EXPERIMENT STATION BULLETINS. 599 



of half-inch gas-pipe and send the stream of liquid through the gas-pipe. 

 At least fifteen feet of hose should be allowed in order to re^ch all parts 

 of the tree. 



Never spray a tree when in bloom, it may kill bees, both wild and 

 hive-bees. 



Stone fruits require especially careful treatment; they are easily in- 

 jured by sprays not properly mixed or prepared. 



INTERNAL POISONS FOR INSECTS THAT CHEW. 



PARIS-GREEN. 



At the head of all the stomach poisons stands Paris-green or arsenite 

 of copper. To prepare Paris-green for spraying, slake one pound of well- 

 burned quick-lime in hot water and stir in one pound of Paris-green. 

 Allow this mixture to stand over night, strain, and then stir it into from 

 150 to 250 gallons of water. Keep the liquid well stirred while spraying. 

 For most insects, one pound to 200 gallons of water is sufficient, and at 

 this rate it will not injure the plant. Stone fruits, such as peach, plum and 

 cherry, should not receive a spray much stronger than this, but apples, 

 pears, etc., may be sprayed with a mixture considerably stronger, viz.: 

 one pound to 150 gallons of water. Potatoes may be sprayed with one 

 pound to 100 gallons of water. Paris-green is fairly uniform in compo- 

 sition if not adulterated, and is perhaps the safest and surest remedy for 

 chewing insects as a whole. 



LONDON-PURPLE. 



Next to Paris-green comes London-purple, which is used in the same 

 way, except that twice as much lime should be mixed with it. Its effect 

 is a good deal the same, though it is far more variable in composition 

 and more likely to burn the foliage; it should never be used without lime. 



DRY METHOD. 



While ordinarily it is most economical to use Paris-green in the form 

 of a spray, in some instances, where only a few plants are to be treated 

 or where no pump is available, it is expedient to use it as a dry powder. 

 It should then be mixed at the rate of one pound of the poison to 100 

 pounds of plaster, flour, or air-slaked lime, and dusted on the plants 

 through a sack of burlaps or some loose, coarse cloth. It is best to make 

 the application in the morning when the dew is on the plants. Never 

 apply dry poisons where the wind can blow the powder into pastures or 

 places where cattle or horses are feeding. 



ARSENITE OF LEAD 



This poison, although not in general use throughout the country, has 

 several advantages; it shows where it has been applied; it is light and 

 does not require such vigorous stirring as Paris-green; it does not easily 



