174 TREES IN" WINTER 



CHAPTER X 

 INSECTICIDES, FUNGICIDES, AND SPRAYING. 

 INSECTICIDES. 

 The reader will understand by this time that there must be two 

 distinct types of insecticides: stomach poisons and contact insecti- 

 cides. There are a great many belonging to each class. A large 

 number of them are superfluous, and to avoid confusion, only 

 those that are necessary and in common use are discussed here. 



Stomach Poisons — The stomach poisons are those that kill 

 by being eaten, and are used for the control of insects that chew 

 their food. The most common stomach poisons are arsenate of 

 lead and Pa^is green. The latter sometimes causes injury to the 

 foliage unless used in combination with lime. It is generally used 

 in the following proportion: 



Paris green 1 pound 



Fresh stone lime 1 pound 



Water 100 gallons 



The Paris green should be mixed first in a small quantity of 

 water to form a thin paste. The lime also should be slaked in a 

 small quantity of water. Both materials may then be strained 

 into the spray tank and the required amount of water added. 



Arsenate of lead, on account of its safeness, its sticking qualities, 

 and its general efficiency, has become the standard insecticide for 

 insects that chew their food. It may be made up at home, but 

 generally it is better to buy it ready prepared. It comes in either 

 paste or powder form. Most people prefer to buy the paste. 

 To prevent it from drying out, the paste should be kept covered 

 with water. It is generally used in the following proportion: 



Arsenate of lead paste 6 to 10 gallons 



Water 100 gallons 



The paste should be mixed up with about two quarts of water 

 and then strained into the tank. Some insects are harder to kill 

 than others and should receive the maximum amount. Most 

 forms, however, are readily killed by using six pounds to one 

 hundred gallons. 



