338 The Principles of Fruit-growing 



arsenic oxid. In the best grades of arsenate of lead paste the chemi- 

 cal is in a finely divided condition, and thus when diluted for use 

 remains in suspension for a considerable time. Arsenate of lead is 

 used at various strengths, depending upon the insect to be killed and 

 on the susceptibihty of the foliage to injury. Four poimds in one 

 hundred gallons can be used on the peach if combined with the seK- 

 boiled lime-sulfur; on apple, four to five pounds in one hundred gal- 

 lons is usually sufficient; on grapes for killing the grape root-worm 

 beetles and the rose-chafer, eight to ten pounds in one hundred 

 gallons have been found necessary. The poison is more readily eaten 

 by these beetles if sweetened by two gallons of molasses in one hun- 

 dred gallons; but, unfortunately, the addition of molasses greatly 

 decreases the adhesiveness of the poison. Some species of fruit flies 

 may be controlled by the use of sweetened arsenate of lead sprayed 

 on the fohage of the plants at the first appearance of the flies. They 

 lap up the poison with their fleshy tongue-Hke mouth-parts and suc- 

 cumb before ovipositing. 



Hellebore is a poisoning insecticide of recognized standing. It is 

 a light brown powder made from the roots of the white hellebore 

 plant (yeiratrum album), one of the hly famUy. It is applied both 

 dry and in water. In the dry state, it is usually apphed without dilu- 

 tion, although the addition of a little flour will render it more adhe- 

 sive. In water, four ounces of the poison is mixed with two or three 

 gallons, and an ounce of glue, or thin 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 should be used in place of them upon ripening 

 fruit. It is used for various leaf-eating insects, particularly for the 

 currant-worm and rose-slug. 



Of the contact insecticides, the most important for the fruit- 

 grower are soaps, kerosene emulsion, hme-sulfur solution and 

 tobacco preparations. 



Soaps. — The most commonly used soap solution is that pre- 

 pared from fish-oil soap. The commercial brands of this soap are 

 usually by-products and contain many impurities; further, many of 

 them contain an excess of free or uncombined alkali, and are thus 

 likely to injure young and tender foliage. A good fish-oil soap may 

 be prepared by the following formula: Caustic soda, six pounds; 

 water, one and one-half gallons; fish-oil, twenty-two pounds. Dissolve 



