Eighth Report of the State Entomologist. 209 



How to Kill the Aphis. 



The best insecticide for use is believed to be kerosene emulsion, pre- 

 pared after the formula which has been so often given in leading 

 agricultural journals. 



The emulsion is made as follows: Take of kerosene, two gallons.; 

 common soap, a half-pound; water, one gallon. Dissolve the soap in the 

 boiling water, and, after removing from the fire and while yet boiling, 

 add the kerosene, emulsifying the mixture by pumping it through 

 a force pump with a spray nozzle into the same vessel until it assumes 

 the appearance of thick cream and the oil does not rise to the surface. 



For ordinary use, on trees, etc., dilute the above mixture with nine 

 parts of water. 



For the hop- vine aphis one part of the emulsion to twenty-five of 

 water should be used, as a greater strength is liable to blacken and 

 injure the leaves. 



Properly applied, by spraying with a suitable force pump through a 

 fine nozzle, it will not fail of killing every aphis with which it comes 

 in contact. It is all important that it be applied so as to bring it in 

 contact with each insect, as it kills only by this means, and not, as do 

 the arsenical mixtures, by depositing the poison on the leaves to be 

 subsequently eaten by the insects. All plant-lice are sucking insects, 

 feeding only on the sap of the vegetation that they infest. 



As the kerosene emulsion requires some labor in its preparation, pos- 

 sibly some of our hop-groAvers would prefer to use the hop wash which, 

 for a long term of years, has been successfully used by the English 

 hop-growers, and we accordingly give the formula for it: 



One hundred gallons of water (if hard water, with soda added). 



Four to five pounds of soft soap. 



Six to eight pounds of quassia chips, first steeped in cold water and 

 afterwards steamed or boiled. 



The eflicacy of this washing has been clearly demonstrated. Hop- 

 growers who have sprayed with it in England have grown «rops of 

 700 to 900 pounds per acre, while those not using it grew nothing, or 

 next to nothing. 



Repeat Spraying as Often as Necessary. 

 As the plum tree brood does not migrate en masse at the same time, 

 a second spraying should follow the first in a few days thereafter. 

 Watch should be kept for the advent of newcomers, either through 

 flight or by reproduction, as the new broods occur at intervals of a few 

 daj^s, and are therefore frequent during the season. The spraving 

 should be repeated as often as is necessary to prevent the multiplication 

 which wotild otherwise destroy the crop. 

 27 



