464 Report of the Entomologists of the 



was evident that spraying would not be a success and so dipping 

 the infested trees in a solution of whale oil soap and water was 

 resorted to. It might at first seem that this method would be 

 impractical because of the time and labor involved, but it should 

 be remembered that the lice appear on comparatively few trees 

 first, others becoming infested from these later in the season, and 

 hence if they are successfully treated more serious injury by the 

 lice may be prevented. 



All of the trees used in the experiments were seedlings, one- 

 year-olds and two-year-olds. As the lice were congregated on the 

 leaves at the tips it was necessary to wet only this portion of the 

 tree. The dipping of the stock was found to be a very simple 

 matter. Three or four men carrying pails filled with the solution 

 passed through the blocks and, picking out the infested trees, 

 bent them over carefully and dipped their tips into the solution, 

 taking care to hold them long enough to wet all of the lice. It 

 was found unnecessary to spend more than two minutes to a tree. 



Experiments. — About a thousand trees were used in experi- 

 ments, which for convenience may be divided into six blocks. 

 Blocks I and II were sweet cherries badly infested with the black 

 cherry aphis, Myzus cerasi. Blocks III and IV were apples also 

 badly infested, but w-ith the apple aphis, Aphis mail. Blocks V 

 and VI were standard pears infested with a species of plant lice. 

 Aphis sp. Blocks I, III and V were treated the same day, a bright, 

 warm day about the middle of July, with a solution of whale oil 

 soap, 1 pound to 3 gallons of water. Blocks II, IV and VI were 

 treated within tw'O days of this time, under practically the same 

 weather conditions, with a solution of whale oil soap, 1 pound 

 to 7 gallons of water. But one application was. made in each 

 case. 



Results. — In nearly every case where the stronger soap solu- 

 tion, 1 pound to 3 gallons, was used, the leaves were more or less 

 injured. The pears were injured most while there was not much 

 difference between the apples and cherries. So far as could be 

 ascertained, all of the lice on these trees were killed. The- weaker 

 solution, 1 pound to 7 gallons, did not injure the foliage in any 



