INJURIOUS TO CABBAGE AND RELATED CROPS 19 



expanse of about f inch. The front wings are reddish buff 

 marked with several transverse, interrupted Hghter hues. The 

 hind wings are hghter in cok^r with darker marginal and discal 

 bands. The eggs are laid on the surface of leaves in bunches 

 of eight to twenty. Hatching takes place in three or four days 

 and the young larviie at first feed on the under surface of the 

 leaves, skeletonizing them, and spin a silken web inclosing their 

 food. The larger caterpillars devour the entire leaves. They 

 become mature in three or four wrecks. The full-grown cater- 

 pillar is nearly an inch in length, dull green above and greenish 

 yellow below, marked on the dorsal surface with numerous 

 shining black piliferous spots. The body is marked with a 

 double pale median line and a whitish lateral line. Pupation 

 takes place in a delicate silken cocoon spun among the debris 

 at the base of its food plants. The pupa is brown in color. 

 In the South there are probably as many as five generations 

 while in Illinois Forbes records four broods annually. 



References 



Riley, Rept. U. S. Ent. for 1885, pp. 265-270. 

 U. S. Bur. Ent. Bull. 57, pp. 11-14. 1906. 



The Purple-Backed Cabbage Worm 



Evergestis straminalis Hiibner 



Although this insect is common throughout the northeastern 

 United States and Canada, it has been reported as injurious 

 only in the maritime provinces. The insect also occurs in 

 Europe. Its food plants include cabbage, turnip and horse- 

 radish. When infesting the last, it is known as the horse- 

 radish web worm. The caterpillars feed on the leaves, often 

 webbing them together, and sometimes attack the crown boring 

 into the stems and roots. The full-grown caterpillar is about 



