PRESERVATIVES AND MATERIALS 209 



in composition according to the insect pests 

 against whose ravages they are to be applied. 

 The Woburn wash is excellent for the 

 American blight, while aphides of most kinds 

 are quickly destroyed by paraffin emulsion in 

 the proportion of one pint of emulsion to six 

 gallons of water. 



Then many of the advertised insecticides 

 are most useful, but it would be invidious to 

 mention names. Kerosene emulsion for cater- 

 pillars and aphides has few equals, and is readily 

 obtained from nurserymen in a compound of 

 paraffin and soft soap, to which only water 

 requires to be added. Paris green, in the 

 proportion of an ounce of the paste or powder 

 to the same weight of lime and ten gallons of 

 water, is a valuable insecticide. London purple, 

 like the latter, is valuable for spraying fruit 

 trees. Tobacco is also a most effective poison 

 to aphis and other insects, but requires careful 

 handling. 



