196 



THE MONTHLY BULLETIN. 



THE IMPORTED CABBAGE WORM. 



I'untia rapa' Sob. (Family Pieridse). 



{Pieris rapw Linn.) 



(Fig. 183.) 



General Appearance. — Though this is an imported insect it has 

 become as common as if it had always been here. The adult butterflies 

 are about one and one fourth inches long with a wing expanse of two 

 inches. The color is white with two small black spots near the middle 

 and a large black spot at the tip of each fore wing. The caterpillars 

 are light velvety green in color and very finely dotted with minute dark 

 spots. The length when full grown varies from one to one and one 

 half inches. The chrysalis is about one inch long and varies in color 

 from yellow to green, light or dark gray. 



Life History. — In the northern part of the State the species win- 

 ters over in the chrvsalis stage, while in the south adult butterflies 



Fig. 183. — Adult and larva of the 

 imported cabbage worm {Pontia rapw 

 Sch.). (U. S. Dept. Agrcl.) 



may be seen almost any time of the year. Thej^ become very much 

 in evidence early in March and are active throughout the entire summer 

 and fall. Egg laying begins soon after the adults leave the chrysalis 

 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 holey. l)ut 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 cabbage 

 leaf or some nearby object and prepare for the chrysalis stage, Avhich, 

 during the first two generations 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. 



Distribution. — Very common in every part of the State. 



Food Plants. — The principal economic food plants are cabbage, cauli- 

 flower, brussels sprouts, turnip, radish, mustard, and horseradish. 



