208 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



tality of 52% at the highest dosage, its further use was precluded because 

 of the severe injury to the plant. Kerosene nicotine oleate emulsion 

 gave varying results as far as mortality was concerned, but owing to 

 the greasy and objectionable condition in which the soil is left after 

 application, this material is ruled out. Sodiiim cyanide in the dry form 

 is also removed from consideration because in all the tests the plants were 

 killed in a very short time after application. Sodium cyanide in solu- 

 tion gave appreciable killing (77%) but as with the dry material its 

 severe injury to the plant caused it to be eliminated. In the trials of 

 paradichlorobenzene excellent kilhng of both larvae and pupae resulted, 

 but in practical tests it was found that the rose plants do not tolerate 

 this substance. 



In summing up these soil experiments it is seen that most materials 

 gave negative results, either because of the plant intolerance or the 

 ineffectiveness against the insect. It is thought that further tests 

 of the tobacco dust and wood ashes may form a basis for the successful 

 control of the soil stages. 



Experiments in Control of Adults 



Spraying: In the preliminary account^ it was pointed out that under 

 the usual growing conditions the use of arsenicals sprayed on the 

 rose plants has been found to be impractical, ineffective, and objec- 

 tionable. It is impractical because the forcing of the plants causes 

 considerable new growth to push forth overnight which necessitates 

 constant and almost daily spraying to keep all of the foliage covered 

 with the poison; it is ineffective because it was found that the beetles 

 avoided the sprayed portions in their feeding; and objectionable be- 

 cause of the whitish deposit left on the foliage. 



There is, however, one phase in the culture of roses when the use of 

 an arsenical as a spray has been proven to be effective. When the 

 rose plants are "cut back" practically all the foliage is removed and the 

 fresh growth develops from new buds. The absence of foliage forces 

 the beetles to feed on the green bark as well as the swelling and breaking 

 "eyes" or buds, causing serious retardation of the growth. By spray- 

 ing the stems and swelling buds with 4 to 5 pounds powdered arsenate 

 of lead, or calcium arsenate, to 05 gallons of water, the plants in several 

 infested rose houses passed this critical stage during the past summer 

 with almost no injury by the beetles. 



Dusting: Experiments with powdered arsenate of lead, one part 

 mixed with nine parts of superfine sulfur, have been carried on during 



^Loc. cit 



