Contact Insecticides 339 



the caustic soda in the water and then add the fish-oil gradually under 

 constant and vigorous stirring. The combination occurs readily at 

 ordinary summer temperatures, and boiling is unnecessary. Stir 

 briskly for about twenty minutes after the last of the oil has been 

 added. There is now on the market a good brand of insecticide 

 soap prepared from cotton-seed oil soap-stock, or from an impure 

 grade known as pancoline. 



Kerosene emulsion is the oldest of our contact insecticides. It is 

 especially valuable for use against plant-lice and other small, soft- 

 bodied insects. It is prepared by the following formula: Soap, one- 

 half pound; water, one gallon; kerosene, two gallons. Dissolve the 

 soap in hot water; remove from the fire and, while still hot, add the 

 kerosene. Pump the liquid back into itself for five or ten minutes 

 or until it becomes a creamy mass. If properly made, the oil will not 

 separate on cooling. For use on dormant trees, dilute with five to 

 seven parts of water. For killing plant-lice on foliage, dilute with 

 ten to fifteen parts of water. Crude-oil emulsion is made in the 

 same way by substituting crude-oil in place of kerosene. The strength 

 of oil emulsions is frequently indicated by the percentage of oil in 

 the diluted liquid; for a 10 per cent emulsion, add seventeen gallons 

 of water to three gallons of stock emulsion; for a 15 per cent emulsion, 

 add ten and one-half gallons of water to three gallons of stock emul- 

 sion; for a 20 per cent emulsion, add seven gallons of water to three 

 gallons of stock emulsion; for a 25 per cent emulsion, add five gal- 

 lons of water to three gallons of stock emulsion. 



Lime-sulfur solution is both insecticide and fungicide. A solution 

 of lime-sulfur was first used as an insecticide in California in 1886. 

 It is now the standard remedy for blister-mite, San Jose scale and 

 similar scales, as well as an efficient fungicide. The lime-sulfur solu- 

 tion may be purchased in the concentrated form, or may be prepared 

 as follows: Lump lime (95 per cent calcium oxid), thirty-eight 

 pounds, or lump lime (90 per cent calcium oxid), forty pounds; sulfur, 

 eighty pounds; water, fifty gallons. Make a paste of the sulfur with 

 about ten gallons of hot water. Add the lime. As the lime slakes, 

 add hot water as necessary to prevent caking. When the lime has 

 slaked, add hot water to make fifty gallons and boil one hour, stirring 

 constantly. Water should be added from time to time to keep the 

 liquid up to fifty gallons. Store in air-tight hardwood barrels. Test 

 the strength of the solution with a Baum6 hydrometer, and dilute 

 for use according to the following table: 



