INSECTS INJURIOUS TO CABBAGE, ETC. 



329 



and as a rule do but little injury, though occasionally they be- 

 come troublesome. 



" The larvae when full grown measures three-tenths inch in 

 length, tapers a little to the extremities, and is of a pale green 

 color. It is active and irritable, in this respect being very 

 different from any of the larger larvae described." The wings 

 of the parent moth " are kept folded against the sides of the body, 

 are a little turned up at the tips, and are provided with a long 

 fringe. The color above on the head, thorax, and upper part 

 of the closed wings is a light clay-yellow. That part of the 

 wings that is lowest when they are folded is bronze brown, this 

 color terminating abruptly where it meets the clay-yellow of 

 the back by a well-defined sinuous margin. The length from 

 the front of the head to 

 the tip of the folded 

 wings is about one- 

 fourth inch."* 



" The eggs are whit- 

 ish, very minute, and 

 are attached to the 

 leaves, though some- 

 times when very abun- 

 dant they are, it is said, 



i j ' ,1 -i * FIG. 279. The cabbage plutella or diamond- 

 placed On the Sides Of back moth (Plutella maculivennis Curtis) : a. 



back moth (Plutella maculipennis 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.) 



crates holding cab- 

 bage." 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 containing pupae are found on old cabbage 

 stalks in the field or on stored cabbage. Two or three genera- 

 tions a year occur in the 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 distribution. 



" 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 



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



