90 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



A Preliminary Report of Dusting for Control^ 



The traction duster has been used the past season in an attempt to 

 control the grape leaf hopper. A 2% nicotine dust was used with both 

 Bordeaux and lime. Applications on different plots varied at the rate 

 of from 20 to 75 pounds per acre and it was only at the rate of 60 pounds 

 per acre or more that a decided killing of both adult and nymphal stages 

 was secured. Scarcely a live hopper could be found in some plots and 

 dead leaf hoppers were observed in great abundance under the vines. 

 On other plots treated on the following evening with apparently the 

 same material and the same amount there was only a small per cent 

 of kilHng. For this reason it is very hard to state what condition caused 

 the killing. The different results obtained may be due entirely to the 

 temperature and humidity conditions and there may have been a dif- 

 ference in the percentage of nicotine in the mixture. 



Although a large amount of experimentation will be necessary to 

 determine the conditions of killing, the interesting fact is that an eco- 

 nomic control has been obtained by the dust on some plots. 



President George A. Dean. The next paper is " Derris as a Promis- 

 ing Insecticide," by R. W. Wells, F. C. Bishopp, and E. W. Laake. 



DERRIS AS A PROMISING INSECTICIDE^ 



By R. W. Wells, F. C. Bishopp and E. W. Laake, 



United States Bureau of Entomology 



There is a distinct demand for an insecticide for use on domestic 

 animals which can be applied in the dry or dust form and be depended 

 upon to give satisfactory control. This is especially true in regard to 

 the control of lice on live stock. The various species of lice seldom 

 become sufficiently numerous to be of marked importance as parasites, 

 except during the winter when the conditions are least favorable for the 

 application of liquids. In an effort to meet this need the authors and 

 their associates have tested a considerable nimaber of dry insecticides 

 under varying conditions and against various external parasites. 

 Among the substances tested was powdered derris. The insecticidal 

 properties of this material were brought to the attention of American 

 entomologists by Messrs. N. E. Mclndoo, A. F. Sievers, and W. S. 

 Abbott.^ As shown by these authors this material has some promise 

 both as a contact and as a stomach poison for insects. 



'All materials used in the trial were furnished by the Niag ara Sprayer Co. through 

 the kindness of Mr. F. J. Sutton. 



^Published by permission of the Chief of the Bureau of Entomology. 



^Derris as an insecticide, Journal of Agr. Research, vol. 17, No 5, pp. 177 — 200, 

 August 15, 1919. 



