MEASURES FOR INSECT CONTROL 319 



For exact preparation the use of the hydrometer is desir- 

 able and the following scale of proportions is recommended. 



Reading on hydrometer Number of gallons of water to 1 gallon 



in degrees (Baum6). of the concentrated lime-sulphur. 



35 9 



34 8f 



33 8i 



32 8 



31 7h 



30 7i 



29 6f 



2S 6^ 



27 6 



2(i 5f 



25 5i 



24 5 



23 4j 



22 4i 



21 3f 



20 3i 



19 3i 



18 3 



17 2| 



16 2| 



15 2i 



14 2 



Reijular Lime-sulphur Wash (for winter spray). 



Lump lime 20 pounds 



Sulphur 12 pounds 



Water 50 gallons 



Kerosene. — The use of kerosene or petroleum combinations 

 has o;i\'en some of the most useful combinations and they 

 still have a wide range of usefulness, although at present 

 less used than the lime-sulphur solutions for scale insects. 

 Generally they may be applied to practically all kinds of 

 insects which are suctorial in habit and cannot be reached 

 by arsenical sprays, but they are especially efficient against 

 the scale insects at time of migration and against such soft- 

 bodied insects as the plant lice. In the preparation of the 

 kerosene emulsion it is extremely important that a thorough 

 emulsion be obtained so there will be no separation of oil 

 from the water, as there is much damage to the foliage if 

 this occurs. 



