39 



salt. In this way compact, convenient packages of the insecti- 

 cide may be rapidly prepared. When desired for use the arsenate 

 of soda should be dissolved in a wooden tub, the acetate of lead 

 being dissolved in a separate tub. The two solutions are then 

 poured into the spraying tank and the arsenate of lead is ready 

 for use. The ingredients should never be dissolved in metallic 

 vessels. 



It is a good plan to first test the formula used, by mixing a trial 

 lot of arsenate of lead and allowing it to settle in the mixing tub. 

 A few drops of chromate of potash solution added to the clear 

 liquid which separates above the arsenate of lead should cause the 

 formation of a yellow precipitate. This indicates that an excess 

 of soluble lead is present and consequently that all the soluble 

 arsenic has been neutralized. A firm of manufacturing chemists, 

 located at Boston, has this year placed upon the market an excel- 

 lent brand of arsenate of lead in paste form, thus saving the delay 

 incident to the preparation of the insecticide. 



Kerosene Emulsion. This insecticide is prepared by dissolving 

 one-fourth pound hard soap in two quarts hot water and adding 

 to the soapsuds thus formed one gallon kerosene oil. The whole 

 is stirred or churned until cool, when a white, creamy emul- 

 sion is formed. This emulsion should be diluted with nine parts 

 of water. Kerosene emulsion kills by contact, and is a valuable 

 agent for killing the larvae and pupae of the elm-leaf beetle clus- 

 tered in the bark or in masses on the ground under the infested 

 trees. 



Useless Measures. 



In cases of extensive injury by the elm-leaf beetle, individuals 

 often spend in useless channels a large amount of energy which 

 intelligently applied would be productive of good results. Among 

 the more common mistakes are : — 



Tar Bands. — These serve to prevent damage by the canker 

 worm by intercepting the wingless female moth on her way up the 

 tree to deposit eggs. The female elm-leaf beetle flies into the 

 tree, hence these bands are valueless against this insect. 



Cotton Bands. — The considerations mentioned above apply to 

 cotton bands. 



Stdphur Plugs. — Nothing better illustrates the credulity of 

 mankind, than that sons of Belial still find victims who are willing 

 to pay for the plugging of trees with sulphur to ward off insect 

 damage. It is needless to say that this treatment is a swindle 

 pure and simple, and that money spent for this purpose is but 

 charity given to unworthy objects. 



