New York Agricultural Experiment Station. 401 



of the worms until considerable damage has been done. In other 

 words, no insecticide is applied until fall, and then not until after 

 the worms are nearly one-half grown, with the result that never 

 more than one-half of them are destroyed. A third reason, and 

 one on which the preceding partially depends, lies in the habits of 

 the cabbage worm and its butterfly and of the cabbage looper and 

 its moth. To show these the life history of each must be briefly 

 reviewed. 



CABBAGE WORM. 



(Pieris rapae.) 



LIFE HISTORY AND HABITS. 



"Worms of the last fall brood pass the winter in the chrysalid 

 or pupal form. These chrysalids are attached to the under side 

 of rails, sticks and dry weeds, and also to the sides of buildings or 

 any place where they can obtain some protection from excessive 

 moisture. 



The white butterflies issue from the chrysalids the latter part 

 of April and during May. They sometimes appear early in April, 

 if the weather is warm for several days. After pairing, the 

 female butterflies lay their eggs on whatever suitable plants can 

 be found at that season of the year, on old stumps of cabbage grow- 

 ing in neglected fields, cabbage set out for seed purposes, Early 

 Wakefield cabbage, Siberian kale (" sprouts ") and on such weeds 

 as wild radish, mustard and cresses. Probably, on Long Island, 

 the latter plants, especially wild radish, are the principal ones on 

 which the worms of the first spring brood exist. The eggs of the 

 butterflies are usually deposited singly on the lower and outer 

 surface of the leaf, each female butterfly laying from 

 100 to 300 eggs. The egg laying of the first brood ex- 

 tends over a period of about 3 weeks. Erom 5 to 10 

 days are required for the eggs to hatch. After hatching from 

 the egg the worms feed for a period of about 10 or 12 days. 

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