INSECTS AND INSECTICIDES 373 



4 ounces of the poison are mixed with 2 or 3 gallons, and an 

 ounce of glue, or tliin flour paste, is sometimes added to make 

 it adhere. A decoction is made by using boiling water in the 

 same proportions. Hellebore soon loses its strength, and a 

 fresh article should always be demanded. It is much less 

 poisonous than the arsenicals, and, therefore, may be used on 

 vegetables soon to be eaten. It is of especial value in the home 

 garden. 



Soaps. 



Soap solutions are often used as contact insecticides for 

 killing plant-lice and other small, soft-bodied insects. The 

 so-called whale-oil or fish-oil soaps are most widely used for 

 this purpose. The commercial brands are usually by-products 

 and contain many impurities ; furthermore, many of them 

 contain an excess of free or uncombined alkali and are con- 

 sequently very likely to injure young and tender foliage. An 

 excellent fish-oil soap may be easily prepared at home by the 

 following formula : 



Caustic soda 6 pounds 



Water i gallon 



Fish-oil 22 pounds 



Completely dissolve the caustic soda in the water, and then 

 add the fish-oil very 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. 



Sulfur. 



Sulfur is commonly sold in two forms, — flowers of sulfur 

 and flour of sulfur. Flowers of sulfur or sublimed sulfur is a 

 fine, impalpable yellow powder insoluble in water, and is 

 formed by condensing sulfur vapor in a large chamber of brick 



