14 MANUAL OF VEGETABLE-GARDEN INSECTS 



stage. In the northern states there are two or three broods 

 annually, which overlap to a considerable extent, but in the 

 tropics breeding is almost continuous. In Colorado there are 

 seven generations annually. On Long Island, larvae and moths 

 are often abundant on cauliflow^er until early December. The 

 insect is usually more destructive in dry seasons than when 

 rains are abundant. On cabbage the greatest injury is usually 

 inflicted early in the season while the plants are small, but in 

 the case of cauliflower the late broods are the most troublesome. 

 A closely related species, Phdella armor acia Busck, has been 

 reported as injurious to horse-radish in Colorado. Its habits 

 are similar to those of the diamond-back moth. 



Control. 



Experiments in Colorado have shown that the diamond- 

 back moth can be controlled by spraying with 2 pounds of 

 paris green and 6 pounds of soap in 100 gallons of water, or 

 arsenate of lead (paste), 8 pounds in 100 gallons. 



References 



Fitch, 1st Kept. State Ent. N. Y., pp. 170-175. 1856. 

 Carpenter, Rept. for 1901, pp. 144-147. 1902. 

 Quanjer, Tijds. Ent. 49, pp. 11-17. 1906. 

 Marsh, Jour. Agr. Research, 10, pp. 1-10. 1917. 



The Cross-Striped Cabbage Worm 



Evergestis rimosalis Guenee 



While widely distributed throughout the United States ex- 

 cept in the extreme north, the cross-striped cabbage worm is 

 most abundant and destructive in the southern states. Locally 

 in some years it often causes more injury than the imported 

 cabbage w^orm and its native relatives. The caterpillars 

 destroy the leaves in much the same way as the common cab- 



