40 



In boxes lime was nearly as efficacious as emulsion, and so also was 

 salt; however, to do good execution, salt must be applied in quantity 

 sufficient to injure the soil. I think there is no doubt but these insects 

 can be easily destroyed if they can be reached, but how to reach them 

 under the soil is the question. Their large, soft bodies are very sus- 

 ceptible to injury. 



PYKETHRr3I. 



This powder was purchased from a local wholesale dealer, and to all 

 appearances was of high grade. It was used in various tests to experi- 

 ment on its use, and as a check on other substances it was used in all 

 tests of whatever nature. 



On Cabbage Worms. 



My earlier experiments lead me to believe that brassicce was much 

 harder to destroy than rapce, and this I still believe to be the case to 

 some extent, but not to such an extent as at first supposed. Quite a 

 large series of tests were made in the field and also in jars and cages to 

 test the above supposition, the result in the main being very satis- 

 factory. Pure and up to 3 dilutions it killed rapce with a precision 

 and certainty that was remarkable, the powder after the 3 dilutions 

 acting nearly as well as if stronger. The time required was varia- 

 ble, but usually the worms were well used up in two hours. Above 3 

 dilutions its action was uncertain and not to be depended upon, although 

 5 dilutions will kill a fair percentage if thoroughly applied. With bras- 

 sicce the results were quite similar up to 3 dilutions. A large quantity 

 of powder was used of this strength on these worms after rapce had 

 nearly disappeared. It was very effective, killing fully 90 per cent, 

 of all worms, although the time required is somewhat longer than with 

 rapce- Above 3 dilutions it is not efficacious on brassicce, killiug 

 scarcely any, and from the whole experience of my experiments I am 

 satisfied that 3 dilutions are all that can safely be made for out-door 

 work. 



In Jars. — A large number of tests were made in jars, with very minute 

 quantities of powder on both worms. Jars were covered. These were 

 very successful, causing death in from forty minutes to two hours. The 

 only exception to this was a full-grown larva of brassicce. In this test 

 dilutions up to twenty times the weight of powder were quite efficacious 

 on rapce, but a few of the last did not destroy brassicce with certainty. 



This series was also repeated in breeding cages with, in the main, 

 corroboratory results. After 5 dilutions its action on brassicce was 

 quite uncertain, depending somewhat upon the amount used; 15 dilu- 

 tions would not kill them at all under any method of treatment. Rapce 

 was killed up to 20 dilutions if thoroughly applied, although in such 

 cases they were more severely treated than would be possible with 

 powder bellows in field work. Experiments with minute portions of 



