New Yoke Ageictjltueal Expeeiment Station. 395 



A second application was made September 17. At this time 

 Paris green was added to. the Bordeaux mixture used on Plat 2. 

 No attempt was made to respray the lower outside leaves as they 

 were still protected by the material applied the first time. Exam- 

 ination of the work on September 21 showed that on Plats 1 and 



3 all the cabbage worms, as well as the loopers, had disappeared. 

 Many dead specimens of each were found. Many of the cabbage 

 worms had disappeared from Plat 2, but no dead specimens were 

 found here. They had apparently crawled away to pupate. 

 Plenty of living loopers were found on Plat 2. 



After two heavy rains the plats were re-examined September 

 29. Very little, if any, difference could be seen in the amount of 

 material still adhering to the plants of Plat 2, as compared with 

 Plats 1 and 3; but a marked difference could be seen in the plants 

 themselves. 10 The leaves of the plants on Plats 1 and 3 were 

 nearly perfect, while those on Plat 2 were completely riddled, as 

 were also those of the checks. 



Paris green and flour.— On September 1st the owner treated 



4 1-2 acres of the field with a mixture of dry Paris green and flour. 

 When examined, September 4, no dead cabbage loopers could be 

 found, but the treatment had disposed of a large number of the 

 cabbage worms. 11 



A final comparison of the tests was made October 19. On. 

 Plats 1 and 3 the cabbage had formed marketable heads, while 

 that of Plat 2 had made no better growth than the checks; in 



10 This indicates one of two conditions ; either there must be enough of the 

 resin lime mixture adhering to the under surface of leaves to kill the worms, 

 or there is an invisible film of the mixture on the upper surface holding Paris 

 green enough to do the required work. 



11 The cabbage looper is an active caterpillar and at the same time sensitive 

 about what it eats. If any foreign substance occurs on a leaf and the looper 

 can possibly find leaves that are clean it will not touch those that are cov- 

 ered with foreign substance. This habit probably accounts for the fact that 

 the looper was not killed by the treatment with Paris green and flour. Such 

 a mixture only adheres to the upper surface and in the folds of the leaves at 

 best, hence the looper is able to find food without feeding upon the treated 

 areas. 



