24r2 Agrioultubal Experiment Station, Ithaca, N. Y. 



which it sucks its food, as does the Pear Psylla, the Squash-bug, Plant- 

 lice and all the other true bugs. As Dr. Lintner has said : " It is evi- 

 dent, therefore, that these insects, living as they do upon the sap of 

 plants, may not be destroyed by means of poisons applied to the sur- 

 face of the leaves. The delicately pointed sucker would penetrate the 

 poison even when thickly coating the leaf, without imbibing any por- 

 tion of it." Thus the application of Paris green, London purple or 

 any other poisonous subject would prove of no avail against the Four- 

 lined Leaf -bug. 



Some have thought that applications of dust, lime, ashes, soot, soap- 

 suds, tobacco water, carbolic acid washes, etc., might be effectual. 

 Dr. Lintner says, however, that they have on trial been found 

 ineffectual. Walsh and Riley thought that " the plant might be pro- 

 tected against their attacks by a proper use of cresylic acid soap." 

 Experiments have been reported in which a strong solution of this soap 

 was used upon a closely allied insect, the Tarnished Leaf -bug {Lygui 

 pratensis); it was entirely ineffectual and would doubtless prove use- 

 less against the Four-lined Leaf -bug. 



The only insecticide with which we have experimented against 

 this pest is kerosene emulsion, the cheapest and most effectual 

 insecticide yet found for sucking insects.* In June, 1892, an 

 adult was sprayed with the emulsion diluted with twenty-five 

 parts of water. The insect dexterously wiped off with its hind leg 

 a large drop which had accumulated on its back and went its way 

 uninjured. Several adults were then sprayed, care being taken to wet 

 them all over, with the emulsion diluted but five times; 'some of them 

 seemed " sea sick " for a few minutes but in an hour all were as lively 

 as ever. Adults sprayed with the emulsion diluted with three parts of 

 water were nearly all dead the next morning. Undiluted kerosene 

 killed them in a minute or two. 



* To make the emulsion thoroughly dissolve one-half pound hard or soft 

 soap in one gallon of boiling water. While this solution is still very hot add 

 two gallons of kerosene and (juickly begin to agitate the whole mass through 

 a syringe or force pump, drawing the liquid into the pump and forcing it 

 back into the dish. Continue this for five minutes or until the whole mass 

 assumes a creamy color and consistency which will adhere to the sides of the 

 vessel and not glide off like oil. It may now be readily diluted with cold 

 rain water, or the whole mass may be allowed to cool when it has a semi- 

 solid, form, not unlike loppered milk. This standard emulsion if covered 

 and placed in a cool, dark place will keep for a long time. In making a 

 dilution from this cold emulsion it is necessary to dissolve the amount required 

 in three or four parts of boiUng water, after which cold rain water'may be 

 added in the required quantities. 



