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 
Kerosene 
Kerosene Emulsion 
Creosote Oil 
Miscible Oils 
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: 
