TREE INSECTS AND THEIR CONTROL 189 



tic action on the tissues. The active elements in these 

 sprays are lime and sulphur compounds, soaps, petroleum 

 oils and tobacco extracts. Some of the sprays are: 



Lime-sulphur Creosote Oil 



Kerosene Miscible Oils 



Kerosene Emulsion 40 per cent. Nicotine Sulphate 



Fish-oil Soap. 



Lime-Sulphur. This is used against the armored 

 scale insects, such as the oyster-shell scale or the San Jose 

 scale. Its use is generally confined to the dormant season, 

 between late fall and early spring. It may be used as a 

 spray, or it may be spread on with a paint brush. The 

 chemicals discolor paint, and for this reason spraying 

 should be avoided where the paint on buildings will be 

 reached. The material, as purchased, must be diluted with 

 water before use, and directions as to dilution will usually 

 be found with each purchase. In general it may be said 

 that the lime-sulphur should be used in proportion of 1 

 pint to each gallon of water. 



Kerosene. Kerosene oil is effective in killing some in- 

 sects and in the destruction of eggs. It is applied by daub- 

 ing on the affected surface by means of a mop fastened to a 

 pole. Kerosene is also used to destroy tent or web caterpil- 

 lars by burning. For this purpose the mop is used as a torch 

 and held against the tent or web, with care to inflict the 

 least possible damage to the tree by the flames. 



Kerosene Emulsion. This is recognized as one of the 

 most effective sprays for contact uses. With variation 

 of the proportion of water, this spray may be used in 

 summer or winter. It is used for the destruction of scales 

 and soft-bodied insects. The emulsion is made of kero- 

 sene, soap and water, the soap being required to bring 

 about the mixing of the other ingredients. This mixture 

 may be made at home. The formula: 



