13 



Spraying with Arsenical Insecticides. 



Sprajang with some arsenical is now recognized as the best means 

 of controlling the codling moth. The object, as noted elsewhere, is 

 to poison the young larvae before they enter the fruit. The larvae get 

 the poison while feeding on the leaves, or in the calyx, or on the sides 

 of the fruit, and are killed. There are several of the arsenical com- 

 pounds upon the market, and others which the fruit grower can pre- 

 pare himself. The most available and best are described below. 



Paris green. — Paris green is probably the best known of these arsen- 

 icals. It is a definite chemical compound of arsenic, copper, and acetic 

 acid, and should have a uniform composition. It is a rather coarse 

 powder, and has the fault of settling rapidly. It costs about 20 cents 

 a pound, but varies in price from year to year with the fluctuation 

 in the cost of the ingredients. It may be prepared for spraying as 

 follows: 



Paris green pounds . . 1 



Lime do 3 



Water gallons. . 150 



The lime should be fresh and should be slaked in quantities as 

 required. Mix the Paris green with a little water until a paste is 

 formed, and then add this to the required amount of water, to which 

 the lime has been added. A good average strength to use is 1 pound 

 to 150 gallons, but it must be weaker on trees with delicate foliage. 

 Many fruit growers are using it on apple trees as strong as 1 pound 

 to 100 gallons, but injury to foliage often results. 



Scheele's green, — Scheele's green is similar to Paris green, but dif- 

 fers from it in lacking the acetic acid. It is a much linei- powder 

 than Paris green and more easily kept in suspension, and it costs 

 only about one-half as much. It is employed in the same wa}^ as 

 Paris green. 



Arsenate of lime with soda. — In the preparation of this insecticide 

 the following formula may be used: 



White arsenic pounds. . 1 



Sal soda (crystal) do 4 



Water gallons. . 1 



The above ingredients are boiled until dissolved, which will be in 

 a very few minutes, and the water lost by evaporation is then replaced. 

 To 40 or 50 gallons of water a pint of this stock solution and 3 to 4 

 pounds of freshly slaked lime are added. This excess of lime is 

 always desired by fruit growers, as they can then see by the amount 

 and distribution of the lime on the foliage how well the spraying 

 has been done. This formula has been thoroughly tested and has 

 been found to be not only as efficient as the other solution, but far 

 cheaper. 



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