are 

 several dark, stiff hairs scattered over the body. 



When ready to transform, this caterpillar spins a delicate gauze- 

 like cocoon. Fig. 25, e, made of white, silken threads, on the under 

 side of a cabbage leaf. The pupa, Fig. 25, cZ, and i', the end of a 

 pupa, is commonly white, sometimes shaded with reddish brown, 

 and can be distinctly seen through the silken case. 



The first brood is more injurious than the second, as it feeds on 

 the young cabbage leaves before the head is formed, and this must 

 surely stunt the growth and make weak, sickly plants ; while the 

 second brood feeds only on the outside leaves. The caterpillars are 

 very active, wriggling violently when disturbed, and falling by a 

 white silken thread. 



Hot dry weather is favorable to them and enables them to multiply 

 rapidly. Advantage has been taken of this fact, and spraying the 

 plants thoroughly with water is strongly recommended. Prof. Riley 

 states that the insects are very readily destroyed by pyrethrum. 

 There are two species of spiders and a species of Ichneumon fly that 

 destrov them. 



