456 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Fig. 466. — The imported cabbage worm, 

 Pontia rapce (Linn.). Eggs on nastur- 

 tium leaf at top, enlarged twice ; larvte 

 in the middle, natural size ; chrysalis at 

 the bottom, natural size. (Original) 



Egg-laying begins soon after the 

 adults leave the pupal stage. The 

 eggs hatch in about a week and the 

 young caterpillars begin feeding at 

 once. They first feed upon the 

 outer leaves, making them ragged 

 and full of holes, but gradually 

 work through towards the heart of 

 the cabbage, leaving the dark-green 

 excrement to mark their paths of 

 destruction. The growth is very 

 rapid, so that in from one to two 

 weeks they are ready to select some 

 secluded spot beneath an old cab- 

 bage leaf or some nearby object 

 and prepare for the pupal stage, 

 which, during the first two genera- 

 tions in the summer months, lasts 

 little longer than the larval stage, 

 but which in the fall continues 

 throughout the winter. There are 

 several generations a year. In fact, 

 in the southern part of the State it 

 seems as if the breeding is only 

 slightly checked during the winter 

 months. 



Nature of Work. — The cater- 

 pillars, or "worms," as they are 

 commonly called, devour the leaves 

 of many plants, but are specially 

 fond of cabbage, which they attack 

 in all stages of its growth. The 

 leaves of young plants are partially 

 eaten and assume a ragged appear- 

 ance. The outer leaves of cabbage 

 beads may also show a similar con- 

 dition, but usually the larvae eat 

 into the heads, making tunnels 

 throughout and leaving dark-green 

 excrement, which is very repulsive, 

 to mark their paths. Much damage 

 is thus done and cabbage growers 

 annually lose large sums because of 

 this pest. 



Distribution. — This butterfly is 

 very common in every part of the 

 State. 



Food Plants. — The caterpillars 

 feed on quite a number of plants, 

 some of which are brussels sprouts, 



