4 MANUAL OF VEGETABLE -GARDEN INSECTS 



The Imported Cabbage Worm 



Pontia rapoe Linnaeus 



The common white cabbage butterfly of the United States 

 and Canada is a native of the Old World. It was first intro- 

 duced into America at Quebec about 1860. Later independent 

 introductions occurred at New York in 1868, at Charleston, 

 South Carolina, in 1873 and at Apalachicola, Florida, at about 

 the same date. From these points as centers the insect spread 

 rapidly and by 1885 it occupied practically the whole territory 

 east of the Pacific slope. The favorite food plant of the im- 

 ported cabbage worm is cabbage, but it also attacks cauli- 

 flower, turnip, horse-radish, radish, mustard, gillyflower, 

 nasturtium and sweet alyssum and it also feeds on a number of 

 wild plants belonging to the mustard family. The cater- 

 pillars are sometimes found abundantly on mignonette. 



The imported cabbage worm hibernates in the pupal state 

 and the white butterflies emerge in early spring, being among 

 the first to appear in our fields and 

 meadows. Their flight is low and 

 unsteady and they alight at frequent 

 intervals. The female deposits her eggs 

 singly on the under surface of the leaves 

 of the food plant. The egg (Fig. 1) is 

 lemon yellow in color, nearly -^ inch 

 Fig. 1- Eggs of the im- j^^ j^ ^.j^ ^^^ attached to the leaf at 



ported cabbage butter- ® 



fly (X 15). one end. It is broadest two thirds 



of the distance from the base, and 

 then tapers to the top, which is flattened. The surface is beau- 

 tifully ridged lengthwise and crosswise. The egg hatches in 

 about a week and the pale greenish yellow caterpillar begins 

 feeding on the under surface of the leaf, which it skeletonizes. 

 A little later the caterpillars are able to eat out holes in the 

 leaves, only the larger veins remaining. When the plants are 



