INJURIOUS INSECTS. 87 



and will often destroy the cabbage crop unless preventive 

 measures are taken. The worms of the imported species are 

 green in color, while our native species are bluish with yellow 



Fig. 34. Imported Cabbage Worm, (a) Larva 3 , 

 butterfly. 



(b) Chrysalis, (c) Male 



Female. 



stripes. The butterflies of both species are much alike. They 



are generally white with indefinite black marks above and 



yellow or green markings 



on the underside, and are 



commonly seen flitting over 



fields of cabbage or of other 



of its food plants during 



the day time. The full 



grown caterpillar is about 



an inch and a half long. 



The winter is passed in the 



chrysalis stage hidden 



away in sheltered places and from these the adult butterfly 



emerges in the spring and lays her eggs on the under side of 



of the leaves where they hatch in about one week. There 



are several broods in a season. 



Remedies. Pyrethrum powder, mixed with five times its bulk 

 of flour and dusted into the cabbage just at night fall, is a good 

 remedy. The flour should be mixed with the pyrethrum over 

 night. In a small way hand picking may be successfully re- 

 sorted to. If the worms are troublesome where cabbage is 

 grown on a large scale it is customary to use arsenical poisons 

 as recommended for the potato bug. These, it is evident to any 



