402 ANNUAL. REPORT OF THE Off. Doc. 



A Member: Don't that application luu-t the foliage of the tree? 



PROF. SURFACE: It will, if continued frequently, but if applied 

 only once or twice in a season, it will not. 1 have tried it on deli- 

 cate plants this year. I have tried it one pound to two gallons of 

 water and killed lice on rose bushes this summer. 



For the chewing insects, the chief remedy is Paris green, but 

 there is one that is better. This is the arsenite of lime. It is the 

 cheapest and most effective and the easiest to apply, because it does 

 not require stirring. It is the best all around poisonous insecticide. 

 This is made by boiling white arsenic in two parts of water. Take 

 half a pound of white arsenic, two parts of sal-soda and two parts 

 of water and boil until the w^hite arsenic is dissolved; then use only 

 one pint of this solution with 50 gallons of water, and two pounds 

 of freshly slacked lime, and you will find it is more effective than 

 Paris green. It has the advantage of not requiring stirring like 

 other applications that are merely mechanical mixtures instead of 

 solutions. 



A Member: Does it stay on the leaf any longer than Paris green? 



PROF. SURFACE: I think it does, and has been found more 

 effective for codling moth, etc. 



A Member: Can it be used in a dry form? 



PROF. SURFACE: It can. I have been thinking of experiment- 

 ing with it. The Missouri Experiment Station has shown good re- 

 sults from dust spraying. I am able to do some experimental work 

 of that kind, and shall take the pains to make the experiment. 



I am asked to repeat the formula : 



One-half pound of w'hite arsenic and tvv^o pounds of sal-soda boiled 

 in two parts of w^ater until the arsenic is dissolved. Then you will 

 have a solution. Whenever you want to use it take one pint of that 

 solution to two pounds of freshly slaked quick lime and 50 gallons 

 of water. 



A Member: Have you ever tried a strong solution of lime water 

 and letting it clear? 



PROF. SURFACE: No, sir; In all cases where we are to use a 

 spray with lime, we must strain the lime after it is slaked and as 

 it is poured into the water. The clear lime water Avonld not have 

 the effect, but if strained through a cloth like cheese-cloth it will 

 not clog the apparatus. 



A Member: Does it make any difference whether the water is 

 hard or soft? 



PROF. SURFACE: Yes, sir; in making up most insecticides soft 

 water or rain water is essential. 



