56 NEW YORK STATE MUSEUM 



elm leaf beetle, use i pound of the poison to 100 gallons of water. The 

 addition of lime is not necessary, specially with paris green, but is a wise 

 precaution as it neutralizes any free arsenic acid and thus prevents 

 burning of the foliage. 



Another substance which has received high praise and may come into 

 general use after its good qualities become better known, is the arsenate 

 of lead. The value of this compound as an insecticide has been brought 

 out by numerous experiments, made in the extensive work against the 

 gypsy moth. One advantage is that it can be applied in very large 

 quantities without injuring the foliage. When properly prepared, it 

 remains for some time suspended in the water, imparting a milky color, 

 and also adheres to the lisaves much longer than either paris green or 

 london purple, and it promises to be of special value against the elm 

 leaf beetle on this account. Its whiteness is another advantage, because 

 of which, it is readily detected upon green foliage. 



In order to obtain the best results, the poison should be prepared just 

 before using, by dissolving 1 1 ounces of acetate of lead (sugar of lead) 

 in 4 quarts of water in a wooden pail, and 4 ounces of arsenate of soda 

 (50%) in 2 quarts of water in another wooden pail. As the acetate or 

 sugar of lead dissolves rather slowly in cold water, the process can be 

 hastened by using warm water. The resulting solutions should then be 

 poured into the spraying tank containing enough watfer to give the 

 desired proportions. In most cases this will mean turning them into 100 

 or 150 gallons of water, or but 80 gallons of water when spraying for the 

 elm leaf beetles, though some recommend a larger proportion of the 

 poison, and the same amounts to 100 gallons will kill the grubs. 



Contact insecticides. These are substances which kill insects by 

 contact and affect only those individuals touched. They are used 

 against the elm bark louse, the woolly scale of the maple and other suck- 

 ing insects 



Kerosene emulsion is one of the principal contact insecticides and is 

 prepared by dissolving ^ pound of hard soap in i gallon of boiling 

 water and while it is still hot add 2 gallons of kerosene and emulsify by 

 passing it rapidly through a force pump and back into the vessel till it 

 assumes a creamy consistency and oil does not rise to the surface. 

 Dilute with 9 to 15 parts of water and spray the young lice as they 

 appear in the summer. In limestone regions where hard water is the 

 rule, better results will probably be obtained by using the sour milk 

 emulsion, which is composed of 2 gallons of kerosene and i gallon of 

 sour milk emulsified by churning or passing through a pump. A 

 mechanical mixture of the two may be used, if desired, with machines 



