INSECTS AFFECTING MAN AND ANIMALS 213 



time for starving out the young ticks in different latitudes 

 and at different seasons have been quite carefully deter- 

 mined, so that it is possible to proceed to eradicate the ticks 

 from large areas at very small cost (see 36). For destroy- 

 ing the ticks the cattle are washed, sprayed or dipped in 

 crude oil emulsion or arsenical dip. Dipping is much the 

 most satisfactory and is the method usually adopted for 

 herds of any size. The crude oil emulsion is made like kero 

 sene emulsion, using one p:und of hard soap, one gallon of 

 soft water and four gallons of crude Beaumont petroleum for 

 making the stock solution and then diluting it to make an 

 emulsion containing 20 or 25 per cent of oil. The arsenical 

 dip is made by the following formula: 



Sodium carbonate (sal soda) 24 pounds 



Arsenic trioxide (white arsenic) .... 8 ' ' 



Pine tar 1 gallon 



Water sufficient to make 500 gallons. 



For further necessary details of dipping see reference 36 

 (p. 340) 



