274 STATE HORTICULTURAL SOCIETY. 



rate of a pound to a few gallons of water; it will cling to the foliage 

 longer through heavy rains, and it is lighter in weight and will remain 

 more evenly mixed in the water than the other preparations. 



Arsenate of lead is not generally found in the drug stores, but the 

 preparation can be made as it is needed. Mr. Fernald gave us the first 

 report of it as an insecticide, and he says:* "A convenient way to prepare 

 this insecticide is to put 11 ounces of acetate of lead and four ounces of 

 arsenate of soda into a hogshead containing 150 gallons of water. These 

 substances quickly dissolve and form arsenate of lead, a fine, white pow- 

 der which remains in suspension in water. 



" It is highly desirable to add two quarts of glucose, or if that can not be 

 obtained, two quarts of molasses, to each 15<J gallons of water used, for the 

 purpose of causing the insecticide to adhere to the leaves. 



" The experiments with this insecticide both here and in Maiden last 

 summer indicate that it will remain on the trees for a long time, even after 

 quite heavy rains." 



In Mr. Fernald's experiments, and in other experiments following his, 

 one pound of the arsenate of lead to 150 gallons of water was found to be a 

 mixture too weak and slow to be effective on most insects. Mr, Marlatt 

 foundf in his experiments on the elm leaf beetle (Galeruca xmithomelcena) 

 that the arsenate of lead gave the best result at the rate of from 50 to 75 

 gallons of water for each pound. At the above rate this compound of 

 arsenic is more expensive than Paris green or London purple, but for cer- 

 tain insects on plants with tender foliage it is no doubt preferable to the 

 other two. 



KEROSENE EMULSION. 



This is a common and well-known remedy for soft-bodied insects that do 

 not feed by chewing, but suck the sap instead. The emulsion is cheap, 

 simple, and effectual. It is made of soap, kerosene, and water — three 

 ingredients that the farmer always has at his command. 



Soft Soap Formula. — Heat a gallon of soft soap until it becomes liquid, 

 then take from the fire, add two quarts of kerosene and agitate for three 

 or five minutes so thoroughly that the soap and oil will become perma- 

 nently mixed; that is, until the oil will not separate from the soap either 

 on standing or when diluted. A hand force pump should be used in mak- 

 ing the emulsion. Slow pumping or stirring with a stick or spoon will 

 not emulsify the soap and oil. 



The emulsion as made is now one third oil and, for the plants, it should 

 be only one fifteenth oil, so it will need four times its own bulk of water 

 before using. In other words, the gallon of soap and two quarts of oil 

 will make seven and one half gallons of the dilute emulsion. 



If the emulsion is to be made in the above or greater quantity, it should 

 always be made with soft soap, if that i^ obtainable, as the emulsion is 

 more difficult to make by the hard soap formula where more water is 

 required. 



Hard Soap Formula. — To two quarts of water add one fourth pound of 

 hard soap, heat to the boiling point, and when the soap is dissolved add 



the pint of kerosene and proceed as in the soft soap formula. This is one 



1 



* Boll. No. 24 of the Hatch Experiment Station of Massachasetts, p. 6. 

 t " Insect Life," Vol. VII, No. 2, p. 123. 



