INSECTS INJURIOUS TO CABBAGE AND OTHER CROPS I4I 



cabbage worm and the harlequin bug, our most important insect 

 enemy of cruciferous crops. It is unusually voracious, devel- 

 oping rapidly, but is kept under partial control by natural in- 

 fluences, and therefore subject to extreme fluctuation in num- 

 bers, doing great damage for one or more seasons in some 

 localities, and remaining absent from them for a number of 

 succeeding years. 



The insect derives its name from the peculiar habit of its 

 larva of "looping" like a measuring worm, due to the lack of 

 legs on the third and fourth joints of the abdomen. The moth 

 which produces it is shown in figure 9, a. The "looper" is at 

 first a pale-green, fragile-looking creature, and varies in 

 color when mature, being strongly marked with white lines, 

 shown in figure 9, c. It constructs for pupation a white, gauzy 

 cocoon, d, which is usually attached to the broad surface of 

 a leaf. The cabbage looper is well distributed throughout that 

 part of the United States lying east of the Rocky Mountains, 

 and is more destructive in the South than in the northern States. 

 It is most troublesome to cabbage, but affects all crucifers and 

 at times does great injury to peas, beets, celery and lettuce, and 

 feeds also on tomato, potato and less frequently on asparagus 

 and clover. It sometimes does damage to carnation, mignonette, 

 and German ivy in greenhouses. 



The species is apparently three-brooded on Long Island and 

 in the District of Columbia, and hibernation takes place chiefly 

 in the pupal stage. Few individuals survive the winter north- 

 ward, but the propagation of the species is so rapid that by the 

 time autumn is reached great numbers of loopers are produced 

 which do much damage to crops in cultivation at this time. This 

 insect is very susceptible to diseases and to parasitism. A par- 

 asitized looper is shown by figure 94. 



Methods of Control employed for other cabbage worms are 

 useful against loopers. Remedial measures should be continued 

 with persistency at frequent intervals in order to insure sue- 



