BULLETIN OF THE 



D 



No. 165 



Contribution from the Bureau of Entomology, L. O, Howard, Chief 

 December 31, 1914. 



(PROFESSIONAL PAPER.) 



QUASSIIN AS A CONTACT INSECTICIDE. 



By William B. Parker, 

 Entomological Assistant, Bureau of Entomology } 



INTRODUCTION. 



Quassia chips, the active principle of which is quassiin, have been 

 employed for many years in the preparation of spray solutions for the 

 control of the hop aphis (Phorodon liumuli Schr.). Several formulas 

 have been followed, and there are .several methods of preparation 

 according to these formulas. Several factors have brought about the 

 variations in the formulas, (1 ) instability in the percentage of quassiin 

 in the chips, (2) the total amount of available quassiin in the chips 

 probably not extracted, due to the method of preparation, and (3) 

 the fact that there appeared to be no fundamental data accumulated 

 on this subject. The writer accordingly commenced the investiga- 

 tion, which has been taken up from an insecticidal standpoint, and 

 any chemistry that is mentioned other than very simple matters is 

 taken from the various sources. Acknowledgments are due to Prof. 

 George P. Grey, of Berkeley, Cal., and Mr. G. H. P. Leichthardt, of 

 Sacramento, Cal., for valuable suggestions, and to Mr. R. E. Camp- 

 bell, of the Bureau of Entomology, who ably assisted the writer in 

 determining the efficiency of the several formulas. 



During the investigation of the life history and control of the hop 

 aphis 2 it was observed that there were several formulas for the use 

 of quassia chips. These all appeared to give satisfactory results 

 when carefully prepared and applied, but it will be observed from 

 the following formulas that if the weaker one killed the aphides, the 

 use of the stronger one resulted in a waste of material and extra 

 expense. 



1 Resigned August 31, 1914. 



2 Parker, Wm. B., The Hop Aphis in the Pacific Region. U. S. Dept. Agr., Bur. Ent. Bui. Ill, 39 p., 

 8 fig., 10 pi., May 6, 1913. 



Note. — The results of an investigation to determine the most suitable solution of quassiin for use as a spray 

 for the control of the hop aphis are discussed in this bulletin. 

 67215°— 14 



