21 



3'ellow line along the back, and a row of small yellow spots along the 

 sides, and eat their way down into the head of the cabbage. 



Fig. 14. 



Having reached its full growth, the caterpillar. Fig. 14, a, which 

 is about an inch in length, wanders off to some sheltered place, as 

 under a board, fence-rail, or even under the edge of clapboards on 

 the side of a building, where it spins a button of silk, in which to 

 secure its hind legs, then the loop of silk to support the forward part 

 of the body. 



It, now casts its skin changing to a chrysalis, Fig. 14, b, about 

 three-fourths of an inch in length, quite rough and uneven, with 

 projecting ridges and angular points on the back, and the head is 

 prolonged into a tapering horn. In color they are very variable, 

 some are pale green, others are flesh colored or pale ashy-gray, and 

 sprinkled with numerous black dots. Tlie winter is passed in the 

 chrysalis stage. 



After the caterpillar changes to a chrysalis, their minute parasites 

 frequently bore through the outside and deposit their eggs within. 

 These hatch before the time for the butterflies to emerge, and feed- 

 ing on the contents, destroy the life of the chrysalis. 



Birds and spiders are of great service in destroying these insects. 



The pupae should be collected and burned if the abdomen is flexi- 

 ble ; but if the joints of the abdomen are stiff and cannot be easily 

 moved, they should be left, as they contain parasites. 



Several applications of poisons have been used, the best results 

 being obtained from the use of pyrethrum as a powder blown on to 

 the plants by a hand bellows, during the hottest pait of the day, in 

 the proportion of one part to four or five of flour. 



As the eggs are laid at different times, any application, to be thor- 

 oughly tested, must be repeated several times. 



