INJURIOUS TO CABBAGE AND CRUCIFEROUS CROPS 367 



the front of the head to the tip of the folded wings is about one- 

 fourth inch."* 



" The eggs are whitish, very minute, and are attached to the 

 leaves, though sometimes when very abundant they are, it is 

 said, placed on the sides of crates holding cabbage." The full- 

 grown larvae pupate in small cocoons composed of a delicate 

 lace-work of silken threads through which the whitish, often 

 brown-striped, pupa may be seen. In winter the cocoons con- 

 taining pupae are found on old cabbage stalks in the field or 

 on stored cabbage. Two or three generations a year occur in the 



$ 



FIG. 266. The cabbage plutella or diamond-back moth (Plutdla maculi- 

 pennis Curtis) : a, larva; b, segment of same greatly enlarged; d, pupa; 

 e, pupa in cocoon; /, adult moth; g, wings of dark variety; h, moth 

 with wings folded. (After Riley, U. S. Dept. Agr.) 



more northern States and four or five generations farther south, 

 while in the extreme South it may be found active practically 

 throughout the year. The species has a world-wide distribu- 

 tion. 



" During very dry weather these little insects become exceed- 

 ingly common, and riddle the cabbage leaves with small holes. 

 Wet weather, on the other hand, has long been known to be 

 unfavorable to them," and drenching the plants with water has 

 been recommended as one of the best means of control, The 

 same remedies applied for the other cabbage worms will readily 

 control this little pest, if necessary. 



* H. Carman, Bulletin 114, Ky. Agr. Exp. Sta., p. 29. 



