No. 4.] SHADE-TREE DSTSECT PROBLEM. 115 



theless it was the present state of the case, and the only way 

 of controlling' insects and other pests distributed impartially 

 on public and private grounds was by co-operation of the 

 public authorities and private owners. Unfortunate as this 

 conclusion may be, it is at all events the condition which 

 confronts us at the present time ; and we must work either on 

 that basis or work for a change of our laws that will recosr- 

 nize, perhaps, what we consider the law of "public nui- 

 sances," and obtain an application of that law to public pests. 

 Perhaps in that line we may look towards relief in the 

 future, if we do not have it at the present time. 



Mr. Kirkland has said, if I understood him correctly, that 

 one-half of the failures of spraying were due to not know- 

 ing how to apply the spray. I entirely agree with Mr. 

 Kirkland in that, and I would like to add that in my opinion 

 the other half of the failures in spraying are due to not 

 knowing how to make the material to put on. Anybody 

 who has tried to make up arsenate of lead from the chemi- 

 cals, and who has gone to a drug store and bought those 

 chemicals and run his risk of the adulteration, and has tried 

 to get arsenate of soda 96 or 98 per cent pure, and then 

 gone to work and tried to get it into a gallon of water in the 

 proper proportion, — by the time he has done that he is 

 generally a pretty thoroughly mixed up man the first time, 

 and sometimes a good many times thereafter. That is one 

 reason why Paris green remains in favor. Most men I find 

 start out with Paris green, and they say it is because the}' 

 have only to dump it into the water. They get mixed when 

 the} r try to prepare insecticides. The trouble is, w T e need 

 more or less of chemical training to keep us from dropping 

 into pitfalls. They are all about. I have never seen a man 

 that succeeded in making a kerosene emulsion, that was an 

 emulsion, the first time. For that reason I think we must 

 look for a fixed supply of definite insecticide materials ; and 

 I do not know but that it is the natural modesty of the 

 speaker who has just concluded, but it seems to me he has 

 left something unsaid. Mr. Kirkland could not speak from 

 his position as I am able to. I acknowledge the feeling that 

 we must have an insecticide which demands only the addi- 



