10 



many of the insects on the lower surface of the curled leaves will not 

 be hit by the spray. Repeated applications nuist be made, therefore, 

 as necessary to keep the insects under control. It will often be 

 found practicable to bend over and immerse the terminal shoots of 

 badly infested young trees in a bucket of the spray solution, and ^his 

 treatment will be very effective. 



Spray mixtures. — The lime-sulphur wash for the destruction of win- 

 ter eggs is made according to the usual fornnila for the wash, namely, 

 lime 20 pounds, sulphur 16 pounds, water to make 50 gallons, and 

 boiled for one hour. 



After the trees are in foliage, a more dilute contact insecticide must 

 be emplo37ed, as strong tobacco decoction, 15 or 20 per cent kerosene 

 emulsion, 15 per cent crude petroleum emulsion, or whale-oil soap at 

 the rate of 1 pound for each 4 gallons of water. Since aphides secure 

 their food by sucking up sap from within the j^lant, none of the 

 arsenical poisons would be effective. 



Tobacco decoction may be made from tobacco stems and other 

 refuse tobacco by boiling at the rate of 1 pound for each 1 or 2 gal- 

 lons of water, sufficient water being added to make up for that lost in 

 boiling. 



A 20 per cent kerosene or crude petroleum emulsion is made as 

 follows: 



Whale-oil or other soap pounds. . 2\ 



Kerosene or crude petroleum gallons. . 10 



Water to make gallons . . 50 



The soap is dissolved in 5 gallons of hot water, which is at once 

 poured into the spray-pump barrel. The 10 gallons of kerosene or 

 crude petroleum is next added and the whole thoroughly emulsiiied 

 by pumping it back through the hose into the barrel for 6 or 8 min- 

 utes. After the oil has become thoroughly emulsified, the barrel is 

 filled with water, and the preparation is ready for use. When a less 

 amount of emulsion is desired than the quantity above indicated, it 

 may be reduced as desired by observing the proportions given. 



Approved : 



James Wilson, 



Secretary of Agriculture. 



Washington, D. C. , December 18., 1906. 



LCir. 81] 



o 



