INJURIOUS TO CABBAGE AND RELATED CROPS 17 



liiiid wings are pale I'useous. The female clej)()sit.s her eggs 

 singly or in small masses on the leaves of the plant. The egg- 

 is about sV inch in length, flattened and often i)r()vided with a 

 distinct nipple-like projection at one end. When first laid it is 

 light yellow or grayish but just before hatching takes on a 

 pinkish brown color. Each female is capable of laying from 

 300 to 350 eggs. In warm weather the eggs hatch in three or 

 four days. 



The young caterpillars begin feeding, on the underside of the 

 leaves, eating off the epidermis in small irregular patches. The 

 caterpillars often burrow into the leaf itself, into the leaf-stems 

 and into the developing head. After the first molt, the cater- 

 pillar usually covers its feeding grounds with a web of silk on 

 which the excrement and other dirt collect. The caterpillars 

 often attack the bud or heart of the plant, stop its growth and 

 in many cases kill it outright. They sometimes eat out holes 

 in the upper part of turnip roots. 



When full-grown, the caterpillar is about f inch in length, 

 dull grayish yellow in color, and marked dorsally wath five 

 conspicuous brownish purple longitudinal stripes. On the 

 sides and below there are similar but less distinct stripes. The 

 caterpillars become full-grow^i in about eighteen days and after 

 constructing their cocoons transform in a day or two to pupae. 

 The pupa is about yo ii^<^h in length and light yellowish brown in 

 color. In the summer the insect spends about six days in the 

 pupal state. There are probably three or four generations a 

 year but the exact number has not been determined under 

 field conditions. 



Control. 



In regions in which the cabbage webworm is likely to appear 

 in injurious numbers, the plants should be protected by fre- 

 quent applications of arsenicals beginning soon after trans- 

 planting. In this way the young caterpillars will be killed 



