1 88 TREES AS GOOD CITIZENS 



recognized standard preparations will give the best results. 

 It is poor economy to use a preparation because it may be 

 bought cheap, and it is unwise to experiment with one 

 which is unknown. 



The Stomach Poisons. The standard stomach poisons 

 are arsenate of lead and arsenate of lime (calcium 

 arsenate). Arsenate of lead is the one most used, because 

 it adheres to the foliage longer than any other stomach 

 poison, is highly effective, and does no damage to the 

 leaves when used in proper dilution. Both arsenate of 

 lead and arsenate of lime may be bought in paste or pow- 

 der form. The powder is to be preferred for the reason that 

 it is not injured by freezing or drying. These poisons are 

 ready for use when purchased, requiring only the addition 

 of water in proportions which will usually be found speci- 

 fied on the label of the container. 



If there is preference for preparing a poison at home 

 the formula for arsenate of lead is as follows: 



Acetate of lead 12 ounces 



Arsenate of soda 4 ounces 



Water 15 to 20 gallons 



Pour the acetate of lead into a half gallon of water and 

 the arsenate of soda into a similar quantity of water in a 

 separate vessel. The contents of the two vessels should 

 then be poured into a holder, containing from 15 to 20 

 gallons of water, and well mixed. 



Because of their poisonous nature, arsenate of lead and 

 arsenate of lime must be handled with care. Especial safe- 

 guards must be used to keep them away from children and 

 domestic animals. 



Contact Sprays. For the killing of sap-sucking in- 

 sects the contact sprays are required. These materials 

 cause death to the insects by coating and clogging the 

 breathing pores, by direct action on the nerves, or by caus- 



